1PERLDIAG(1)            Perl Programmers Reference Guide            PERLDIAG(1)
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NAME

6       perldiag - various Perl diagnostics
7

DESCRIPTION

9       These messages are classified as follows (listed in increasing order of
10       desperation):
11
12           (W) A warning (optional).
13           (D) A deprecation (enabled by default).
14           (S) A severe warning (enabled by default).
15           (F) A fatal error (trappable).
16           (P) An internal error you should never see (trappable).
17           (X) A very fatal error (nontrappable).
18           (A) An alien error message (not generated by Perl).
19
20       The majority of messages from the first three classifications above (W,
21       D & S) can be controlled using the "warnings" pragma.
22
23       If a message can be controlled by the "warnings" pragma, its warning
24       category is included with the classification letter in the description
25       below.  E.g. "(W closed)" means a warning in the "closed" category.
26
27       Optional warnings are enabled by using the "warnings" pragma or the -w
28       and -W switches.  Warnings may be captured by setting $SIG{__WARN__} to
29       a reference to a routine that will be called on each warning instead of
30       printing it.  See perlvar.
31
32       Severe warnings are always enabled, unless they are explicitly disabled
33       with the "warnings" pragma or the -X switch.
34
35       Trappable errors may be trapped using the eval operator.  See "eval" in
36       perlfunc.  In almost all cases, warnings may be selectively disabled or
37       promoted to fatal errors using the "warnings" pragma.  See warnings.
38
39       The messages are in alphabetical order, without regard to upper or
40       lower-case.  Some of these messages are generic.  Spots that vary are
41       denoted with a %s or other printf-style escape.  These escapes are
42       ignored by the alphabetical order, as are all characters other than
43       letters.  To look up your message, just ignore anything that is not a
44       letter.
45
46       accept() on closed socket %s
47           (W closed) You tried to do an accept on a closed socket.  Did you
48           forget to check the return value of your socket() call?  See
49           "accept" in perlfunc.
50
51       Aliasing via reference is experimental
52           (S experimental::refaliasing) This warning is emitted if you use a
53           reference constructor on the left-hand side of an assignment to
54           alias one variable to another.  Simply suppress the warning if you
55           want to use the feature, but know that in doing so you are taking
56           the risk of using an experimental feature which may change or be
57           removed in a future Perl version:
58
59               no warnings "experimental::refaliasing";
60               use feature "refaliasing";
61               \$x = \$y;
62
63       Allocation too large: %x
64           (X) You can't allocate more than 64K on an MS-DOS machine.
65
66       '%c' allowed only after types %s in %s
67           (F) The modifiers '!', '<' and '>' are allowed in pack() or
68           unpack() only after certain types.  See "pack" in perlfunc.
69
70       alpha->numify() is lossy
71           (W numeric) An alpha version can not be numified without losing
72           information.
73
74       Ambiguous call resolved as CORE::%s(), qualify as such or use &
75           (W ambiguous) A subroutine you have declared has the same name as a
76           Perl keyword, and you have used the name without qualification for
77           calling one or the other.  Perl decided to call the builtin because
78           the subroutine is not imported.
79
80           To force interpretation as a subroutine call, either put an
81           ampersand before the subroutine name, or qualify the name with its
82           package.  Alternatively, you can import the subroutine (or pretend
83           that it's imported with the "use subs" pragma).
84
85           To silently interpret it as the Perl operator, use the "CORE::"
86           prefix on the operator (e.g. "CORE::log($x)") or declare the
87           subroutine to be an object method (see "Subroutine Attributes" in
88           perlsub or attributes).
89
90       Ambiguous range in transliteration operator
91           (F) You wrote something like "tr/a-z-0//" which doesn't mean
92           anything at all.  To include a "-" character in a transliteration,
93           put it either first or last.  (In the past, "tr/a-z-0//" was
94           synonymous with "tr/a-y//", which was probably not what you would
95           have expected.)
96
97       Ambiguous use of %s resolved as %s
98           (S ambiguous) You said something that may not be interpreted the
99           way you thought.  Normally it's pretty easy to disambiguate it by
100           supplying a missing quote, operator, parenthesis pair or
101           declaration.
102
103       Ambiguous use of -%s resolved as -&%s()
104           (S ambiguous) You wrote something like "-foo", which might be the
105           string "-foo", or a call to the function "foo", negated.  If you
106           meant the string, just write "-foo".  If you meant the function
107           call, write "-foo()".
108
109       Ambiguous use of %c resolved as operator %c
110           (S ambiguous) "%", "&", and "*" are both infix operators (modulus,
111           bitwise and, and multiplication) and initial special characters
112           (denoting hashes, subroutines and typeglobs), and you said
113           something like "*foo * foo" that might be interpreted as either of
114           them.  We assumed you meant the infix operator, but please try to
115           make it more clear -- in the example given, you might write "*foo *
116           foo()" if you really meant to multiply a glob by the result of
117           calling a function.
118
119       Ambiguous use of %c{%s} resolved to %c%s
120           (W ambiguous) You wrote something like "@{foo}", which might be
121           asking for the variable @foo, or it might be calling a function
122           named foo, and dereferencing it as an array reference.  If you
123           wanted the variable, you can just write @foo.  If you wanted to
124           call the function, write "@{foo()}" ... or you could just not have
125           a variable and a function with the same name, and save yourself a
126           lot of trouble.
127
128       Ambiguous use of %c{%s[...]} resolved to %c%s[...]
129       Ambiguous use of %c{%s{...}} resolved to %c%s{...}
130           (W ambiguous) You wrote something like "${foo[2]}" (where foo
131           represents the name of a Perl keyword), which might be looking for
132           element number 2 of the array named @foo, in which case please
133           write $foo[2], or you might have meant to pass an anonymous
134           arrayref to the function named foo, and then do a scalar deref on
135           the value it returns.  If you meant that, write "${foo([2])}".
136
137           In regular expressions, the "${foo[2]}" syntax is sometimes
138           necessary to disambiguate between array subscripts and character
139           classes.  "/$length[2345]/", for instance, will be interpreted as
140           $length followed by the character class "[2345]".  If an array
141           subscript is what you want, you can avoid the warning by changing
142           "/${length[2345]}/" to the unsightly "/${\$length[2345]}/", by
143           renaming your array to something that does not coincide with a
144           built-in keyword, or by simply turning off warnings with "no
145           warnings 'ambiguous';".
146
147       '|' and '<' may not both be specified on command line
148           (F) An error peculiar to VMS.  Perl does its own command line
149           redirection, and found that STDIN was a pipe, and that you also
150           tried to redirect STDIN using '<'.  Only one STDIN stream to a
151           customer, please.
152
153       '|' and '>' may not both be specified on command line
154           (F) An error peculiar to VMS.  Perl does its own command line
155           redirection, and thinks you tried to redirect stdout both to a file
156           and into a pipe to another command.  You need to choose one or the
157           other, though nothing's stopping you from piping into a program or
158           Perl script which 'splits' output into two streams, such as
159
160               open(OUT,">$ARGV[0]") or die "Can't write to $ARGV[0]: $!";
161               while (<STDIN>) {
162                   print;
163                   print OUT;
164               }
165               close OUT;
166
167       Applying %s to %s will act on scalar(%s)
168           (W misc) The pattern match ("//"), substitution ("s///"), and
169           transliteration ("tr///") operators work on scalar values.  If you
170           apply one of them to an array or a hash, it will convert the array
171           or hash to a scalar value (the length of an array, or the
172           population info of a hash) and then work on that scalar value.
173           This is probably not what you meant to do.  See "grep" in perlfunc
174           and "map" in perlfunc for alternatives.
175
176       Arg too short for msgsnd
177           (F) msgsnd() requires a string at least as long as sizeof(long).
178
179       Argument "%s" isn't numeric%s
180           (W numeric) The indicated string was fed as an argument to an
181           operator that expected a numeric value instead.  If you're
182           fortunate the message will identify which operator was so
183           unfortunate.
184
185           Note that for the "Inf" and "NaN" (infinity and not-a-number) the
186           definition of "numeric" is somewhat unusual: the strings themselves
187           (like "Inf") are considered numeric, and anything following them is
188           considered non-numeric.
189
190       Argument list not closed for PerlIO layer "%s"
191           (W layer) When pushing a layer with arguments onto the Perl I/O
192           system you forgot the ) that closes the argument list.  (Layers
193           take care of transforming data between external and internal
194           representations.)  Perl stopped parsing the layer list at this
195           point and did not attempt to push this layer.  If your program
196           didn't explicitly request the failing operation, it may be the
197           result of the value of the environment variable PERLIO.
198
199       Argument "%s" treated as 0 in increment (++)
200           (W numeric) The indicated string was fed as an argument to the "++"
201           operator which expects either a number or a string matching
202           "/^[a-zA-Z]*[0-9]*\z/".  See "Auto-increment and Auto-decrement" in
203           perlop for details.
204
205       Array passed to stat will be coerced to a scalar%s
206           (W syntax) You called stat() on an array, but the array will be
207           coerced to a scalar - the number of elements in the array.
208
209       A signature parameter must start with '$', '@' or '%'
210           (F) Each subroutine signature parameter declaration must start with
211           a valid sigil; for example:
212
213               sub foo ($a, $, $b = 1, @c) {}
214
215       A slurpy parameter may not have a default value
216           (F) Only scalar subroutine signature parameters may have a default
217           value; for example:
218
219               sub foo ($a = 1)        {} # legal
220               sub foo (@a = (1))      {} # invalid
221               sub foo (%a = (a => b)) {} # invalid
222
223       assertion botched: %s
224           (X) The malloc package that comes with Perl had an internal
225           failure.
226
227       Assertion %s failed: file "%s", line %d
228           (X) A general assertion failed.  The file in question must be
229           examined.
230
231       Assigned value is not a reference
232           (F) You tried to assign something that was not a reference to an
233           lvalue reference (e.g., "\$x = $y").  If you meant to make $x an
234           alias to $y, use "\$x = \$y".
235
236       Assigned value is not %s reference
237           (F) You tried to assign a reference to a reference constructor, but
238           the two references were not of the same type.  You cannot alias a
239           scalar to an array, or an array to a hash; the two types must
240           match.
241
242               \$x = \@y;  # error
243               \@x = \%y;  # error
244                $y = [];
245               \$x = $y;   # error; did you mean \$y?
246
247       Assigning non-zero to $[ is no longer possible
248           (F) When the "array_base" feature is disabled (e.g., and under "use
249           v5.16;", and as of Perl 5.30) the special variable $[, which is
250           deprecated, is now a fixed zero value.
251
252       Assignment to both a list and a scalar
253           (F) If you assign to a conditional operator, the 2nd and 3rd
254           arguments must either both be scalars or both be lists.  Otherwise
255           Perl won't know which context to supply to the right side.
256
257       Assuming NOT a POSIX class since %s in regex; marked by <-- HERE in
258       m/%s/
259           (W regexp) You had something like these:
260
261            [[:alnum]]
262            [[:digit:xyz]
263
264           They look like they might have been meant to be the POSIX classes
265           "[:alnum:]" or "[:digit:]".  If so, they should be written:
266
267            [[:alnum:]]
268            [[:digit:]xyz]
269
270           Since these aren't legal POSIX class specifications, but are legal
271           bracketed character classes, Perl treats them as the latter.  In
272           the first example, it matches the characters ":", "[", "a", "l",
273           "m", "n", and "u".
274
275           If these weren't meant to be POSIX classes, this warning message is
276           spurious, and can be suppressed by reordering things, such as
277
278            [[al:num]]
279
280           or
281
282            [[:munla]]
283
284       <> at require-statement should be quotes
285           (F) You wrote "require <file>" when you should have written
286           "require 'file'".
287
288       Attempt to access disallowed key '%s' in a restricted hash
289           (F) The failing code has attempted to get or set a key which is not
290           in the current set of allowed keys of a restricted hash.
291
292       Attempt to bless into a freed package
293           (F) You wrote "bless $foo" with one argument after somehow causing
294           the current package to be freed.  Perl cannot figure out what to
295           do, so it throws up its hands in despair.
296
297       Attempt to bless into a reference
298           (F) The CLASSNAME argument to the bless() operator is expected to
299           be the name of the package to bless the resulting object into.
300           You've supplied instead a reference to something: perhaps you wrote
301
302               bless $self, $proto;
303
304           when you intended
305
306               bless $self, ref($proto) || $proto;
307
308           If you actually want to bless into the stringified version of the
309           reference supplied, you need to stringify it yourself, for example
310           by:
311
312               bless $self, "$proto";
313
314       Attempt to clear deleted array
315           (S debugging) An array was assigned to when it was being freed.
316           Freed values are not supposed to be visible to Perl code.  This can
317           also happen if XS code calls "av_clear" from a custom magic
318           callback on the array.
319
320       Attempt to delete disallowed key '%s' from a restricted hash
321           (F) The failing code attempted to delete from a restricted hash a
322           key which is not in its key set.
323
324       Attempt to delete readonly key '%s' from a restricted hash
325           (F) The failing code attempted to delete a key whose value has been
326           declared readonly from a restricted hash.
327
328       Attempt to free non-arena SV: 0x%x
329           (S internal) All SV objects are supposed to be allocated from
330           arenas that will be garbage collected on exit.  An SV was
331           discovered to be outside any of those arenas.
332
333       Attempt to free nonexistent shared string '%s'%s
334           (S internal) Perl maintains a reference-counted internal table of
335           strings to optimize the storage and access of hash keys and other
336           strings.  This indicates someone tried to decrement the reference
337           count of a string that can no longer be found in the table.
338
339       Attempt to free temp prematurely: SV 0x%x
340           (S debugging) Mortalized values are supposed to be freed by the
341           free_tmps() routine.  This indicates that something else is freeing
342           the SV before the free_tmps() routine gets a chance, which means
343           that the free_tmps() routine will be freeing an unreferenced scalar
344           when it does try to free it.
345
346       Attempt to free unreferenced glob pointers
347           (S internal) The reference counts got screwed up on symbol aliases.
348
349       Attempt to free unreferenced scalar: SV 0x%x
350           (S internal) Perl went to decrement the reference count of a scalar
351           to see if it would go to 0, and discovered that it had already gone
352           to 0 earlier, and should have been freed, and in fact, probably was
353           freed.  This could indicate that SvREFCNT_dec() was called too many
354           times, or that SvREFCNT_inc() was called too few times, or that the
355           SV was mortalized when it shouldn't have been, or that memory has
356           been corrupted.
357
358       Attempt to pack pointer to temporary value
359           (W pack) You tried to pass a temporary value (like the result of a
360           function, or a computed expression) to the "p" pack() template.
361           This means the result contains a pointer to a location that could
362           become invalid anytime, even before the end of the current
363           statement.  Use literals or global values as arguments to the "p"
364           pack() template to avoid this warning.
365
366       Attempt to reload %s aborted.
367           (F) You tried to load a file with "use" or "require" that failed to
368           compile once already.  Perl will not try to compile this file again
369           unless you delete its entry from %INC.  See "require" in perlfunc
370           and "%INC" in perlvar.
371
372       Attempt to set length of freed array
373           (W misc) You tried to set the length of an array which has been
374           freed.  You can do this by storing a reference to the scalar
375           representing the last index of an array and later assigning through
376           that reference.  For example
377
378               $r = do {my @a; \$#a};
379               $$r = 503
380
381       Attempt to use reference as lvalue in substr
382           (W substr) You supplied a reference as the first argument to
383           substr() used as an lvalue, which is pretty strange.  Perhaps you
384           forgot to dereference it first.  See "substr" in perlfunc.
385
386       Attribute prototype(%s) discards earlier prototype attribute in same
387       sub
388           (W misc) A sub was declared as sub foo : prototype(A) :
389           prototype(B) {}, for example.  Since each sub can only have one
390           prototype, the earlier declaration(s) are discarded while the last
391           one is applied.
392
393       av_reify called on tied array
394           (S debugging) This indicates that something went wrong and Perl got
395           very confused about @_ or @DB::args being tied.
396
397       Bad arg length for %s, is %u, should be %d
398           (F) You passed a buffer of the wrong size to one of msgctl(),
399           semctl() or shmctl().  In C parlance, the correct sizes are,
400           respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *),
401           and sizeof(struct shmid_ds *).
402
403       Bad evalled substitution pattern
404           (F) You've used the "/e" switch to evaluate the replacement for a
405           substitution, but perl found a syntax error in the code to
406           evaluate, most likely an unexpected right brace '}'.
407
408       Bad filehandle: %s
409           (F) A symbol was passed to something wanting a filehandle, but the
410           symbol has no filehandle associated with it.  Perhaps you didn't do
411           an open(), or did it in another package.
412
413       Bad free() ignored
414           (S malloc) An internal routine called free() on something that had
415           never been malloc()ed in the first place.  Mandatory, but can be
416           disabled by setting environment variable "PERL_BADFREE" to 0.
417
418           This message can be seen quite often with DB_File on systems with
419           "hard" dynamic linking, like "AIX" and "OS/2".  It is a bug of
420           "Berkeley DB" which is left unnoticed if "DB" uses forgiving system
421           malloc().
422
423       Bad hash
424           (P) One of the internal hash routines was passed a null HV pointer.
425
426       Badly placed ()'s
427           (A) You've accidentally run your script through csh instead of
428           Perl.  Check the #! line, or manually feed your script into Perl
429           yourself.
430
431       Bad name after %s
432           (F) You started to name a symbol by using a package prefix, and
433           then didn't finish the symbol.  In particular, you can't
434           interpolate outside of quotes, so
435
436               $var = 'myvar';
437               $sym = mypack::$var;
438
439           is not the same as
440
441               $var = 'myvar';
442               $sym = "mypack::$var";
443
444       Bad plugin affecting keyword '%s'
445           (F) An extension using the keyword plugin mechanism violated the
446           plugin API.
447
448       Bad realloc() ignored
449           (S malloc) An internal routine called realloc() on something that
450           had never been malloc()ed in the first place.  Mandatory, but can
451           be disabled by setting the environment variable "PERL_BADFREE" to
452           1.
453
454       Bad symbol for array
455           (P) An internal request asked to add an array entry to something
456           that wasn't a symbol table entry.
457
458       Bad symbol for dirhandle
459           (P) An internal request asked to add a dirhandle entry to something
460           that wasn't a symbol table entry.
461
462       Bad symbol for filehandle
463           (P) An internal request asked to add a filehandle entry to
464           something that wasn't a symbol table entry.
465
466       Bad symbol for hash
467           (P) An internal request asked to add a hash entry to something that
468           wasn't a symbol table entry.
469
470       Bad symbol for scalar
471           (P) An internal request asked to add a scalar entry to something
472           that wasn't a symbol table entry.
473
474       Bareword found in conditional
475           (W bareword) The compiler found a bareword where it expected a
476           conditional, which often indicates that an || or && was parsed as
477           part of the last argument of the previous construct, for example:
478
479               open FOO || die;
480
481           It may also indicate a misspelled constant that has been
482           interpreted as a bareword:
483
484               use constant TYPO => 1;
485               if (TYOP) { print "foo" }
486
487           The "strict" pragma is useful in avoiding such errors.
488
489       Bareword in require contains "%s"
490       Bareword in require maps to disallowed filename "%s"
491       Bareword in require maps to empty filename
492           (F) The bareword form of require has been invoked with a filename
493           which could not have been generated by a valid bareword permitted
494           by the parser.  You shouldn't be able to get this error from Perl
495           code, but XS code may throw it if it passes an invalid module name
496           to "Perl_load_module".
497
498       Bareword in require must not start with a double-colon: "%s"
499           (F) In "require Bare::Word", the bareword is not allowed to start
500           with a double-colon.  Write "require ::Foo::Bar" as  "require
501           Foo::Bar" instead.
502
503       Bareword "%s" not allowed while "strict subs" in use
504           (F) With "strict subs" in use, a bareword is only allowed as a
505           subroutine identifier, in curly brackets or to the left of the "=>"
506           symbol.  Perhaps you need to predeclare a subroutine?
507
508       Bareword "%s" refers to nonexistent package
509           (W bareword) You used a qualified bareword of the form "Foo::", but
510           the compiler saw no other uses of that namespace before that point.
511           Perhaps you need to predeclare a package?
512
513       BEGIN failed--compilation aborted
514           (F) An untrapped exception was raised while executing a BEGIN
515           subroutine.  Compilation stops immediately and the interpreter is
516           exited.
517
518       BEGIN not safe after errors--compilation aborted
519           (F) Perl found a "BEGIN {}" subroutine (or a "use" directive, which
520           implies a "BEGIN {}") after one or more compilation errors had
521           already occurred.  Since the intended environment for the "BEGIN
522           {}" could not be guaranteed (due to the errors), and since
523           subsequent code likely depends on its correct operation, Perl just
524           gave up.
525
526       \%d better written as $%d
527           (W syntax) Outside of patterns, backreferences live on as
528           variables.  The use of backslashes is grandfathered on the right-
529           hand side of a substitution, but stylistically it's better to use
530           the variable form because other Perl programmers will expect it,
531           and it works better if there are more than 9 backreferences.
532
533       Binary number > 0b11111111111111111111111111111111 non-portable
534           (W portable) The binary number you specified is larger than 2**32-1
535           (4294967295) and therefore non-portable between systems.  See
536           perlport for more on portability concerns.
537
538       bind() on closed socket %s
539           (W closed) You tried to do a bind on a closed socket.  Did you
540           forget to check the return value of your socket() call?  See "bind"
541           in perlfunc.
542
543       binmode() on closed filehandle %s
544           (W unopened) You tried binmode() on a filehandle that was never
545           opened.  Check your control flow and number of arguments.
546
547       Bit vector size > 32 non-portable
548           (W portable) Using bit vector sizes larger than 32 is non-portable.
549
550       Bizarre copy of %s
551           (P) Perl detected an attempt to copy an internal value that is not
552           copiable.
553
554       Bizarre SvTYPE [%d]
555           (P) When starting a new thread or returning values from a thread,
556           Perl encountered an invalid data type.
557
558       Both or neither range ends should be Unicode in regex; marked by
559       <-- HERE in m/%s/
560           (W regexp) (only under "use re 'strict'" or within "(?[...])")
561
562           In a bracketed character class in a regular expression pattern, you
563           had a range which has exactly one end of it specified using "\N{}",
564           and the other end is specified using a non-portable mechanism.
565           Perl treats the range as a Unicode range, that is, all the
566           characters in it are considered to be the Unicode characters, and
567           which may be different code points on some platforms Perl runs on.
568           For example, "[\N{U+06}-\x08]" is treated as if you had instead
569           said "[\N{U+06}-\N{U+08}]", that is it matches the characters whose
570           code points in Unicode are 6, 7, and 8.  But that "\x08" might
571           indicate that you meant something different, so the warning gets
572           raised.
573
574       Buffer overflow in prime_env_iter: %s
575           (W internal) A warning peculiar to VMS.  While Perl was preparing
576           to iterate over %ENV, it encountered a logical name or symbol
577           definition which was too long, so it was truncated to the string
578           shown.
579
580       Callback called exit
581           (F) A subroutine invoked from an external package via call_sv()
582           exited by calling exit.
583
584       %s() called too early to check prototype
585           (W prototype) You've called a function that has a prototype before
586           the parser saw a definition or declaration for it, and Perl could
587           not check that the call conforms to the prototype.  You need to
588           either add an early prototype declaration for the subroutine in
589           question, or move the subroutine definition ahead of the call to
590           get proper prototype checking.  Alternatively, if you are certain
591           that you're calling the function correctly, you may put an
592           ampersand before the name to avoid the warning.  See perlsub.
593
594       Cannot chr %f
595           (F) You passed an invalid number (like an infinity or not-a-number)
596           to "chr".
597
598       Cannot complete in-place edit of %s: %s
599           (F) Your perl script appears to have changed directory while
600           performing an in-place edit of a file specified by a relative path,
601           and your system doesn't include the directory relative POSIX
602           functions needed to handle that.
603
604       Cannot compress %f in pack
605           (F) You tried compressing an infinity or not-a-number as an
606           unsigned integer with BER, which makes no sense.
607
608       Cannot compress integer in pack
609           (F) An argument to pack("w",...) was too large to compress.  The
610           BER compressed integer format can only be used with positive
611           integers, and you attempted to compress a very large number (>
612           1e308).  See "pack" in perlfunc.
613
614       Cannot compress negative numbers in pack
615           (F) An argument to pack("w",...) was negative.  The BER compressed
616           integer format can only be used with positive integers.  See "pack"
617           in perlfunc.
618
619       Cannot convert a reference to %s to typeglob
620           (F) You manipulated Perl's symbol table directly, stored a
621           reference in it, then tried to access that symbol via conventional
622           Perl syntax.  The access triggers Perl to autovivify that typeglob,
623           but it there is no legal conversion from that type of reference to
624           a typeglob.
625
626       Cannot copy to %s
627           (P) Perl detected an attempt to copy a value to an internal type
628           that cannot be directly assigned to.
629
630       Cannot find encoding "%s"
631           (S io) You tried to apply an encoding that did not exist to a
632           filehandle, either with open() or binmode().
633
634       Cannot open %s as a dirhandle: it is already open as a filehandle
635           (F) You tried to use opendir() to associate a dirhandle to a symbol
636           (glob or scalar) that already holds a filehandle.  Since this idiom
637           might render your code confusing, it was deprecated in Perl 5.10.
638           As of Perl 5.28, it is a fatal error.
639
640       Cannot open %s as a filehandle: it is already open as a dirhandle
641           (F) You tried to use open() to associate a filehandle to a symbol
642           (glob or scalar) that already holds a dirhandle.  Since this idiom
643           might render your code confusing, it was deprecated in Perl 5.10.
644           As of Perl 5.28, it is a fatal error.
645
646       Cannot pack %f with '%c'
647           (F) You tried converting an infinity or not-a-number to an integer,
648           which makes no sense.
649
650       Cannot printf %f with '%c'
651           (F) You tried printing an infinity or not-a-number as a character
652           (%c), which makes no sense.  Maybe you meant '%s', or just
653           stringifying it?
654
655       Cannot set tied @DB::args
656           (F) "caller" tried to set @DB::args, but found it tied.  Tying
657           @DB::args is not supported.  (Before this error was added, it used
658           to crash.)
659
660       Cannot tie unreifiable array
661           (P) You somehow managed to call "tie" on an array that does not
662           keep a reference count on its arguments and cannot be made to do
663           so.  Such arrays are not even supposed to be accessible to Perl
664           code, but are only used internally.
665
666       Cannot yet reorder sv_vcatpvfn() arguments from va_list
667           (F) Some XS code tried to use "sv_vcatpvfn()" or a related function
668           with a format string that specifies explicit indexes for some of
669           the elements, and using a C-style variable-argument list (a
670           "va_list").  This is not currently supported.  XS authors wanting
671           to do this must instead construct a C array of "SV*" scalars
672           containing the arguments.
673
674       Can only compress unsigned integers in pack
675           (F) An argument to pack("w",...) was not an integer.  The BER
676           compressed integer format can only be used with positive integers,
677           and you attempted to compress something else.  See "pack" in
678           perlfunc.
679
680       Can't bless non-reference value
681           (F) Only hard references may be blessed.  This is how Perl
682           "enforces" encapsulation of objects.  See perlobj.
683
684       Can't "break" in a loop topicalizer
685           (F) You called "break", but you're in a "foreach" block rather than
686           a "given" block.  You probably meant to use "next" or "last".
687
688       Can't "break" outside a given block
689           (F) You called "break", but you're not inside a "given" block.
690
691       Can't call method "%s" on an undefined value
692           (F) You used the syntax of a method call, but the slot filled by
693           the object reference or package name contains an undefined value.
694           Something like this will reproduce the error:
695
696               $BADREF = undef;
697               process $BADREF 1,2,3;
698               $BADREF->process(1,2,3);
699
700       Can't call method "%s" on unblessed reference
701           (F) A method call must know in what package it's supposed to run.
702           It ordinarily finds this out from the object reference you supply,
703           but you didn't supply an object reference in this case.  A
704           reference isn't an object reference until it has been blessed.  See
705           perlobj.
706
707       Can't call method "%s" without a package or object reference
708           (F) You used the syntax of a method call, but the slot filled by
709           the object reference or package name contains an expression that
710           returns a defined value which is neither an object reference nor a
711           package name.  Something like this will reproduce the error:
712
713               $BADREF = 42;
714               process $BADREF 1,2,3;
715               $BADREF->process(1,2,3);
716
717       Can't call mro_isa_changed_in() on anonymous symbol table
718           (P) Perl got confused as to whether a hash was a plain hash or a
719           symbol table hash when trying to update @ISA caches.
720
721       Can't call mro_method_changed_in() on anonymous symbol table
722           (F) An XS module tried to call "mro_method_changed_in" on a hash
723           that was not attached to the symbol table.
724
725       Can't chdir to %s
726           (F) You called "perl -x/foo/bar", but /foo/bar is not a directory
727           that you can chdir to, possibly because it doesn't exist.
728
729       Can't check filesystem of script "%s" for nosuid
730           (P) For some reason you can't check the filesystem of the script
731           for nosuid.
732
733       Can't coerce %s to %s in %s
734           (F) Certain types of SVs, in particular real symbol table entries
735           (typeglobs), can't be forced to stop being what they are.  So you
736           can't say things like:
737
738               *foo += 1;
739
740           You CAN say
741
742               $foo = *foo;
743               $foo += 1;
744
745           but then $foo no longer contains a glob.
746
747       Can't "continue" outside a when block
748           (F) You called "continue", but you're not inside a "when" or
749           "default" block.
750
751       Can't create pipe mailbox
752           (P) An error peculiar to VMS.  The process is suffering from
753           exhausted quotas or other plumbing problems.
754
755       Can't declare %s in "%s"
756           (F) Only scalar, array, and hash variables may be declared as "my",
757           "our" or "state" variables.  They must have ordinary identifiers as
758           names.
759
760       Can't "default" outside a topicalizer
761           (F) You have used a "default" block that is neither inside a
762           "foreach" loop nor a "given" block.  (Note that this error is
763           issued on exit from the "default" block, so you won't get the error
764           if you use an explicit "continue".)
765
766       Can't determine class of operator %s, assuming BASEOP
767           (S) This warning indicates something wrong in the internals of
768           perl.  Perl was trying to find the class (e.g. LISTOP) of a
769           particular OP, and was unable to do so. This is likely to be due to
770           a bug in the perl internals, or due to a bug in XS code which
771           manipulates perl optrees.
772
773       Can't do inplace edit: %s is not a regular file
774           (S inplace) You tried to use the -i switch on a special file, such
775           as a file in /dev, a FIFO or an uneditable directory.  The file was
776           ignored.
777
778       Can't do inplace edit on %s: %s
779           (S inplace) The creation of the new file failed for the indicated
780           reason.
781
782       Can't do inplace edit: %s would not be unique
783           (S inplace) Your filesystem does not support filenames longer than
784           14 characters and Perl was unable to create a unique filename
785           during inplace editing with the -i switch.  The file was ignored.
786
787       Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".
788           (W locale) You are 1) running under ""use locale""; 2) the current
789           locale is not a UTF-8 one; 3) you tried to do the designated case-
790           change operation on the specified Unicode character; and 4) the
791           result of this operation would mix Unicode and locale rules, which
792           likely conflict.  Mixing of different rule types is forbidden, so
793           the operation was not done; instead the result is the indicated
794           value, which is the best available that uses entirely Unicode
795           rules.  That turns out to almost always be the original character,
796           unchanged.
797
798           It is generally a bad idea to mix non-UTF-8 locales and Unicode,
799           and this issue is one of the reasons why.  This warning is raised
800           when Unicode rules would normally cause the result of this
801           operation to contain a character that is in the range specified by
802           the locale, 0..255, and hence is subject to the locale's rules, not
803           Unicode's.
804
805           If you are using locale purely for its characteristics related to
806           things like its numeric and time formatting (and not "LC_CTYPE"),
807           consider using a restricted form of the locale pragma (see "The
808           "use locale" pragma" in perllocale) like
809           ""use locale ':not_characters'"".
810
811           Note that failed case-changing operations done as a result of case-
812           insensitive "/i" regular expression matching will show up in this
813           warning as having the "fc" operation (as that is what the regular
814           expression engine calls behind the scenes.)
815
816       Can't do waitpid with flags
817           (F) This machine doesn't have either waitpid() or wait4(), so only
818           waitpid() without flags is emulated.
819
820       Can't emulate -%s on #! line
821           (F) The #! line specifies a switch that doesn't make sense at this
822           point.  For example, it'd be kind of silly to put a -x on the #!
823           line.
824
825       Can't %s %s-endian %ss on this platform
826           (F) Your platform's byte-order is neither big-endian nor little-
827           endian, or it has a very strange pointer size.  Packing and
828           unpacking big- or little-endian floating point values and pointers
829           may not be possible.  See "pack" in perlfunc.
830
831       Can't exec "%s": %s
832           (W exec) A system(), exec(), or piped open call could not execute
833           the named program for the indicated reason.  Typical reasons
834           include: the permissions were wrong on the file, the file wasn't
835           found in $ENV{PATH}, the executable in question was compiled for
836           another architecture, or the #! line in a script points to an
837           interpreter that can't be run for similar reasons.  (Or maybe your
838           system doesn't support #! at all.)
839
840       Can't exec %s
841           (F) Perl was trying to execute the indicated program for you
842           because that's what the #! line said.  If that's not what you
843           wanted, you may need to mention "perl" on the #! line somewhere.
844
845       Can't execute %s
846           (F) You used the -S switch, but the copies of the script to execute
847           found in the PATH did not have correct permissions.
848
849       Can't find an opnumber for "%s"
850           (F) A string of a form "CORE::word" was given to prototype(), but
851           there is no builtin with the name "word".
852
853       Can't find label %s
854           (F) You said to goto a label that isn't mentioned anywhere that
855           it's possible for us to go to.  See "goto" in perlfunc.
856
857       Can't find %s on PATH
858           (F) You used the -S switch, but the script to execute could not be
859           found in the PATH.
860
861       Can't find %s on PATH, '.' not in PATH
862           (F) You used the -S switch, but the script to execute could not be
863           found in the PATH, or at least not with the correct permissions.
864           The script exists in the current directory, but PATH prohibits
865           running it.
866
867       Can't find string terminator %s anywhere before EOF
868           (F) Perl strings can stretch over multiple lines.  This message
869           means that the closing delimiter was omitted.  Because bracketed
870           quotes count nesting levels, the following is missing its final
871           parenthesis:
872
873               print q(The character '(' starts a side comment.);
874
875           If you're getting this error from a here-document, you may have
876           included unseen whitespace before or after your closing tag or
877           there may not be a linebreak after it.  A good programmer's editor
878           will have a way to help you find these characters (or lack of
879           characters).  See perlop for the full details on here-documents.
880
881       Can't find Unicode property definition "%s"
882       Can't find Unicode property definition "%s" in regex; marked by <--
883       HERE in m/%s/
884           (F) The named property which you specified via "\p" or "\P" is not
885           one known to Perl.  Perhaps you misspelled the name?  See
886           "Properties accessible through \p{} and \P{}" in perluniprops for a
887           complete list of available official properties.  If it is a user-
888           defined property it must have been defined by the time the regular
889           expression is matched.
890
891           If you didn't mean to use a Unicode property, escape the "\p",
892           either by "\\p" (just the "\p") or by "\Q\p" (the rest of the
893           string, or until "\E").
894
895       Can't fork: %s
896           (F) A fatal error occurred while trying to fork while opening a
897           pipeline.
898
899       Can't fork, trying again in 5 seconds
900           (W pipe) A fork in a piped open failed with EAGAIN and will be
901           retried after five seconds.
902
903       Can't get filespec - stale stat buffer?
904           (S) A warning peculiar to VMS.  This arises because of the
905           difference between access checks under VMS and under the Unix model
906           Perl assumes.  Under VMS, access checks are done by filename,
907           rather than by bits in the stat buffer, so that ACLs and other
908           protections can be taken into account.  Unfortunately, Perl assumes
909           that the stat buffer contains all the necessary information, and
910           passes it, instead of the filespec, to the access-checking routine.
911           It will try to retrieve the filespec using the device name and FID
912           present in the stat buffer, but this works only if you haven't made
913           a subsequent call to the CRTL stat() routine, because the device
914           name is overwritten with each call.  If this warning appears, the
915           name lookup failed, and the access-checking routine gave up and
916           returned FALSE, just to be conservative.  (Note: The access-
917           checking routine knows about the Perl "stat" operator and file
918           tests, so you shouldn't ever see this warning in response to a Perl
919           command; it arises only if some internal code takes stat buffers
920           lightly.)
921
922       Can't get pipe mailbox device name
923           (P) An error peculiar to VMS.  After creating a mailbox to act as a
924           pipe, Perl can't retrieve its name for later use.
925
926       Can't get SYSGEN parameter value for MAXBUF
927           (P) An error peculiar to VMS.  Perl asked $GETSYI how big you want
928           your mailbox buffers to be, and didn't get an answer.
929
930       Can't "goto" into a binary or list expression
931           (F) A "goto" statement was executed to jump into the middle of a
932           binary or list expression.  You can't get there from here.  The
933           reason for this restriction is that the interpreter would get
934           confused as to how many arguments there are, resulting in stack
935           corruption or crashes.  This error occurs in cases such as these:
936
937               goto F;
938               print do { F: }; # Can't jump into the arguments to print
939
940               goto G;
941               $x + do { G: $y }; # How is + supposed to get its first operand?
942
943       Can't "goto" into a "given" block
944           (F) A "goto" statement was executed to jump into the middle of a
945           "given" block.  You can't get there from here.  See "goto" in
946           perlfunc.
947
948       Can't "goto" into the middle of a foreach loop
949           (F) A "goto" statement was executed to jump into the middle of a
950           foreach loop.  You can't get there from here.  See "goto" in
951           perlfunc.
952
953       Can't "goto" out of a pseudo block
954           (F) A "goto" statement was executed to jump out of what might look
955           like a block, except that it isn't a proper block.  This usually
956           occurs if you tried to jump out of a sort() block or subroutine,
957           which is a no-no.  See "goto" in perlfunc.
958
959       Can't goto subroutine from an eval-%s
960           (F) The "goto subroutine" call can't be used to jump out of an eval
961           "string" or block.
962
963       Can't goto subroutine from a sort sub (or similar callback)
964           (F) The "goto subroutine" call can't be used to jump out of the
965           comparison sub for a sort(), or from a similar callback (such as
966           the reduce() function in List::Util).
967
968       Can't goto subroutine outside a subroutine
969           (F) The deeply magical "goto subroutine" call can only replace one
970           subroutine call for another.  It can't manufacture one out of whole
971           cloth.  In general you should be calling it out of only an AUTOLOAD
972           routine anyway.  See "goto" in perlfunc.
973
974       Can't ignore signal CHLD, forcing to default
975           (W signal) Perl has detected that it is being run with the SIGCHLD
976           signal (sometimes known as SIGCLD) disabled.  Since disabling this
977           signal will interfere with proper determination of exit status of
978           child processes, Perl has reset the signal to its default value.
979           This situation typically indicates that the parent program under
980           which Perl may be running (e.g. cron) is being very careless.
981
982       Can't kill a non-numeric process ID
983           (F) Process identifiers must be (signed) integers.  It is a fatal
984           error to attempt to kill() an undefined, empty-string or otherwise
985           non-numeric process identifier.
986
987       Can't "last" outside a loop block
988           (F) A "last" statement was executed to break out of the current
989           block, except that there's this itty bitty problem called there
990           isn't a current block.  Note that an "if" or "else" block doesn't
991           count as a "loopish" block, as doesn't a block given to sort(),
992           map() or grep().  You can usually double the curlies to get the
993           same effect though, because the inner curlies will be considered a
994           block that loops once.  See "last" in perlfunc.
995
996       Can't linearize anonymous symbol table
997           (F) Perl tried to calculate the method resolution order (MRO) of a
998           package, but failed because the package stash has no name.
999
1000       Can't load '%s' for module %s
1001           (F) The module you tried to load failed to load a dynamic
1002           extension.  This may either mean that you upgraded your version of
1003           perl to one that is incompatible with your old dynamic extensions
1004           (which is known to happen between major versions of perl), or (more
1005           likely) that your dynamic extension was built against an older
1006           version of the library that is installed on your system.  You may
1007           need to rebuild your old dynamic extensions.
1008
1009       Can't localize lexical variable %s
1010           (F) You used local on a variable name that was previously declared
1011           as a lexical variable using "my" or "state".  This is not allowed.
1012           If you want to localize a package variable of the same name,
1013           qualify it with the package name.
1014
1015       Can't localize through a reference
1016           (F) You said something like "local $$ref", which Perl can't
1017           currently handle, because when it goes to restore the old value of
1018           whatever $ref pointed to after the scope of the local() is
1019           finished, it can't be sure that $ref will still be a reference.
1020
1021       Can't locate %s
1022           (F) You said to "do" (or "require", or "use") a file that couldn't
1023           be found.  Perl looks for the file in all the locations mentioned
1024           in @INC, unless the file name included the full path to the file.
1025           Perhaps you need to set the PERL5LIB or PERL5OPT environment
1026           variable to say where the extra library is, or maybe the script
1027           needs to add the library name to @INC.  Or maybe you just
1028           misspelled the name of the file.  See "require" in perlfunc and
1029           lib.
1030
1031       Can't locate auto/%s.al in @INC
1032           (F) A function (or method) was called in a package which allows
1033           autoload, but there is no function to autoload.  Most probable
1034           causes are a misprint in a function/method name or a failure to
1035           "AutoSplit" the file, say, by doing "make install".
1036
1037       Can't locate loadable object for module %s in @INC
1038           (F) The module you loaded is trying to load an external library,
1039           like for example, foo.so or bar.dll, but the DynaLoader module was
1040           unable to locate this library.  See DynaLoader.
1041
1042       Can't locate object method "%s" via package "%s"
1043           (F) You called a method correctly, and it correctly indicated a
1044           package functioning as a class, but that package doesn't define
1045           that particular method, nor does any of its base classes.  See
1046           perlobj.
1047
1048       Can't locate object method "%s" via package "%s" (perhaps you forgot to
1049       load "%s"?)
1050           (F) You called a method on a class that did not exist, and the
1051           method could not be found in UNIVERSAL.  This often means that a
1052           method requires a package that has not been loaded.
1053
1054       Can't locate package %s for @%s::ISA
1055           (W syntax) The @ISA array contained the name of another package
1056           that doesn't seem to exist.
1057
1058       Can't locate PerlIO%s
1059           (F) You tried to use in open() a PerlIO layer that does not exist,
1060           e.g. open(FH, ">:nosuchlayer", "somefile").
1061
1062       Can't make list assignment to %ENV on this system
1063           (F) List assignment to %ENV is not supported on some systems,
1064           notably VMS.
1065
1066       Can't make loaded symbols global on this platform while loading %s
1067           (S) A module passed the flag 0x01 to DynaLoader::dl_load_file() to
1068           request that symbols from the stated file are made available
1069           globally within the process, but that functionality is not
1070           available on this platform.  Whilst the module likely will still
1071           work, this may prevent the perl interpreter from loading other XS-
1072           based extensions which need to link directly to functions defined
1073           in the C or XS code in the stated file.
1074
1075       Can't modify %s in %s
1076           (F) You aren't allowed to assign to the item indicated, or
1077           otherwise try to change it, such as with an auto-increment.
1078
1079       Can't modify nonexistent substring
1080           (P) The internal routine that does assignment to a substr() was
1081           handed a NULL.
1082
1083       Can't modify non-lvalue subroutine call of &%s
1084       Can't modify non-lvalue subroutine call of &%s in %s
1085           (F) Subroutines meant to be used in lvalue context should be
1086           declared as such.  See "Lvalue subroutines" in perlsub.
1087
1088       Can't modify reference to %s in %s assignment
1089           (F) Only a limited number of constructs can be used as the argument
1090           to a reference constructor on the left-hand side of an assignment,
1091           and what you used was not one of them.  See "Assigning to
1092           References" in perlref.
1093
1094       Can't modify reference to localized parenthesized array in list
1095       assignment
1096           (F) Assigning to "\local(@array)" or "\(local @array)" is not
1097           supported, as it is not clear exactly what it should do.  If you
1098           meant to make @array refer to some other array, use "\@array =
1099           \@other_array".  If you want to make the elements of @array aliases
1100           of the scalars referenced on the right-hand side, use "\(@array) =
1101           @scalar_refs".
1102
1103       Can't modify reference to parenthesized hash in list assignment
1104           (F) Assigning to "\(%hash)" is not supported.  If you meant to make
1105           %hash refer to some other hash, use "\%hash = \%other_hash".  If
1106           you want to make the elements of %hash into aliases of the scalars
1107           referenced on the right-hand side, use a hash slice: "\@hash{@keys}
1108           = @those_scalar_refs".
1109
1110       Can't msgrcv to read-only var
1111           (F) The target of a msgrcv must be modifiable to be used as a
1112           receive buffer.
1113
1114       Can't "next" outside a loop block
1115           (F) A "next" statement was executed to reiterate the current block,
1116           but there isn't a current block.  Note that an "if" or "else" block
1117           doesn't count as a "loopish" block, as doesn't a block given to
1118           sort(), map() or grep().  You can usually double the curlies to get
1119           the same effect though, because the inner curlies will be
1120           considered a block that loops once.  See "next" in perlfunc.
1121
1122       Can't open %s: %s
1123           (S inplace) The implicit opening of a file through use of the "<>"
1124           filehandle, either implicitly under the "-n" or "-p" command-line
1125           switches, or explicitly, failed for the indicated reason.  Usually
1126           this is because you don't have read permission for a file which you
1127           named on the command line.
1128
1129           (F) You tried to call perl with the -e switch, but /dev/null (or
1130           your operating system's equivalent) could not be opened.
1131
1132       Can't open a reference
1133           (W io) You tried to open a scalar reference for reading or writing,
1134           using the 3-arg open() syntax:
1135
1136               open FH, '>', $ref;
1137
1138           but your version of perl is compiled without perlio, and this form
1139           of open is not supported.
1140
1141       Can't open bidirectional pipe
1142           (W pipe) You tried to say "open(CMD, "|cmd|")", which is not
1143           supported.  You can try any of several modules in the Perl library
1144           to do this, such as IPC::Open2.  Alternately, direct the pipe's
1145           output to a file using ">", and then read it in under a different
1146           file handle.
1147
1148       Can't open error file %s as stderr
1149           (F) An error peculiar to VMS.  Perl does its own command line
1150           redirection, and couldn't open the file specified after '2>' or
1151           '2>>' on the command line for writing.
1152
1153       Can't open input file %s as stdin
1154           (F) An error peculiar to VMS.  Perl does its own command line
1155           redirection, and couldn't open the file specified after '<' on the
1156           command line for reading.
1157
1158       Can't open output file %s as stdout
1159           (F) An error peculiar to VMS.  Perl does its own command line
1160           redirection, and couldn't open the file specified after '>' or '>>'
1161           on the command line for writing.
1162
1163       Can't open output pipe (name: %s)
1164           (P) An error peculiar to VMS.  Perl does its own command line
1165           redirection, and couldn't open the pipe into which to send data
1166           destined for stdout.
1167
1168       Can't open perl script "%s": %s
1169           (F) The script you specified can't be opened for the indicated
1170           reason.
1171
1172           If you're debugging a script that uses #!, and normally relies on
1173           the shell's $PATH search, the -S option causes perl to do that
1174           search, so you don't have to type the path or "`which
1175           $scriptname`".
1176
1177       Can't read CRTL environ
1178           (S) A warning peculiar to VMS.  Perl tried to read an element of
1179           %ENV from the CRTL's internal environment array and discovered the
1180           array was missing.  You need to figure out where your CRTL
1181           misplaced its environ or define PERL_ENV_TABLES (see perlvms) so
1182           that environ is not searched.
1183
1184       Can't redeclare "%s" in "%s"
1185           (F) A "my", "our" or "state" declaration was found within another
1186           declaration, such as "my ($x, my($y), $z)" or "our (my $x)".
1187
1188       Can't "redo" outside a loop block
1189           (F) A "redo" statement was executed to restart the current block,
1190           but there isn't a current block.  Note that an "if" or "else" block
1191           doesn't count as a "loopish" block, as doesn't a block given to
1192           sort(), map() or grep().  You can usually double the curlies to get
1193           the same effect though, because the inner curlies will be
1194           considered a block that loops once.  See "redo" in perlfunc.
1195
1196       Can't remove %s: %s, skipping file
1197           (S inplace) You requested an inplace edit without creating a backup
1198           file.  Perl was unable to remove the original file to replace it
1199           with the modified file.  The file was left unmodified.
1200
1201       Can't rename in-place work file '%s' to '%s': %s
1202           (F) When closed implicitly, the temporary file for in-place editing
1203           couldn't be renamed to the original filename.
1204
1205       Can't rename %s to %s: %s, skipping file
1206           (F) The rename done by the -i switch failed for some reason,
1207           probably because you don't have write permission to the directory.
1208
1209       Can't reopen input pipe (name: %s) in binary mode
1210           (P) An error peculiar to VMS.  Perl thought stdin was a pipe, and
1211           tried to reopen it to accept binary data.  Alas, it failed.
1212
1213       Can't represent character for Ox%X on this platform
1214           (F) There is a hard limit to how big a character code point can be
1215           due to the fundamental properties of UTF-8, especially on EBCDIC
1216           platforms.  The given code point exceeds that.  The only work-
1217           around is to not use such a large code point.
1218
1219       Can't reset %ENV on this system
1220           (F) You called "reset('E')" or similar, which tried to reset all
1221           variables in the current package beginning with "E".  In the main
1222           package, that includes %ENV.  Resetting %ENV is not supported on
1223           some systems, notably VMS.
1224
1225       Can't resolve method "%s" overloading "%s" in package "%s"
1226           (F)(P) Error resolving overloading specified by a method name (as
1227           opposed to a subroutine reference): no such method callable via the
1228           package.  If the method name is "???", this is an internal error.
1229
1230       Can't return %s from lvalue subroutine
1231           (F) Perl detected an attempt to return illegal lvalues (such as
1232           temporary or readonly values) from a subroutine used as an lvalue.
1233           This is not allowed.
1234
1235       Can't return outside a subroutine
1236           (F) The return statement was executed in mainline code, that is,
1237           where there was no subroutine call to return out of.  See perlsub.
1238
1239       Can't return %s to lvalue scalar context
1240           (F) You tried to return a complete array or hash from an lvalue
1241           subroutine, but you called the subroutine in a way that made Perl
1242           think you meant to return only one value.  You probably meant to
1243           write parentheses around the call to the subroutine, which tell
1244           Perl that the call should be in list context.
1245
1246       Can't stat script "%s"
1247           (P) For some reason you can't fstat() the script even though you
1248           have it open already.  Bizarre.
1249
1250       Can't take log of %g
1251           (F) For ordinary real numbers, you can't take the logarithm of a
1252           negative number or zero.  There's a Math::Complex package that
1253           comes standard with Perl, though, if you really want to do that for
1254           the negative numbers.
1255
1256       Can't take sqrt of %g
1257           (F) For ordinary real numbers, you can't take the square root of a
1258           negative number.  There's a Math::Complex package that comes
1259           standard with Perl, though, if you really want to do that.
1260
1261       Can't undef active subroutine
1262           (F) You can't undefine a routine that's currently running.  You
1263           can, however, redefine it while it's running, and you can even
1264           undef the redefined subroutine while the old routine is running.
1265           Go figure.
1266
1267       Can't unweaken a nonreference
1268           (F) You attempted to unweaken something that was not a reference.
1269           Only references can be unweakened.
1270
1271       Can't upgrade %s (%d) to %d
1272           (P) The internal sv_upgrade routine adds "members" to an SV, making
1273           it into a more specialized kind of SV.  The top several SV types
1274           are so specialized, however, that they cannot be interconverted.
1275           This message indicates that such a conversion was attempted.
1276
1277       Can't use '%c' after -mname
1278           (F) You tried to call perl with the -m switch, but you put
1279           something other than "=" after the module name.
1280
1281       Can't use a hash as a reference
1282           (F) You tried to use a hash as a reference, as in "%foo->{"bar"}"
1283           or "%$ref->{"hello"}".  Versions of perl <= 5.22.0 used to allow
1284           this syntax, but shouldn't have.  This was deprecated in perl
1285           5.6.1.
1286
1287       Can't use an array as a reference
1288           (F) You tried to use an array as a reference, as in "@foo->[23]" or
1289           "@$ref->[99]".  Versions of perl <= 5.22.0 used to allow this
1290           syntax, but shouldn't have.  This was deprecated in perl 5.6.1.
1291
1292       Can't use anonymous symbol table for method lookup
1293           (F) The internal routine that does method lookup was handed a
1294           symbol table that doesn't have a name.  Symbol tables can become
1295           anonymous for example by undefining stashes: "undef
1296           %Some::Package::".
1297
1298       Can't use an undefined value as %s reference
1299           (F) A value used as either a hard reference or a symbolic reference
1300           must be a defined value.  This helps to delurk some insidious
1301           errors.
1302
1303       Can't use bareword ("%s") as %s ref while "strict refs" in use
1304           (F) Only hard references are allowed by "strict refs".  Symbolic
1305           references are disallowed.  See perlref.
1306
1307       Can't use %! because Errno.pm is not available
1308           (F) The first time the "%!" hash is used, perl automatically loads
1309           the Errno.pm module.  The Errno module is expected to tie the %!
1310           hash to provide symbolic names for $! errno values.
1311
1312       Can't use both '<' and '>' after type '%c' in %s
1313           (F) A type cannot be forced to have both big-endian and little-
1314           endian byte-order at the same time, so this combination of
1315           modifiers is not allowed.  See "pack" in perlfunc.
1316
1317       Can't use 'defined(@array)' (Maybe you should just omit the defined()?)
1318           (F) defined() is not useful on arrays because it checks for an
1319           undefined scalar value.  If you want to see if the array is empty,
1320           just use "if (@array) { # not empty }" for example.
1321
1322       Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)
1323           (F) "defined()" is not usually right on hashes.
1324
1325           Although "defined %hash" is false on a plain not-yet-used hash, it
1326           becomes true in several non-obvious circumstances, including
1327           iterators, weak references, stash names, even remaining true after
1328           "undef %hash".  These things make "defined %hash" fairly useless in
1329           practice, so it now generates a fatal error.
1330
1331           If a check for non-empty is what you wanted then just put it in
1332           boolean context (see "Scalar values" in perldata):
1333
1334               if (%hash) {
1335                  # not empty
1336               }
1337
1338           If you had "defined %Foo::Bar::QUUX" to check whether such a
1339           package variable exists then that's never really been reliable, and
1340           isn't a good way to enquire about the features of a package, or
1341           whether it's loaded, etc.
1342
1343       Can't use %s for loop variable
1344           (P) The parser got confused when trying to parse a "foreach" loop.
1345
1346       Can't use global %s in %s
1347           (F) You tried to declare a magical variable as a lexical variable.
1348           This is not allowed, because the magic can be tied to only one
1349           location (namely the global variable) and it would be incredibly
1350           confusing to have variables in your program that looked like
1351           magical variables but weren't.
1352
1353       Can't use '%c' in a group with different byte-order in %s
1354           (F) You attempted to force a different byte-order on a type that is
1355           already inside a group with a byte-order modifier.  For example you
1356           cannot force little-endianness on a type that is inside a big-
1357           endian group.
1358
1359       Can't use "my %s" in sort comparison
1360           (F) The global variables $a and $b are reserved for sort
1361           comparisons.  You mentioned $a or $b in the same line as the <=> or
1362           cmp operator, and the variable had earlier been declared as a
1363           lexical variable.  Either qualify the sort variable with the
1364           package name, or rename the lexical variable.
1365
1366       Can't use %s ref as %s ref
1367           (F) You've mixed up your reference types.  You have to dereference
1368           a reference of the type needed.  You can use the ref() function to
1369           test the type of the reference, if need be.
1370
1371       Can't use string ("%s") as %s ref while "strict refs" in use
1372       Can't use string ("%s"...) as %s ref while "strict refs" in use
1373           (F) You've told Perl to dereference a string, something which "use
1374           strict" blocks to prevent it happening accidentally.  See "Symbolic
1375           references" in perlref.  This can be triggered by an "@" or "$" in
1376           a double-quoted string immediately before interpolating a variable,
1377           for example in "user @$twitter_id", which says to treat the
1378           contents of $twitter_id as an array reference; use a "\" to have a
1379           literal "@" symbol followed by the contents of $twitter_id: "user
1380           \@$twitter_id".
1381
1382       Can't use subscript on %s
1383           (F) The compiler tried to interpret a bracketed expression as a
1384           subscript.  But to the left of the brackets was an expression that
1385           didn't look like a hash or array reference, or anything else
1386           subscriptable.
1387
1388       Can't use \%c to mean $%c in expression
1389           (W syntax) In an ordinary expression, backslash is a unary operator
1390           that creates a reference to its argument.  The use of backslash to
1391           indicate a backreference to a matched substring is valid only as
1392           part of a regular expression pattern.  Trying to do this in
1393           ordinary Perl code produces a value that prints out looking like
1394           SCALAR(0xdecaf).  Use the $1 form instead.
1395
1396       Can't weaken a nonreference
1397           (F) You attempted to weaken something that was not a reference.
1398           Only references can be weakened.
1399
1400       Can't "when" outside a topicalizer
1401           (F) You have used a when() block that is neither inside a "foreach"
1402           loop nor a "given" block.  (Note that this error is issued on exit
1403           from the "when" block, so you won't get the error if the match
1404           fails, or if you use an explicit "continue".)
1405
1406       Can't x= to read-only value
1407           (F) You tried to repeat a constant value (often the undefined
1408           value) with an assignment operator, which implies modifying the
1409           value itself.  Perhaps you need to copy the value to a temporary,
1410           and repeat that.
1411
1412       Character following "\c" must be printable ASCII
1413           (F) In "\cX", X must be a printable (non-control) ASCII character.
1414
1415           Note that ASCII characters that don't map to control characters are
1416           discouraged, and will generate the warning (when enabled) ""\c%c"
1417           is more clearly written simply as "%s"".
1418
1419       Character following \%c must be '{' or a single-character Unicode
1420       property name in regex; marked by <-- HERE in m/%s/
1421           (F) (In the above the %c is replaced by either "p" or "P".)  You
1422           specified something that isn't a legal Unicode property name.  Most
1423           Unicode properties are specified by "\p{...}".  But if the name is
1424           a single character one, the braces may be omitted.
1425
1426       Character in 'C' format wrapped in pack
1427           (W pack) You said
1428
1429               pack("C", $x)
1430
1431           where $x is either less than 0 or more than 255; the "C" format is
1432           only for encoding native operating system characters (ASCII,
1433           EBCDIC, and so on) and not for Unicode characters, so Perl behaved
1434           as if you meant
1435
1436               pack("C", $x & 255)
1437
1438           If you actually want to pack Unicode codepoints, use the "U" format
1439           instead.
1440
1441       Character in 'c' format wrapped in pack
1442           (W pack) You said
1443
1444               pack("c", $x)
1445
1446           where $x is either less than -128 or more than 127; the "c" format
1447           is only for encoding native operating system characters (ASCII,
1448           EBCDIC, and so on) and not for Unicode characters, so Perl behaved
1449           as if you meant
1450
1451               pack("c", $x & 255);
1452
1453           If you actually want to pack Unicode codepoints, use the "U" format
1454           instead.
1455
1456       Character in '%c' format wrapped in unpack
1457           (W unpack) You tried something like
1458
1459              unpack("H", "\x{2a1}")
1460
1461           where the format expects to process a byte (a character with a
1462           value below 256), but a higher value was provided instead.  Perl
1463           uses the value modulus 256 instead, as if you had provided:
1464
1465              unpack("H", "\x{a1}")
1466
1467       Character in 'W' format wrapped in pack
1468           (W pack) You said
1469
1470               pack("U0W", $x)
1471
1472           where $x is either less than 0 or more than 255.  However,
1473           "U0"-mode expects all values to fall in the interval [0, 255], so
1474           Perl behaved as if you meant:
1475
1476               pack("U0W", $x & 255)
1477
1478       Character(s) in '%c' format wrapped in pack
1479           (W pack) You tried something like
1480
1481              pack("u", "\x{1f3}b")
1482
1483           where the format expects to process a sequence of bytes (character
1484           with a value below 256), but some of the characters had a higher
1485           value.  Perl uses the character values modulus 256 instead, as if
1486           you had provided:
1487
1488              pack("u", "\x{f3}b")
1489
1490       Character(s) in '%c' format wrapped in unpack
1491           (W unpack) You tried something like
1492
1493              unpack("s", "\x{1f3}b")
1494
1495           where the format expects to process a sequence of bytes (character
1496           with a value below 256), but some of the characters had a higher
1497           value.  Perl uses the character values modulus 256 instead, as if
1498           you had provided:
1499
1500              unpack("s", "\x{f3}b")
1501
1502       charnames alias definitions may not contain a sequence of multiple
1503       spaces; marked by <-- HERE in %s
1504           (F) You defined a character name which had multiple space
1505           characters in a row.  Change them to single spaces.  Usually these
1506           names are defined in the ":alias" import argument to "use
1507           charnames", but they could be defined by a translator installed
1508           into $^H{charnames}.  See "CUSTOM ALIASES" in charnames.
1509
1510       charnames alias definitions may not contain trailing white-space;
1511       marked by <-- HERE in %s
1512           (F) You defined a character name which ended in a space character.
1513           Remove the trailing space(s).  Usually these names are defined in
1514           the ":alias" import argument to "use charnames", but they could be
1515           defined by a translator installed into $^H{charnames}.  See "CUSTOM
1516           ALIASES" in charnames.
1517
1518       chdir() on unopened filehandle %s
1519           (W unopened) You tried chdir() on a filehandle that was never
1520           opened.
1521
1522       "\c%c" is more clearly written simply as "%s"
1523           (W syntax) The "\cX" construct is intended to be a way to specify
1524           non-printable characters.  You used it for a printable one, which
1525           is better written as simply itself, perhaps preceded by a backslash
1526           for non-word characters.  Doing it the way you did is not portable
1527           between ASCII and EBCDIC platforms.
1528
1529       Cloning substitution context is unimplemented
1530           (F) Creating a new thread inside the "s///" operator is not
1531           supported.
1532
1533       closedir() attempted on invalid dirhandle %s
1534           (W io) The dirhandle you tried to close is either closed or not
1535           really a dirhandle.  Check your control flow.
1536
1537       close() on unopened filehandle %s
1538           (W unopened) You tried to close a filehandle that was never opened.
1539
1540       Closure prototype called
1541           (F) If a closure has attributes, the subroutine passed to an
1542           attribute handler is the prototype that is cloned when a new
1543           closure is created.  This subroutine cannot be called.
1544
1545       \C no longer supported in regex; marked by <-- HERE in m/%s/
1546           (F) The \C character class used to allow a match of single byte
1547           within a multi-byte utf-8 character, but was removed in v5.24 as it
1548           broke encapsulation and its implementation was extremely buggy.  If
1549           you really need to process the individual bytes, you probably want
1550           to convert your string to one where each underlying byte is stored
1551           as a character, with utf8::encode().
1552
1553       Code missing after '/'
1554           (F) You had a (sub-)template that ends with a '/'.  There must be
1555           another template code following the slash.  See "pack" in perlfunc.
1556
1557       Code point 0x%X is not Unicode, and not portable
1558           (S non_unicode portable) You had a code point that has never been
1559           in any standard, so it is likely that languages other than Perl
1560           will NOT understand it.  This code point also will not fit in a
1561           32-bit word on ASCII platforms and therefore is non-portable
1562           between systems.
1563
1564           At one time, it was legal in some standards to have code points up
1565           to 0x7FFF_FFFF, but not higher, and this code point is higher.
1566
1567           Acceptance of these code points is a Perl extension, and you should
1568           expect that nothing other than Perl can handle them; Perl itself on
1569           EBCDIC platforms before v5.24 does not handle them.
1570
1571           Perl also makes no guarantees that the representation of these code
1572           points won't change at some point in the future, say when machines
1573           become available that have larger than a 64-bit word.  At that
1574           time, files containing any of these, written by an older Perl might
1575           require conversion before being readable by a newer Perl.
1576
1577       Code point 0x%X is not Unicode, may not be portable
1578           (S non_unicode) You had a code point above the Unicode maximum of
1579           U+10FFFF.
1580
1581           Perl allows strings to contain a superset of Unicode code points,
1582           but these may not be accepted by other languages/systems.  Further,
1583           even if these languages/systems accept these large code points,
1584           they may have chosen a different representation for them than the
1585           UTF-8-like one that Perl has, which would mean files are not
1586           exchangeable between them and Perl.
1587
1588           On EBCDIC platforms, code points above 0x3FFF_FFFF have a different
1589           representation in Perl v5.24 than before, so any file containing
1590           these that was written before that version will require conversion
1591           before being readable by a later Perl.
1592
1593       %s: Command not found
1594           (A) You've accidentally run your script through csh or another
1595           shell instead of Perl.  Check the #! line, or manually feed your
1596           script into Perl yourself.  The #! line at the top of your file
1597           could look like
1598
1599             #!/usr/bin/perl
1600
1601       %s: command not found
1602           (A) You've accidentally run your script through bash or another
1603           shell instead of Perl.  Check the #! line, or manually feed your
1604           script into Perl yourself.  The #! line at the top of your file
1605           could look like
1606
1607             #!/usr/bin/perl
1608
1609       %s: command not found: %s
1610           (A) You've accidentally run your script through zsh or another
1611           shell instead of Perl.  Check the #! line, or manually feed your
1612           script into Perl yourself.  The #! line at the top of your file
1613           could look like
1614
1615             #!/usr/bin/perl
1616
1617       Compilation failed in require
1618           (F) Perl could not compile a file specified in a "require"
1619           statement.  Perl uses this generic message when none of the errors
1620           that it encountered were severe enough to halt compilation
1621           immediately.
1622
1623       Complex regular subexpression recursion limit (%d) exceeded
1624           (W regexp) The regular expression engine uses recursion in complex
1625           situations where back-tracking is required.  Recursion depth is
1626           limited to 32766, or perhaps less in architectures where the stack
1627           cannot grow arbitrarily.  ("Simple" and "medium" situations are
1628           handled without recursion and are not subject to a limit.)  Try
1629           shortening the string under examination; looping in Perl code (e.g.
1630           with "while") rather than in the regular expression engine; or
1631           rewriting the regular expression so that it is simpler or
1632           backtracks less.  (See perlfaq2 for information on Mastering
1633           Regular Expressions.)
1634
1635       connect() on closed socket %s
1636           (W closed) You tried to do a connect on a closed socket.  Did you
1637           forget to check the return value of your socket() call?  See
1638           "connect" in perlfunc.
1639
1640       Constant(%s): Call to &{$^H{%s}} did not return a defined value
1641           (F) The subroutine registered to handle constant overloading (see
1642           overload) or a custom charnames handler (see "CUSTOM TRANSLATORS"
1643           in charnames) returned an undefined value.
1644
1645       Constant(%s): $^H{%s} is not defined
1646           (F) The parser found inconsistencies while attempting to define an
1647           overloaded constant.  Perhaps you forgot to load the corresponding
1648           overload pragma?
1649
1650       Constant is not %s reference
1651           (F) A constant value (perhaps declared using the "use constant"
1652           pragma) is being dereferenced, but it amounts to the wrong type of
1653           reference.  The message indicates the type of reference that was
1654           expected.  This usually indicates a syntax error in dereferencing
1655           the constant value.  See "Constant Functions" in perlsub and
1656           constant.
1657
1658       Constants from lexical variables potentially modified elsewhere are no
1659       longer permitted
1660           (F) You wrote something like
1661
1662               my $var;
1663               $sub = sub () { $var };
1664
1665           but $var is referenced elsewhere and could be modified after the
1666           "sub" expression is evaluated.  Either it is explicitly modified
1667           elsewhere ("$var = 3") or it is passed to a subroutine or to an
1668           operator like "printf" or "map", which may or may not modify the
1669           variable.
1670
1671           Traditionally, Perl has captured the value of the variable at that
1672           point and turned the subroutine into a constant eligible for
1673           inlining.  In those cases where the variable can be modified
1674           elsewhere, this breaks the behavior of closures, in which the
1675           subroutine captures the variable itself, rather than its value, so
1676           future changes to the variable are reflected in the subroutine's
1677           return value.
1678
1679           This usage was deprecated, and as of Perl 5.32 is no longer
1680           allowed, making it possible to change the behavior in the future.
1681
1682           If you intended for the subroutine to be eligible for inlining,
1683           then make sure the variable is not referenced elsewhere, possibly
1684           by copying it:
1685
1686               my $var2 = $var;
1687               $sub = sub () { $var2 };
1688
1689           If you do want this subroutine to be a closure that reflects future
1690           changes to the variable that it closes over, add an explicit
1691           "return":
1692
1693               my $var;
1694               $sub = sub () { return $var };
1695
1696       Constant subroutine %s redefined
1697           (W redefine)(S) You redefined a subroutine which had previously
1698           been eligible for inlining.  See "Constant Functions" in perlsub
1699           for commentary and workarounds.
1700
1701       Constant subroutine %s undefined
1702           (W misc) You undefined a subroutine which had previously been
1703           eligible for inlining.  See "Constant Functions" in perlsub for
1704           commentary and workarounds.
1705
1706       Constant(%s) unknown
1707           (F) The parser found inconsistencies either while attempting to
1708           define an overloaded constant, or when trying to find the character
1709           name specified in the "\N{...}" escape.  Perhaps you forgot to load
1710           the corresponding overload pragma?
1711
1712       :const is experimental
1713           (S experimental::const_attr) The "const" attribute is experimental.
1714           If you want to use the feature, disable the warning with "no
1715           warnings 'experimental::const_attr'", but know that in doing so you
1716           are taking the risk that your code may break in a future Perl
1717           version.
1718
1719       :const is not permitted on named subroutines
1720           (F) The "const" attribute causes an anonymous subroutine to be run
1721           and its value captured at the time that it is cloned.  Named
1722           subroutines are not cloned like this, so the attribute does not
1723           make sense on them.
1724
1725       Copy method did not return a reference
1726           (F) The method which overloads "=" is buggy.  See "Copy
1727           Constructor" in overload.
1728
1729       &CORE::%s cannot be called directly
1730           (F) You tried to call a subroutine in the "CORE::" namespace with
1731           &foo syntax or through a reference.  Some subroutines in this
1732           package cannot yet be called that way, but must be called as
1733           barewords.  Something like this will work:
1734
1735               BEGIN { *shove = \&CORE::push; }
1736               shove @array, 1,2,3; # pushes on to @array
1737
1738       CORE::%s is not a keyword
1739           (F) The CORE:: namespace is reserved for Perl keywords.
1740
1741       Corrupted regexp opcode %d > %d
1742           (P) This is either an error in Perl, or, if you're using one, your
1743           custom regular expression engine.  If not the latter, report the
1744           problem to <https://github.com/Perl/perl5/issues>.
1745
1746       corrupted regexp pointers
1747           (P) The regular expression engine got confused by what the regular
1748           expression compiler gave it.
1749
1750       corrupted regexp program
1751           (P) The regular expression engine got passed a regexp program
1752           without a valid magic number.
1753
1754       Corrupt malloc ptr 0x%x at 0x%x
1755           (P) The malloc package that comes with Perl had an internal
1756           failure.
1757
1758       Count after length/code in unpack
1759           (F) You had an unpack template indicating a counted-length string,
1760           but you have also specified an explicit size for the string.  See
1761           "pack" in perlfunc.
1762
1763       Declaring references is experimental
1764           (S experimental::declared_refs) This warning is emitted if you use
1765           a reference constructor on the right-hand side of "my", "state",
1766           "our", or "local".  Simply suppress the warning if you want to use
1767           the feature, but know that in doing so you are taking the risk of
1768           using an experimental feature which may change or be removed in a
1769           future Perl version:
1770
1771               no warnings "experimental::declared_refs";
1772               use feature "declared_refs";
1773               $fooref = my \$foo;
1774
1775       Deep recursion on anonymous subroutine
1776       Deep recursion on subroutine "%s"
1777           (W recursion) This subroutine has called itself (directly or
1778           indirectly) 100 times more than it has returned.  This probably
1779           indicates an infinite recursion, unless you're writing strange
1780           benchmark programs, in which case it indicates something else.
1781
1782           This threshold can be changed from 100, by recompiling the perl
1783           binary, setting the C pre-processor macro "PERL_SUB_DEPTH_WARN" to
1784           the desired value.
1785
1786       (?(DEFINE)....) does not allow branches in regex; marked by <-- HERE in
1787       m/%s/
1788           (F) You used something like "(?(DEFINE)...|..)" which is illegal.
1789           The most likely cause of this error is that you left out a
1790           parenthesis inside of the "...." part.
1791
1792           The <-- HERE shows whereabouts in the regular expression the
1793           problem was discovered.
1794
1795       %s defines neither package nor VERSION--version check failed
1796           (F) You said something like "use Module 42" but in the Module file
1797           there are neither package declarations nor a $VERSION.
1798
1799       delete argument is not a HASH or ARRAY element or slice
1800           (F) The argument to "delete" must be either a hash or array
1801           element, such as:
1802
1803               $foo{$bar}
1804               $ref->{"susie"}[12]
1805
1806           or a hash or array slice, such as:
1807
1808               @foo[$bar, $baz, $xyzzy]
1809               @{$ref->[12]}{"susie", "queue"}
1810
1811           or a hash key/value or array index/value slice, such as:
1812
1813               %foo[$bar, $baz, $xyzzy]
1814               %{$ref->[12]}{"susie", "queue"}
1815
1816       Delimiter for here document is too long
1817           (F) In a here document construct like "<<FOO", the label "FOO" is
1818           too long for Perl to handle.  You have to be seriously twisted to
1819           write code that triggers this error.
1820
1821       Deprecated use of my() in false conditional. This will be a fatal error
1822       in Perl 5.30
1823           (D deprecated) You used a declaration similar to "my $x if 0".
1824           There has been a long-standing bug in Perl that causes a lexical
1825           variable not to be cleared at scope exit when its declaration
1826           includes a false conditional.  Some people have exploited this bug
1827           to achieve a kind of static variable.  Since we intend to fix this
1828           bug, we don't want people relying on this behavior.  You can
1829           achieve a similar static effect by declaring the variable in a
1830           separate block outside the function, eg
1831
1832               sub f { my $x if 0; return $x++ }
1833
1834           becomes
1835
1836               { my $x; sub f { return $x++ } }
1837
1838           Beginning with perl 5.10.0, you can also use "state" variables to
1839           have lexicals that are initialized only once (see feature):
1840
1841               sub f { state $x; return $x++ }
1842
1843           This use of "my()" in a false conditional has been deprecated since
1844           Perl 5.10, and it will become a fatal error in Perl 5.30.
1845
1846       DESTROY created new reference to dead object '%s'
1847           (F) A DESTROY() method created a new reference to the object which
1848           is just being DESTROYed.  Perl is confused, and prefers to abort
1849           rather than to create a dangling reference.
1850
1851       Did not produce a valid header
1852           See "500 Server error".
1853
1854       %s did not return a true value
1855           (F) A required (or used) file must return a true value to indicate
1856           that it compiled correctly and ran its initialization code
1857           correctly.  It's traditional to end such a file with a "1;", though
1858           any true value would do.  See "require" in perlfunc.
1859
1860       (Did you mean &%s instead?)
1861           (W misc) You probably referred to an imported subroutine &FOO as
1862           $FOO or some such.
1863
1864       (Did you mean "local" instead of "our"?)
1865           (W shadow) Remember that "our" does not localize the declared
1866           global variable.  You have declared it again in the same lexical
1867           scope, which seems superfluous.
1868
1869       (Did you mean $ or @ instead of %?)
1870           (W) You probably said %hash{$key} when you meant $hash{$key} or
1871           @hash{@keys}.  On the other hand, maybe you just meant %hash and
1872           got carried away.
1873
1874       Died
1875           (F) You passed die() an empty string (the equivalent of "die """)
1876           or you called it with no args and $@ was empty.
1877
1878       Document contains no data
1879           See "500 Server error".
1880
1881       %s does not define %s::VERSION--version check failed
1882           (F) You said something like "use Module 42" but the Module did not
1883           define a $VERSION.
1884
1885       '/' does not take a repeat count
1886           (F) You cannot put a repeat count of any kind right after the '/'
1887           code.  See "pack" in perlfunc.
1888
1889       do "%s" failed, '.' is no longer in @INC; did you mean do "./%s"?
1890           (D deprecated) Previously " do "somefile"; " would search the
1891           current directory for the specified file.  Since perl v5.26.0, .
1892           has been removed from @INC by default, so this is no longer true.
1893           To search the current directory (and only the current directory)
1894           you can write " do "./somefile"; ".
1895
1896       Don't know how to get file name
1897           (P) "PerlIO_getname", a perl internal I/O function specific to VMS,
1898           was somehow called on another platform.  This should not happen.
1899
1900       Don't know how to handle magic of type \%o
1901           (P) The internal handling of magical variables has been cursed.
1902
1903       do_study: out of memory
1904           (P) This should have been caught by safemalloc() instead.
1905
1906       (Do you need to predeclare %s?)
1907           (S syntax) This is an educated guess made in conjunction with the
1908           message "%s found where operator expected".  It often means a
1909           subroutine or module name is being referenced that hasn't been
1910           declared yet.  This may be because of ordering problems in your
1911           file, or because of a missing "sub", "package", "require", or "use"
1912           statement.  If you're referencing something that isn't defined yet,
1913           you don't actually have to define the subroutine or package before
1914           the current location.  You can use an empty "sub foo;" or "package
1915           FOO;" to enter a "forward" declaration.
1916
1917       dump() must be written as CORE::dump() as of Perl 5.30
1918           (F) You used the obsolete "dump()" built-in function.  That was
1919           deprecated in Perl 5.8.0.  As of Perl 5.30 it must be written in
1920           fully qualified format: "CORE::dump()".
1921
1922           See "dump" in perlfunc.
1923
1924       dump is not supported
1925           (F) Your machine doesn't support dump/undump.
1926
1927       Duplicate free() ignored
1928           (S malloc) An internal routine called free() on something that had
1929           already been freed.
1930
1931       Duplicate modifier '%c' after '%c' in %s
1932           (W unpack) You have applied the same modifier more than once after
1933           a type in a pack template.  See "pack" in perlfunc.
1934
1935       elseif should be elsif
1936           (S syntax) There is no keyword "elseif" in Perl because Larry
1937           thinks it's ugly.  Your code will be interpreted as an attempt to
1938           call a method named "elseif" for the class returned by the
1939           following block.  This is unlikely to be what you want.
1940
1941       Empty \%c in regex; marked by <-- HERE in m/%s/
1942       Empty \%c{}
1943       Empty \%c{} in regex; marked by <-- HERE in m/%s/
1944           (F) You used something like "\b{}", "\B{}", "\o{}", "\p", "\P", or
1945           "\x" without specifying anything for it to operate on.
1946
1947           Unfortunately, for backwards compatibility reasons, an empty "\x"
1948           is legal outside "use re 'strict'" and expands to a NUL character.
1949
1950       Empty (?) without any modifiers in regex; marked by <-- HERE in m/%s/
1951           (W regexp) (only under "use re 'strict'") "(?)" does nothing, so
1952           perhaps this is a typo.
1953
1954       ${^ENCODING} is no longer supported
1955           (F) The special variable "${^ENCODING}", formerly used to implement
1956           the "encoding" pragma, is no longer supported as of Perl 5.26.0.
1957
1958           Setting it to anything other than "undef" is a fatal error as of
1959           Perl 5.28.
1960
1961       entering effective %s failed
1962           (F) While under the "use filetest" pragma, switching the real and
1963           effective uids or gids failed.
1964
1965       %ENV is aliased to %s
1966           (F) You're running under taint mode, and the %ENV variable has been
1967           aliased to another hash, so it doesn't reflect anymore the state of
1968           the program's environment.  This is potentially insecure.
1969
1970       Error converting file specification %s
1971           (F) An error peculiar to VMS.  Because Perl may have to deal with
1972           file specifications in either VMS or Unix syntax, it converts them
1973           to a single form when it must operate on them directly.  Either
1974           you've passed an invalid file specification to Perl, or you've
1975           found a case the conversion routines don't handle.  Drat.
1976
1977       Error %s in expansion of %s
1978           (F) An error was encountered in handling a user-defined property
1979           ("User-Defined Character Properties" in perlunicode).  These are
1980           programmer written subroutines, hence subject to errors that may
1981           prevent them from compiling or running.  The calls to these subs
1982           are "eval"'d, and if there is a failure, this message is raised,
1983           using the contents of $@ from the failed "eval".
1984
1985           Another possibility is that tainted data was encountered somewhere
1986           in the chain of expanding the property.  If so, the message wording
1987           will indicate that this is the problem.  See "Insecure user-defined
1988           property %s".
1989
1990       Eval-group in insecure regular expression
1991           (F) Perl detected tainted data when trying to compile a regular
1992           expression that contains the "(?{ ... })" zero-width assertion,
1993           which is unsafe.  See "(?{ code })" in perlre, and perlsec.
1994
1995       Eval-group not allowed at runtime, use re 'eval' in regex m/%s/
1996           (F) Perl tried to compile a regular expression containing the "(?{
1997           ... })" zero-width assertion at run time, as it would when the
1998           pattern contains interpolated values.  Since that is a security
1999           risk, it is not allowed.  If you insist, you may still do this by
2000           using the "re 'eval'" pragma or by explicitly building the pattern
2001           from an interpolated string at run time and using that in an
2002           eval().  See "(?{ code })" in perlre.
2003
2004       Eval-group not allowed, use re 'eval' in regex m/%s/
2005           (F) A regular expression contained the "(?{ ... })" zero-width
2006           assertion, but that construct is only allowed when the "use re
2007           'eval'" pragma is in effect.  See "(?{ code })" in perlre.
2008
2009       EVAL without pos change exceeded limit in regex; marked by <-- HERE in
2010       m/%s/
2011           (F) You used a pattern that nested too many EVAL calls without
2012           consuming any text.  Restructure the pattern so that text is
2013           consumed.
2014
2015           The <-- HERE shows whereabouts in the regular expression the
2016           problem was discovered.
2017
2018       Excessively long <> operator
2019           (F) The contents of a <> operator may not exceed the maximum size
2020           of a Perl identifier.  If you're just trying to glob a long list of
2021           filenames, try using the glob() operator, or put the filenames into
2022           a variable and glob that.
2023
2024       exec? I'm not *that* kind of operating system
2025           (F) The "exec" function is not implemented on some systems, e.g.,
2026           Symbian OS.  See perlport.
2027
2028       %sExecution of %s aborted due to compilation errors.
2029           (F) The final summary message when a Perl compilation fails.
2030
2031       exists argument is not a HASH or ARRAY element or a subroutine
2032           (F) The argument to "exists" must be a hash or array element or a
2033           subroutine with an ampersand, such as:
2034
2035               $foo{$bar}
2036               $ref->{"susie"}[12]
2037               &do_something
2038
2039       exists argument is not a subroutine name
2040           (F) The argument to "exists" for "exists &sub" must be a subroutine
2041           name, and not a subroutine call.  "exists &sub()" will generate
2042           this error.
2043
2044       Exiting eval via %s
2045           (W exiting) You are exiting an eval by unconventional means, such
2046           as a goto, or a loop control statement.
2047
2048       Exiting format via %s
2049           (W exiting) You are exiting a format by unconventional means, such
2050           as a goto, or a loop control statement.
2051
2052       Exiting pseudo-block via %s
2053           (W exiting) You are exiting a rather special block construct (like
2054           a sort block or subroutine) by unconventional means, such as a
2055           goto, or a loop control statement.  See "sort" in perlfunc.
2056
2057       Exiting subroutine via %s
2058           (W exiting) You are exiting a subroutine by unconventional means,
2059           such as a goto, or a loop control statement.
2060
2061       Exiting substitution via %s
2062           (W exiting) You are exiting a substitution by unconventional means,
2063           such as a return, a goto, or a loop control statement.
2064
2065       Expecting close bracket in regex; marked by <-- HERE in m/%s/
2066           (F) You wrote something like
2067
2068            (?13
2069
2070           to denote a capturing group of the form "(?PARNO)", but omitted the
2071           ")".
2072
2073       Expecting interpolated extended charclass in regex; marked by <-- HERE
2074       in m/%s/
2075           (F) It looked like you were attempting to interpolate an already-
2076           compiled extended character class, like so:
2077
2078            my $thai_or_lao = qr/(?[ \p{Thai} + \p{Lao} ])/;
2079            ...
2080            qr/(?[ \p{Digit} & $thai_or_lao ])/;
2081
2082           But the marked code isn't syntactically correct to be such an
2083           interpolated class.
2084
2085       Experimental aliasing via reference not enabled
2086           (F) To do aliasing via references, you must first enable the
2087           feature:
2088
2089               no warnings "experimental::refaliasing";
2090               use feature "refaliasing";
2091               \$x = \$y;
2092
2093       Experimental %s on scalar is now forbidden
2094           (F) An experimental feature added in Perl 5.14 allowed "each",
2095           "keys", "push", "pop", "shift", "splice", "unshift", and "values"
2096           to be called with a scalar argument.  This experiment is considered
2097           unsuccessful, and has been removed.  The "postderef" feature may
2098           meet your needs better.
2099
2100       Experimental subroutine signatures not enabled
2101           (F) To use subroutine signatures, you must first enable them:
2102
2103               no warnings "experimental::signatures";
2104               use feature "signatures";
2105               sub foo ($left, $right) { ... }
2106
2107       Explicit blessing to '' (assuming package main)
2108           (W misc) You are blessing a reference to a zero length string.
2109           This has the effect of blessing the reference into the package
2110           main.  This is usually not what you want.  Consider providing a
2111           default target package, e.g. bless($ref, $p || 'MyPackage');
2112
2113       %s: Expression syntax
2114           (A) You've accidentally run your script through csh instead of
2115           Perl.  Check the #! line, or manually feed your script into Perl
2116           yourself.
2117
2118       %s failed--call queue aborted
2119           (F) An untrapped exception was raised while executing a UNITCHECK,
2120           CHECK, INIT, or END subroutine.  Processing of the remainder of the
2121           queue of such routines has been prematurely ended.
2122
2123       Failed to close in-place work file %s: %s
2124           (F) Closing an output file from in-place editing, as with the "-i"
2125           command-line switch, failed.
2126
2127       False [] range "%s" in regex; marked by <-- HERE in m/%s/
2128           (W regexp)(F) A character class range must start and end at a
2129           literal character, not another character class like "\d" or
2130           "[:alpha:]".  The "-" in your false range is interpreted as a
2131           literal "-".  In a "(?[...])"  construct, this is an error, rather
2132           than a warning.  Consider quoting the "-", "\-".  The <-- HERE
2133           shows whereabouts in the regular expression the problem was
2134           discovered.  See perlre.
2135
2136       Fatal VMS error (status=%d) at %s, line %d
2137           (P) An error peculiar to VMS.  Something untoward happened in a VMS
2138           system service or RTL routine; Perl's exit status should provide
2139           more details.  The filename in "at %s" and the line number in "line
2140           %d" tell you which section of the Perl source code is distressed.
2141
2142       fcntl is not implemented
2143           (F) Your machine apparently doesn't implement fcntl().  What is
2144           this, a PDP-11 or something?
2145
2146       FETCHSIZE returned a negative value
2147           (F) A tied array claimed to have a negative number of elements,
2148           which is not possible.
2149
2150       Field too wide in 'u' format in pack
2151           (W pack) Each line in an uuencoded string starts with a length
2152           indicator which can't encode values above 63.  So there is no point
2153           in asking for a line length bigger than that.  Perl will behave as
2154           if you specified "u63" as the format.
2155
2156       File::Glob::glob() will disappear in perl 5.30. Use
2157       File::Glob::bsd_glob() instead.
2158           (D deprecated) "File::Glob" has a function called "glob", which
2159           just calls "bsd_glob". However, its prototype is different from the
2160           prototype of "CORE::glob", and hence, "File::Glob::glob" should not
2161           be used.
2162
2163           "File::Glob::glob()" was deprecated in perl 5.8.0. A deprecation
2164           message was issued from perl 5.26.0 onwards, and the function will
2165           disappear in perl 5.30.0.
2166
2167           Code using "File::Glob::glob()" should call
2168           "File::Glob::bsd_glob()" instead.
2169
2170       Filehandle %s opened only for input
2171           (W io) You tried to write on a read-only filehandle.  If you
2172           intended it to be a read-write filehandle, you needed to open it
2173           with "+<" or "+>" or "+>>" instead of with "<" or nothing.  If you
2174           intended only to write the file, use ">" or ">>".  See "open" in
2175           perlfunc.
2176
2177       Filehandle %s opened only for output
2178           (W io) You tried to read from a filehandle opened only for writing,
2179           If you intended it to be a read/write filehandle, you needed to
2180           open it with "+<" or "+>" or "+>>" instead of with ">".  If you
2181           intended only to read from the file, use "<".  See "open" in
2182           perlfunc.  Another possibility is that you attempted to open
2183           filedescriptor 0 (also known as STDIN) for output (maybe you closed
2184           STDIN earlier?).
2185
2186       Filehandle %s reopened as %s only for input
2187           (W io) You opened for reading a filehandle that got the same
2188           filehandle id as STDOUT or STDERR.  This occurred because you
2189           closed STDOUT or STDERR previously.
2190
2191       Filehandle STDIN reopened as %s only for output
2192           (W io) You opened for writing a filehandle that got the same
2193           filehandle id as STDIN.  This occurred because you closed STDIN
2194           previously.
2195
2196       Final $ should be \$ or $name
2197           (F) You must now decide whether the final $ in a string was meant
2198           to be a literal dollar sign, or was meant to introduce a variable
2199           name that happens to be missing.  So you have to put either the
2200           backslash or the name.
2201
2202       flock() on closed filehandle %s
2203           (W closed) The filehandle you're attempting to flock() got itself
2204           closed some time before now.  Check your control flow.  flock()
2205           operates on filehandles.  Are you attempting to call flock() on a
2206           dirhandle by the same name?
2207
2208       Format not terminated
2209           (F) A format must be terminated by a line with a solitary dot.
2210           Perl got to the end of your file without finding such a line.
2211
2212       Format %s redefined
2213           (W redefine) You redefined a format.  To suppress this warning, say
2214
2215               {
2216                   no warnings 'redefine';
2217                   eval "format NAME =...";
2218               }
2219
2220       Found = in conditional, should be ==
2221           (W syntax) You said
2222
2223               if ($foo = 123)
2224
2225           when you meant
2226
2227               if ($foo == 123)
2228
2229           (or something like that).
2230
2231       %s found where operator expected
2232           (S syntax) The Perl lexer knows whether to expect a term or an
2233           operator.  If it sees what it knows to be a term when it was
2234           expecting to see an operator, it gives you this warning.  Usually
2235           it indicates that an operator or delimiter was omitted, such as a
2236           semicolon.
2237
2238       gdbm store returned %d, errno %d, key "%s"
2239           (S) A warning from the GDBM_File extension that a store failed.
2240
2241       gethostent not implemented
2242           (F) Your C library apparently doesn't implement gethostent(),
2243           probably because if it did, it'd feel morally obligated to return
2244           every hostname on the Internet.
2245
2246       get%sname() on closed socket %s
2247           (W closed) You tried to get a socket or peer socket name on a
2248           closed socket.  Did you forget to check the return value of your
2249           socket() call?
2250
2251       getpwnam returned invalid UIC %#o for user "%s"
2252           (S) A warning peculiar to VMS.  The call to "sys$getuai" underlying
2253           the "getpwnam" operator returned an invalid UIC.
2254
2255       getsockopt() on closed socket %s
2256           (W closed) You tried to get a socket option on a closed socket.
2257           Did you forget to check the return value of your socket() call?
2258           See "getsockopt" in perlfunc.
2259
2260       given is experimental
2261           (S experimental::smartmatch) "given" depends on smartmatch, which
2262           is experimental, so its behavior may change or even be removed in
2263           any future release of perl.  See the explanation under
2264           "Experimental Details on given and when" in perlsyn.
2265
2266       Global symbol "%s" requires explicit package name (did you forget to
2267       declare "my %s"?)
2268           (F) You've said "use strict" or "use strict vars", which indicates
2269           that all variables must either be lexically scoped (using "my" or
2270           "state"), declared beforehand using "our", or explicitly qualified
2271           to say which package the global variable is in (using "::").
2272
2273       glob failed (%s)
2274           (S glob) Something went wrong with the external program(s) used for
2275           "glob" and "<*.c>".  Usually, this means that you supplied a "glob"
2276           pattern that caused the external program to fail and exit with a
2277           nonzero status.  If the message indicates that the abnormal exit
2278           resulted in a coredump, this may also mean that your csh (C shell)
2279           is broken.  If so, you should change all of the csh-related
2280           variables in config.sh:  If you have tcsh, make the variables refer
2281           to it as if it were csh (e.g. "full_csh='/usr/bin/tcsh'");
2282           otherwise, make them all empty (except that "d_csh" should be
2283           'undef') so that Perl will think csh is missing.  In either case,
2284           after editing config.sh, run "./Configure -S" and rebuild Perl.
2285
2286       Glob not terminated
2287           (F) The lexer saw a left angle bracket in a place where it was
2288           expecting a term, so it's looking for the corresponding right angle
2289           bracket, and not finding it.  Chances are you left some needed
2290           parentheses out earlier in the line, and you really meant a "less
2291           than".
2292
2293       gmtime(%f) failed
2294           (W overflow) You called "gmtime" with a number that it could not
2295           handle: too large, too small, or NaN.  The returned value is
2296           "undef".
2297
2298       gmtime(%f) too large
2299           (W overflow) You called "gmtime" with a number that was larger than
2300           it can reliably handle and "gmtime" probably returned the wrong
2301           date.  This warning is also triggered with NaN (the special not-a-
2302           number value).
2303
2304       gmtime(%f) too small
2305           (W overflow) You called "gmtime" with a number that was smaller
2306           than it can reliably handle and "gmtime" probably returned the
2307           wrong date.
2308
2309       Got an error from DosAllocMem
2310           (P) An error peculiar to OS/2.  Most probably you're using an
2311           obsolete version of Perl, and this should not happen anyway.
2312
2313       goto must have label
2314           (F) Unlike with "next" or "last", you're not allowed to goto an
2315           unspecified destination.  See "goto" in perlfunc.
2316
2317       Goto undefined subroutine%s
2318           (F) You tried to call a subroutine with "goto &sub" syntax, but the
2319           indicated subroutine hasn't been defined, or if it was, it has
2320           since been undefined.
2321
2322       Group name must start with a non-digit word character in regex; marked
2323       by <-- HERE in m/%s/
2324           (F) Group names must follow the rules for perl identifiers, meaning
2325           they must start with a non-digit word character.  A common cause of
2326           this error is using (?&0) instead of (?0).  See perlre.
2327
2328       ()-group starts with a count
2329           (F) A ()-group started with a count.  A count is supposed to follow
2330           something: a template character or a ()-group.  See "pack" in
2331           perlfunc.
2332
2333       %s had compilation errors.
2334           (F) The final summary message when a "perl -c" fails.
2335
2336       Had to create %s unexpectedly
2337           (S internal) A routine asked for a symbol from a symbol table that
2338           ought to have existed already, but for some reason it didn't, and
2339           had to be created on an emergency basis to prevent a core dump.
2340
2341       %s has too many errors
2342           (F) The parser has given up trying to parse the program after 10
2343           errors.  Further error messages would likely be uninformative.
2344
2345       Hexadecimal float: exponent overflow
2346           (W overflow) The hexadecimal floating point has a larger exponent
2347           than the floating point supports.
2348
2349       Hexadecimal float: exponent underflow
2350           (W overflow) The hexadecimal floating point has a smaller exponent
2351           than the floating point supports.  With the IEEE 754 floating
2352           point, this may also mean that the subnormals (formerly known as
2353           denormals) are being used, which may or may not be an error.
2354
2355       Hexadecimal float: internal error (%s)
2356           (F) Something went horribly bad in hexadecimal float handling.
2357
2358       Hexadecimal float: mantissa overflow
2359           (W overflow) The hexadecimal floating point literal had more bits
2360           in the mantissa (the part between the 0x and the exponent, also
2361           known as the fraction or the significand) than the floating point
2362           supports.
2363
2364       Hexadecimal float: precision loss
2365           (W overflow) The hexadecimal floating point had internally more
2366           digits than could be output.  This can be caused by unsupported
2367           long double formats, or by 64-bit integers not being available
2368           (needed to retrieve the digits under some configurations).
2369
2370       Hexadecimal float: unsupported long double format
2371           (F) You have configured Perl to use long doubles but the internals
2372           of the long double format are unknown; therefore the hexadecimal
2373           float output is impossible.
2374
2375       Hexadecimal number > 0xffffffff non-portable
2376           (W portable) The hexadecimal number you specified is larger than
2377           2**32-1 (4294967295) and therefore non-portable between systems.
2378           See perlport for more on portability concerns.
2379
2380       Identifier too long
2381           (F) Perl limits identifiers (names for variables, functions, etc.)
2382           to about 250 characters for simple names, and somewhat more for
2383           compound names (like $A::B).  You've exceeded Perl's limits.
2384           Future versions of Perl are likely to eliminate these arbitrary
2385           limitations.
2386
2387       Ignoring zero length \N{} in character class in regex; marked by
2388       <-- HERE in m/%s/
2389           (W regexp) Named Unicode character escapes ("\N{...}") may return a
2390           zero-length sequence.  When such an escape is used in a character
2391           class its behavior is not well defined.  Check that the correct
2392           escape has been used, and the correct charname handler is in scope.
2393
2394       Illegal %s digit '%c' ignored
2395           (W digit) Here %s is one of "binary", "octal", or "hex".  You may
2396           have tried to use a digit other than one that is legal for the
2397           given type, such as only 0 and 1 for binary.  For octals, this is
2398           raised only if the illegal character is an '8' or '9'.  For hex,
2399           'A' - 'F' and 'a' - 'f' are legal.  Interpretation of the number
2400           stopped just before the offending digit or character.
2401
2402       Illegal binary digit '%c'
2403           (F) You used a digit other than 0 or 1 in a binary number.
2404
2405       Illegal character after '_' in prototype for %s : %s
2406           (W illegalproto) An illegal character was found in a prototype
2407           declaration.  The '_' in a prototype must be followed by a ';',
2408           indicating the rest of the parameters are optional, or one of '@'
2409           or '%', since those two will accept 0 or more final parameters.
2410
2411       Illegal character \%o (carriage return)
2412           (F) Perl normally treats carriage returns in the program text as it
2413           would any other whitespace, which means you should never see this
2414           error when Perl was built using standard options.  For some reason,
2415           your version of Perl appears to have been built without this
2416           support.  Talk to your Perl administrator.
2417
2418       Illegal character following sigil in a subroutine signature
2419           (F) A parameter in a subroutine signature contained an unexpected
2420           character following the "$", "@" or "%" sigil character.  Normally
2421           the sigil should be followed by the variable name or "=" etc.
2422           Perhaps you are trying use a prototype while in the scope of "use
2423           feature 'signatures'"?  For example:
2424
2425               sub foo ($$) {}            # legal - a prototype
2426
2427               use feature 'signatures;
2428               sub foo ($$) {}            # illegal - was expecting a signature
2429               sub foo ($a, $b)
2430                       :prototype($$) {}  # legal
2431
2432       Illegal character in prototype for %s : %s
2433           (W illegalproto) An illegal character was found in a prototype
2434           declaration.  Legal characters in prototypes are $, @, %, *, ;, [,
2435           ], &, \, and +.  Perhaps you were trying to write a subroutine
2436           signature but didn't enable that feature first ("use feature
2437           'signatures'"), so your signature was instead interpreted as a bad
2438           prototype.
2439
2440       Illegal declaration of anonymous subroutine
2441           (F) When using the "sub" keyword to construct an anonymous
2442           subroutine, you must always specify a block of code.  See perlsub.
2443
2444       Illegal declaration of subroutine %s
2445           (F) A subroutine was not declared correctly.  See perlsub.
2446
2447       Illegal division by zero
2448           (F) You tried to divide a number by 0.  Either something was wrong
2449           in your logic, or you need to put a conditional in to guard against
2450           meaningless input.
2451
2452       Illegal modulus zero
2453           (F) You tried to divide a number by 0 to get the remainder.  Most
2454           numbers don't take to this kindly.
2455
2456       Illegal number of bits in vec
2457           (F) The number of bits in vec() (the third argument) must be a
2458           power of two from 1 to 32 (or 64, if your platform supports that).
2459
2460       Illegal octal digit '%c'
2461           (F) You used an 8 or 9 in an octal number.
2462
2463       Illegal operator following parameter in a subroutine signature
2464           (F) A parameter in a subroutine signature, was followed by
2465           something other than "=" introducing a default, "," or ")".
2466
2467               use feature 'signatures';
2468               sub foo ($=1) {}           # legal
2469               sub foo ($a = 1) {}        # legal
2470               sub foo ($a += 1) {}       # illegal
2471               sub foo ($a == 1) {}       # illegal
2472
2473       Illegal pattern in regex; marked by <-- HERE in m/%s/
2474           (F) You wrote something like
2475
2476            (?+foo)
2477
2478           The "+" is valid only when followed by digits, indicating a
2479           capturing group.  See "(?PARNO)".
2480
2481       Illegal suidscript
2482           (F) The script run under suidperl was somehow illegal.
2483
2484       Illegal switch in PERL5OPT: -%c
2485           (X) The PERL5OPT environment variable may only be used to set the
2486           following switches: -[CDIMUdmtw].
2487
2488       Illegal user-defined property name
2489           (F) You specified a Unicode-like property name in a regular
2490           expression pattern (using "\p{}" or "\P{}") that Perl knows isn't
2491           an official Unicode property, and was likely meant to be a user-
2492           defined property name, but it can't be one of those, as they must
2493           begin with either "In" or "Is".  Check the spelling.  See also
2494           "Can't find Unicode property definition "%s"".
2495
2496       Ill-formed CRTL environ value "%s"
2497           (W internal) A warning peculiar to VMS.  Perl tried to read the
2498           CRTL's internal environ array, and encountered an element without
2499           the "=" delimiter used to separate keys from values.  The element
2500           is ignored.
2501
2502       Ill-formed message in prime_env_iter: |%s|
2503           (W internal) A warning peculiar to VMS.  Perl tried to read a
2504           logical name or CLI symbol definition when preparing to iterate
2505           over %ENV, and didn't see the expected delimiter between key and
2506           value, so the line was ignored.
2507
2508       (in cleanup) %s
2509           (W misc) This prefix usually indicates that a DESTROY() method
2510           raised the indicated exception.  Since destructors are usually
2511           called by the system at arbitrary points during execution, and
2512           often a vast number of times, the warning is issued only once for
2513           any number of failures that would otherwise result in the same
2514           message being repeated.
2515
2516           Failure of user callbacks dispatched using the "G_KEEPERR" flag
2517           could also result in this warning.  See "G_KEEPERR" in perlcall.
2518
2519       Incomplete expression within '(?[ ])' in regex; marked by <-- HERE in
2520       m/%s/
2521           (F) There was a syntax error within the "(?[ ])".  This can happen
2522           if the expression inside the construct was completely empty, or if
2523           there are too many or few operands for the number of operators.
2524           Perl is not smart enough to give you a more precise indication as
2525           to what is wrong.
2526
2527       Inconsistent hierarchy during C3 merge of class '%s': merging failed on
2528       parent '%s'
2529           (F) The method resolution order (MRO) of the given class is not
2530           C3-consistent, and you have enabled the C3 MRO for this class.  See
2531           the C3 documentation in mro for more information.
2532
2533       Indentation on line %d of here-doc doesn't match delimiter
2534           (F) You have an indented here-document where one or more of its
2535           lines have whitespace at the beginning that does not match the
2536           closing delimiter.
2537
2538           For example, line 2 below is wrong because it does not have at
2539           least 2 spaces, but lines 1 and 3 are fine because they have at
2540           least 2:
2541
2542               if ($something) {
2543                 print <<~EOF;
2544                   Line 1
2545                  Line 2 not
2546                     Line 3
2547                   EOF
2548               }
2549
2550           Note that tabs and spaces are compared strictly, meaning 1 tab will
2551           not match 8 spaces.
2552
2553       Infinite recursion in regex
2554           (F) You used a pattern that references itself without consuming any
2555           input text.  You should check the pattern to ensure that recursive
2556           patterns either consume text or fail.
2557
2558       Infinite recursion in user-defined property
2559           (F) A user-defined property ("User-Defined Character Properties" in
2560           perlunicode) can depend on the definitions of other user-defined
2561           properties.  If the chain of dependencies leads back to this
2562           property, infinite recursion would occur, were it not for the check
2563           that raised this error.
2564
2565           Restructure your property definitions to avoid this.
2566
2567       Infinite recursion via empty pattern
2568           (F) You tried to use the empty pattern inside of a regex code
2569           block, for instance "/(?{ s!!! })/", which resulted in re-executing
2570           the same pattern, which is an infinite loop which is broken by
2571           throwing an exception.
2572
2573       Initialization of state variables in list currently forbidden
2574           (F) "state" only permits initializing a single variable, specified
2575           without parentheses.  So "state $a = 42" and "state @a = qw(a b c)"
2576           are allowed, but not "state ($a) = 42" or "(state $a) = 42".  To
2577           initialize more than one "state" variable, initialize them one at a
2578           time.
2579
2580       %%s[%s] in scalar context better written as $%s[%s]
2581           (W syntax) In scalar context, you've used an array index/value
2582           slice (indicated by %) to select a single element of an array.
2583           Generally it's better to ask for a scalar value (indicated by $).
2584           The difference is that $foo[&bar] always behaves like a scalar,
2585           both in the value it returns and when evaluating its argument,
2586           while %foo[&bar] provides a list context to its subscript, which
2587           can do weird things if you're expecting only one subscript.  When
2588           called in list context, it also returns the index (what &bar
2589           returns) in addition to the value.
2590
2591       %%s{%s} in scalar context better written as $%s{%s}
2592           (W syntax) In scalar context, you've used a hash key/value slice
2593           (indicated by %) to select a single element of a hash.  Generally
2594           it's better to ask for a scalar value (indicated by $).  The
2595           difference is that $foo{&bar} always behaves like a scalar, both in
2596           the value it returns and when evaluating its argument, while
2597           @foo{&bar} and provides a list context to its subscript, which can
2598           do weird things if you're expecting only one subscript.  When
2599           called in list context, it also returns the key in addition to the
2600           value.
2601
2602       Insecure dependency in %s
2603           (F) You tried to do something that the tainting mechanism didn't
2604           like.  The tainting mechanism is turned on when you're running
2605           setuid or setgid, or when you specify -T to turn it on explicitly.
2606           The tainting mechanism labels all data that's derived directly or
2607           indirectly from the user, who is considered to be unworthy of your
2608           trust.  If any such data is used in a "dangerous" operation, you
2609           get this error.  See perlsec for more information.
2610
2611       Insecure directory in %s
2612           (F) You can't use system(), exec(), or a piped open in a setuid or
2613           setgid script if $ENV{PATH} contains a directory that is writable
2614           by the world.  Also, the PATH must not contain any relative
2615           directory.  See perlsec.
2616
2617       Insecure $ENV{%s} while running %s
2618           (F) You can't use system(), exec(), or a piped open in a setuid or
2619           setgid script if any of $ENV{PATH}, $ENV{IFS}, $ENV{CDPATH},
2620           $ENV{ENV}, $ENV{BASH_ENV} or $ENV{TERM} are derived from data
2621           supplied (or potentially supplied) by the user.  The script must
2622           set the path to a known value, using trustworthy data.  See
2623           perlsec.
2624
2625       Insecure user-defined property %s
2626           (F) Perl detected tainted data when trying to compile a regular
2627           expression that contains a call to a user-defined character
2628           property function, i.e. "\p{IsFoo}" or "\p{InFoo}".  See "User-
2629           Defined Character Properties" in perlunicode and perlsec.
2630
2631       Integer overflow in format string for %s
2632           (F) The indexes and widths specified in the format string of
2633           "printf()" or "sprintf()" are too large.  The numbers must not
2634           overflow the size of integers for your architecture.
2635
2636       Integer overflow in %s number
2637           (S overflow) The hexadecimal, octal or binary number you have
2638           specified either as a literal or as an argument to hex() or oct()
2639           is too big for your architecture, and has been converted to a
2640           floating point number.  On a 32-bit architecture the largest
2641           hexadecimal, octal or binary number representable without overflow
2642           is 0xFFFFFFFF, 037777777777, or 0b11111111111111111111111111111111
2643           respectively.  Note that Perl transparently promotes all numbers to
2644           a floating point representation internally--subject to loss of
2645           precision errors in subsequent operations.
2646
2647       Integer overflow in srand
2648           (S overflow) The number you have passed to srand is too big to fit
2649           in your architecture's integer representation.  The number has been
2650           replaced with the largest integer supported (0xFFFFFFFF on 32-bit
2651           architectures).  This means you may be getting less randomness than
2652           you expect, because different random seeds above the maximum will
2653           return the same sequence of random numbers.
2654
2655       Integer overflow in version
2656       Integer overflow in version %d
2657           (W overflow) Some portion of a version initialization is too large
2658           for the size of integers for your architecture.  This is not a
2659           warning because there is no rational reason for a version to try
2660           and use an element larger than typically 2**32.  This is usually
2661           caused by trying to use some odd mathematical operation as a
2662           version, like 100/9.
2663
2664       Internal disaster in regex; marked by <-- HERE in m/%s/
2665           (P) Something went badly wrong in the regular expression parser.
2666           The <-- HERE shows whereabouts in the regular expression the
2667           problem was discovered.
2668
2669       Internal inconsistency in tracking vforks
2670           (S) A warning peculiar to VMS.  Perl keeps track of the number of
2671           times you've called "fork" and "exec", to determine whether the
2672           current call to "exec" should affect the current script or a
2673           subprocess (see "exec LIST" in perlvms).  Somehow, this count has
2674           become scrambled, so Perl is making a guess and treating this
2675           "exec" as a request to terminate the Perl script and execute the
2676           specified command.
2677
2678       internal %<num>p might conflict with future printf extensions
2679           (S internal) Perl's internal routine that handles "printf" and
2680           "sprintf" formatting follows a slightly different set of rules when
2681           called from C or XS code.  Specifically, formats consisting of
2682           digits followed by "p" (e.g., "%7p") are reserved for future use.
2683           If you see this message, then an XS module tried to call that
2684           routine with one such reserved format.
2685
2686       Internal urp in regex; marked by <-- HERE in m/%s/
2687           (P) Something went badly awry in the regular expression parser.
2688           The <-- HERE shows whereabouts in the regular expression the
2689           problem was discovered.
2690
2691       %s (...) interpreted as function
2692           (W syntax) You've run afoul of the rule that says that any list
2693           operator followed by parentheses turns into a function, with all
2694           the list operators arguments found inside the parentheses.  See
2695           "Terms and List Operators (Leftward)" in perlop.
2696
2697       In '(?...)', the '(' and '?' must be adjacent in regex; marked by
2698       <-- HERE in m/%s/
2699           (F) The two-character sequence "(?" in this context in a regular
2700           expression pattern should be an indivisible token, with nothing
2701           intervening between the "(" and the "?", but you separated them
2702           with whitespace.
2703
2704       In '(*...)', the '(' and '*' must be adjacent in regex; marked by
2705       <-- HERE in m/%s/
2706           (F) The two-character sequence "(*" in this context in a regular
2707           expression pattern should be an indivisible token, with nothing
2708           intervening between the "(" and the "*", but you separated them.
2709           Fix the pattern and retry.
2710
2711       Invalid %s attribute: %s
2712           (F) The indicated attribute for a subroutine or variable was not
2713           recognized by Perl or by a user-supplied handler.  See attributes.
2714
2715       Invalid %s attributes: %s
2716           (F) The indicated attributes for a subroutine or variable were not
2717           recognized by Perl or by a user-supplied handler.  See attributes.
2718
2719       Invalid character in charnames alias definition; marked by <-- HERE in
2720       '%s
2721           (F) You tried to create a custom alias for a character name, with
2722           the ":alias" option to "use charnames" and the specified character
2723           in the indicated name isn't valid.  See "CUSTOM ALIASES" in
2724           charnames.
2725
2726       Invalid \0 character in %s for %s: %s\0%s
2727           (W syscalls) Embedded \0 characters in pathnames or other system
2728           call arguments produce a warning as of 5.20.  The parts after the
2729           \0 were formerly ignored by system calls.
2730
2731       Invalid character in \N{...}; marked by <-- HERE in \N{%s}
2732           (F) Only certain characters are valid for character names.  The
2733           indicated one isn't.  See "CUSTOM ALIASES" in charnames.
2734
2735       Invalid conversion in %s: "%s"
2736           (W printf) Perl does not understand the given format conversion.
2737           See "sprintf" in perlfunc.
2738
2739       Invalid escape in the specified encoding in regex; marked by <-- HERE
2740       in m/%s/
2741           (W regexp)(F) The numeric escape (for example "\xHH") of value <
2742           256 didn't correspond to a single character through the conversion
2743           from the encoding specified by the encoding pragma.  The escape was
2744           replaced with REPLACEMENT CHARACTER (U+FFFD) instead, except within
2745           "(?[   ])", where it is a fatal error.  The <-- HERE shows
2746           whereabouts in the regular expression the escape was discovered.
2747
2748       Invalid hexadecimal number in \N{U+...}
2749       Invalid hexadecimal number in \N{U+...} in regex; marked by <-- HERE in
2750       m/%s/
2751           (F) The character constant represented by "..." is not a valid
2752           hexadecimal number.  Either it is empty, or you tried to use a
2753           character other than 0 - 9 or A - F, a - f in a hexadecimal number.
2754
2755       Invalid module name %s with -%c option: contains single ':'
2756           (F) The module argument to perl's -m and -M command-line options
2757           cannot contain single colons in the module name, but only in the
2758           arguments after "=".  In other words, -MFoo::Bar=:baz is ok, but
2759           -MFoo:Bar=baz is not.
2760
2761       Invalid mro name: '%s'
2762           (F) You tried to "mro::set_mro("classname", "foo")" or "use mro
2763           'foo'", where "foo" is not a valid method resolution order (MRO).
2764           Currently, the only valid ones supported are "dfs" and "c3", unless
2765           you have loaded a module that is a MRO plugin.  See mro and
2766           perlmroapi.
2767
2768       Invalid negative number (%s) in chr
2769           (W utf8) You passed a negative number to "chr".  Negative numbers
2770           are not valid character numbers, so it returns the Unicode
2771           replacement character (U+FFFD).
2772
2773       Invalid number '%s' for -C option.
2774           (F) You supplied a number to the -C option that either has extra
2775           leading zeroes or overflows perl's unsigned integer representation.
2776
2777       invalid option -D%c, use -D'' to see choices
2778           (S debugging) Perl was called with invalid debugger flags.  Call
2779           perl with the -D option with no flags to see the list of acceptable
2780           values.  See also "-Dletters" in perlrun.
2781
2782       Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/
2783           (F) The pattern looks like a {min,max} quantifier, but the min or
2784           max could not be parsed as a valid number - either it has leading
2785           zeroes, or it represents too big a number to cope with.  The
2786           <-- HERE shows where in the regular expression the problem was
2787           discovered.  See perlre.
2788
2789       Invalid [] range "%s" in regex; marked by <-- HERE in m/%s/
2790           (F) The range specified in a character class had a minimum
2791           character greater than the maximum character.  One possibility is
2792           that you forgot the "{}" from your ending "\x{}" - "\x" without the
2793           curly braces can go only up to "ff".  The <-- HERE shows
2794           whereabouts in the regular expression the problem was discovered.
2795           See perlre.
2796
2797       Invalid range "%s" in transliteration operator
2798           (F) The range specified in the tr/// or y/// operator had a minimum
2799           character greater than the maximum character.  See perlop.
2800
2801       Invalid reference to group in regex; marked by <-- HERE in m/%s/
2802           (F) The capture group you specified can't possibly exist because
2803           the number you used is not within the legal range of possible
2804           values for this machine.
2805
2806       Invalid separator character %s in attribute list
2807           (F) Something other than a colon or whitespace was seen between the
2808           elements of an attribute list.  If the previous attribute had a
2809           parenthesised parameter list, perhaps that list was terminated too
2810           soon.  See attributes.
2811
2812       Invalid separator character %s in PerlIO layer specification %s
2813           (W layer) When pushing layers onto the Perl I/O system, something
2814           other than a colon or whitespace was seen between the elements of a
2815           layer list.  If the previous attribute had a parenthesised
2816           parameter list, perhaps that list was terminated too soon.
2817
2818       Invalid strict version format (%s)
2819           (F) A version number did not meet the "strict" criteria for
2820           versions.  A "strict" version number is a positive decimal number
2821           (integer or decimal-fraction) without exponentiation or else a
2822           dotted-decimal v-string with a leading 'v' character and at least
2823           three components.  The parenthesized text indicates which criteria
2824           were not met.  See the version module for more details on allowed
2825           version formats.
2826
2827       Invalid type '%s' in %s
2828           (F) The given character is not a valid pack or unpack type.  See
2829           "pack" in perlfunc.
2830
2831           (W) The given character is not a valid pack or unpack type but used
2832           to be silently ignored.
2833
2834       Invalid version format (%s)
2835           (F) A version number did not meet the "lax" criteria for versions.
2836           A "lax" version number is a positive decimal number (integer or
2837           decimal-fraction) without exponentiation or else a dotted-decimal
2838           v-string.  If the v-string has fewer than three components, it must
2839           have a leading 'v' character.  Otherwise, the leading 'v' is
2840           optional.  Both decimal and dotted-decimal versions may have a
2841           trailing "alpha" component separated by an underscore character
2842           after a fractional or dotted-decimal component.  The parenthesized
2843           text indicates which criteria were not met.  See the version module
2844           for more details on allowed version formats.
2845
2846       Invalid version object
2847           (F) The internal structure of the version object was invalid.
2848           Perhaps the internals were modified directly in some way or an
2849           arbitrary reference was blessed into the "version" class.
2850
2851       In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by
2852       <-- HERE in m/%s/
2853       Inverting a character class which contains a multi-character sequence
2854       is illegal in regex; marked by <-- HERE in m/%s/
2855           (F) You wrote something like
2856
2857            qr/\P{name=KATAKANA LETTER AINU P}/
2858            qr/[^\p{name=KATAKANA LETTER AINU P}]/
2859
2860           This name actually evaluates to a sequence of two Katakana
2861           characters, not just a single one, and it is illegal to try to take
2862           the complement of a sequence.  (Mathematically it would mean any
2863           sequence of characters from 0 to infinity in length that weren't
2864           these two in a row, and that is likely not of any real use.)
2865
2866           (F) The two-character sequence "(*" in this context in a regular
2867           expression pattern should be an indivisible token, with nothing
2868           intervening between the "(" and the "*", but you separated them.
2869
2870       ioctl is not implemented
2871           (F) Your machine apparently doesn't implement ioctl(), which is
2872           pretty strange for a machine that supports C.
2873
2874       ioctl() on unopened %s
2875           (W unopened) You tried ioctl() on a filehandle that was never
2876           opened.  Check your control flow and number of arguments.
2877
2878       IO layers (like '%s') unavailable
2879           (F) Your Perl has not been configured to have PerlIO, and therefore
2880           you cannot use IO layers.  To have PerlIO, Perl must be configured
2881           with 'useperlio'.
2882
2883       IO::Socket::atmark not implemented on this architecture
2884           (F) Your machine doesn't implement the sockatmark() functionality,
2885           neither as a system call nor an ioctl call (SIOCATMARK).
2886
2887       '%s' is an unknown bound type in regex; marked by <-- HERE in m/%s/
2888           (F) You used "\b{...}" or "\B{...}" and the "..." is not known to
2889           Perl.  The current valid ones are given in "\b{}, \b, \B{}, \B" in
2890           perlrebackslash.
2891
2892       %s is forbidden - matches null string many times in regex; marked by
2893       <-- HERE in m/%s/
2894           (F) The pattern you've specified might cause the regular expression
2895           to infinite loop so it is forbidden.  The <-- HERE shows
2896           whereabouts in the regular expression the problem was discovered.
2897           See perlre.
2898
2899       %s() isn't allowed on :utf8 handles
2900           (F) The sysread(), recv(), syswrite() and send() operators are not
2901           allowed on handles that have the ":utf8" layer, either explicitly,
2902           or implicitly, eg., with the ":encoding(UTF-16LE)" layer.
2903
2904           Previously sysread() and recv() currently use only the ":utf8" flag
2905           for the stream, ignoring the actual layers.  Since sysread() and
2906           recv() did no UTF-8 validation they can end up creating invalidly
2907           encoded scalars.
2908
2909           Similarly, syswrite() and send() used only the ":utf8" flag,
2910           otherwise ignoring any layers.  If the flag is set, both wrote the
2911           value UTF-8 encoded, even if the layer is some different encoding,
2912           such as the example above.
2913
2914           Ideally, all of these operators would completely ignore the ":utf8"
2915           state, working only with bytes, but this would result in silently
2916           breaking existing code.
2917
2918       "%s" is more clearly written simply as "%s" in regex; marked by
2919       <-- HERE in m/%s/
2920           (W regexp) (only under "use re 'strict'" or within "(?[...])")
2921
2922           You specified a character that has the given plainer way of writing
2923           it, and which is also portable to platforms running with different
2924           character sets.
2925
2926       $* is no longer supported as of Perl 5.30
2927           (F) The special variable $*, deprecated in older perls, was removed
2928           in 5.10.0, is no longer supported and is a fatal error as of Perl
2929           5.30.  In previous versions of perl the use of $* enabled or
2930           disabled multi-line matching within a string.
2931
2932           Instead of using $* you should use the "/m" (and maybe "/s") regexp
2933           modifiers.  You can enable "/m" for a lexical scope (even a whole
2934           file) with "use re '/m'".  (In older versions: when $* was set to a
2935           true value then all regular expressions behaved as if they were
2936           written using "/m".)
2937
2938           Use of this variable will be a fatal error in Perl 5.30.
2939
2940       $# is no longer supported as of Perl 5.30
2941           (F) The special variable $#, deprecated in older perls, was removed
2942           as of 5.10.0, is no longer supported and is a fatal error as of
2943           Perl 5.30.  You should use the printf/sprintf functions instead.
2944
2945       '%s' is not a code reference
2946           (W overload) The second (fourth, sixth, ...) argument of
2947           overload::constant needs to be a code reference.  Either an
2948           anonymous subroutine, or a reference to a subroutine.
2949
2950       '%s' is not an overloadable type
2951           (W overload) You tried to overload a constant type the overload
2952           package is unaware of.
2953
2954       isa is experimental
2955           (S experimental::isa) This warning is emitted if you use the
2956           ("isa") operator. This operator is currently experimental and its
2957           behaviour may change in future releases of Perl.
2958
2959       -i used with no filenames on the command line, reading from STDIN
2960           (S inplace) The "-i" option was passed on the command line,
2961           indicating that the script is intended to edit files in place, but
2962           no files were given.  This is usually a mistake, since editing
2963           STDIN in place doesn't make sense, and can be confusing because it
2964           can make perl look like it is hanging when it is really just trying
2965           to read from STDIN.  You should either pass a filename to edit, or
2966           remove "-i" from the command line.  See perlrun for more details.
2967
2968       Junk on end of regexp in regex m/%s/
2969           (P) The regular expression parser is confused.
2970
2971       \K not permitted in lookahead/lookbehind in regex; marked by <-- HERE
2972       in m/%s/
2973           (F) Your regular expression used "\K" in a lookahead or lookbehind
2974           assertion, which currently isn't permitted.
2975
2976           This may change in the future, see Support \K in lookarounds
2977           <https://github.com/Perl/perl5/issues/18134>.
2978
2979       Label not found for "last %s"
2980           (F) You named a loop to break out of, but you're not currently in a
2981           loop of that name, not even if you count where you were called
2982           from.  See "last" in perlfunc.
2983
2984       Label not found for "next %s"
2985           (F) You named a loop to continue, but you're not currently in a
2986           loop of that name, not even if you count where you were called
2987           from.  See "last" in perlfunc.
2988
2989       Label not found for "redo %s"
2990           (F) You named a loop to restart, but you're not currently in a loop
2991           of that name, not even if you count where you were called from.
2992           See "last" in perlfunc.
2993
2994       leaving effective %s failed
2995           (F) While under the "use filetest" pragma, switching the real and
2996           effective uids or gids failed.
2997
2998       length/code after end of string in unpack
2999           (F) While unpacking, the string buffer was already used up when an
3000           unpack length/code combination tried to obtain more data.  This
3001           results in an undefined value for the length.  See "pack" in
3002           perlfunc.
3003
3004       length() used on %s (did you mean "scalar(%s)"?)
3005           (W syntax) You used length() on either an array or a hash when you
3006           probably wanted a count of the items.
3007
3008           Array size can be obtained by doing:
3009
3010               scalar(@array);
3011
3012           The number of items in a hash can be obtained by doing:
3013
3014               scalar(keys %hash);
3015
3016       Lexing code attempted to stuff non-Latin-1 character into Latin-1 input
3017           (F) An extension is attempting to insert text into the current
3018           parse (using lex_stuff_pvn or similar), but tried to insert a
3019           character that couldn't be part of the current input.  This is an
3020           inherent pitfall of the stuffing mechanism, and one of the reasons
3021           to avoid it.  Where it is necessary to stuff, stuffing only plain
3022           ASCII is recommended.
3023
3024       Lexing code internal error (%s)
3025           (F) Lexing code supplied by an extension violated the lexer's API
3026           in a detectable way.
3027
3028       listen() on closed socket %s
3029           (W closed) You tried to do a listen on a closed socket.  Did you
3030           forget to check the return value of your socket() call?  See
3031           "listen" in perlfunc.
3032
3033       List form of piped open not implemented
3034           (F) On some platforms, notably Windows, the three-or-more-arguments
3035           form of "open" does not support pipes, such as "open($pipe, '|-',
3036           @args)".  Use the two-argument "open($pipe, '|prog arg1 arg2...')"
3037           form instead.
3038
3039       Literal vertical space in [] is illegal except under /x in regex;
3040       marked by <-- HERE in m/%s/
3041           (F) (only under "use re 'strict'" or within "(?[...])")
3042
3043           Likely you forgot the "/x" modifier or there was a typo in the
3044           pattern.  For example, did you really mean to match a form-feed?
3045           If so, all the ASCII vertical space control characters are
3046           representable by escape sequences which won't present such a
3047           jarring appearance as your pattern does when displayed.
3048
3049             \r    carriage return
3050             \f    form feed
3051             \n    line feed
3052             \cK   vertical tab
3053
3054       %s: loadable library and perl binaries are mismatched (got handshake
3055       key %p, needed %p)
3056           (P) A dynamic loading library ".so" or ".dll" was being loaded into
3057           the process that was built against a different build of perl than
3058           the said library was compiled against.  Reinstalling the XS module
3059           will likely fix this error.
3060
3061       Locale '%s' contains (at least) the following characters which have
3062       unexpected meanings: %s  The Perl program will use the expected
3063       meanings
3064           (W locale) You are using the named UTF-8 locale.  UTF-8 locales are
3065           expected to have very particular behavior, which most do.  This
3066           message arises when perl found some departures from the
3067           expectations, and is notifying you that the expected behavior
3068           overrides these differences.  In some cases the differences are
3069           caused by the locale definition being defective, but the most
3070           common causes of this warning are when there are ambiguities and
3071           conflicts in following the Standard, and the locale has chosen an
3072           approach that differs from Perl's.
3073
3074           One of these is because that, contrary to the claims, Unicode is
3075           not completely locale insensitive.  Turkish and some related
3076           languages have two types of "I" characters.  One is dotted in both
3077           upper- and lowercase, and the other is dotless in both cases.
3078           Unicode allows a locale to use either the Turkish rules, or the
3079           rules used in all other instances, where there is only one type of
3080           "I", which is dotless in the uppercase, and dotted in the lower.
3081           The perl core does not (yet) handle the Turkish case, and this
3082           message warns you of that.  Instead, the Unicode::Casing module
3083           allows you to mostly implement the Turkish casing rules.
3084
3085           The other common cause is for the characters
3086
3087            $ + < = > ^ ` | ~
3088
3089           These are probematic.  The C standard says that these should be
3090           considered punctuation in the C locale (and the POSIX standard
3091           defers to the C standard), and Unicode is generally considered a
3092           superset of the C locale.  But Unicode has added an extra category,
3093           "Symbol", and classifies these particular characters as being
3094           symbols.  Most UTF-8 locales have them treated as punctuation, so
3095           that ispunct(2) returns non-zero for them.  But a few locales have
3096           it return 0.   Perl takes the first approach, not using "ispunct()"
3097           at all (see Note [5] in perlrecharclass), and this message is
3098           raised to notify you that you are getting Perl's approach, not the
3099           locale's.
3100
3101       Locale '%s' may not work well.%s
3102           (W locale) You are using the named locale, which is a non-UTF-8
3103           one, and which perl has determined is not fully compatible with
3104           what it can handle.  The second %s gives a reason.
3105
3106           By far the most common reason is that the locale has characters in
3107           it that are represented by more than one byte.  The only such
3108           locales that Perl can handle are the UTF-8 locales.  Most likely
3109           the specified locale is a non-UTF-8 one for an East Asian language
3110           such as Chinese or Japanese.  If the locale is a superset of ASCII,
3111           the ASCII portion of it may work in Perl.
3112
3113           Some essentially obsolete locales that aren't supersets of ASCII,
3114           mainly those in ISO 646 or other 7-bit locales, such as ASMO 449,
3115           can also have problems, depending on what portions of the ASCII
3116           character set get changed by the locale and are also used by the
3117           program.  The warning message lists the determinable conflicting
3118           characters.
3119
3120           Note that not all incompatibilities are found.
3121
3122           If this happens to you, there's not much you can do except switch
3123           to use a different locale or use Encode to translate from the
3124           locale into UTF-8; if that's impracticable, you have been warned
3125           that some things may break.
3126
3127           This message is output once each time a bad locale is switched into
3128           within the scope of "use locale", or on the first possibly-affected
3129           operation if the "use locale" inherits a bad one.  It is not raised
3130           for any operations from the POSIX module.
3131
3132       localtime(%f) failed
3133           (W overflow) You called "localtime" with a number that it could not
3134           handle: too large, too small, or NaN.  The returned value is
3135           "undef".
3136
3137       localtime(%f) too large
3138           (W overflow) You called "localtime" with a number that was larger
3139           than it can reliably handle and "localtime" probably returned the
3140           wrong date.  This warning is also triggered with NaN (the special
3141           not-a-number value).
3142
3143       localtime(%f) too small
3144           (W overflow) You called "localtime" with a number that was smaller
3145           than it can reliably handle and "localtime" probably returned the
3146           wrong date.
3147
3148       Lookbehind longer than %d not implemented in regex m/%s/
3149           (F) There is currently a limit on the length of string which
3150           lookbehind can handle.  This restriction may be eased in a future
3151           release.
3152
3153       Lost precision when %s %f by 1
3154           (W imprecision) The value you attempted to increment or decrement
3155           by one is too large for the underlying floating point
3156           representation to store accurately, hence the target of "++" or
3157           "--" is unchanged.  Perl issues this warning because it has already
3158           switched from integers to floating point when values are too large
3159           for integers, and now even floating point is insufficient.  You may
3160           wish to switch to using Math::BigInt explicitly.
3161
3162       lstat() on filehandle%s
3163           (W io) You tried to do an lstat on a filehandle.  What did you mean
3164           by that?  lstat() makes sense only on filenames.  (Perl did a
3165           fstat() instead on the filehandle.)
3166
3167       lvalue attribute %s already-defined subroutine
3168           (W misc) Although attributes.pm allows this, turning the lvalue
3169           attribute on or off on a Perl subroutine that is already defined
3170           does not always work properly.  It may or may not do what you want,
3171           depending on what code is inside the subroutine, with exact details
3172           subject to change between Perl versions.  Only do this if you
3173           really know what you are doing.
3174
3175       lvalue attribute ignored after the subroutine has been defined
3176           (W misc) Using the ":lvalue" declarative syntax to make a Perl
3177           subroutine an lvalue subroutine after it has been defined is not
3178           permitted.  To make the subroutine an lvalue subroutine, add the
3179           lvalue attribute to the definition, or put the "sub foo :lvalue;"
3180           declaration before the definition.
3181
3182           See also attributes.pm.
3183
3184       Magical list constants are not supported
3185           (F) You assigned a magical array to a stash element, and then tried
3186           to use the subroutine from the same slot.  You are asking Perl to
3187           do something it cannot do, details subject to change between Perl
3188           versions.
3189
3190       Malformed integer in [] in pack
3191           (F) Between the brackets enclosing a numeric repeat count only
3192           digits are permitted.  See "pack" in perlfunc.
3193
3194       Malformed integer in [] in unpack
3195           (F) Between the brackets enclosing a numeric repeat count only
3196           digits are permitted.  See "pack" in perlfunc.
3197
3198       Malformed PERLLIB_PREFIX
3199           (F) An error peculiar to OS/2.  PERLLIB_PREFIX should be of the
3200           form
3201
3202               prefix1;prefix2
3203
3204           or
3205               prefix1 prefix2
3206
3207           with nonempty prefix1 and prefix2.  If "prefix1" is indeed a prefix
3208           of a builtin library search path, prefix2 is substituted.  The
3209           error may appear if components are not found, or are too long.  See
3210           "PERLLIB_PREFIX" in perlos2.
3211
3212       Malformed prototype for %s: %s
3213           (F) You tried to use a function with a malformed prototype.  The
3214           syntax of function prototypes is given a brief compile-time check
3215           for obvious errors like invalid characters.  A more rigorous check
3216           is run when the function is called.  Perhaps the function's author
3217           was trying to write a subroutine signature but didn't enable that
3218           feature first ("use feature 'signatures'"), so the signature was
3219           instead interpreted as a bad prototype.
3220
3221       Malformed UTF-8 character%s
3222           (S utf8)(F) Perl detected a string that should be UTF-8, but didn't
3223           comply with UTF-8 encoding rules, or represents a code point whose
3224           ordinal integer value doesn't fit into the word size of the current
3225           platform (overflows).  Details as to the exact malformation are
3226           given in the variable, %s, part of the message.
3227
3228           One possible cause is that you set the UTF8 flag yourself for data
3229           that you thought to be in UTF-8 but it wasn't (it was for example
3230           legacy 8-bit data).  To guard against this, you can use
3231           "Encode::decode('UTF-8', ...)".
3232
3233           If you use the ":encoding(UTF-8)" PerlIO layer for input, invalid
3234           byte sequences are handled gracefully, but if you use ":utf8", the
3235           flag is set without validating the data, possibly resulting in this
3236           error message.
3237
3238           See also "Handling Malformed Data" in Encode.
3239
3240       Malformed UTF-8 returned by \N{%s} immediately after '%s'
3241           (F) The charnames handler returned malformed UTF-8.
3242
3243       Malformed UTF-8 string in "%s"
3244           (F) This message indicates a bug either in the Perl core or in XS
3245           code. Such code was trying to find out if a character, allegedly
3246           stored internally encoded as UTF-8, was of a given type, such as
3247           being punctuation or a digit.  But the character was not encoded in
3248           legal UTF-8.  The %s is replaced by a string that can be used by
3249           knowledgeable people to determine what the type being checked
3250           against was.
3251
3252           Passing malformed strings was deprecated in Perl 5.18, and became
3253           fatal in Perl 5.26.
3254
3255       Malformed UTF-8 string in '%c' format in unpack
3256           (F) You tried to unpack something that didn't comply with UTF-8
3257           encoding rules and perl was unable to guess how to make more
3258           progress.
3259
3260       Malformed UTF-8 string in pack
3261           (F) You tried to pack something that didn't comply with UTF-8
3262           encoding rules and perl was unable to guess how to make more
3263           progress.
3264
3265       Malformed UTF-8 string in unpack
3266           (F) You tried to unpack something that didn't comply with UTF-8
3267           encoding rules and perl was unable to guess how to make more
3268           progress.
3269
3270       Malformed UTF-16 surrogate
3271           (F) Perl thought it was reading UTF-16 encoded character data but
3272           while doing it Perl met a malformed Unicode surrogate.
3273
3274       Mandatory parameter follows optional parameter
3275           (F) In a subroutine signature, you wrote something like "$a =
3276           undef, $b", making an earlier parameter optional and a later one
3277           mandatory.  Parameters are filled from left to right, so it's
3278           impossible for the caller to omit an earlier one and pass a later
3279           one.  If you want to act as if the parameters are filled from right
3280           to left, declare the rightmost optional and then shuffle the
3281           parameters around in the subroutine's body.
3282
3283       Matched non-Unicode code point 0x%X against Unicode property; may not
3284       be portable
3285           (S non_unicode) Perl allows strings to contain a superset of
3286           Unicode code points; each code point may be as large as what is
3287           storable in a signed integer on your system, but these may not be
3288           accepted by other languages/systems.  This message occurs when you
3289           matched a string containing such a code point against a regular
3290           expression pattern, and the code point was matched against a
3291           Unicode property, "\p{...}" or "\P{...}".  Unicode properties are
3292           only defined on Unicode code points, so the result of this match is
3293           undefined by Unicode, but Perl (starting in v5.20) treats non-
3294           Unicode code points as if they were typical unassigned Unicode
3295           ones, and matched this one accordingly.  Whether a given property
3296           matches these code points or not is specified in "Properties
3297           accessible through \p{} and \P{}" in perluniprops.
3298
3299           This message is suppressed (unless it has been made fatal) if it is
3300           immaterial to the results of the match if the code point is Unicode
3301           or not.  For example, the property "\p{ASCII_Hex_Digit}" only can
3302           match the 22 characters "[0-9A-Fa-f]", so obviously all other code
3303           points, Unicode or not, won't match it.  (And "\P{ASCII_Hex_Digit}"
3304           will match every code point except these 22.)
3305
3306           Getting this message indicates that the outcome of the match
3307           arguably should have been the opposite of what actually happened.
3308           If you think that is the case, you may wish to make the
3309           "non_unicode" warnings category fatal; if you agree with Perl's
3310           decision, you may wish to turn off this category.
3311
3312           See "Beyond Unicode code points" in perlunicode for more
3313           information.
3314
3315       %s matches null string many times in regex; marked by <-- HERE in m/%s/
3316           (W regexp) The pattern you've specified would be an infinite loop
3317           if the regular expression engine didn't specifically check for
3318           that.  The <-- HERE shows whereabouts in the regular expression the
3319           problem was discovered.  See perlre.
3320
3321       Maximal count of pending signals (%u) exceeded
3322           (F) Perl aborted due to too high a number of signals pending.  This
3323           usually indicates that your operating system tried to deliver
3324           signals too fast (with a very high priority), starving the perl
3325           process from resources it would need to reach a point where it can
3326           process signals safely.  (See "Deferred Signals (Safe Signals)" in
3327           perlipc.)
3328
3329       "%s" may clash with future reserved word
3330           (W) This warning may be due to running a perl5 script through a
3331           perl4 interpreter, especially if the word that is being warned
3332           about is "use" or "my".
3333
3334       '%' may not be used in pack
3335           (F) You can't pack a string by supplying a checksum, because the
3336           checksumming process loses information, and you can't go the other
3337           way.  See "unpack" in perlfunc.
3338
3339       Method for operation %s not found in package %s during blessing
3340           (F) An attempt was made to specify an entry in an overloading table
3341           that doesn't resolve to a valid subroutine.  See overload.
3342
3343       Method %s not permitted
3344           See "500 Server error".
3345
3346       Might be a runaway multi-line %s string starting on line %d
3347           (S) An advisory indicating that the previous error may have been
3348           caused by a missing delimiter on a string or pattern, because it
3349           eventually ended earlier on the current line.
3350
3351       Misplaced _ in number
3352           (W syntax) An underscore (underbar) in a numeric constant did not
3353           separate two digits.
3354
3355       Missing argument for %n in %s
3356           (F) A %n was used in a format string with no corresponding argument
3357           for perl to write the current string length to.
3358
3359       Missing argument in %s
3360           (W missing) You called a function with fewer arguments than other
3361           arguments you supplied indicated would be needed.
3362
3363           Currently only emitted when a printf-type format required more
3364           arguments than were supplied, but might be used in the future for
3365           other cases where we can statically determine that arguments to
3366           functions are missing, e.g. for the "pack" in perlfunc function.
3367
3368       Missing argument to -%c
3369           (F) The argument to the indicated command line switch must follow
3370           immediately after the switch, without intervening spaces.
3371
3372       Missing braces on \N{}
3373       Missing braces on \N{} in regex; marked by <-- HERE in m/%s/
3374           (F) Wrong syntax of character name literal "\N{charname}" within
3375           double-quotish context.  This can also happen when there is a space
3376           (or comment) between the "\N" and the "{" in a regex with the "/x"
3377           modifier.  This modifier does not change the requirement that the
3378           brace immediately follow the "\N".
3379
3380       Missing braces on \o{}
3381           (F) A "\o" must be followed immediately by a "{" in double-quotish
3382           context.
3383
3384       Missing comma after first argument to %s function
3385           (F) While certain functions allow you to specify a filehandle or an
3386           "indirect object" before the argument list, this ain't one of them.
3387
3388       Missing command in piped open
3389           (W pipe) You used the "open(FH, "| command")" or "open(FH, "command
3390           |")" construction, but the command was missing or blank.
3391
3392       Missing control char name in \c
3393           (F) A double-quoted string ended with "\c", without the required
3394           control character name.
3395
3396       Missing ']' in prototype for %s : %s
3397           (W illegalproto) A grouping was started with "[" but never closed
3398           with "]".
3399
3400       Missing name in "%s sub"
3401           (F) The syntax for lexically scoped subroutines requires that they
3402           have a name with which they can be found.
3403
3404       Missing $ on loop variable
3405           (F) Apparently you've been programming in csh too much.  Variables
3406           are always mentioned with the $ in Perl, unlike in the shells,
3407           where it can vary from one line to the next.
3408
3409       (Missing operator before %s?)
3410           (S syntax) This is an educated guess made in conjunction with the
3411           message "%s found where operator expected".  Often the missing
3412           operator is a comma.
3413
3414       Missing or undefined argument to %s
3415           (F) You tried to call require or do with no argument or with an
3416           undefined value as an argument.  Require expects either a package
3417           name or a file-specification as an argument; do expects a filename.
3418           See "require EXPR" in perlfunc and "do EXPR" in perlfunc.
3419
3420       Missing right brace on \%c{} in regex; marked by <-- HERE in m/%s/
3421           (F) Missing right brace in "\x{...}", "\p{...}", "\P{...}", or
3422           "\N{...}".
3423
3424       Missing right brace on \N{}
3425       Missing right brace on \N{} or unescaped left brace after \N
3426           (F) "\N" has two meanings.
3427
3428           The traditional one has it followed by a name enclosed in braces,
3429           meaning the character (or sequence of characters) given by that
3430           name.  Thus "\N{ASTERISK}" is another way of writing "*", valid in
3431           both double-quoted strings and regular expression patterns.  In
3432           patterns, it doesn't have the meaning an unescaped "*" does.
3433
3434           Starting in Perl 5.12.0, "\N" also can have an additional meaning
3435           (only) in patterns, namely to match a non-newline character.  (This
3436           is short for "[^\n]", and like "." but is not affected by the "/s"
3437           regex modifier.)
3438
3439           This can lead to some ambiguities.  When "\N" is not followed
3440           immediately by a left brace, Perl assumes the "[^\n]" meaning.
3441           Also, if the braces form a valid quantifier such as "\N{3}" or
3442           "\N{5,}", Perl assumes that this means to match the given quantity
3443           of non-newlines (in these examples, 3; and 5 or more,
3444           respectively).  In all other case, where there is a "\N{" and a
3445           matching "}", Perl assumes that a character name is desired.
3446
3447           However, if there is no matching "}", Perl doesn't know if it was
3448           mistakenly omitted, or if "[^\n]{" was desired, and raises this
3449           error.  If you meant the former, add the right brace; if you meant
3450           the latter, escape the brace with a backslash, like so: "\N\{"
3451
3452       Missing right curly or square bracket
3453           (F) The lexer counted more opening curly or square brackets than
3454           closing ones.  As a general rule, you'll find it's missing near the
3455           place you were last editing.
3456
3457       (Missing semicolon on previous line?)
3458           (S syntax) This is an educated guess made in conjunction with the
3459           message "%s found where operator expected".  Don't automatically
3460           put a semicolon on the previous line just because you saw this
3461           message.
3462
3463       Modification of a read-only value attempted
3464           (F) You tried, directly or indirectly, to change the value of a
3465           constant.  You didn't, of course, try "2 = 1", because the compiler
3466           catches that.  But an easy way to do the same thing is:
3467
3468               sub mod { $_[0] = 1 }
3469               mod(2);
3470
3471           Another way is to assign to a substr() that's off the end of the
3472           string.
3473
3474           Yet another way is to assign to a "foreach" loop VAR when VAR is
3475           aliased to a constant in the look LIST:
3476
3477               $x = 1;
3478               foreach my $n ($x, 2) {
3479                   $n *= 2; # modifies the $x, but fails on attempt to
3480               }            # modify the 2
3481
3482       Modification of non-creatable array value attempted, %s
3483           (F) You tried to make an array value spring into existence, and the
3484           subscript was probably negative, even counting from end of the
3485           array backwards.
3486
3487       Modification of non-creatable hash value attempted, %s
3488           (P) You tried to make a hash value spring into existence, and it
3489           couldn't be created for some peculiar reason.
3490
3491       Module name must be constant
3492           (F) Only a bare module name is allowed as the first argument to a
3493           "use".
3494
3495       Module name required with -%c option
3496           (F) The "-M" or "-m" options say that Perl should load some module,
3497           but you omitted the name of the module.  Consult perlrun for full
3498           details about "-M" and "-m".
3499
3500       More than one argument to '%s' open
3501           (F) The "open" function has been asked to open multiple files.
3502           This can happen if you are trying to open a pipe to a command that
3503           takes a list of arguments, but have forgotten to specify a piped
3504           open mode.  See "open" in perlfunc for details.
3505
3506       mprotect for COW string %p %u failed with %d
3507           (S) You compiled perl with -DPERL_DEBUG_READONLY_COW (see "Copy on
3508           Write" in perlguts), but a shared string buffer could not be made
3509           read-only.
3510
3511       mprotect for %p %u failed with %d
3512           (S) You compiled perl with -DPERL_DEBUG_READONLY_OPS (see
3513           perlhacktips), but an op tree could not be made read-only.
3514
3515       mprotect RW for COW string %p %u failed with %d
3516           (S) You compiled perl with -DPERL_DEBUG_READONLY_COW (see "Copy on
3517           Write" in perlguts), but a read-only shared string buffer could not
3518           be made mutable.
3519
3520       mprotect RW for %p %u failed with %d
3521           (S) You compiled perl with -DPERL_DEBUG_READONLY_OPS (see
3522           perlhacktips), but a read-only op tree could not be made mutable
3523           before freeing the ops.
3524
3525       msg%s not implemented
3526           (F) You don't have System V message IPC on your system.
3527
3528       Multidimensional syntax %s not supported
3529           (W syntax) Multidimensional arrays aren't written like $foo[1,2,3].
3530           They're written like $foo[1][2][3], as in C.
3531
3532       Multiple slurpy parameters not allowed
3533           (F) In subroutine signatures, a slurpy parameter ("@" or "%") must
3534           be the last parameter, and there must not be more than one of them;
3535           for example:
3536
3537               sub foo ($a, @b)    {} # legal
3538               sub foo ($a, @b, %) {} # invalid
3539
3540       '/' must follow a numeric type in unpack
3541           (F) You had an unpack template that contained a '/', but this did
3542           not follow some unpack specification producing a numeric value.
3543           See "pack" in perlfunc.
3544
3545       %s must not be a named sequence in transliteration operator
3546           (F) Transliteration ("tr///" and "y///") transliterates individual
3547           characters.  But a named sequence by definition is more than an
3548           individual character, and hence doing this operation on it doesn't
3549           make sense.
3550
3551       "my sub" not yet implemented
3552           (F) Lexically scoped subroutines are not yet implemented.  Don't
3553           try that yet.
3554
3555       "my" subroutine %s can't be in a package
3556           (F) Lexically scoped subroutines aren't in a package, so it doesn't
3557           make sense to try to declare one with a package qualifier on the
3558           front.
3559
3560       "my %s" used in sort comparison
3561           (W syntax) The package variables $a and $b are used for sort
3562           comparisons.  You used $a or $b in as an operand to the "<=>" or
3563           "cmp" operator inside a sort comparison block, and the variable had
3564           earlier been declared as a lexical variable.  Either qualify the
3565           sort variable with the package name, or rename the lexical
3566           variable.
3567
3568       "my" variable %s can't be in a package
3569           (F) Lexically scoped variables aren't in a package, so it doesn't
3570           make sense to try to declare one with a package qualifier on the
3571           front.  Use local() if you want to localize a package variable.
3572
3573       Name "%s::%s" used only once: possible typo
3574           (W once) Typographical errors often show up as unique variable
3575           names.  If you had a good reason for having a unique name, then
3576           just mention it again somehow to suppress the message.  The "our"
3577           declaration is also provided for this purpose.
3578
3579           NOTE: This warning detects package symbols that have been used only
3580           once.  This means lexical variables will never trigger this
3581           warning.  It also means that all of the package variables $c, @c,
3582           %c, as well as *c, &c, sub c{}, c(), and c (the filehandle or
3583           format) are considered the same; if a program uses $c only once but
3584           also uses any of the others it will not trigger this warning.
3585           Symbols beginning with an underscore and symbols using special
3586           identifiers (q.v. perldata) are exempt from this warning.
3587
3588       Need exactly 3 octal digits in regex; marked by <-- HERE in m/%s/
3589           (F) Within "(?[   ])", all constants interpreted as octal need to
3590           be exactly 3 digits long.  This helps catch some ambiguities.  If
3591           your constant is too short, add leading zeros, like
3592
3593            (?[ [ \078 ] ])     # Syntax error!
3594            (?[ [ \0078 ] ])    # Works
3595            (?[ [ \007 8 ] ])   # Clearer
3596
3597           The maximum number this construct can express is "\777".  If you
3598           need a larger one, you need to use \o{} instead.  If you meant two
3599           separate things, you need to separate them:
3600
3601            (?[ [ \7776 ] ])        # Syntax error!
3602            (?[ [ \o{7776} ] ])     # One meaning
3603            (?[ [ \777 6 ] ])       # Another meaning
3604            (?[ [ \777 \006 ] ])    # Still another
3605
3606       Negative '/' count in unpack
3607           (F) The length count obtained from a length/code unpack operation
3608           was negative.  See "pack" in perlfunc.
3609
3610       Negative length
3611           (F) You tried to do a read/write/send/recv operation with a buffer
3612           length that is less than 0.  This is difficult to imagine.
3613
3614       Negative offset to vec in lvalue context
3615           (F) When "vec" is called in an lvalue context, the second argument
3616           must be greater than or equal to zero.
3617
3618       Negative repeat count does nothing
3619           (W numeric) You tried to execute the "x" repetition operator fewer
3620           than 0 times, which doesn't make sense.
3621
3622       Nested quantifiers in regex; marked by <-- HERE in m/%s/
3623           (F) You can't quantify a quantifier without intervening
3624           parentheses.  So things like ** or +* or ?* are illegal.  The
3625           <-- HERE shows whereabouts in the regular expression the problem
3626           was discovered.
3627
3628           Note that the minimal matching quantifiers, "*?", "+?", and "??"
3629           appear to be nested quantifiers, but aren't.  See perlre.
3630
3631       %s never introduced
3632           (S internal) The symbol in question was declared but somehow went
3633           out of scope before it could possibly have been used.
3634
3635       next::method/next::can/maybe::next::method cannot find enclosing method
3636           (F) "next::method" needs to be called within the context of a real
3637           method in a real package, and it could not find such a context.
3638           See mro.
3639
3640       \N in a character class must be a named character: \N{...} in regex;
3641       marked by <-- HERE in m/%s/
3642           (F) The new (as of Perl 5.12) meaning of "\N" as "[^\n]" is not
3643           valid in a bracketed character class, for the same reason that "."
3644           in a character class loses its specialness: it matches almost
3645           everything, which is probably not what you want.
3646
3647       \N{} here is restricted to one character in regex; marked by <-- HERE
3648       in m/%s/
3649           (F) Named Unicode character escapes ("\N{...}") may return a multi-
3650           character sequence.  Even though a character class is supposed to
3651           match just one character of input, perl will match the whole thing
3652           correctly, except under certain conditions.  These currently are
3653
3654           When the class is inverted ("[^...]")
3655               The mathematically logical behavior for what matches when
3656               inverting is very different from what people expect, so we have
3657               decided to forbid it.
3658
3659           The escape is the beginning or final end point of a range
3660               Similarly unclear is what should be generated when the
3661               "\N{...}" is used as one of the end points of the range, such
3662               as in
3663
3664                [\x{41}-\N{ARABIC SEQUENCE YEH WITH HAMZA ABOVE WITH AE}]
3665
3666               What is meant here is unclear, as the "\N{...}" escape is a
3667               sequence of code points, so this is made an error.
3668
3669           In a regex set
3670               The syntax "(?[   ])" in a regular expression yields a list of
3671               single code points, none can be a sequence.
3672
3673       No %s allowed while running setuid
3674           (F) Certain operations are deemed to be too insecure for a setuid
3675           or setgid script to even be allowed to attempt.  Generally speaking
3676           there will be another way to do what you want that is, if not
3677           secure, at least securable.  See perlsec.
3678
3679       No code specified for -%c
3680           (F) Perl's -e and -E command-line options require an argument.  If
3681           you want to run an empty program, pass the empty string as a
3682           separate argument or run a program consisting of a single 0 or 1:
3683
3684               perl -e ""
3685               perl -e0
3686               perl -e1
3687
3688       No comma allowed after %s
3689           (F) A list operator that has a filehandle or "indirect object" is
3690           not allowed to have a comma between that and the following
3691           arguments.  Otherwise it'd be just another one of the arguments.
3692
3693           One possible cause for this is that you expected to have imported a
3694           constant to your name space with use or import while no such
3695           importing took place, it may for example be that your operating
3696           system does not support that particular constant.  Hopefully you
3697           did use an explicit import list for the constants you expect to
3698           see; please see "use" in perlfunc and "import" in perlfunc.  While
3699           an explicit import list would probably have caught this error
3700           earlier it naturally does not remedy the fact that your operating
3701           system still does not support that constant.  Maybe you have a typo
3702           in the constants of the symbol import list of use or import or in
3703           the constant name at the line where this error was triggered?
3704
3705       No command into which to pipe on command line
3706           (F) An error peculiar to VMS.  Perl handles its own command line
3707           redirection, and found a '|' at the end of the command line, so it
3708           doesn't know where you want to pipe the output from this command.
3709
3710       No DB::DB routine defined
3711           (F) The currently executing code was compiled with the -d switch,
3712           but for some reason the current debugger (e.g. perl5db.pl or a
3713           "Devel::" module) didn't define a routine to be called at the
3714           beginning of each statement.
3715
3716       No dbm on this machine
3717           (P) This is counted as an internal error, because every machine
3718           should supply dbm nowadays, because Perl comes with SDBM.  See
3719           SDBM_File.
3720
3721       No DB::sub routine defined
3722           (F) The currently executing code was compiled with the -d switch,
3723           but for some reason the current debugger (e.g. perl5db.pl or a
3724           "Devel::" module) didn't define a "DB::sub" routine to be called at
3725           the beginning of each ordinary subroutine call.
3726
3727       No digits found for %s literal
3728           (F) No hexadecimal digits were found following "0x" or no binary
3729           digits were found following "0b".
3730
3731       No directory specified for -I
3732           (F) The -I command-line switch requires a directory name as part of
3733           the same argument.  Use -Ilib, for instance.  -I lib won't work.
3734
3735       No error file after 2> or 2>> on command line
3736           (F) An error peculiar to VMS.  Perl handles its own command line
3737           redirection, and found a '2>' or a '2>>' on the command line, but
3738           can't find the name of the file to which to write data destined for
3739           stderr.
3740
3741       No group ending character '%c' found in template
3742           (F) A pack or unpack template has an opening '(' or '[' without its
3743           matching counterpart.  See "pack" in perlfunc.
3744
3745       No input file after < on command line
3746           (F) An error peculiar to VMS.  Perl handles its own command line
3747           redirection, and found a '<' on the command line, but can't find
3748           the name of the file from which to read data for stdin.
3749
3750       No next::method '%s' found for %s
3751           (F) "next::method" found no further instances of this method name
3752           in the remaining packages of the MRO of this class.  If you don't
3753           want it throwing an exception, use "maybe::next::method" or
3754           "next::can".  See mro.
3755
3756       Non-finite repeat count does nothing
3757           (W numeric) You tried to execute the "x" repetition operator "Inf"
3758           (or "-Inf") or "NaN" times, which doesn't make sense.
3759
3760       Non-hex character in regex; marked by <-- HERE in m/%s/
3761           (F) In a regular expression, there was a non-hexadecimal character
3762           where a hex one was expected, like
3763
3764            (?[ [ \xDG ] ])
3765            (?[ [ \x{DEKA} ] ])
3766
3767       Non-hex character '%c' terminates \x early.  Resolved as "%s"
3768           (W digit) In parsing a hexadecimal numeric constant, a character
3769           was unexpectedly encountered that isn't hexadecimal.  The resulting
3770           value is as indicated.
3771
3772           Note that, within braces, every character starting with the first
3773           non-hexadecimal up to the ending brace is ignored.
3774
3775       Non-octal character in regex; marked by <-- HERE in m/%s/
3776           (F) In a regular expression, there was a non-octal character where
3777           an octal one was expected, like
3778
3779            (?[ [ \o{1278} ] ])
3780
3781       Non-octal character '%c' terminates \o early.  Resolved as "%s"
3782           (W digit) In parsing an octal numeric constant, a character was
3783           unexpectedly encountered that isn't octal.  The resulting value is
3784           as indicated.
3785
3786           When not using "\o{...}", you wrote something like "\08", or "\179"
3787           in a double-quotish string.  The resolution is as indicated, with
3788           all but the last digit treated as a single character, specified in
3789           octal.  The last digit is the next character in the string.  To
3790           tell Perl that this is indeed what you want, you can use the "\o{
3791           }" syntax, or use exactly three digits to specify the octal for the
3792           character.
3793
3794           Note that, within braces, every character starting with the first
3795           non-octal up to the ending brace is ignored.
3796
3797       "no" not allowed in expression
3798           (F) The "no" keyword is recognized and executed at compile time,
3799           and returns no useful value.  See perlmod.
3800
3801       Non-string passed as bitmask
3802           (W misc) A number has been passed as a bitmask argument to
3803           select().  Use the vec() function to construct the file descriptor
3804           bitmasks for select.  See "select" in perlfunc.
3805
3806       No output file after > on command line
3807           (F) An error peculiar to VMS.  Perl handles its own command line
3808           redirection, and found a lone '>' at the end of the command line,
3809           so it doesn't know where you wanted to redirect stdout.
3810
3811       No output file after > or >> on command line
3812           (F) An error peculiar to VMS.  Perl handles its own command line
3813           redirection, and found a '>' or a '>>' on the command line, but
3814           can't find the name of the file to which to write data destined for
3815           stdout.
3816
3817       No package name allowed for subroutine %s in "our"
3818       No package name allowed for variable %s in "our"
3819           (F) Fully qualified subroutine and variable names are not allowed
3820           in "our" declarations, because that doesn't make much sense under
3821           existing rules.  Such syntax is reserved for future extensions.
3822
3823       No Perl script found in input
3824           (F) You called "perl -x", but no line was found in the file
3825           beginning with #! and containing the word "perl".
3826
3827       No setregid available
3828           (F) Configure didn't find anything resembling the setregid() call
3829           for your system.
3830
3831       No setreuid available
3832           (F) Configure didn't find anything resembling the setreuid() call
3833           for your system.
3834
3835       No such class %s
3836           (F) You provided a class qualifier in a "my", "our" or "state"
3837           declaration, but this class doesn't exist at this point in your
3838           program.
3839
3840       No such class field "%s" in variable %s of type %s
3841           (F) You tried to access a key from a hash through the indicated
3842           typed variable but that key is not allowed by the package of the
3843           same type.  The indicated package has restricted the set of allowed
3844           keys using the fields pragma.
3845
3846       No such hook: %s
3847           (F) You specified a signal hook that was not recognized by Perl.
3848           Currently, Perl accepts "__DIE__" and "__WARN__" as valid signal
3849           hooks.
3850
3851       No such pipe open
3852           (P) An error peculiar to VMS.  The internal routine my_pclose()
3853           tried to close a pipe which hadn't been opened.  This should have
3854           been caught earlier as an attempt to close an unopened filehandle.
3855
3856       No such signal: SIG%s
3857           (W signal) You specified a signal name as a subscript to %SIG that
3858           was not recognized.  Say "kill -l" in your shell to see the valid
3859           signal names on your system.
3860
3861       No Unicode property value wildcard matches:
3862           (W regexp) You specified a wildcard for a Unicode property value,
3863           but there is no property value in the current Unicode release that
3864           matches it.  Check your spelling.
3865
3866       Not a CODE reference
3867           (F) Perl was trying to evaluate a reference to a code value (that
3868           is, a subroutine), but found a reference to something else instead.
3869           You can use the ref() function to find out what kind of ref it
3870           really was.  See also perlref.
3871
3872       Not a GLOB reference
3873           (F) Perl was trying to evaluate a reference to a "typeglob" (that
3874           is, a symbol table entry that looks like *foo), but found a
3875           reference to something else instead.  You can use the ref()
3876           function to find out what kind of ref it really was.  See perlref.
3877
3878       Not a HASH reference
3879           (F) Perl was trying to evaluate a reference to a hash value, but
3880           found a reference to something else instead.  You can use the ref()
3881           function to find out what kind of ref it really was.  See perlref.
3882
3883       '#' not allowed immediately following a sigil in a subroutine signature
3884           (F) In a subroutine signature definition, a comment following a
3885           sigil ("$", "@" or "%"), needs to be separated by whitespace or a
3886           comma etc., in particular to avoid confusion with the $# variable.
3887           For example:
3888
3889               # bad
3890               sub f ($# ignore first arg
3891                      , $b) {}
3892               # good
3893               sub f ($, # ignore first arg
3894                      $b) {}
3895
3896       Not an ARRAY reference
3897           (F) Perl was trying to evaluate a reference to an array value, but
3898           found a reference to something else instead.  You can use the ref()
3899           function to find out what kind of ref it really was.  See perlref.
3900
3901       Not a SCALAR reference
3902           (F) Perl was trying to evaluate a reference to a scalar value, but
3903           found a reference to something else instead.  You can use the ref()
3904           function to find out what kind of ref it really was.  See perlref.
3905
3906       Not a subroutine reference
3907           (F) Perl was trying to evaluate a reference to a code value (that
3908           is, a subroutine), but found a reference to something else instead.
3909           You can use the ref() function to find out what kind of ref it
3910           really was.  See also perlref.
3911
3912       Not a subroutine reference in overload table
3913           (F) An attempt was made to specify an entry in an overloading table
3914           that doesn't somehow point to a valid subroutine.  See overload.
3915
3916       Not enough arguments for %s
3917           (F) The function requires more arguments than you specified.
3918
3919       Not enough format arguments
3920           (W syntax) A format specified more picture fields than the next
3921           line supplied.  See perlform.
3922
3923       %s: not found
3924           (A) You've accidentally run your script through the Bourne shell
3925           instead of Perl.  Check the #! line, or manually feed your script
3926           into Perl yourself.
3927
3928       no UTC offset information; assuming local time is UTC
3929           (S) A warning peculiar to VMS.  Perl was unable to find the local
3930           timezone offset, so it's assuming that local system time is
3931           equivalent to UTC.  If it's not, define the logical name
3932           SYS$TIMEZONE_DIFFERENTIAL to translate to the number of seconds
3933           which need to be added to UTC to get local time.
3934
3935       NULL OP IN RUN
3936           (S debugging) Some internal routine called run() with a null opcode
3937           pointer.
3938
3939       Null picture in formline
3940           (F) The first argument to formline must be a valid format picture
3941           specification.  It was found to be empty, which probably means you
3942           supplied it an uninitialized value.  See perlform.
3943
3944       Null realloc
3945           (P) An attempt was made to realloc NULL.
3946
3947       NULL regexp argument
3948           (P) The internal pattern matching routines blew it big time.
3949
3950       NULL regexp parameter
3951           (P) The internal pattern matching routines are out of their gourd.
3952
3953       Number too long
3954           (F) Perl limits the representation of decimal numbers in programs
3955           to about 250 characters.  You've exceeded that length.  Future
3956           versions of Perl are likely to eliminate this arbitrary limitation.
3957           In the meantime, try using scientific notation (e.g. "1e6" instead
3958           of "1_000_000").
3959
3960       Number with no digits
3961           (F) Perl was looking for a number but found nothing that looked
3962           like a number.  This happens, for example with "\o{}", with no
3963           number between the braces.
3964
3965       Numeric format result too large
3966           (F) The length of the result of a numeric format supplied to
3967           sprintf() or printf() would have been too large for the underlying
3968           C function to report.  This limit is typically 2GB.
3969
3970       Numeric variables with more than one digit may not start with '0'
3971           (F) The only numeric variable which is allowed to start with a 0 is
3972           $0, and you mentioned a variable that starts with 0 that has more
3973           than one digit. You probably want to remove the leading 0, or if
3974           the intent was to express a variable name in octal you should
3975           convert to decimal.
3976
3977       Octal number > 037777777777 non-portable
3978           (W portable) The octal number you specified is larger than 2**32-1
3979           (4294967295) and therefore non-portable between systems.  See
3980           perlport for more on portability concerns.
3981
3982       Odd name/value argument for subroutine '%s'
3983           (F) A subroutine using a slurpy hash parameter in its signature
3984           received an odd number of arguments to populate the hash.  It
3985           requires the arguments to be paired, with the same number of keys
3986           as values.  The caller of the subroutine is presumably at fault.
3987
3988           The message attempts to include the name of the called subroutine.
3989           If the subroutine has been aliased, the subroutine's original name
3990           will be shown, regardless of what name the caller used.
3991
3992       Odd number of arguments for overload::constant
3993           (W overload) The call to overload::constant contained an odd number
3994           of arguments.  The arguments should come in pairs.
3995
3996       Odd number of elements in anonymous hash
3997           (W misc) You specified an odd number of elements to initialize a
3998           hash, which is odd, because hashes come in key/value pairs.
3999
4000       Odd number of elements in hash assignment
4001           (W misc) You specified an odd number of elements to initialize a
4002           hash, which is odd, because hashes come in key/value pairs.
4003
4004       Offset outside string
4005           (F)(W layer) You tried to do a read/write/send/recv/seek operation
4006           with an offset pointing outside the buffer.  This is difficult to
4007           imagine.  The sole exceptions to this are that zero padding will
4008           take place when going past the end of the string when either
4009           "sysread()"ing a file, or when seeking past the end of a scalar
4010           opened for I/O (in anticipation of future reads and to imitate the
4011           behavior with real files).
4012
4013       Old package separator used in string
4014           (W syntax) You used the old package separator, "'", in a variable
4015           named inside a double-quoted string; e.g., "In $name's house".
4016           This is equivalent to "In $name::s house".  If you meant the
4017           former, put a backslash before the apostrophe ("In $name\'s
4018           house").
4019
4020       %s() on unopened %s
4021           (W unopened) An I/O operation was attempted on a filehandle that
4022           was never initialized.  You need to do an open(), a sysopen(), or a
4023           socket() call, or call a constructor from the FileHandle package.
4024
4025       -%s on unopened filehandle %s
4026           (W unopened) You tried to invoke a file test operator on a
4027           filehandle that isn't open.  Check your control flow.  See also
4028           "-X" in perlfunc.
4029
4030       oops: oopsAV
4031           (S internal) An internal warning that the grammar is screwed up.
4032
4033       oops: oopsHV
4034           (S internal) An internal warning that the grammar is screwed up.
4035
4036       Operand with no preceding operator in regex; marked by <-- HERE in
4037       m/%s/
4038           (F) You wrote something like
4039
4040            (?[ \p{Digit} \p{Thai} ])
4041
4042           There are two operands, but no operator giving how you want to
4043           combine them.
4044
4045       Operation "%s": no method found, %s
4046           (F) An attempt was made to perform an overloaded operation for
4047           which no handler was defined.  While some handlers can be
4048           autogenerated in terms of other handlers, there is no default
4049           handler for any operation, unless the "fallback" overloading key is
4050           specified to be true.  See overload.
4051
4052       Operation "%s" returns its argument for non-Unicode code point 0x%X
4053           (S non_unicode) You performed an operation requiring Unicode rules
4054           on a code point that is not in Unicode, so what it should do is not
4055           defined.  Perl has chosen to have it do nothing, and warn you.
4056
4057           If the operation shown is "ToFold", it means that case-insensitive
4058           matching in a regular expression was done on the code point.
4059
4060           If you know what you are doing you can turn off this warning by "no
4061           warnings 'non_unicode';".
4062
4063       Operation "%s" returns its argument for UTF-16 surrogate U+%X
4064           (S surrogate) You performed an operation requiring Unicode rules on
4065           a Unicode surrogate.  Unicode frowns upon the use of surrogates for
4066           anything but storing strings in UTF-16, but rules are (reluctantly)
4067           defined for the surrogates, and they are to do nothing for this
4068           operation.  Because the use of surrogates can be dangerous, Perl
4069           warns.
4070
4071           If the operation shown is "ToFold", it means that case-insensitive
4072           matching in a regular expression was done on the code point.
4073
4074           If you know what you are doing you can turn off this warning by "no
4075           warnings 'surrogate';".
4076
4077       Operator or semicolon missing before %s
4078           (S ambiguous) You used a variable or subroutine call where the
4079           parser was expecting an operator.  The parser has assumed you
4080           really meant to use an operator, but this is highly likely to be
4081           incorrect.  For example, if you say "*foo *foo" it will be
4082           interpreted as if you said "*foo * 'foo'".
4083
4084       Optional parameter lacks default expression
4085           (F) In a subroutine signature, you wrote something like "$a =",
4086           making a named optional parameter without a default value.  A
4087           nameless optional parameter is permitted to have no default value,
4088           but a named one must have a specific default.  You probably want
4089           "$a = undef".
4090
4091       "our" variable %s redeclared
4092           (W shadow) You seem to have already declared the same global once
4093           before in the current lexical scope.
4094
4095       Out of memory!
4096           (X) The malloc() function returned 0, indicating there was
4097           insufficient remaining memory (or virtual memory) to satisfy the
4098           request.  Perl has no option but to exit immediately.
4099
4100           At least in Unix you may be able to get past this by increasing
4101           your process datasize limits: in csh/tcsh use "limit" and "limit
4102           datasize n" (where "n" is the number of kilobytes) to check the
4103           current limits and change them, and in ksh/bash/zsh use "ulimit -a"
4104           and "ulimit -d n", respectively.
4105
4106       Out of memory during %s extend
4107           (X) An attempt was made to extend an array, a list, or a string
4108           beyond the largest possible memory allocation.
4109
4110       Out of memory during "large" request for %s
4111           (F) The malloc() function returned 0, indicating there was
4112           insufficient remaining memory (or virtual memory) to satisfy the
4113           request.  However, the request was judged large enough (compile-
4114           time default is 64K), so a possibility to shut down by trapping
4115           this error is granted.
4116
4117       Out of memory during request for %s
4118           (X)(F) The malloc() function returned 0, indicating there was
4119           insufficient remaining memory (or virtual memory) to satisfy the
4120           request.
4121
4122           The request was judged to be small, so the possibility to trap it
4123           depends on the way perl was compiled.  By default it is not
4124           trappable.  However, if compiled for this, Perl may use the
4125           contents of $^M as an emergency pool after die()ing with this
4126           message.  In this case the error is trappable once, and the error
4127           message will include the line and file where the failed request
4128           happened.
4129
4130       Out of memory during ridiculously large request
4131           (F) You can't allocate more than 2^31+"small amount" bytes.  This
4132           error is most likely to be caused by a typo in the Perl program.
4133           e.g., $arr[time] instead of $arr[$time].
4134
4135       Out of memory for yacc stack
4136           (F) The yacc parser wanted to grow its stack so it could continue
4137           parsing, but realloc() wouldn't give it more memory, virtual or
4138           otherwise.
4139
4140       '.' outside of string in pack
4141           (F) The argument to a '.' in your template tried to move the
4142           working position to before the start of the packed string being
4143           built.
4144
4145       '@' outside of string in unpack
4146           (F) You had a template that specified an absolute position outside
4147           the string being unpacked.  See "pack" in perlfunc.
4148
4149       '@' outside of string with malformed UTF-8 in unpack
4150           (F) You had a template that specified an absolute position outside
4151           the string being unpacked.  The string being unpacked was also
4152           invalid UTF-8.  See "pack" in perlfunc.
4153
4154       overload arg '%s' is invalid
4155           (W overload) The overload pragma was passed an argument it did not
4156           recognize.  Did you mistype an operator?
4157
4158       Overloaded dereference did not return a reference
4159           (F) An object with an overloaded dereference operator was
4160           dereferenced, but the overloaded operation did not return a
4161           reference.  See overload.
4162
4163       Overloaded qr did not return a REGEXP
4164           (F) An object with a "qr" overload was used as part of a match, but
4165           the overloaded operation didn't return a compiled regexp.  See
4166           overload.
4167
4168       %s package attribute may clash with future reserved word: %s
4169           (W reserved) A lowercase attribute name was used that had a
4170           package-specific handler.  That name might have a meaning to Perl
4171           itself some day, even though it doesn't yet.  Perhaps you should
4172           use a mixed-case attribute name, instead.  See attributes.
4173
4174       pack/unpack repeat count overflow
4175           (F) You can't specify a repeat count so large that it overflows
4176           your signed integers.  See "pack" in perlfunc.
4177
4178       page overflow
4179           (W io) A single call to write() produced more lines than can fit on
4180           a page.  See perlform.
4181
4182       panic: %s
4183           (P) An internal error.
4184
4185       panic: attempt to call %s in %s
4186           (P) One of the file test operators entered a code branch that calls
4187           an ACL related-function, but that function is not available on this
4188           platform.  Earlier checks mean that it should not be possible to
4189           enter this branch on this platform.
4190
4191       panic: child pseudo-process was never scheduled
4192           (P) A child pseudo-process in the ithreads implementation on
4193           Windows was not scheduled within the time period allowed and
4194           therefore was not able to initialize properly.
4195
4196       panic: ck_grep, type=%u
4197           (P) Failed an internal consistency check trying to compile a grep.
4198
4199       panic: corrupt saved stack index %ld
4200           (P) The savestack was requested to restore more localized values
4201           than there are in the savestack.
4202
4203       panic: del_backref
4204           (P) Failed an internal consistency check while trying to reset a
4205           weak reference.
4206
4207       panic: do_subst
4208           (P) The internal pp_subst() routine was called with invalid
4209           operational data.
4210
4211       panic: do_trans_%s
4212           (P) The internal do_trans routines were called with invalid
4213           operational data.
4214
4215       panic: fold_constants JMPENV_PUSH returned %d
4216           (P) While attempting folding constants an exception other than an
4217           "eval" failure was caught.
4218
4219       panic: frexp: %f
4220           (P) The library function frexp() failed, making printf("%f")
4221           impossible.
4222
4223       panic: goto, type=%u, ix=%ld
4224           (P) We popped the context stack to a context with the specified
4225           label, and then discovered it wasn't a context we know how to do a
4226           goto in.
4227
4228       panic: gp_free failed to free glob pointer
4229           (P) The internal routine used to clear a typeglob's entries tried
4230           repeatedly, but each time something re-created entries in the glob.
4231           Most likely the glob contains an object with a reference back to
4232           the glob and a destructor that adds a new object to the glob.
4233
4234       panic: INTERPCASEMOD, %s
4235           (P) The lexer got into a bad state at a case modifier.
4236
4237       panic: INTERPCONCAT, %s
4238           (P) The lexer got into a bad state parsing a string with brackets.
4239
4240       panic: kid popen errno read
4241           (F) A forked child returned an incomprehensible message about its
4242           errno.
4243
4244       panic: last, type=%u
4245           (P) We popped the context stack to a block context, and then
4246           discovered it wasn't a block context.
4247
4248       panic: leave_scope clearsv
4249           (P) A writable lexical variable became read-only somehow within the
4250           scope.
4251
4252       panic: leave_scope inconsistency %u
4253           (P) The savestack probably got out of sync.  At least, there was an
4254           invalid enum on the top of it.
4255
4256       panic: magic_killbackrefs
4257           (P) Failed an internal consistency check while trying to reset all
4258           weak references to an object.
4259
4260       panic: malloc, %s
4261           (P) Something requested a negative number of bytes of malloc.
4262
4263       panic: memory wrap
4264           (P) Something tried to allocate either more memory than possible or
4265           a negative amount.
4266
4267       panic: pad_alloc, %p!=%p
4268           (P) The compiler got confused about which scratch pad it was
4269           allocating and freeing temporaries and lexicals from.
4270
4271       panic: pad_free curpad, %p!=%p
4272           (P) The compiler got confused about which scratch pad it was
4273           allocating and freeing temporaries and lexicals from.
4274
4275       panic: pad_free po
4276           (P) A zero scratch pad offset was detected internally.  An attempt
4277           was made to free a target that had not been allocated to begin
4278           with.
4279
4280       panic: pad_reset curpad, %p!=%p
4281           (P) The compiler got confused about which scratch pad it was
4282           allocating and freeing temporaries and lexicals from.
4283
4284       panic: pad_sv po
4285           (P) A zero scratch pad offset was detected internally.  Most likely
4286           an operator needed a target but that target had not been allocated
4287           for whatever reason.
4288
4289       panic: pad_swipe curpad, %p!=%p
4290           (P) The compiler got confused about which scratch pad it was
4291           allocating and freeing temporaries and lexicals from.
4292
4293       panic: pad_swipe po
4294           (P) An invalid scratch pad offset was detected internally.
4295
4296       panic: pp_iter, type=%u
4297           (P) The foreach iterator got called in a non-loop context frame.
4298
4299       panic: pp_match%s
4300           (P) The internal pp_match() routine was called with invalid
4301           operational data.
4302
4303       panic: realloc, %s
4304           (P) Something requested a negative number of bytes of realloc.
4305
4306       panic: reference miscount on nsv in sv_replace() (%d != 1)
4307           (P) The internal sv_replace() function was handed a new SV with a
4308           reference count other than 1.
4309
4310       panic: restartop in %s
4311           (P) Some internal routine requested a goto (or something like it),
4312           and didn't supply the destination.
4313
4314       panic: return, type=%u
4315           (P) We popped the context stack to a subroutine or eval context,
4316           and then discovered it wasn't a subroutine or eval context.
4317
4318       panic: scan_num, %s
4319           (P) scan_num() got called on something that wasn't a number.
4320
4321       panic: Sequence (?{...}): no code block found in regex m/%s/
4322           (P) While compiling a pattern that has embedded (?{}) or (??{})
4323           code blocks, perl couldn't locate the code block that should have
4324           already been seen and compiled by perl before control passed to the
4325           regex compiler.
4326
4327       panic: strxfrm() gets absurd - a => %u, ab => %u
4328           (P) The interpreter's sanity check of the C function strxfrm()
4329           failed.  In your current locale the returned transformation of the
4330           string "ab" is shorter than that of the string "a", which makes no
4331           sense.
4332
4333       panic: sv_chop %s
4334           (P) The sv_chop() routine was passed a position that is not within
4335           the scalar's string buffer.
4336
4337       panic: sv_insert, midend=%p, bigend=%p
4338           (P) The sv_insert() routine was told to remove more string than
4339           there was string.
4340
4341       panic: top_env
4342           (P) The compiler attempted to do a goto, or something weird like
4343           that.
4344
4345       panic: unimplemented op %s (#%d) called
4346           (P) The compiler is screwed up and attempted to use an op that
4347           isn't permitted at run time.
4348
4349       panic: unknown OA_*: %x
4350           (P) The internal routine that handles arguments to "&CORE::foo()"
4351           subroutine calls was unable to determine what type of arguments
4352           were expected.
4353
4354       panic: utf16_to_utf8: odd bytelen
4355           (P) Something tried to call utf16_to_utf8 with an odd (as opposed
4356           to even) byte length.
4357
4358       panic: utf16_to_utf8_reversed: odd bytelen
4359           (P) Something tried to call utf16_to_utf8_reversed with an odd (as
4360           opposed to even) byte length.
4361
4362       panic: yylex, %s
4363           (P) The lexer got into a bad state while processing a case
4364           modifier.
4365
4366       Parentheses missing around "%s" list
4367           (W parenthesis) You said something like
4368
4369               my $foo, $bar = @_;
4370
4371           when you meant
4372
4373               my ($foo, $bar) = @_;
4374
4375           Remember that "my", "our", "local" and "state" bind tighter than
4376           comma.
4377
4378       Parsing code internal error (%s)
4379           (F) Parsing code supplied by an extension violated the parser's API
4380           in a detectable way.
4381
4382       Pattern subroutine nesting without pos change exceeded limit in regex
4383           (F) You used a pattern that uses too many nested subpattern calls
4384           without consuming any text.  Restructure the pattern so text is
4385           consumed before the nesting limit is exceeded.
4386
4387       "-p" destination: %s
4388           (F) An error occurred during the implicit output invoked by the
4389           "-p" command-line switch.  (This output goes to STDOUT unless
4390           you've redirected it with select().)
4391
4392       Perl API version %s of %s does not match %s
4393           (F) The XS module in question was compiled against a different
4394           incompatible version of Perl than the one that has loaded the XS
4395           module.
4396
4397       Perl folding rules are not up-to-date for 0x%X; please use the perlbug
4398       utility to report; in regex; marked by <-- HERE in m/%s/
4399           (S regexp) You used a regular expression with case-insensitive
4400           matching, and there is a bug in Perl in which the built-in regular
4401           expression folding rules are not accurate.  This may lead to
4402           incorrect results.  Please report this as a bug to
4403           <https://github.com/Perl/perl5/issues>.
4404
4405       PerlIO layer ':win32' is experimental
4406           (S experimental::win32_perlio) The ":win32" PerlIO layer is
4407           experimental.  If you want to take the risk of using this layer,
4408           simply disable this warning:
4409
4410               no warnings "experimental::win32_perlio";
4411
4412       Perl_my_%s() not available
4413           (F) Your platform has very uncommon byte-order and integer size, so
4414           it was not possible to set up some or all fixed-width byte-order
4415           conversion functions.  This is only a problem when you're using the
4416           '<' or '>' modifiers in (un)pack templates.  See "pack" in
4417           perlfunc.
4418
4419       Perl %s required (did you mean %s?)--this is only %s, stopped
4420           (F) The code you are trying to run has asked for a newer version of
4421           Perl than you are running.  Perhaps "use 5.10" was written instead
4422           of "use 5.010" or "use v5.10".  Without the leading "v", the number
4423           is interpreted as a decimal, with every three digits after the
4424           decimal point representing a part of the version number.  So 5.10
4425           is equivalent to v5.100.
4426
4427       Perl %s required--this is only %s, stopped
4428           (F) The module in question uses features of a version of Perl more
4429           recent than the currently running version.  How long has it been
4430           since you upgraded, anyway?  See "require" in perlfunc.
4431
4432       PERL_SH_DIR too long
4433           (F) An error peculiar to OS/2.  PERL_SH_DIR is the directory to
4434           find the "sh"-shell in.  See "PERL_SH_DIR" in perlos2.
4435
4436       PERL_SIGNALS illegal: "%s"
4437           (X) See "PERL_SIGNALS" in perlrun for legal values.
4438
4439       Perls since %s too modern--this is %s, stopped
4440           (F) The code you are trying to run claims it will not run on the
4441           version of Perl you are using because it is too new.  Maybe the
4442           code needs to be updated, or maybe it is simply wrong and the
4443           version check should just be removed.
4444
4445       perl: warning: Non hex character in '$ENV{PERL_HASH_SEED}', seed only
4446       partially set
4447           (S) PERL_HASH_SEED should match /^\s*(?:0x)?[0-9a-fA-F]+\s*\z/ but
4448           it contained a non hex character.  This could mean you are not
4449           using the hash seed you think you are.
4450
4451       perl: warning: Setting locale failed.
4452           (S) The whole warning message will look something like:
4453
4454                   perl: warning: Setting locale failed.
4455                   perl: warning: Please check that your locale settings:
4456                           LC_ALL = "En_US",
4457                           LANG = (unset)
4458                       are supported and installed on your system.
4459                   perl: warning: Falling back to the standard locale ("C").
4460
4461           Exactly what were the failed locale settings varies.  In the above
4462           the settings were that the LC_ALL was "En_US" and the LANG had no
4463           value.  This error means that Perl detected that you and/or your
4464           operating system supplier and/or system administrator have set up
4465           the so-called locale system but Perl could not use those settings.
4466           This was not dead serious, fortunately: there is a "default locale"
4467           called "C" that Perl can and will use, and the script will be run.
4468           Before you really fix the problem, however, you will get the same
4469           error message each time you run Perl.  How to really fix the
4470           problem can be found in perllocale section LOCALE PROBLEMS.
4471
4472       perl: warning: strange setting in '$ENV{PERL_PERTURB_KEYS}': '%s'
4473           (S) Perl was run with the environment variable PERL_PERTURB_KEYS
4474           defined but containing an unexpected value.  The legal values of
4475           this setting are as follows.
4476
4477             Numeric | String        | Result
4478             --------+---------------+-----------------------------------------
4479             0       | NO            | Disables key traversal randomization
4480             1       | RANDOM        | Enables full key traversal randomization
4481             2       | DETERMINISTIC | Enables repeatable key traversal
4482                     |               | randomization
4483
4484           Both numeric and string values are accepted, but note that string
4485           values are case sensitive.  The default for this setting is
4486           "RANDOM" or 1.
4487
4488       pid %x not a child
4489           (W exec) A warning peculiar to VMS.  Waitpid() was asked to wait
4490           for a process which isn't a subprocess of the current process.
4491           While this is fine from VMS' perspective, it's probably not what
4492           you intended.
4493
4494       'P' must have an explicit size in unpack
4495           (F) The unpack format P must have an explicit size, not "*".
4496
4497       POSIX class [:%s:] unknown in regex; marked by <-- HERE in m/%s/
4498           (F) The class in the character class [: :] syntax is unknown.  The
4499           <-- HERE shows whereabouts in the regular expression the problem
4500           was discovered.  Note that the POSIX character classes do not have
4501           the "is" prefix the corresponding C interfaces have: in other
4502           words, it's "[[:print:]]", not "isprint".  See perlre.
4503
4504       POSIX getpgrp can't take an argument
4505           (F) Your system has POSIX getpgrp(), which takes no argument,
4506           unlike the BSD version, which takes a pid.
4507
4508       POSIX syntax [%c %c] belongs inside character classes%s in regex;
4509       marked by <-- HERE in m/%s/
4510           (W regexp) Perl thinks that you intended to write a POSIX character
4511           class, but didn't use enough brackets.  These POSIX class
4512           constructs [: :], [= =], and [. .]  go inside character classes,
4513           the [] are part of the construct, for example:
4514           "qr/[012[:alpha:]345]/".  What the regular expression pattern
4515           compiled to is probably not what you were intending.  For example,
4516           "qr/[:alpha:]/" compiles to a regular bracketed character class
4517           consisting of the four characters ":",  "a",  "l", "h", and "p".
4518           To specify the POSIX class, it should have been written
4519           "qr/[[:alpha:]]/".
4520
4521           Note that [= =] and [. .] are not currently implemented; they are
4522           simply placeholders for future extensions and will cause fatal
4523           errors.  The <-- HERE shows whereabouts in the regular expression
4524           the problem was discovered.  See perlre.
4525
4526           If the specification of the class was not completely valid, the
4527           message indicates that.
4528
4529       POSIX syntax [. .] is reserved for future extensions in regex; marked
4530       by <-- HERE in m/%s/
4531           (F) Within regular expression character classes ([]) the syntax
4532           beginning with "[." and ending with ".]" is reserved for future
4533           extensions.  If you need to represent those character sequences
4534           inside a regular expression character class, just quote the square
4535           brackets with the backslash: "\[."  and ".\]".  The <-- HERE shows
4536           whereabouts in the regular expression the problem was discovered.
4537           See perlre.
4538
4539       POSIX syntax [= =] is reserved for future extensions in regex; marked
4540       by <-- HERE in m/%s/
4541           (F) Within regular expression character classes ([]) the syntax
4542           beginning with "[=" and ending with "=]" is reserved for future
4543           extensions.  If you need to represent those character sequences
4544           inside a regular expression character class, just quote the square
4545           brackets with the backslash: "\[=" and "=\]".  The <-- HERE shows
4546           whereabouts in the regular expression the problem was discovered.
4547           See perlre.
4548
4549       Possible attempt to put comments in qw() list
4550           (W qw) qw() lists contain items separated by whitespace; as with
4551           literal strings, comment characters are not ignored, but are
4552           instead treated as literal data.  (You may have used different
4553           delimiters than the parentheses shown here; braces are also
4554           frequently used.)
4555
4556           You probably wrote something like this:
4557
4558               @list = qw(
4559                   a # a comment
4560                   b # another comment
4561               );
4562
4563           when you should have written this:
4564
4565               @list = qw(
4566                   a
4567                   b
4568               );
4569
4570           If you really want comments, build your list the old-fashioned way,
4571           with quotes and commas:
4572
4573               @list = (
4574                   'a',    # a comment
4575                   'b',    # another comment
4576               );
4577
4578       Possible attempt to separate words with commas
4579           (W qw) qw() lists contain items separated by whitespace; therefore
4580           commas aren't needed to separate the items.  (You may have used
4581           different delimiters than the parentheses shown here; braces are
4582           also frequently used.)
4583
4584           You probably wrote something like this:
4585
4586               qw! a, b, c !;
4587
4588           which puts literal commas into some of the list items.  Write it
4589           without commas if you don't want them to appear in your data:
4590
4591               qw! a b c !;
4592
4593       Possible memory corruption: %s overflowed 3rd argument
4594           (F) An ioctl() or fcntl() returned more than Perl was bargaining
4595           for.  Perl guesses a reasonable buffer size, but puts a sentinel
4596           byte at the end of the buffer just in case.  This sentinel byte got
4597           clobbered, and Perl assumes that memory is now corrupted.  See
4598           "ioctl" in perlfunc.
4599
4600       Possible precedence issue with control flow operator
4601           (W syntax) There is a possible problem with the mixing of a control
4602           flow operator (e.g. "return") and a low-precedence operator like
4603           "or".  Consider:
4604
4605               sub { return $a or $b; }
4606
4607           This is parsed as:
4608
4609               sub { (return $a) or $b; }
4610
4611           Which is effectively just:
4612
4613               sub { return $a; }
4614
4615           Either use parentheses or the high-precedence variant of the
4616           operator.
4617
4618           Note this may be also triggered for constructs like:
4619
4620               sub { 1 if die; }
4621
4622       Possible precedence problem on bitwise %s operator
4623           (W precedence) Your program uses a bitwise logical operator in
4624           conjunction with a numeric comparison operator, like this :
4625
4626               if ($x & $y == 0) { ... }
4627
4628           This expression is actually equivalent to "$x & ($y == 0)", due to
4629           the higher precedence of "==".  This is probably not what you want.
4630           (If you really meant to write this, disable the warning, or,
4631           better, put the parentheses explicitly and write "$x & ($y == 0)").
4632
4633       Possible unintended interpolation of $\ in regex
4634           (W ambiguous) You said something like "m/$\/" in a regex.  The
4635           regex "m/foo$\s+bar/m" translates to: match the word 'foo', the
4636           output record separator (see "$\" in perlvar) and the letter 's'
4637           (one time or more) followed by the word 'bar'.
4638
4639           If this is what you intended then you can silence the warning by
4640           using "m/${\}/" (for example: "m/foo${\}s+bar/").
4641
4642           If instead you intended to match the word 'foo' at the end of the
4643           line followed by whitespace and the word 'bar' on the next line
4644           then you can use "m/$(?)\/" (for example: "m/foo$(?)\s+bar/").
4645
4646       Possible unintended interpolation of %s in string
4647           (W ambiguous) You said something like '@foo' in a double-quoted
4648           string but there was no array @foo in scope at the time.  If you
4649           wanted a literal @foo, then write it as \@foo; otherwise find out
4650           what happened to the array you apparently lost track of.
4651
4652       Precedence problem: open %s should be open(%s)
4653           (S precedence) The old irregular construct
4654
4655               open FOO || die;
4656
4657           is now misinterpreted as
4658
4659               open(FOO || die);
4660
4661           because of the strict regularization of Perl 5's grammar into unary
4662           and list operators.  (The old open was a little of both.)  You must
4663           put parentheses around the filehandle, or use the new "or" operator
4664           instead of "||".
4665
4666       Premature end of script headers
4667           See "500 Server error".
4668
4669       printf() on closed filehandle %s
4670           (W closed) The filehandle you're writing to got itself closed
4671           sometime before now.  Check your control flow.
4672
4673       print() on closed filehandle %s
4674           (W closed) The filehandle you're printing on got itself closed
4675           sometime before now.  Check your control flow.
4676
4677       Process terminated by SIG%s
4678           (W) This is a standard message issued by OS/2 applications, while
4679           *nix applications die in silence.  It is considered a feature of
4680           the OS/2 port.  One can easily disable this by appropriate
4681           sighandlers, see "Signals" in perlipc.  See also "Process
4682           terminated by SIGTERM/SIGINT" in perlos2.
4683
4684       Prototype after '%c' for %s : %s
4685           (W illegalproto) A character follows % or @ in a prototype.  This
4686           is useless, since % and @ gobble the rest of the subroutine
4687           arguments.
4688
4689       Prototype mismatch: %s vs %s
4690           (S prototype) The subroutine being declared or defined had
4691           previously been declared or defined with a different function
4692           prototype.
4693
4694       Prototype not terminated
4695           (F) You've omitted the closing parenthesis in a function prototype
4696           definition.
4697
4698       Prototype '%s' overridden by attribute 'prototype(%s)' in %s
4699           (W prototype) A prototype was declared in both the parentheses
4700           after the sub name and via the prototype attribute.  The prototype
4701           in parentheses is useless, since it will be replaced by the
4702           prototype from the attribute before it's ever used.
4703
4704       Quantifier follows nothing in regex; marked by <-- HERE in m/%s/
4705           (F) You started a regular expression with a quantifier.  Backslash
4706           it if you meant it literally.  The <-- HERE shows whereabouts in
4707           the regular expression the problem was discovered.  See perlre.
4708
4709       Quantifier in {,} bigger than %d in regex; marked by <-- HERE in m/%s/
4710           (F) There is currently a limit to the size of the min and max
4711           values of the {min,max} construct.  The <-- HERE shows whereabouts
4712           in the regular expression the problem was discovered.  See perlre.
4713
4714       Quantifier {n,m} with n > m can't match in regex
4715       Quantifier {n,m} with n > m can't match in regex; marked by <-- HERE in
4716       m/%s/
4717           (W regexp) Minima should be less than or equal to maxima.  If you
4718           really want your regexp to match something 0 times, just put {0}.
4719
4720       Quantifier unexpected on zero-length expression in regex m/%s/
4721           (W regexp) You applied a regular expression quantifier in a place
4722           where it makes no sense, such as on a zero-width assertion.  Try
4723           putting the quantifier inside the assertion instead.  For example,
4724           the way to match "abc" provided that it is followed by three
4725           repetitions of "xyz" is "/abc(?=(?:xyz){3})/", not
4726           "/abc(?=xyz){3}/".
4727
4728       Range iterator outside integer range
4729           (F) One (or both) of the numeric arguments to the range operator
4730           ".."  are outside the range which can be represented by integers
4731           internally.  One possible workaround is to force Perl to use
4732           magical string increment by prepending "0" to your numbers.
4733
4734       Ranges of ASCII printables should be some subset of "0-9", "A-Z", or
4735       "a-z" in regex; marked by <-- HERE in m/%s/
4736           (W regexp) (only under "use re 'strict'" or within "(?[...])")
4737
4738           Stricter rules help to find typos and other errors.  Perhaps you
4739           didn't even intend a range here, if the "-" was meant to be some
4740           other character, or should have been escaped (like "\-").  If you
4741           did intend a range, the one that was used is not portable between
4742           ASCII and EBCDIC platforms, and doesn't have an obvious meaning to
4743           a casual reader.
4744
4745            [3-7]    # OK; Obvious and portable
4746            [d-g]    # OK; Obvious and portable
4747            [A-Y]    # OK; Obvious and portable
4748            [A-z]    # WRONG; Not portable; not clear what is meant
4749            [a-Z]    # WRONG; Not portable; not clear what is meant
4750            [%-.]    # WRONG; Not portable; not clear what is meant
4751            [\x41-Z] # WRONG; Not portable; not obvious to non-geek
4752
4753           (You can force portability by specifying a Unicode range, which
4754           means that the endpoints are specified by "\N{...}", but the
4755           meaning may still not be obvious.)  The stricter rules require that
4756           ranges that start or stop with an ASCII character that is not a
4757           control have all their endpoints be the literal character, and not
4758           some escape sequence (like "\x41"), and the ranges must be all
4759           digits, or all uppercase letters, or all lowercase letters.
4760
4761       Ranges of digits should be from the same group in regex; marked by
4762       <-- HERE in m/%s/
4763           (W regexp) (only under "use re 'strict'" or within "(?[...])")
4764
4765           Stricter rules help to find typos and other errors.  You included a
4766           range, and at least one of the end points is a decimal digit.
4767           Under the stricter rules, when this happens, both end points should
4768           be digits in the same group of 10 consecutive digits.
4769
4770       readdir() attempted on invalid dirhandle %s
4771           (W io) The dirhandle you're reading from is either closed or not
4772           really a dirhandle.  Check your control flow.
4773
4774       readline() on closed filehandle %s
4775           (W closed) The filehandle you're reading from got itself closed
4776           sometime before now.  Check your control flow.
4777
4778       read() on closed filehandle %s
4779           (W closed) You tried to read from a closed filehandle.
4780
4781       read() on unopened filehandle %s
4782           (W unopened) You tried to read from a filehandle that was never
4783           opened.
4784
4785       Reallocation too large: %x
4786           (F) You can't allocate more than 64K on an MS-DOS machine.
4787
4788       realloc() of freed memory ignored
4789           (S malloc) An internal routine called realloc() on something that
4790           had already been freed.
4791
4792       Recompile perl with -DDEBUGGING to use -D switch
4793           (S debugging) You can't use the -D option unless the code to
4794           produce the desired output is compiled into Perl, which entails
4795           some overhead, which is why it's currently left out of your copy.
4796
4797       Recursive call to Perl_load_module in PerlIO_find_layer
4798           (P) It is currently not permitted to load modules when creating a
4799           filehandle inside an %INC hook.  This can happen with "open my $fh,
4800           '<', \$scalar", which implicitly loads PerlIO::scalar.  Try loading
4801           PerlIO::scalar explicitly first.
4802
4803       Recursive inheritance detected in package '%s'
4804           (F) While calculating the method resolution order (MRO) of a
4805           package, Perl believes it found an infinite loop in the @ISA
4806           hierarchy.  This is a crude check that bails out after 100 levels
4807           of @ISA depth.
4808
4809       Redundant argument in %s
4810           (W redundant) You called a function with more arguments than other
4811           arguments you supplied indicated would be needed.  Currently only
4812           emitted when a printf-type format required fewer arguments than
4813           were supplied, but might be used in the future for e.g. "pack" in
4814           perlfunc.
4815
4816       refcnt_dec: fd %d%s
4817       refcnt: fd %d%s
4818       refcnt_inc: fd %d%s
4819           (P) Perl's I/O implementation failed an internal consistency check.
4820           If you see this message, something is very wrong.
4821
4822       Reference found where even-sized list expected
4823           (W misc) You gave a single reference where Perl was expecting a
4824           list with an even number of elements (for assignment to a hash).
4825           This usually means that you used the anon hash constructor when you
4826           meant to use parens.  In any case, a hash requires key/value pairs.
4827
4828               %hash = { one => 1, two => 2, };    # WRONG
4829               %hash = [ qw/ an anon array / ];    # WRONG
4830               %hash = ( one => 1, two => 2, );    # right
4831               %hash = qw( one 1 two 2 );                  # also fine
4832
4833       Reference is already weak
4834           (W misc) You have attempted to weaken a reference that is already
4835           weak.  Doing so has no effect.
4836
4837       Reference is not weak
4838           (W misc) You have attempted to unweaken a reference that is not
4839           weak.  Doing so has no effect.
4840
4841       Reference to invalid group 0 in regex; marked by <-- HERE in m/%s/
4842           (F) You used "\g0" or similar in a regular expression.  You may
4843           refer to capturing parentheses only with strictly positive integers
4844           (normal backreferences) or with strictly negative integers
4845           (relative backreferences).  Using 0 does not make sense.
4846
4847       Reference to nonexistent group in regex; marked by <-- HERE in m/%s/
4848           (F) You used something like "\7" in your regular expression, but
4849           there are not at least seven sets of capturing parentheses in the
4850           expression.  If you wanted to have the character with ordinal 7
4851           inserted into the regular expression, prepend zeroes to make it
4852           three digits long: "\007"
4853
4854           The <-- HERE shows whereabouts in the regular expression the
4855           problem was discovered.
4856
4857       Reference to nonexistent named group in regex; marked by <-- HERE in
4858       m/%s/
4859           (F) You used something like "\k'NAME'" or "\k<NAME>" in your
4860           regular expression, but there is no corresponding named capturing
4861           parentheses such as "(?'NAME'...)" or "(?<NAME>...)".  Check if the
4862           name has been spelled correctly both in the backreference and the
4863           declaration.
4864
4865           The <-- HERE shows whereabouts in the regular expression the
4866           problem was discovered.
4867
4868       Reference to nonexistent or unclosed group in regex; marked by <-- HERE
4869       in m/%s/
4870           (F) You used something like "\g{-7}" in your regular expression,
4871           but there are not at least seven sets of closed capturing
4872           parentheses in the expression before where the "\g{-7}" was
4873           located.
4874
4875           The <-- HERE shows whereabouts in the regular expression the
4876           problem was discovered.
4877
4878       regexp memory corruption
4879           (P) The regular expression engine got confused by what the regular
4880           expression compiler gave it.
4881
4882       Regexp modifier "/%c" may appear a maximum of twice
4883       Regexp modifier "%c" may appear a maximum of twice in regex; marked by
4884       <-- HERE in m/%s/
4885           (F) The regular expression pattern had too many occurrences of the
4886           specified modifier.  Remove the extraneous ones.
4887
4888       Regexp modifier "%c" may not appear after the "-" in regex; marked by
4889       <-- HERE in m/%s/
4890           (F) Turning off the given modifier has the side effect of turning
4891           on another one.  Perl currently doesn't allow this.  Reword the
4892           regular expression to use the modifier you want to turn on (and
4893           place it before the minus), instead of the one you want to turn
4894           off.
4895
4896       Regexp modifier "/%c" may not appear twice
4897       Regexp modifier "%c" may not appear twice in regex; marked by <-- HERE
4898       in m/%s/
4899           (F) The regular expression pattern had too many occurrences of the
4900           specified modifier.  Remove the extraneous ones.
4901
4902       Regexp modifiers "/%c" and "/%c" are mutually exclusive
4903       Regexp modifiers "%c" and "%c" are mutually exclusive in regex; marked
4904       by <-- HERE in m/%s/
4905           (F) The regular expression pattern had more than one of these
4906           mutually exclusive modifiers.  Retain only the modifier that is
4907           supposed to be there.
4908
4909       Regexp out of space in regex m/%s/
4910           (P) A "can't happen" error, because safemalloc() should have caught
4911           it earlier.
4912
4913       Repeated format line will never terminate (~~ and @#)
4914           (F) Your format contains the ~~ repeat-until-blank sequence and a
4915           numeric field that will never go blank so that the repetition never
4916           terminates.  You might use ^# instead.  See perlform.
4917
4918       Replacement list is longer than search list
4919           (W misc) You have used a replacement list that is longer than the
4920           search list.  So the additional elements in the replacement list
4921           are meaningless.
4922
4923       '(*%s' requires a terminating ':' in regex; marked by <-- HERE in m/%s/
4924           (F) You used a construct that needs a colon and pattern argument.
4925           Supply these or check that you are using the right construct.
4926
4927       '%s' resolved to '\o{%s}%d'
4928           As of Perl 5.32, this message is no longer generated.  Instead, see
4929           "Non-octal character '%c' terminates \o early.  Resolved as "%s"".
4930           (W misc, regexp)  You wrote something like "\08", or "\179" in a
4931           double-quotish string.  All but the last digit is treated as a
4932           single character, specified in octal.  The last digit is the next
4933           character in the string.  To tell Perl that this is indeed what you
4934           want, you can use the "\o{ }" syntax, or use exactly three digits
4935           to specify the octal for the character.
4936
4937       Reversed %s= operator
4938           (W syntax) You wrote your assignment operator backwards.  The =
4939           must always come last, to avoid ambiguity with subsequent unary
4940           operators.
4941
4942       rewinddir() attempted on invalid dirhandle %s
4943           (W io) The dirhandle you tried to do a rewinddir() on is either
4944           closed or not really a dirhandle.  Check your control flow.
4945
4946       Scalars leaked: %d
4947           (S internal) Something went wrong in Perl's internal bookkeeping of
4948           scalars: not all scalar variables were deallocated by the time Perl
4949           exited.  What this usually indicates is a memory leak, which is of
4950           course bad, especially if the Perl program is intended to be long-
4951           running.
4952
4953       Scalar value @%s[%s] better written as $%s[%s]
4954           (W syntax) You've used an array slice (indicated by @) to select a
4955           single element of an array.  Generally it's better to ask for a
4956           scalar value (indicated by $).  The difference is that $foo[&bar]
4957           always behaves like a scalar, both when assigning to it and when
4958           evaluating its argument, while @foo[&bar] behaves like a list when
4959           you assign to it, and provides a list context to its subscript,
4960           which can do weird things if you're expecting only one subscript.
4961
4962           On the other hand, if you were actually hoping to treat the array
4963           element as a list, you need to look into how references work,
4964           because Perl will not magically convert between scalars and lists
4965           for you.  See perlref.
4966
4967       Scalar value @%s{%s} better written as $%s{%s}
4968           (W syntax) You've used a hash slice (indicated by @) to select a
4969           single element of a hash.  Generally it's better to ask for a
4970           scalar value (indicated by $).  The difference is that $foo{&bar}
4971           always behaves like a scalar, both when assigning to it and when
4972           evaluating its argument, while @foo{&bar} behaves like a list when
4973           you assign to it, and provides a list context to its subscript,
4974           which can do weird things if you're expecting only one subscript.
4975
4976           On the other hand, if you were actually hoping to treat the hash
4977           element as a list, you need to look into how references work,
4978           because Perl will not magically convert between scalars and lists
4979           for you.  See perlref.
4980
4981       Search pattern not terminated
4982           (F) The lexer couldn't find the final delimiter of a // or m{}
4983           construct.  Remember that bracketing delimiters count nesting
4984           level.  Missing the leading "$" from a variable $m may cause this
4985           error.
4986
4987           Note that since Perl 5.10.0 a // can also be the defined-or
4988           construct, not just the empty search pattern.  Therefore code
4989           written in Perl 5.10.0 or later that uses the // as the defined-or
4990           can be misparsed by pre-5.10.0 Perls as a non-terminated search
4991           pattern.
4992
4993       seekdir() attempted on invalid dirhandle %s
4994           (W io) The dirhandle you are doing a seekdir() on is either closed
4995           or not really a dirhandle.  Check your control flow.
4996
4997       %sseek() on unopened filehandle
4998           (W unopened) You tried to use the seek() or sysseek() function on a
4999           filehandle that was either never opened or has since been closed.
5000
5001       select not implemented
5002           (F) This machine doesn't implement the select() system call.
5003
5004       Self-ties of arrays and hashes are not supported
5005           (F) Self-ties are of arrays and hashes are not supported in the
5006           current implementation.
5007
5008       Semicolon seems to be missing
5009           (W semicolon) A nearby syntax error was probably caused by a
5010           missing semicolon, or possibly some other missing operator, such as
5011           a comma.
5012
5013       semi-panic: attempt to dup freed string
5014           (S internal) The internal newSVsv() routine was called to duplicate
5015           a scalar that had previously been marked as free.
5016
5017       sem%s not implemented
5018           (F) You don't have System V semaphore IPC on your system.
5019
5020       send() on closed socket %s
5021           (W closed) The socket you're sending to got itself closed sometime
5022           before now.  Check your control flow.
5023
5024       Sequence "\c{" invalid
5025           (F) These three characters may not appear in sequence in a double-
5026           quotish context.  This message is raised only on non-ASCII
5027           platforms (a different error message is output on ASCII ones).  If
5028           you were intending to specify a control character with this
5029           sequence, you'll have to use a different way to specify it.
5030
5031       Sequence (? incomplete in regex; marked by <-- HERE in m/%s/
5032           (F) A regular expression ended with an incomplete extension (?.
5033           The <-- HERE shows whereabouts in the regular expression the
5034           problem was discovered.  See perlre.
5035
5036       Sequence (?%c...) not implemented in regex; marked by <-- HERE in m/%s/
5037           (F) A proposed regular expression extension has the character
5038           reserved but has not yet been written.  The <-- HERE shows
5039           whereabouts in the regular expression the problem was discovered.
5040           See perlre.
5041
5042       Sequence (?%s...) not recognized in regex; marked by <-- HERE in m/%s/
5043           (F) You used a regular expression extension that doesn't make
5044           sense.  The <-- HERE shows whereabouts in the regular expression
5045           the problem was discovered.  This may happen when using the
5046           "(?^...)" construct to tell Perl to use the default regular
5047           expression modifiers, and you redundantly specify a default
5048           modifier.  For other causes, see perlre.
5049
5050       Sequence (?#... not terminated in regex m/%s/
5051           (F) A regular expression comment must be terminated by a closing
5052           parenthesis.  Embedded parentheses aren't allowed.  See perlre.
5053
5054       Sequence (?&... not terminated in regex; marked by <-- HERE in m/%s/
5055           (F) A named reference of the form "(?&...)" was missing the final
5056           closing parenthesis after the name.  The <-- HERE shows whereabouts
5057           in the regular expression the problem was discovered.
5058
5059       Sequence (?%c... not terminated in regex; marked by <-- HERE in m/%s/
5060           (F) A named group of the form "(?'...')" or "(?<...>)" was missing
5061           the final closing quote or angle bracket.  The <-- HERE shows
5062           whereabouts in the regular expression the problem was discovered.
5063
5064       Sequence (?(%c... not terminated in regex; marked by <-- HERE in m/%s/
5065           (F) A named reference of the form "(?('...')...)" or
5066           "(?(<...>)...)" was missing the final closing quote or angle
5067           bracket after the name.  The <-- HERE shows whereabouts in the
5068           regular expression the problem was discovered.
5069
5070       Sequence (?... not terminated in regex; marked by <-- HERE in m/%s/
5071           (F) There was no matching closing parenthesis for the '('.  The
5072           <-- HERE shows whereabouts in the regular expression the problem
5073           was discovered.
5074
5075       Sequence \%s... not terminated in regex; marked by <-- HERE in m/%s/
5076           (F) The regular expression expects a mandatory argument following
5077           the escape sequence and this has been omitted or incorrectly
5078           written.
5079
5080       Sequence (?{...}) not terminated with ')'
5081           (F) The end of the perl code contained within the {...} must be
5082           followed immediately by a ')'.
5083
5084       Sequence (?P>... not terminated in regex; marked by <-- HERE in m/%s/
5085           (F) A named reference of the form "(?P>...)" was missing the final
5086           closing parenthesis after the name.  The <-- HERE shows whereabouts
5087           in the regular expression the problem was discovered.
5088
5089       Sequence (?P<... not terminated in regex; marked by <-- HERE in m/%s/
5090           (F) A named group of the form "(?P<...>')" was missing the final
5091           closing angle bracket.  The <-- HERE shows whereabouts in the
5092           regular expression the problem was discovered.
5093
5094       Sequence ?P=... not terminated in regex; marked by <-- HERE in m/%s/
5095           (F) A named reference of the form "(?P=...)" was missing the final
5096           closing parenthesis after the name.  The <-- HERE shows whereabouts
5097           in the regular expression the problem was discovered.
5098
5099       Sequence (?R) not terminated in regex m/%s/
5100           (F) An "(?R)" or "(?0)" sequence in a regular expression was
5101           missing the final parenthesis.
5102
5103       500 Server error
5104           (A) This is the error message generally seen in a browser window
5105           when trying to run a CGI program (including SSI) over the web.  The
5106           actual error text varies widely from server to server.  The most
5107           frequently-seen variants are "500 Server error", "Method
5108           (something) not permitted", "Document contains no data", "Premature
5109           end of script headers", and "Did not produce a valid header".
5110
5111           This is a CGI error, not a Perl error.
5112
5113           You need to make sure your script is executable, is accessible by
5114           the user CGI is running the script under (which is probably not the
5115           user account you tested it under), does not rely on any environment
5116           variables (like PATH) from the user it isn't running under, and
5117           isn't in a location where the CGI server can't find it, basically,
5118           more or less.  Please see the following for more information:
5119
5120                   https://www.perl.org/CGI_MetaFAQ.html
5121                   http://www.htmlhelp.org/faq/cgifaq.html
5122                   http://www.w3.org/Security/Faq/
5123
5124           You should also look at perlfaq9.
5125
5126       setegid() not implemented
5127           (F) You tried to assign to $), and your operating system doesn't
5128           support the setegid() system call (or equivalent), or at least
5129           Configure didn't think so.
5130
5131       seteuid() not implemented
5132           (F) You tried to assign to $>, and your operating system doesn't
5133           support the seteuid() system call (or equivalent), or at least
5134           Configure didn't think so.
5135
5136       setpgrp can't take arguments
5137           (F) Your system has the setpgrp() from BSD 4.2, which takes no
5138           arguments, unlike POSIX setpgid(), which takes a process ID and
5139           process group ID.
5140
5141       setrgid() not implemented
5142           (F) You tried to assign to $(, and your operating system doesn't
5143           support the setrgid() system call (or equivalent), or at least
5144           Configure didn't think so.
5145
5146       setruid() not implemented
5147           (F) You tried to assign to $<, and your operating system doesn't
5148           support the setruid() system call (or equivalent), or at least
5149           Configure didn't think so.
5150
5151       setsockopt() on closed socket %s
5152           (W closed) You tried to set a socket option on a closed socket.
5153           Did you forget to check the return value of your socket() call?
5154           See "setsockopt" in perlfunc.
5155
5156       Setting $/ to a reference to %s is forbidden
5157           (F) You assigned a reference to a scalar to $/ where the referenced
5158           item is not a positive integer.  In older perls this appeared to
5159           work the same as setting it to "undef" but was in fact internally
5160           different, less efficient and with very bad luck could have
5161           resulted in your file being split by a stringified form of the
5162           reference.
5163
5164           In Perl 5.20.0 this was changed so that it would be exactly the
5165           same as setting $/ to undef, with the exception that this warning
5166           would be thrown.
5167
5168           You are recommended to change your code to set $/ to "undef"
5169           explicitly if you wish to slurp the file.  As of Perl 5.28
5170           assigning $/ to a reference to an integer which isn't positive is a
5171           fatal error.
5172
5173       Setting $/ to %s reference is forbidden
5174           (F) You tried to assign a reference to a non integer to $/.  In
5175           older Perls this would have behaved similarly to setting it to a
5176           reference to a positive integer, where the integer was the address
5177           of the reference.  As of Perl 5.20.0 this is a fatal error, to
5178           allow future versions of Perl to use non-integer refs for more
5179           interesting purposes.
5180
5181       shm%s not implemented
5182           (F) You don't have System V shared memory IPC on your system.
5183
5184       !=~ should be !~
5185           (W syntax) The non-matching operator is !~, not !=~.  !=~ will be
5186           interpreted as the != (numeric not equal) and ~ (1's complement)
5187           operators: probably not what you intended.
5188
5189       /%s/ should probably be written as "%s"
5190           (W syntax) You have used a pattern where Perl expected to find a
5191           string, as in the first argument to "join".  Perl will treat the
5192           true or false result of matching the pattern against $_ as the
5193           string, which is probably not what you had in mind.
5194
5195       shutdown() on closed socket %s
5196           (W closed) You tried to do a shutdown on a closed socket.  Seems a
5197           bit superfluous.
5198
5199       SIG%s handler "%s" not defined
5200           (W signal) The signal handler named in %SIG doesn't, in fact,
5201           exist.  Perhaps you put it into the wrong package?
5202
5203       Slab leaked from cv %p
5204           (S) If you see this message, then something is seriously wrong with
5205           the internal bookkeeping of op trees.  An op tree needed to be
5206           freed after a compilation error, but could not be found, so it was
5207           leaked instead.
5208
5209       sleep(%u) too large
5210           (W overflow) You called "sleep" with a number that was larger than
5211           it can reliably handle and "sleep" probably slept for less time
5212           than requested.
5213
5214       Slurpy parameter not last
5215           (F) In a subroutine signature, you put something after a slurpy
5216           (array or hash) parameter.  The slurpy parameter takes all the
5217           available arguments, so there can't be any left to fill later
5218           parameters.
5219
5220       Smart matching a non-overloaded object breaks encapsulation
5221           (F) You should not use the "~~" operator on an object that does not
5222           overload it: Perl refuses to use the object's underlying structure
5223           for the smart match.
5224
5225       Smartmatch is experimental
5226           (S experimental::smartmatch) This warning is emitted if you use the
5227           smartmatch ("~~") operator.  This is currently an experimental
5228           feature, and its details are subject to change in future releases
5229           of Perl.  Particularly, its current behavior is noticed for being
5230           unnecessarily complex and unintuitive, and is very likely to be
5231           overhauled.
5232
5233       Sorry, hash keys must be smaller than 2**31 bytes
5234           (F) You tried to create a hash containing a very large key, where
5235           "very large" means that it needs at least 2 gigabytes to store.
5236           Unfortunately, Perl doesn't yet handle such large hash keys. You
5237           should reconsider your design to avoid hashing such a long string
5238           directly.
5239
5240       sort is now a reserved word
5241           (F) An ancient error message that almost nobody ever runs into
5242           anymore.  But before sort was a keyword, people sometimes used it
5243           as a filehandle.
5244
5245       Source filters apply only to byte streams
5246           (F) You tried to activate a source filter (usually by loading a
5247           source filter module) within a string passed to "eval".  This is
5248           not permitted under the "unicode_eval" feature.  Consider using
5249           "evalbytes" instead.  See feature.
5250
5251       splice() offset past end of array
5252           (W misc) You attempted to specify an offset that was past the end
5253           of the array passed to splice().  Splicing will instead commence at
5254           the end of the array, rather than past it.  If this isn't what you
5255           want, try explicitly pre-extending the array by assigning $#array =
5256           $offset.  See "splice" in perlfunc.
5257
5258       Split loop
5259           (P) The split was looping infinitely.  (Obviously, a split
5260           shouldn't iterate more times than there are characters of input,
5261           which is what happened.)  See "split" in perlfunc.
5262
5263       Statement unlikely to be reached
5264           (W exec) You did an exec() with some statement after it other than
5265           a die().  This is almost always an error, because exec() never
5266           returns unless there was a failure.  You probably wanted to use
5267           system() instead, which does return.  To suppress this warning, put
5268           the exec() in a block by itself.
5269
5270       "state" subroutine %s can't be in a package
5271           (F) Lexically scoped subroutines aren't in a package, so it doesn't
5272           make sense to try to declare one with a package qualifier on the
5273           front.
5274
5275       "state %s" used in sort comparison
5276           (W syntax) The package variables $a and $b are used for sort
5277           comparisons.  You used $a or $b in as an operand to the "<=>" or
5278           "cmp" operator inside a sort comparison block, and the variable had
5279           earlier been declared as a lexical variable.  Either qualify the
5280           sort variable with the package name, or rename the lexical
5281           variable.
5282
5283       "state" variable %s can't be in a package
5284           (F) Lexically scoped variables aren't in a package, so it doesn't
5285           make sense to try to declare one with a package qualifier on the
5286           front.  Use local() if you want to localize a package variable.
5287
5288       stat() on unopened filehandle %s
5289           (W unopened) You tried to use the stat() function on a filehandle
5290           that was either never opened or has since been closed.
5291
5292       Strings with code points over 0xFF may not be mapped into in-memory
5293       file handles
5294           (W utf8) You tried to open a reference to a scalar for read or
5295           append where the scalar contained code points over 0xFF.  In-memory
5296           files model on-disk files and can only contain bytes.
5297
5298       Stub found while resolving method "%s" overloading "%s" in package "%s"
5299           (P) Overloading resolution over @ISA tree may be broken by
5300           importation stubs.  Stubs should never be implicitly created, but
5301           explicit calls to "can" may break this.
5302
5303       Subroutine attributes must come before the signature
5304           (F) When subroutine signatures are enabled, any subroutine
5305           attributes must come before the signature. Note that this order was
5306           the opposite in versions 5.22..5.26. So:
5307
5308               sub foo :lvalue ($a, $b) { ... }  # 5.20 and 5.28 +
5309               sub foo ($a, $b) :lvalue { ... }  # 5.22 .. 5.26
5310
5311       Subroutine "&%s" is not available
5312           (W closure) During compilation, an inner named subroutine or eval
5313           is attempting to capture an outer lexical subroutine that is not
5314           currently available.  This can happen for one of two reasons.
5315           First, the lexical subroutine may be declared in an outer anonymous
5316           subroutine that has not yet been created.  (Remember that named
5317           subs are created at compile time, while anonymous subs are created
5318           at run-time.)  For example,
5319
5320               sub { my sub a {...} sub f { \&a } }
5321
5322           At the time that f is created, it can't capture the current "a"
5323           sub, since the anonymous subroutine hasn't been created yet.
5324           Conversely, the following won't give a warning since the anonymous
5325           subroutine has by now been created and is live:
5326
5327               sub { my sub a {...} eval 'sub f { \&a }' }->();
5328
5329           The second situation is caused by an eval accessing a lexical
5330           subroutine that has gone out of scope, for example,
5331
5332               sub f {
5333                   my sub a {...}
5334                   sub { eval '\&a' }
5335               }
5336               f()->();
5337
5338           Here, when the '\&a' in the eval is being compiled, f() is not
5339           currently being executed, so its &a is not available for capture.
5340
5341       "%s" subroutine &%s masks earlier declaration in same %s
5342           (W shadow) A "my" or "state" subroutine has been redeclared in the
5343           current scope or statement, effectively eliminating all access to
5344           the previous instance.  This is almost always a typographical
5345           error.  Note that the earlier subroutine will still exist until the
5346           end of the scope or until all closure references to it are
5347           destroyed.
5348
5349       Subroutine %s redefined
5350           (W redefine) You redefined a subroutine.  To suppress this warning,
5351           say
5352
5353               {
5354                   no warnings 'redefine';
5355                   eval "sub name { ... }";
5356               }
5357
5358       Subroutine "%s" will not stay shared
5359           (W closure) An inner (nested) named subroutine is referencing a
5360           "my" subroutine defined in an outer named subroutine.
5361
5362           When the inner subroutine is called, it will see the value of the
5363           outer subroutine's lexical subroutine as it was before and during
5364           the *first* call to the outer subroutine; in this case, after the
5365           first call to the outer subroutine is complete, the inner and outer
5366           subroutines will no longer share a common value for the lexical
5367           subroutine.  In other words, it will no longer be shared.  This
5368           will especially make a difference if the lexical subroutines
5369           accesses lexical variables declared in its surrounding scope.
5370
5371           This problem can usually be solved by making the inner subroutine
5372           anonymous, using the "sub {}" syntax.  When inner anonymous subs
5373           that reference lexical subroutines in outer subroutines are
5374           created, they are automatically rebound to the current values of
5375           such lexical subs.
5376
5377       Substitution loop
5378           (P) The substitution was looping infinitely.  (Obviously, a
5379           substitution shouldn't iterate more times than there are characters
5380           of input, which is what happened.)  See the discussion of
5381           substitution in "Regexp Quote-Like Operators" in perlop.
5382
5383       Substitution pattern not terminated
5384           (F) The lexer couldn't find the interior delimiter of an s/// or
5385           s{}{} construct.  Remember that bracketing delimiters count nesting
5386           level.  Missing the leading "$" from variable $s may cause this
5387           error.
5388
5389       Substitution replacement not terminated
5390           (F) The lexer couldn't find the final delimiter of an s/// or s{}{}
5391           construct.  Remember that bracketing delimiters count nesting
5392           level.  Missing the leading "$" from variable $s may cause this
5393           error.
5394
5395       substr outside of string
5396           (W substr)(F) You tried to reference a substr() that pointed
5397           outside of a string.  That is, the absolute value of the offset was
5398           larger than the length of the string.  See "substr" in perlfunc.
5399           This warning is fatal if substr is used in an lvalue context (as
5400           the left hand side of an assignment or as a subroutine argument for
5401           example).
5402
5403       sv_upgrade from type %d down to type %d
5404           (P) Perl tried to force the upgrade of an SV to a type which was
5405           actually inferior to its current type.
5406
5407       Switch (?(condition)... contains too many branches in regex; marked by
5408       <-- HERE in m/%s/
5409           (F) A (?(condition)if-clause|else-clause) construct can have at
5410           most two branches (the if-clause and the else-clause).  If you want
5411           one or both to contain alternation, such as using
5412           "this|that|other", enclose it in clustering parentheses:
5413
5414               (?(condition)(?:this|that|other)|else-clause)
5415
5416           The <-- HERE shows whereabouts in the regular expression the
5417           problem was discovered.  See perlre.
5418
5419       Switch condition not recognized in regex; marked by <-- HERE in m/%s/
5420           (F) The condition part of a (?(condition)if-clause|else-clause)
5421           construct is not known.  The condition must be one of the
5422           following:
5423
5424            (1) (2) ...        true if 1st, 2nd, etc., capture matched
5425            (<NAME>) ('NAME')  true if named capture matched
5426            (?=...) (?<=...)   true if subpattern matches
5427            (?!...) (?<!...)   true if subpattern fails to match
5428            (?{ CODE })        true if code returns a true value
5429            (R)                true if evaluating inside recursion
5430            (R1) (R2) ...      true if directly inside capture group 1, 2, etc.
5431            (R&NAME)           true if directly inside named capture
5432            (DEFINE)           always false; for defining named subpatterns
5433
5434           The <-- HERE shows whereabouts in the regular expression the
5435           problem was discovered.  See perlre.
5436
5437       Switch (?(condition)... not terminated in regex; marked by <-- HERE in
5438       m/%s/
5439           (F) You omitted to close a (?(condition)...) block somewhere in the
5440           pattern.  Add a closing parenthesis in the appropriate position.
5441           See perlre.
5442
5443       switching effective %s is not implemented
5444           (F) While under the "use filetest" pragma, we cannot switch the
5445           real and effective uids or gids.
5446
5447       syntax error
5448           (F) Probably means you had a syntax error.  Common reasons include:
5449
5450               A keyword is misspelled.
5451               A semicolon is missing.
5452               A comma is missing.
5453               An opening or closing parenthesis is missing.
5454               An opening or closing brace is missing.
5455               A closing quote is missing.
5456
5457           Often there will be another error message associated with the
5458           syntax error giving more information.  (Sometimes it helps to turn
5459           on -w.)  The error message itself often tells you where it was in
5460           the line when it decided to give up.  Sometimes the actual error is
5461           several tokens before this, because Perl is good at understanding
5462           random input.  Occasionally the line number may be misleading, and
5463           once in a blue moon the only way to figure out what's triggering
5464           the error is to call "perl -c" repeatedly, chopping away half the
5465           program each time to see if the error went away.  Sort of the
5466           cybernetic version of 20 questions.
5467
5468       syntax error at line %d: '%s' unexpected
5469           (A) You've accidentally run your script through the Bourne shell
5470           instead of Perl.  Check the #! line, or manually feed your script
5471           into Perl yourself.
5472
5473       syntax error in file %s at line %d, next 2 tokens "%s"
5474           (F) This error is likely to occur if you run a perl5 script through
5475           a perl4 interpreter, especially if the next 2 tokens are "use
5476           strict" or "my $var" or "our $var".
5477
5478       Syntax error in (?[...]) in regex; marked by <-- HERE in m/%s/
5479           (F) Perl could not figure out what you meant inside this construct;
5480           this notifies you that it is giving up trying.
5481
5482       %s syntax OK
5483           (F) The final summary message when a "perl -c" succeeds.
5484
5485       sysread() on closed filehandle %s
5486           (W closed) You tried to read from a closed filehandle.
5487
5488       sysread() on unopened filehandle %s
5489           (W unopened) You tried to read from a filehandle that was never
5490           opened.
5491
5492       System V %s is not implemented on this machine
5493           (F) You tried to do something with a function beginning with "sem",
5494           "shm", or "msg" but that System V IPC is not implemented in your
5495           machine.  In some machines the functionality can exist but be
5496           unconfigured.  Consult your system support.
5497
5498       syswrite() on closed filehandle %s
5499           (W closed) The filehandle you're writing to got itself closed
5500           sometime before now.  Check your control flow.
5501
5502       "-T" and "-B" not implemented on filehandles
5503           (F) Perl can't peek at the stdio buffer of filehandles when it
5504           doesn't know about your kind of stdio.  You'll have to use a
5505           filename instead.
5506
5507       Target of goto is too deeply nested
5508           (F) You tried to use "goto" to reach a label that was too deeply
5509           nested for Perl to reach.  Perl is doing you a favor by refusing.
5510
5511       telldir() attempted on invalid dirhandle %s
5512           (W io) The dirhandle you tried to telldir() is either closed or not
5513           really a dirhandle.  Check your control flow.
5514
5515       tell() on unopened filehandle
5516           (W unopened) You tried to use the tell() function on a filehandle
5517           that was either never opened or has since been closed.
5518
5519       The crypt() function is unimplemented due to excessive paranoia.
5520           (F) Configure couldn't find the crypt() function on your machine,
5521           probably because your vendor didn't supply it, probably because
5522           they think the U.S. Government thinks it's a secret, or at least
5523           that they will continue to pretend that it is.  And if you quote me
5524           on that, I will deny it.
5525
5526       The experimental declared_refs feature is not enabled
5527           (F) To declare references to variables, as in "my \%x", you must
5528           first enable the feature:
5529
5530               no warnings "experimental::declared_refs";
5531               use feature "declared_refs";
5532
5533       The %s function is unimplemented
5534           (F) The function indicated isn't implemented on this architecture,
5535           according to the probings of Configure.
5536
5537       The private_use feature is experimental
5538           (S experimental::private_use) This feature is actually a hook for
5539           future use.
5540
5541       The regex_sets feature is experimental
5542           (S experimental::regex_sets) This warning is emitted if you use the
5543           syntax "(?[   ])" in a regular expression.  The details of this
5544           feature are subject to change.  If you want to use it, but know
5545           that in doing so you are taking the risk of using an experimental
5546           feature which may change in a future Perl version, you can do this
5547           to silence the warning:
5548
5549               no warnings "experimental::regex_sets";
5550
5551       The signatures feature is experimental
5552           (S experimental::signatures) This warning is emitted if you unwrap
5553           a subroutine's arguments using a signature.  Simply suppress the
5554           warning if you want to use the feature, but know that in doing so
5555           you are taking the risk of using an experimental feature which may
5556           change or be removed in a future Perl version:
5557
5558               no warnings "experimental::signatures";
5559               use feature "signatures";
5560               sub foo ($left, $right) { ... }
5561
5562       The stat preceding %s wasn't an lstat
5563           (F) It makes no sense to test the current stat buffer for symbolic
5564           linkhood if the last stat that wrote to the stat buffer already
5565           went past the symlink to get to the real file.  Use an actual
5566           filename instead.
5567
5568       The Unicode property wildcards feature is experimental
5569           (S experimental::uniprop_wildcards) This feature is experimental
5570           and its behavior may in any future release of perl.  See "Wildcards
5571           in Property Values" in perlunicode.
5572
5573       The 'unique' attribute may only be applied to 'our' variables
5574           (F) This attribute was never supported on "my" or "sub"
5575           declarations.
5576
5577       This Perl can't reset CRTL environ elements (%s)
5578       This Perl can't set CRTL environ elements (%s=%s)
5579           (W internal) Warnings peculiar to VMS.  You tried to change or
5580           delete an element of the CRTL's internal environ array, but your
5581           copy of Perl wasn't built with a CRTL that contained the setenv()
5582           function.  You'll need to rebuild Perl with a CRTL that does, or
5583           redefine PERL_ENV_TABLES (see perlvms) so that the environ array
5584           isn't the target of the change to %ENV which produced the warning.
5585
5586       This Perl has not been built with support for randomized hash key
5587       traversal but something called Perl_hv_rand_set().
5588           (F) Something has attempted to use an internal API call which
5589           depends on Perl being compiled with the default support for
5590           randomized hash key traversal, but this Perl has been compiled
5591           without it.  You should report this warning to the relevant
5592           upstream party, or recompile perl with default options.
5593
5594       This use of my() in false conditional is no longer allowed
5595           (F) You used a declaration similar to "my $x if 0".  There has been
5596           a long-standing bug in Perl that causes a lexical variable not to
5597           be cleared at scope exit when its declaration includes a false
5598           conditional.  Some people have exploited this bug to achieve a kind
5599           of static variable.  Since we intend to fix this bug, we don't want
5600           people relying on this behavior.  You can achieve a similar static
5601           effect by declaring the variable in a separate block outside the
5602           function, eg
5603
5604               sub f { my $x if 0; return $x++ }
5605
5606           becomes
5607
5608               { my $x; sub f { return $x++ } }
5609
5610           Beginning with perl 5.10.0, you can also use "state" variables to
5611           have lexicals that are initialized only once (see feature):
5612
5613               sub f { state $x; return $x++ }
5614
5615           This use of "my()" in a false conditional was deprecated beginning
5616           in Perl 5.10 and became a fatal error in Perl 5.30.
5617
5618       Timeout waiting for another thread to define \p{%s}
5619           (F) The first time a user-defined property ("User-Defined Character
5620           Properties" in perlunicode) is used, its definition is looked up
5621           and converted into an internal form for more efficient handling in
5622           subsequent uses.  There could be a race if two or more threads
5623           tried to do this processing nearly simultaneously.  Instead, a
5624           critical section is created around this task, locking out all but
5625           one thread from doing it.  This message indicates that the thread
5626           that is doing the conversion is taking an unexpectedly long time.
5627           The timeout exists solely to prevent deadlock; it's long enough
5628           that the system was likely thrashing and about to crash.  There is
5629           no real remedy but rebooting.
5630
5631       times not implemented
5632           (F) Your version of the C library apparently doesn't do times().  I
5633           suspect you're not running on Unix.
5634
5635       "-T" is on the #! line, it must also be used on the command line
5636           (X) The #! line (or local equivalent) in a Perl script contains the
5637           -T option (or the -t option), but Perl was not invoked with -T in
5638           its command line.  This is an error because, by the time Perl
5639           discovers a -T in a script, it's too late to properly taint
5640           everything from the environment.  So Perl gives up.
5641
5642           If the Perl script is being executed as a command using the #!
5643           mechanism (or its local equivalent), this error can usually be
5644           fixed by editing the #! line so that the -%c option is a part of
5645           Perl's first argument: e.g. change "perl -n -%c" to "perl -%c -n".
5646
5647           If the Perl script is being executed as "perl scriptname", then the
5648           -%c option must appear on the command line: "perl -%c scriptname".
5649
5650       To%s: illegal mapping '%s'
5651           (F) You tried to define a customized To-mapping for lc(), lcfirst,
5652           uc(), or ucfirst() (or their string-inlined versions), but you
5653           specified an illegal mapping.  See "User-Defined Character
5654           Properties" in perlunicode.
5655
5656       Too deeply nested ()-groups
5657           (F) Your template contains ()-groups with a ridiculously deep
5658           nesting level.
5659
5660       Too few args to syscall
5661           (F) There has to be at least one argument to syscall() to specify
5662           the system call to call, silly dilly.
5663
5664       Too few arguments for subroutine '%s'
5665           (F) A subroutine using a signature fewer arguments than required by
5666           the signature.  The caller of the subroutine is presumably at
5667           fault.
5668
5669           The message attempts to include the name of the called subroutine.
5670           If the subroutine has been aliased, the subroutine's original name
5671           will be shown, regardless of what name the caller used.
5672
5673       Too late for "-%s" option
5674           (X) The #! line (or local equivalent) in a Perl script contains the
5675           -M, -m or -C option.
5676
5677           In the case of -M and -m, this is an error because those options
5678           are not intended for use inside scripts.  Use the "use" pragma
5679           instead.
5680
5681           The -C option only works if it is specified on the command line as
5682           well (with the same sequence of letters or numbers following).
5683           Either specify this option on the command line, or, if your system
5684           supports it, make your script executable and run it directly
5685           instead of passing it to perl.
5686
5687       Too late to run %s block
5688           (W void) A CHECK or INIT block is being defined during run time
5689           proper, when the opportunity to run them has already passed.
5690           Perhaps you are loading a file with "require" or "do" when you
5691           should be using "use" instead.  Or perhaps you should put the
5692           "require" or "do" inside a BEGIN block.
5693
5694       Too many args to syscall
5695           (F) Perl supports a maximum of only 14 args to syscall().
5696
5697       Too many arguments for %s
5698           (F) The function requires fewer arguments than you specified.
5699
5700       Too many arguments for subroutine '%s'
5701           (F) A subroutine using a signature received more arguments than
5702           permitted by the signature.  The caller of the subroutine is
5703           presumably at fault.
5704
5705           The message attempts to include the name of the called subroutine.
5706           If the subroutine has been aliased, the subroutine's original name
5707           will be shown, regardless of what name the caller used.
5708
5709       Too many nested open parens in regex; marked by <-- HERE in m/%s/
5710           (F) You have exceeded the number of open "(" parentheses that
5711           haven't been matched by corresponding closing ones.  This limit
5712           prevents eating up too much memory.  It is initially set to 1000,
5713           but may be changed by setting "${^RE_COMPILE_RECURSION_LIMIT}" to
5714           some other value.  This may need to be done in a BEGIN block before
5715           the regular expression pattern is compiled.
5716
5717       Too many )'s
5718           (A) You've accidentally run your script through csh instead of
5719           Perl.  Check the #! line, or manually feed your script into Perl
5720           yourself.
5721
5722       Too many ('s
5723           (A) You've accidentally run your script through csh instead of
5724           Perl.  Check the #! line, or manually feed your script into Perl
5725           yourself.
5726
5727       Trailing \ in regex m/%s/
5728           (F) The regular expression ends with an unbackslashed backslash.
5729           Backslash it.   See perlre.
5730
5731       Transliteration pattern not terminated
5732           (F) The lexer couldn't find the interior delimiter of a tr/// or
5733           tr[][] or y/// or y[][] construct.  Missing the leading "$" from
5734           variables $tr or $y may cause this error.
5735
5736       Transliteration replacement not terminated
5737           (F) The lexer couldn't find the final delimiter of a tr///, tr[][],
5738           y/// or y[][] construct.
5739
5740       '%s' trapped by operation mask
5741           (F) You tried to use an operator from a Safe compartment in which
5742           it's disallowed.  See Safe.
5743
5744       truncate not implemented
5745           (F) Your machine doesn't implement a file truncation mechanism that
5746           Configure knows about.
5747
5748       Type of arg %d to &CORE::%s must be %s
5749           (F) The subroutine in question in the CORE package requires its
5750           argument to be a hard reference to data of the specified type.
5751           Overloading is ignored, so a reference to an object that is not the
5752           specified type, but nonetheless has overloading to handle it, will
5753           still not be accepted.
5754
5755       Type of arg %d to %s must be %s (not %s)
5756           (F) This function requires the argument in that position to be of a
5757           certain type.  Arrays must be @NAME or "@{EXPR}".  Hashes must be
5758           %NAME or "%{EXPR}".  No implicit dereferencing is allowed--use the
5759           {EXPR} forms as an explicit dereference.  See perlref.
5760
5761       umask not implemented
5762           (F) Your machine doesn't implement the umask function and you tried
5763           to use it to restrict permissions for yourself (EXPR & 0700).
5764
5765       Unbalanced context: %d more PUSHes than POPs
5766           (S internal) The exit code detected an internal inconsistency in
5767           how many execution contexts were entered and left.
5768
5769       Unbalanced saves: %d more saves than restores
5770           (S internal) The exit code detected an internal inconsistency in
5771           how many values were temporarily localized.
5772
5773       Unbalanced scopes: %d more ENTERs than LEAVEs
5774           (S internal) The exit code detected an internal inconsistency in
5775           how many blocks were entered and left.
5776
5777       Unbalanced string table refcount: (%d) for "%s"
5778           (S internal) On exit, Perl found some strings remaining in the
5779           shared string table used for copy on write and for hash keys.  The
5780           entries should have been freed, so this indicates a bug somewhere.
5781
5782       Unbalanced tmps: %d more allocs than frees
5783           (S internal) The exit code detected an internal inconsistency in
5784           how many mortal scalars were allocated and freed.
5785
5786       Undefined format "%s" called
5787           (F) The format indicated doesn't seem to exist.  Perhaps it's
5788           really in another package?  See perlform.
5789
5790       Undefined sort subroutine "%s" called
5791           (F) The sort comparison routine specified doesn't seem to exist.
5792           Perhaps it's in a different package?  See "sort" in perlfunc.
5793
5794       Undefined subroutine &%s called
5795           (F) The subroutine indicated hasn't been defined, or if it was, it
5796           has since been undefined.
5797
5798       Undefined subroutine called
5799           (F) The anonymous subroutine you're trying to call hasn't been
5800           defined, or if it was, it has since been undefined.
5801
5802       Undefined subroutine in sort
5803           (F) The sort comparison routine specified is declared but doesn't
5804           seem to have been defined yet.  See "sort" in perlfunc.
5805
5806       Undefined top format "%s" called
5807           (F) The format indicated doesn't seem to exist.  Perhaps it's
5808           really in another package?  See perlform.
5809
5810       Undefined value assigned to typeglob
5811           (W misc) An undefined value was assigned to a typeglob, a la "*foo
5812           = undef".  This does nothing.  It's possible that you really mean
5813           "undef *foo".
5814
5815       %s: Undefined variable
5816           (A) You've accidentally run your script through csh instead of
5817           Perl.  Check the #! line, or manually feed your script into Perl
5818           yourself.
5819
5820       Unescaped left brace in regex is illegal here in regex; marked by
5821       <-- HERE in m/%s/
5822           (F) The simple rule to remember, if you want to match a literal "{"
5823           character (U+007B "LEFT CURLY BRACKET") in a regular expression
5824           pattern, is to escape each literal instance of it in some way.
5825           Generally easiest is to precede it with a backslash, like "\{" or
5826           enclose it in square brackets ("[{]").  If the pattern delimiters
5827           are also braces, any matching right brace ("}") should also be
5828           escaped to avoid confusing the parser, for example,
5829
5830            qr{abc\{def\}ghi}
5831
5832           Forcing literal "{" characters to be escaped enables the Perl
5833           language to be extended in various ways in future releases.  To
5834           avoid needlessly breaking existing code, the restriction is not
5835           enforced in contexts where there are unlikely to ever be extensions
5836           that could conflict with the use there of "{" as a literal.  Those
5837           that are not potentially ambiguous do not warn; those that are do
5838           raise a non-deprecation warning.
5839
5840           The contexts where no warnings or errors are raised are:
5841
5842           ·   as the first character in a pattern, or following "^"
5843               indicating to anchor the match to the beginning of a line.
5844
5845           ·   as the first character following a "|" indicating alternation.
5846
5847           ·   as the first character in a parenthesized grouping like
5848
5849                /foo({bar)/
5850                /foo(?:{bar)/
5851
5852           ·   as the first character following a quantifier
5853
5854                /\s*{/
5855
5856       Unescaped left brace in regex is passed through in regex; marked by
5857       <-- HERE in m/%s/
5858           (W regexp)  The simple rule to remember, if you want to match a
5859           literal "{" character (U+007B "LEFT CURLY BRACKET") in a regular
5860           expression pattern, is to escape each literal instance of it in
5861           some way.  Generally easiest is to precede it with a backslash,
5862           like "\{" or enclose it in square brackets ("[{]").  If the pattern
5863           delimiters are also braces, any matching right brace ("}") should
5864           also be escaped to avoid confusing the parser, for example,
5865
5866            qr{abc\{def\}ghi}
5867
5868           Forcing literal "{" characters to be escaped enables the Perl
5869           language to be extended in various ways in future releases.  To
5870           avoid needlessly breaking existing code, the restriction is not
5871           enforced in contexts where there are unlikely to ever be extensions
5872           that could conflict with the use there of "{" as a literal.  Those
5873           that are not potentially ambiguous do not warn; those that are
5874           raise this warning.  This makes sure that an inadvertent typo
5875           doesn't silently cause the pattern to compile to something
5876           unintended.
5877
5878           The contexts where no warnings or errors are raised are:
5879
5880           ·   as the first character in a pattern, or following "^"
5881               indicating to anchor the match to the beginning of a line.
5882
5883           ·   as the first character following a "|" indicating alternation.
5884
5885           ·   as the first character in a parenthesized grouping like
5886
5887                /foo({bar)/
5888                /foo(?:{bar)/
5889
5890           ·   as the first character following a quantifier
5891
5892                /\s*{/
5893
5894       Unescaped literal '%c' in regex; marked by <-- HERE in m/%s/
5895           (W regexp) (only under "use re 'strict'")
5896
5897           Within the scope of "use re 'strict'" in a regular expression
5898           pattern, you included an unescaped "}" or "]" which was interpreted
5899           literally.  These two characters are sometimes metacharacters, and
5900           sometimes literals, depending on what precedes them in the pattern.
5901           This is unlike the similar ")" which is always a metacharacter
5902           unless escaped.
5903
5904           This action at a distance, perhaps a large distance, can lead to
5905           Perl silently misinterpreting what you meant, so when you specify
5906           that you want extra checking by "use re 'strict'", this warning is
5907           generated.  If you meant the character as a literal, simply confirm
5908           that to Perl by preceding the character with a backslash, or make
5909           it into a bracketed character class (like "[}]").  If you meant it
5910           as closing a corresponding "[" or "{", you'll need to look back
5911           through the pattern to find out why that isn't happening.
5912
5913       unexec of %s into %s failed!
5914           (F) The unexec() routine failed for some reason.  See your local
5915           FSF representative, who probably put it there in the first place.
5916
5917       Unexpected binary operator '%c' with no preceding operand in regex;
5918       marked by <-- HERE in m/%s/
5919           (F) You had something like this:
5920
5921            (?[ | \p{Digit} ])
5922
5923           where the "|" is a binary operator with an operand on the right,
5924           but no operand on the left.
5925
5926       Unexpected character in regex; marked by <-- HERE in m/%s/
5927           (F) You had something like this:
5928
5929            (?[ z ])
5930
5931           Within "(?[ ])", no literal characters are allowed unless they are
5932           within an inner pair of square brackets, like
5933
5934            (?[ [ z ] ])
5935
5936           Another possibility is that you forgot a backslash.  Perl isn't
5937           smart enough to figure out what you really meant.
5938
5939       Unexpected constant lvalue entersub entry via type/targ %d:%d
5940           (P) When compiling a subroutine call in lvalue context, Perl failed
5941           an internal consistency check.  It encountered a malformed op tree.
5942
5943       Unexpected exit %u
5944           (S) exit() was called or the script otherwise finished gracefully
5945           when "PERL_EXIT_WARN" was set in "PL_exit_flags".
5946
5947       Unexpected exit failure %d
5948           (S) An uncaught die() was called when "PERL_EXIT_WARN" was set in
5949           "PL_exit_flags".
5950
5951       Unexpected ')' in regex; marked by <-- HERE in m/%s/
5952           (F) You had something like this:
5953
5954            (?[ ( \p{Digit} + ) ])
5955
5956           The ")" is out-of-place.  Something apparently was supposed to be
5957           combined with the digits, or the "+" shouldn't be there, or
5958           something like that.  Perl can't figure out what was intended.
5959
5960       Unexpected ']' with no following ')' in (?[... in regex; marked by <--
5961       HERE in m/%s/
5962           (F) While parsing an extended character class a ']' character was
5963           encountered at a point in the definition where the only legal use
5964           of ']' is to close the character class definition as part of a
5965           '])', you may have forgotten the close paren, or otherwise confused
5966           the parser.
5967
5968       Unexpected '(' with no preceding operator in regex; marked by <-- HERE
5969       in m/%s/
5970           (F) You had something like this:
5971
5972            (?[ \p{Digit} ( \p{Lao} + \p{Thai} ) ])
5973
5974           There should be an operator before the "(", as there's no
5975           indication as to how the digits are to be combined with the
5976           characters in the Lao and Thai scripts.
5977
5978       Unicode non-character U+%X is not recommended for open interchange
5979           (S nonchar) Certain codepoints, such as U+FFFE and U+FFFF, are
5980           defined by the Unicode standard to be non-characters.  Those are
5981           legal codepoints, but are reserved for internal use; so,
5982           applications shouldn't attempt to exchange them.  An application
5983           may not be expecting any of these characters at all, and receiving
5984           them may lead to bugs.  If you know what you are doing you can turn
5985           off this warning by "no warnings 'nonchar';".
5986
5987           This is not really a "severe" error, but it is supposed to be
5988           raised by default even if warnings are not enabled, and currently
5989           the only way to do that in Perl is to mark it as serious.
5990
5991       Unicode property wildcard not terminated
5992           (F) A Unicode property wildcard looks like a delimited regular
5993           expression pattern (all within the braces of the enclosing
5994           "\p{...}".  The closing delimtter to match the opening one was not
5995           found.  If the opening one is escaped by preceding it with a
5996           backslash, the closing one must also be so escaped.
5997
5998       Unicode string properties are not implemented in (?[...]) in regex;
5999       marked by <-- HERE in m/%s/
6000           (F) A Unicode string property is one which expands to a sequence of
6001           multiple characters.  An example is "\p{name=KATAKANA LETTER AINU
6002           P}", which is comprised of the sequence "\N{KATAKANA LETTER SMALL
6003           H}" followed by "\N{COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND
6004           MARK}".  Extended character classes, "(?[...])" currently cannot
6005           handle these.
6006
6007       Unicode surrogate U+%X is illegal in UTF-8
6008           (S surrogate) You had a UTF-16 surrogate in a context where they
6009           are not considered acceptable.  These code points, between U+D800
6010           and U+DFFF (inclusive), are used by Unicode only for UTF-16.
6011           However, Perl internally allows all unsigned integer code points
6012           (up to the size limit available on your platform), including
6013           surrogates.  But these can cause problems when being input or
6014           output, which is likely where this message came from.  If you
6015           really really know what you are doing you can turn off this warning
6016           by "no warnings 'surrogate';".
6017
6018       Unknown charname '%s'
6019           (F) The name you used inside "\N{}" is unknown to Perl.  Check the
6020           spelling.  You can say "use charnames ":loose"" to not have to be
6021           so precise about spaces, hyphens, and capitalization on standard
6022           Unicode names.  (Any custom aliases that have been created must be
6023           specified exactly, regardless of whether ":loose" is used or not.)
6024           This error may also happen if the "\N{}" is not in the scope of the
6025           corresponding "use charnames".
6026
6027       Unknown '(*...)' construct '%s' in regex; marked by <-- HERE in m/%s/
6028           (F) The "(*" was followed by something that the regular expression
6029           compiler does not recognize.  Check your spelling.
6030
6031       Unknown error
6032           (P) Perl was about to print an error message in $@, but the $@
6033           variable did not exist, even after an attempt to create it.
6034
6035       Unknown locale category %d; can't set it to %s
6036           (W locale) You used a locale category that perl doesn't recognize,
6037           so it cannot carry out your request.  Check that you are using a
6038           valid category.  If so, see "Multi-threaded" in perllocale for
6039           advice on reporting this as a bug, and for modifying perl locally
6040           to accommodate your needs.
6041
6042       Unknown open() mode '%s'
6043           (F) The second argument of 3-argument open() is not among the list
6044           of valid modes: "<", ">", ">>", "+<", "+>", "+>>", "-|", "|-",
6045           "<&", ">&".
6046
6047       Unknown PerlIO layer "%s"
6048           (W layer) An attempt was made to push an unknown layer onto the
6049           Perl I/O system.  (Layers take care of transforming data between
6050           external and internal representations.)  Note that some layers,
6051           such as "mmap", are not supported in all environments.  If your
6052           program didn't explicitly request the failing operation, it may be
6053           the result of the value of the environment variable PERLIO.
6054
6055       Unknown process %x sent message to prime_env_iter: %s
6056           (P) An error peculiar to VMS.  Perl was reading values for %ENV
6057           before iterating over it, and someone else stuck a message in the
6058           stream of data Perl expected.  Someone's very confused, or perhaps
6059           trying to subvert Perl's population of %ENV for nefarious purposes.
6060
6061       Unknown regexp modifier "/%s"
6062           (F) Alphanumerics immediately following the closing delimiter of a
6063           regular expression pattern are interpreted by Perl as modifier
6064           flags for the regex.  One of the ones you specified is invalid.
6065           One way this can happen is if you didn't put in white space between
6066           the end of the regex and a following alphanumeric operator:
6067
6068            if ($a =~ /foo/and $bar == 3) { ... }
6069
6070           The "a" is a valid modifier flag, but the "n" is not, and raises
6071           this error.  Likely what was meant instead was:
6072
6073            if ($a =~ /foo/ and $bar == 3) { ... }
6074
6075       Unknown "re" subpragma '%s' (known ones are: %s)
6076           (W) You tried to use an unknown subpragma of the "re" pragma.
6077
6078       Unknown switch condition (?(...)) in regex; marked by <-- HERE in m/%s/
6079           (F) The condition part of a (?(condition)if-clause|else-clause)
6080           construct is not known.  The condition must be one of the
6081           following:
6082
6083            (1) (2) ...            true if 1st, 2nd, etc., capture matched
6084            (<NAME>) ('NAME')      true if named capture matched
6085            (?=...) (?<=...)       true if subpattern matches
6086            (*pla:...) (*plb:...)  true if subpattern matches; also
6087                                        (*positive_lookahead:...)
6088                                        (*positive_lookbehind:...)
6089            (*nla:...) (*nlb:...)  true if subpattern fails to match; also
6090                                        (*negative_lookahead:...)
6091                                        (*negative_lookbehind:...)
6092            (?{ CODE })            true if code returns a true value
6093            (R)                    true if evaluating inside recursion
6094            (R1) (R2) ...          true if directly inside capture group 1, 2,
6095                                        etc.
6096            (R&NAME)               true if directly inside named capture
6097            (DEFINE)               always false; for defining named subpatterns
6098
6099           The <-- HERE shows whereabouts in the regular expression the
6100           problem was discovered.  See perlre.
6101
6102       Unknown Unicode option letter '%c'
6103           (F) You specified an unknown Unicode option.  See perlrun
6104           documentation of the "-C" switch for the list of known options.
6105
6106       Unknown Unicode option value %d
6107           (F) You specified an unknown Unicode option.  See perlrun
6108           documentation of the "-C" switch for the list of known options.
6109
6110       Unknown user-defined property name \p{%s}
6111           (F) You specified to use a property within the "\p{...}" which was
6112           a syntactically valid user-defined property, but no definition was
6113           found for it by the time one was required to proceed.  Check your
6114           spelling.  See "User-Defined Character Properties" in perlunicode.
6115
6116       Unknown verb pattern '%s' in regex; marked by <-- HERE in m/%s/
6117           (F) You either made a typo or have incorrectly put a "*" quantifier
6118           after an open brace in your pattern.  Check the pattern and review
6119           perlre for details on legal verb patterns.
6120
6121       Unknown warnings category '%s'
6122           (F) An error issued by the "warnings" pragma.  You specified a
6123           warnings category that is unknown to perl at this point.
6124
6125           Note that if you want to enable a warnings category registered by a
6126           module (e.g. "use warnings 'File::Find'"), you must have loaded
6127           this module first.
6128
6129       Unmatched [ in regex; marked by <-- HERE in m/%s/
6130           (F) The brackets around a character class must match.  If you wish
6131           to include a closing bracket in a character class, backslash it or
6132           put it first.  The <-- HERE shows whereabouts in the regular
6133           expression the problem was discovered.  See perlre.
6134
6135       Unmatched ( in regex; marked by <-- HERE in m/%s/
6136       Unmatched ) in regex; marked by <-- HERE in m/%s/
6137           (F) Unbackslashed parentheses must always be balanced in regular
6138           expressions.  If you're a vi user, the % key is valuable for
6139           finding the matching parenthesis.  The <-- HERE shows whereabouts
6140           in the regular expression the problem was discovered.  See perlre.
6141
6142       Unmatched right %s bracket
6143           (F) The lexer counted more closing curly or square brackets than
6144           opening ones, so you're probably missing a matching opening
6145           bracket.  As a general rule, you'll find the missing one (so to
6146           speak) near the place you were last editing.
6147
6148       Unquoted string "%s" may clash with future reserved word
6149           (W reserved) You used a bareword that might someday be claimed as a
6150           reserved word.  It's best to put such a word in quotes, or
6151           capitalize it somehow, or insert an underbar into it.  You might
6152           also declare it as a subroutine.
6153
6154       Unrecognized character %s; marked by <-- HERE after %s near column %d
6155           (F) The Perl parser has no idea what to do with the specified
6156           character in your Perl script (or eval) near the specified column.
6157           Perhaps you tried  to run a compressed script, a binary program, or
6158           a directory as a Perl program.
6159
6160       Unrecognized escape \%c in character class in regex; marked by <-- HERE
6161       in m/%s/
6162           (F) You used a backslash-character combination which is not
6163           recognized by Perl inside character classes.  This is a fatal error
6164           when the character class is used within "(?[ ])".
6165
6166       Unrecognized escape \%c in character class passed through in regex;
6167       marked by <-- HERE in m/%s/
6168           (W regexp) You used a backslash-character combination which is not
6169           recognized by Perl inside character classes.  The character was
6170           understood literally, but this may change in a future version of
6171           Perl.  The <-- HERE shows whereabouts in the regular expression the
6172           escape was discovered.
6173
6174       Unrecognized escape \%c passed through
6175           (W misc) You used a backslash-character combination which is not
6176           recognized by Perl.  The character was understood literally, but
6177           this may change in a future version of Perl.
6178
6179       Unrecognized escape \%s passed through in regex; marked by <-- HERE in
6180       m/%s/
6181           (W regexp) You used a backslash-character combination which is not
6182           recognized by Perl.  The character(s) were understood literally,
6183           but this may change in a future version of Perl.  The <-- HERE
6184           shows whereabouts in the regular expression the escape was
6185           discovered.
6186
6187       Unrecognized signal name "%s"
6188           (F) You specified a signal name to the kill() function that was not
6189           recognized.  Say "kill -l" in your shell to see the valid signal
6190           names on your system.
6191
6192       Unrecognized switch: -%s  (-h will show valid options)
6193           (F) You specified an illegal option to Perl.  Don't do that.  (If
6194           you think you didn't do that, check the #! line to see if it's
6195           supplying the bad switch on your behalf.)
6196
6197       Unsuccessful %s on filename containing newline
6198           (W newline) A file operation was attempted on a filename, and that
6199           operation failed, PROBABLY because the filename contained a
6200           newline, PROBABLY because you forgot to chomp() it off.  See
6201           "chomp" in perlfunc.
6202
6203       Unsupported directory function "%s" called
6204           (F) Your machine doesn't support opendir() and readdir().
6205
6206       Unsupported function %s
6207           (F) This machine doesn't implement the indicated function,
6208           apparently.  At least, Configure doesn't think so.
6209
6210       Unsupported function fork
6211           (F) Your version of executable does not support forking.
6212
6213           Note that under some systems, like OS/2, there may be different
6214           flavors of Perl executables, some of which may support fork, some
6215           not.  Try changing the name you call Perl by to "perl_", "perl__",
6216           and so on.
6217
6218       Unsupported script encoding %s
6219           (F) Your program file begins with a Unicode Byte Order Mark (BOM)
6220           which declares it to be in a Unicode encoding that Perl cannot
6221           read.
6222
6223       Unsupported socket function "%s" called
6224           (F) Your machine doesn't support the Berkeley socket mechanism, or
6225           at least that's what Configure thought.
6226
6227       Unterminated '(*...' argument in regex; marked by <-- HERE in m/%s/
6228           (F) You used a pattern of the form "(*...:...)" but did not
6229           terminate the pattern with a ")".  Fix the pattern and retry.
6230
6231       Unterminated attribute list
6232           (F) The lexer found something other than a simple identifier at the
6233           start of an attribute, and it wasn't a semicolon or the start of a
6234           block.  Perhaps you terminated the parameter list of the previous
6235           attribute too soon.  See attributes.
6236
6237       Unterminated attribute parameter in attribute list
6238           (F) The lexer saw an opening (left) parenthesis character while
6239           parsing an attribute list, but the matching closing (right)
6240           parenthesis character was not found.  You may need to add (or
6241           remove) a backslash character to get your parentheses to balance.
6242           See attributes.
6243
6244       Unterminated compressed integer
6245           (F) An argument to unpack("w",...) was incompatible with the BER
6246           compressed integer format and could not be converted to an integer.
6247           See "pack" in perlfunc.
6248
6249       Unterminated '(*...' construct in regex; marked by <-- HERE in m/%s/
6250           (F) You used a pattern of the form "(*...)" but did not terminate
6251           the pattern with a ")".  Fix the pattern and retry.
6252
6253       Unterminated delimiter for here document
6254           (F) This message occurs when a here document label has an initial
6255           quotation mark but the final quotation mark is missing.  Perhaps
6256           you wrote:
6257
6258               <<"foo
6259
6260           instead of:
6261
6262               <<"foo"
6263
6264       Unterminated \g... pattern in regex; marked by <-- HERE in m/%s/
6265       Unterminated \g{...} pattern in regex; marked by <-- HERE in m/%s/
6266           (F) In a regular expression, you had a "\g" that wasn't followed by
6267           a proper group reference.  In the case of "\g{", the closing brace
6268           is missing; otherwise the "\g" must be followed by an integer.  Fix
6269           the pattern and retry.
6270
6271       Unterminated <> operator
6272           (F) The lexer saw a left angle bracket in a place where it was
6273           expecting a term, so it's looking for the corresponding right angle
6274           bracket, and not finding it.  Chances are you left some needed
6275           parentheses out earlier in the line, and you really meant a "less
6276           than".
6277
6278       Unterminated verb pattern argument in regex; marked by <-- HERE in
6279       m/%s/
6280           (F) You used a pattern of the form "(*VERB:ARG)" but did not
6281           terminate the pattern with a ")".  Fix the pattern and retry.
6282
6283       Unterminated verb pattern in regex; marked by <-- HERE in m/%s/
6284           (F) You used a pattern of the form "(*VERB)" but did not terminate
6285           the pattern with a ")".  Fix the pattern and retry.
6286
6287       untie attempted while %d inner references still exist
6288           (W untie) A copy of the object returned from "tie" (or "tied") was
6289           still valid when "untie" was called.
6290
6291       Usage: POSIX::%s(%s)
6292           (F) You called a POSIX function with incorrect arguments.  See
6293           "FUNCTIONS" in POSIX for more information.
6294
6295       Usage: Win32::%s(%s)
6296           (F) You called a Win32 function with incorrect arguments.  See
6297           Win32 for more information.
6298
6299       $[ used in %s (did you mean $] ?)
6300           (W syntax) You used $[ in a comparison, such as:
6301
6302               if ($[ > 5.006) {
6303                   ...
6304               }
6305
6306           You probably meant to use $] instead.  $[ is the base for indexing
6307           arrays.  $] is the Perl version number in decimal.
6308
6309       Use "%s" instead of "%s"
6310           (F) The second listed construct is no longer legal.  Use the first
6311           one instead.
6312
6313       Useless assignment to a temporary
6314           (W misc) You assigned to an lvalue subroutine, but what the
6315           subroutine returned was a temporary scalar about to be discarded,
6316           so the assignment had no effect.
6317
6318       Useless (?-%s) - don't use /%s modifier in regex; marked by <-- HERE in
6319       m/%s/
6320           (W regexp) You have used an internal modifier such as (?-o) that
6321           has no meaning unless removed from the entire regexp:
6322
6323               if ($string =~ /(?-o)$pattern/o) { ... }
6324
6325           must be written as
6326
6327               if ($string =~ /$pattern/) { ... }
6328
6329           The <-- HERE shows whereabouts in the regular expression the
6330           problem was discovered.  See perlre.
6331
6332       Useless localization of %s
6333           (W syntax) The localization of lvalues such as "local($x=10)" is
6334           legal, but in fact the local() currently has no effect.  This may
6335           change at some point in the future, but in the meantime such code
6336           is discouraged.
6337
6338       Useless (?%s) - use /%s modifier in regex; marked by <-- HERE in m/%s/
6339           (W regexp) You have used an internal modifier such as (?o) that has
6340           no meaning unless applied to the entire regexp:
6341
6342               if ($string =~ /(?o)$pattern/) { ... }
6343
6344           must be written as
6345
6346               if ($string =~ /$pattern/o) { ... }
6347
6348           The <-- HERE shows whereabouts in the regular expression the
6349           problem was discovered.  See perlre.
6350
6351       Useless use of attribute "const"
6352           (W misc) The "const" attribute has no effect except on anonymous
6353           closure prototypes.  You applied it to a subroutine via
6354           attributes.pm.  This is only useful inside an attribute handler for
6355           an anonymous subroutine.
6356
6357       Useless use of /d modifier in transliteration operator
6358           (W misc) You have used the /d modifier where the searchlist has the
6359           same length as the replacelist.  See perlop for more information
6360           about the /d modifier.
6361
6362       Useless use of \E
6363           (W misc) You have a \E in a double-quotish string without a "\U",
6364           "\L" or "\Q" preceding it.
6365
6366       Useless use of greediness modifier '%c' in regex; marked by <-- HERE in
6367       m/%s/
6368           (W regexp) You specified something like these:
6369
6370            qr/a{3}?/
6371            qr/b{1,1}+/
6372
6373           The "?" and "+" don't have any effect, as they modify whether to
6374           match more or fewer when there is a choice, and by specifying to
6375           match exactly a given numer, there is no room left for a choice.
6376
6377       Useless use of %s in void context
6378           (W void) You did something without a side effect in a context that
6379           does nothing with the return value, such as a statement that
6380           doesn't return a value from a block, or the left side of a scalar
6381           comma operator.  Very often this points not to stupidity on your
6382           part, but a failure of Perl to parse your program the way you
6383           thought it would.  For example, you'd get this if you mixed up your
6384           C precedence with Python precedence and said
6385
6386               $one, $two = 1, 2;
6387
6388           when you meant to say
6389
6390               ($one, $two) = (1, 2);
6391
6392           Another common error is to use ordinary parentheses to construct a
6393           list reference when you should be using square or curly brackets,
6394           for example, if you say
6395
6396               $array = (1,2);
6397
6398           when you should have said
6399
6400               $array = [1,2];
6401
6402           The square brackets explicitly turn a list value into a scalar
6403           value, while parentheses do not.  So when a parenthesized list is
6404           evaluated in a scalar context, the comma is treated like C's comma
6405           operator, which throws away the left argument, which is not what
6406           you want.  See perlref for more on this.
6407
6408           This warning will not be issued for numerical constants equal to 0
6409           or 1 since they are often used in statements like
6410
6411               1 while sub_with_side_effects();
6412
6413           String constants that would normally evaluate to 0 or 1 are warned
6414           about.
6415
6416       Useless use of (?-p) in regex; marked by <-- HERE in m/%s/
6417           (W regexp) The "p" modifier cannot be turned off once set.  Trying
6418           to do so is futile.
6419
6420       Useless use of "re" pragma
6421           (W) You did "use re;" without any arguments.  That isn't very
6422           useful.
6423
6424       Useless use of sort in scalar context
6425           (W void) You used sort in scalar context, as in :
6426
6427               my $x = sort @y;
6428
6429           This is not very useful, and perl currently optimizes this away.
6430
6431       Useless use of %s with no values
6432           (W syntax) You used the push() or unshift() function with no
6433           arguments apart from the array, like "push(@x)" or "unshift(@foo)".
6434           That won't usually have any effect on the array, so is completely
6435           useless.  It's possible in principle that push(@tied_array) could
6436           have some effect if the array is tied to a class which implements a
6437           PUSH method.  If so, you can write it as "push(@tied_array,())" to
6438           avoid this warning.
6439
6440       "use" not allowed in expression
6441           (F) The "use" keyword is recognized and executed at compile time,
6442           and returns no useful value.  See perlmod.
6443
6444       Use of bare << to mean <<"" is forbidden
6445           (F) You are now required to use the explicitly quoted form if you
6446           wish to use an empty line as the terminator of the here-document.
6447
6448           Use of a bare terminator was deprecated in Perl 5.000, and is a
6449           fatal error as of Perl 5.28.
6450
6451       Use of /c modifier is meaningless in s///
6452           (W regexp) You used the /c modifier in a substitution.  The /c
6453           modifier is not presently meaningful in substitutions.
6454
6455       Use of /c modifier is meaningless without /g
6456           (W regexp) You used the /c modifier with a regex operand, but
6457           didn't use the /g modifier.  Currently, /c is meaningful only when
6458           /g is used.  (This may change in the future.)
6459
6460       Use of code point 0x%s is not allowed; the permissible max is 0x%X
6461       Use of code point 0x%s is not allowed; the permissible max is 0x%X in
6462       regex; marked by <-- HERE in m/%s/
6463           (F) You used a code point that is not allowed, because it is too
6464           large.  Unicode only allows code points up to 0x10FFFF, but Perl
6465           allows much larger ones. Earlier versions of Perl allowed code
6466           points above IV_MAX (0x7FFFFFF on 32-bit platforms,
6467           0x7FFFFFFFFFFFFFFF on 64-bit platforms), however, this could
6468           possibly break the perl interpreter in some constructs, including
6469           causing it to hang in a few cases.
6470
6471           If your code is to run on various platforms, keep in mind that the
6472           upper limit depends on the platform.  It is much larger on 64-bit
6473           word sizes than 32-bit ones.
6474
6475           The use of out of range code points was deprecated in Perl 5.24,
6476           and became a fatal error in Perl 5.28.
6477
6478       Use of each() on hash after insertion without resetting hash iterator
6479       results in undefined behavior
6480           (S internal) The behavior of "each()" after insertion is undefined;
6481           it may skip items, or visit items more than once.  Consider using
6482           "keys()" instead of "each()".
6483
6484       Use of := for an empty attribute list is not allowed
6485           (F) The construction "my $x := 42" used to parse as equivalent to
6486           "my $x : = 42" (applying an empty attribute list to $x).  This
6487           construct was deprecated in 5.12.0, and has now been made a syntax
6488           error, so ":=" can be reclaimed as a new operator in the future.
6489
6490           If you need an empty attribute list, for example in a code
6491           generator, add a space before the "=".
6492
6493       Use of %s for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale
6494           (W locale)  You are matching a regular expression using locale
6495           rules, and the specified construct was encountered.  This construct
6496           is only valid for UTF-8 locales, which the current locale isn't.
6497           This doesn't make sense.  Perl will continue, assuming a Unicode
6498           (UTF-8) locale, but the results are likely to be wrong.
6499
6500       Use of freed value in iteration
6501           (F) Perhaps you modified the iterated array within the loop?  This
6502           error is typically caused by code like the following:
6503
6504               @a = (3,4);
6505               @a = () for (1,2,@a);
6506
6507           You are not supposed to modify arrays while they are being iterated
6508           over.  For speed and efficiency reasons, Perl internally does not
6509           do full reference-counting of iterated items, hence deleting such
6510           an item in the middle of an iteration causes Perl to see a freed
6511           value.
6512
6513       Use of /g modifier is meaningless in split
6514           (W regexp) You used the /g modifier on the pattern for a "split"
6515           operator.  Since "split" always tries to match the pattern
6516           repeatedly, the "/g" has no effect.
6517
6518       Use of "goto" to jump into a construct is deprecated
6519           (D deprecated) Using "goto" to jump from an outer scope into an
6520           inner scope is deprecated and should be avoided.
6521
6522           This was deprecated in Perl 5.12.
6523
6524       Use of '%s' in \p{} or \P{} is deprecated because: %s
6525           (D deprecated) Certain properties are deprecated by Unicode, and
6526           may eventually be removed from the Standard, at which time Perl
6527           will follow along.  In the meantime, this message is raised to
6528           notify you.
6529
6530       Use of inherited AUTOLOAD for non-method %s::%s() is no longer allowed
6531           (F) As an accidental feature, "AUTOLOAD" subroutines were looked up
6532           as methods (using the @ISA hierarchy), even when the subroutines to
6533           be autoloaded were called as plain functions (e.g. "Foo::bar()"),
6534           not as methods (e.g. "Foo->bar()" or "$obj->bar()").
6535
6536           This was deprecated in Perl 5.004, and was made fatal in Perl 5.28.
6537
6538       Use of %s in printf format not supported
6539           (F) You attempted to use a feature of printf that is accessible
6540           from only C.  This usually means there's a better way to do it in
6541           Perl.
6542
6543       Use of %s is not allowed in Unicode property wildcard subpatterns in
6544       regex; marked by <-- HERE in m/%s/
6545           (F) You were using a wildcard subpattern a Unicode property value,
6546           and the subpattern contained something that is illegal.  Not all
6547           regular expression capabilities are legal in such subpatterns, and
6548           this is one.  Rewrite your subppattern to not use the offending
6549           construct.  See "Wildcards in Property Values" in perlunicode.
6550
6551       Use of -l on filehandle%s
6552           (W io) A filehandle represents an opened file, and when you opened
6553           the file it already went past any symlink you are presumably trying
6554           to look for.  The operation returned "undef".  Use a filename
6555           instead.
6556
6557       Use of reference "%s" as array index
6558           (W misc) You tried to use a reference as an array index; this
6559           probably isn't what you mean, because references in numerical
6560           context tend to be huge numbers, and so usually indicates
6561           programmer error.
6562
6563           If you really do mean it, explicitly numify your reference, like
6564           so: $array[0+$ref].  This warning is not given for overloaded
6565           objects, however, because you can overload the numification and
6566           stringification operators and then you presumably know what you are
6567           doing.
6568
6569       Use of strings with code points over 0xFF as arguments to %s operator
6570       is not allowed
6571           (F) You tried to use one of the string bitwise operators ("&" or
6572           "|" or "^" or "~") on a string containing a code point over 0xFF.
6573           The string bitwise operators treat their operands as strings of
6574           bytes, and values beyond 0xFF are nonsensical in this context.
6575
6576           Certain instances became fatal in Perl 5.28; others in perl 5.32.
6577
6578       Use of strings with code points over 0xFF as arguments to vec is
6579       forbidden
6580           (F) You tried to use "vec" on a string containing a code point over
6581           0xFF, which is nonsensical here.
6582
6583           This became fatal in Perl 5.32.
6584
6585       Use of tainted arguments in %s is deprecated
6586           (W taint, deprecated) You have supplied "system()" or "exec()" with
6587           multiple arguments and at least one of them is tainted.  This used
6588           to be allowed but will become a fatal error in a future version of
6589           perl.  Untaint your arguments.  See perlsec.
6590
6591       Use of unassigned code point or non-standalone grapheme for a delimiter
6592       is not allowed
6593           (F) A grapheme is what appears to a native-speaker of a language to
6594           be a character.  In Unicode (and hence Perl) a grapheme may
6595           actually be several adjacent characters that together form a
6596           complete grapheme.  For example, there can be a base character,
6597           like "R" and an accent, like a circumflex "^", that appear when
6598           displayed to be a single character with the circumflex hovering
6599           over the "R".  Perl currently allows things like that circumflex to
6600           be delimiters of strings, patterns, etc.  When displayed, the
6601           circumflex would look like it belongs to the character just to the
6602           left of it.  In order to move the language to be able to accept
6603           graphemes as delimiters, we cannot allow the use of delimiters
6604           which aren't graphemes by themselves.  Also, a delimiter must
6605           already be assigned (or known to be never going to be assigned) to
6606           try to future-proof code, for otherwise code that works today would
6607           fail to compile if the currently unassigned delimiter ends up being
6608           something that isn't a stand-alone grapheme.  Because Unicode is
6609           never going to assign non-character code points, nor code points
6610           that are above the legal Unicode maximum, those can be delimiters,
6611           and their use is legal.
6612
6613       Use of uninitialized value%s
6614           (W uninitialized) An undefined value was used as if it were already
6615           defined.  It was interpreted as a "" or a 0, but maybe it was a
6616           mistake.  To suppress this warning assign a defined value to your
6617           variables.
6618
6619           To help you figure out what was undefined, perl will try to tell
6620           you the name of the variable (if any) that was undefined.  In some
6621           cases it cannot do this, so it also tells you what operation you
6622           used the undefined value in.  Note, however, that perl optimizes
6623           your program and the operation displayed in the warning may not
6624           necessarily appear literally in your program.  For example, "that
6625           $foo" is usually optimized into ""that " . $foo", and the warning
6626           will refer to the "concatenation (.)" operator, even though there
6627           is no "." in your program.
6628
6629       "use re 'strict'" is experimental
6630           (S experimental::re_strict) The things that are different when a
6631           regular expression pattern is compiled under 'strict' are subject
6632           to change in future Perl releases in incompatible ways.  This means
6633           that a pattern that compiles today may not in a future Perl
6634           release.  This warning is to alert you to that risk.
6635
6636       Use \x{...} for more than two hex characters in regex; marked by
6637       <-- HERE in m/%s/
6638           (F) In a regular expression, you said something like
6639
6640            (?[ [ \xBEEF ] ])
6641
6642           Perl isn't sure if you meant this
6643
6644            (?[ [ \x{BEEF} ] ])
6645
6646           or if you meant this
6647
6648            (?[ [ \x{BE} E F ] ])
6649
6650           You need to add either braces or blanks to disambiguate.
6651
6652       Using just the first character returned by \N{} in character class in
6653       regex; marked by <-- HERE in m/%s/
6654           (W regexp) Named Unicode character escapes "(\N{...})" may return a
6655           multi-character sequence.  Even though a character class is
6656           supposed to match just one character of input, perl will match the
6657           whole thing correctly, except when the class is inverted
6658           ("[^...]"), or the escape is the beginning or final end point of a
6659           range.  For these, what should happen isn't clear at all.  In these
6660           circumstances, Perl discards all but the first character of the
6661           returned sequence, which is not likely what you want.
6662
6663       Using just the single character results returned by \p{} in (?[...]) in
6664       regex; marked by <-- HERE in m/%s/
6665           (W regexp) Extended character classes currently cannot handle
6666           operands that evaluate to more than one character.  These are
6667           removed from the results of the expansion of the "\p{}".
6668
6669           This situation can happen, for example, in
6670
6671            (?[ \p{name=/KATAKANA/} ])
6672
6673           "KATAKANA LETTER AINU P" is a legal Unicode name (technically a
6674           "named sequence"), but it is actually two characters.  The above
6675           expression with match only the Unicode names containing KATAKANA
6676           that represent single characters.
6677
6678       Using /u for '%s' instead of /%s in regex; marked by <-- HERE in m/%s/
6679           (W regexp) You used a Unicode boundary ("\b{...}" or "\B{...}") in
6680           a portion of a regular expression where the character set modifiers
6681           "/a" or "/aa" are in effect.  These two modifiers indicate an ASCII
6682           interpretation, and this doesn't make sense for a Unicode
6683           definition.  The generated regular expression will compile so that
6684           the boundary uses all of Unicode.  No other portion of the regular
6685           expression is affected.
6686
6687       Using !~ with %s doesn't make sense
6688           (F) Using the "!~" operator with "s///r", "tr///r" or "y///r" is
6689           currently reserved for future use, as the exact behavior has not
6690           been decided.  (Simply returning the boolean opposite of the
6691           modified string is usually not particularly useful.)
6692
6693       UTF-16 surrogate U+%X
6694           (S surrogate) You had a UTF-16 surrogate in a context where they
6695           are not considered acceptable.  These code points, between U+D800
6696           and U+DFFF (inclusive), are used by Unicode only for UTF-16.
6697           However, Perl internally allows all unsigned integer code points
6698           (up to the size limit available on your platform), including
6699           surrogates.  But these can cause problems when being input or
6700           output, which is likely where this message came from.  If you
6701           really really know what you are doing you can turn off this warning
6702           by "no warnings 'surrogate';".
6703
6704       Value of %s can be "0"; test with defined()
6705           (W misc) In a conditional expression, you used <HANDLE>, <*>
6706           (glob), "each()", or "readdir()" as a boolean value.  Each of these
6707           constructs can return a value of "0"; that would make the
6708           conditional expression false, which is probably not what you
6709           intended.  When using these constructs in conditional expressions,
6710           test their values with the "defined" operator.
6711
6712       Value of CLI symbol "%s" too long
6713           (W misc) A warning peculiar to VMS.  Perl tried to read the value
6714           of an %ENV element from a CLI symbol table, and found a resultant
6715           string longer than 1024 characters.  The return value has been
6716           truncated to 1024 characters.
6717
6718       Variable "%s" is not available
6719           (W closure) During compilation, an inner named subroutine or eval
6720           is attempting to capture an outer lexical that is not currently
6721           available.  This can happen for one of two reasons.  First, the
6722           outer lexical may be declared in an outer anonymous subroutine that
6723           has not yet been created.  (Remember that named subs are created at
6724           compile time, while anonymous subs are created at run-time.)  For
6725           example,
6726
6727               sub { my $a; sub f { $a } }
6728
6729           At the time that f is created, it can't capture the current value
6730           of $a, since the anonymous subroutine hasn't been created yet.
6731           Conversely, the following won't give a warning since the anonymous
6732           subroutine has by now been created and is live:
6733
6734               sub { my $a; eval 'sub f { $a }' }->();
6735
6736           The second situation is caused by an eval accessing a variable that
6737           has gone out of scope, for example,
6738
6739               sub f {
6740                   my $a;
6741                   sub { eval '$a' }
6742               }
6743               f()->();
6744
6745           Here, when the '$a' in the eval is being compiled, f() is not
6746           currently being executed, so its $a is not available for capture.
6747
6748       Variable "%s" is not imported%s
6749           (S misc) With "use strict" in effect, you referred to a global
6750           variable that you apparently thought was imported from another
6751           module, because something else of the same name (usually a
6752           subroutine) is exported by that module.  It usually means you put
6753           the wrong funny character on the front of your variable.
6754
6755       Variable length lookbehind not implemented in regex m/%s/
6756           (F) This message no longer should be raised as of Perl 5.30.  It is
6757           retained in this document as a convenience for people using an
6758           earlier Perl version.
6759
6760           In Perl 5.30 and earlier, lookbehind is allowed only for
6761           subexpressions whose length is fixed and known at compile time.
6762           For positive lookbehind, you can use the "\K" regex construct as a
6763           way to get the equivalent functionality.  See (?<=pattern) and \K
6764           in perlre.
6765
6766           Starting in Perl 5.18, there are non-obvious Unicode rules under
6767           "/i" that can match variably, but which you might not think could.
6768           For example, the substring "ss" can match the single character
6769           LATIN SMALL LETTER SHARP S.  Here's a complete list of the current
6770           ones affecting ASCII characters:
6771
6772              ASCII
6773             sequence      Matches single letter under /i
6774               FF          U+FB00 LATIN SMALL LIGATURE FF
6775               FFI         U+FB03 LATIN SMALL LIGATURE FFI
6776               FFL         U+FB04 LATIN SMALL LIGATURE FFL
6777               FI          U+FB01 LATIN SMALL LIGATURE FI
6778               FL          U+FB02 LATIN SMALL LIGATURE FL
6779               SS          U+00DF LATIN SMALL LETTER SHARP S
6780                           U+1E9E LATIN CAPITAL LETTER SHARP S
6781               ST          U+FB06 LATIN SMALL LIGATURE ST
6782                           U+FB05 LATIN SMALL LIGATURE LONG S T
6783
6784           This list is subject to change, but is quite unlikely to.  Each
6785           ASCII sequence can be any combination of upper- and lowercase.
6786
6787           You can avoid this by using a bracketed character class in the
6788           lookbehind assertion, like
6789
6790            (?<![sS]t)
6791            (?<![fF]f[iI])
6792
6793           This fools Perl into not matching the ligatures.
6794
6795           Another option for Perls starting with 5.16, if you only care about
6796           ASCII matches, is to add the "/aa" modifier to the regex.  This
6797           will exclude all these non-obvious matches, thus getting rid of
6798           this message.  You can also say
6799
6800            use if $] ge 5.016, re => '/aa';
6801
6802           to apply "/aa" to all regular expressions compiled within its
6803           scope.  See re.
6804
6805       "%s" variable %s masks earlier declaration in same %s
6806           (W shadow) A "my", "our" or "state" variable has been redeclared in
6807           the current scope or statement, effectively eliminating all access
6808           to the previous instance.  This is almost always a typographical
6809           error.  Note that the earlier variable will still exist until the
6810           end of the scope or until all closure references to it are
6811           destroyed.
6812
6813       Variable syntax
6814           (A) You've accidentally run your script through csh instead of
6815           Perl.  Check the #! line, or manually feed your script into Perl
6816           yourself.
6817
6818       Variable "%s" will not stay shared
6819           (W closure) An inner (nested) named subroutine is referencing a
6820           lexical variable defined in an outer named subroutine.
6821
6822           When the inner subroutine is called, it will see the value of the
6823           outer subroutine's variable as it was before and during the *first*
6824           call to the outer subroutine; in this case, after the first call to
6825           the outer subroutine is complete, the inner and outer subroutines
6826           will no longer share a common value for the variable.  In other
6827           words, the variable will no longer be shared.
6828
6829           This problem can usually be solved by making the inner subroutine
6830           anonymous, using the "sub {}" syntax.  When inner anonymous subs
6831           that reference variables in outer subroutines are created, they are
6832           automatically rebound to the current values of such variables.
6833
6834       vector argument not supported with alpha versions
6835           (S printf) The %vd (s)printf format does not support version
6836           objects with alpha parts.
6837
6838       Verb pattern '%s' has a mandatory argument in regex; marked by <-- HERE
6839       in m/%s/
6840           (F) You used a verb pattern that requires an argument.  Supply an
6841           argument or check that you are using the right verb.
6842
6843       Verb pattern '%s' may not have an argument in regex; marked by <-- HERE
6844       in m/%s/
6845           (F) You used a verb pattern that is not allowed an argument.
6846           Remove the argument or check that you are using the right verb.
6847
6848       Version control conflict marker
6849           (F) The parser found a line starting with "<<<<<<<", ">>>>>>>", or
6850           "=======".  These may be left by a version control system to mark
6851           conflicts after a failed merge operation.
6852
6853       Version number must be a constant number
6854           (P) The attempt to translate a "use Module n.n LIST" statement into
6855           its equivalent "BEGIN" block found an internal inconsistency with
6856           the version number.
6857
6858       Version string '%s' contains invalid data; ignoring: '%s'
6859           (W misc) The version string contains invalid characters at the end,
6860           which are being ignored.
6861
6862       Warning: something's wrong
6863           (W) You passed warn() an empty string (the equivalent of "warn """)
6864           or you called it with no args and $@ was empty.
6865
6866       Warning: unable to close filehandle %s properly
6867           (S) The implicit close() done by an open() got an error indication
6868           on the close().  This usually indicates your file system ran out of
6869           disk space.
6870
6871       Warning: unable to close filehandle properly: %s
6872       Warning: unable to close filehandle %s properly: %s
6873           (S io) There were errors during the implicit close() done on a
6874           filehandle when its reference count reached zero while it was still
6875           open, e.g.:
6876
6877               {
6878                   open my $fh, '>', $file  or die "open: '$file': $!\n";
6879                   print $fh $data or die "print: $!";
6880               } # implicit close here
6881
6882           Because various errors may only be detected by close() (e.g.
6883           buffering could allow the "print" in this example to return true
6884           even when the disk is full), it is dangerous to ignore its result.
6885           So when it happens implicitly, perl will signal errors by warning.
6886
6887           Prior to version 5.22.0, perl ignored such errors, so the common
6888           idiom shown above was liable to cause silent data loss.
6889
6890       Warning: Use of "%s" without parentheses is ambiguous
6891           (S ambiguous) You wrote a unary operator followed by something that
6892           looks like a binary operator that could also have been interpreted
6893           as a term or unary operator.  For instance, if you know that the
6894           rand function has a default argument of 1.0, and you write
6895
6896               rand + 5;
6897
6898           you may THINK you wrote the same thing as
6899
6900               rand() + 5;
6901
6902           but in actual fact, you got
6903
6904               rand(+5);
6905
6906           So put in parentheses to say what you really mean.
6907
6908       when is experimental
6909           (S experimental::smartmatch) "when" depends on smartmatch, which is
6910           experimental.  Additionally, it has several special cases that may
6911           not be immediately obvious, and their behavior may change or even
6912           be removed in any future release of perl.  See the explanation
6913           under "Experimental Details on given and when" in perlsyn.
6914
6915       Wide character in %s
6916           (S utf8) Perl met a wide character (ordinal >255) when it wasn't
6917           expecting one.  This warning is by default on for I/O (like print).
6918
6919           If this warning does come from I/O, the easiest way to quiet it is
6920           simply to add the ":utf8" layer, e.g., "binmode STDOUT, ':utf8'".
6921           Another way to turn off the warning is to add "no warnings 'utf8';"
6922           but that is often closer to cheating.  In general, you are supposed
6923           to explicitly mark the filehandle with an encoding, see open and
6924           "binmode" in perlfunc.
6925
6926           If the warning comes from other than I/O, this diagnostic probably
6927           indicates that incorrect results are being obtained.  You should
6928           examine your code to determine how a wide character is getting to
6929           an operation that doesn't handle them.
6930
6931       Wide character (U+%X) in %s
6932           (W locale) While in a single-byte locale (i.e., a non-UTF-8 one), a
6933           multi-byte character was encountered.   Perl considers this
6934           character to be the specified Unicode code point.  Combining
6935           non-UTF-8 locales and Unicode is dangerous.  Almost certainly some
6936           characters will have two different representations.  For example,
6937           in the ISO 8859-7 (Greek) locale, the code point 0xC3 represents a
6938           Capital Gamma.  But so also does 0x393.  This will make string
6939           comparisons unreliable.
6940
6941           You likely need to figure out how this multi-byte character got
6942           mixed up with your single-byte locale (or perhaps you thought you
6943           had a UTF-8 locale, but Perl disagrees).
6944
6945       Within []-length '%c' not allowed
6946           (F) The count in the (un)pack template may be replaced by
6947           "[TEMPLATE]" only if "TEMPLATE" always matches the same amount of
6948           packed bytes that can be determined from the template alone.  This
6949           is not possible if it contains any of the codes @, /, U, u, w or a
6950           *-length.  Redesign the template.
6951
6952       While trying to resolve method call %s->%s() can not locate package
6953       "%s" yet it is mentioned in @%s::ISA (perhaps you forgot to load "%s"?)
6954           (W syntax) It is possible that the @ISA contains a misspelled or
6955           never loaded package name, which can result in perl choosing an
6956           unexpected parent class's method to resolve the method call. If
6957           this is deliberate you can do something like
6958
6959             @Missing::Package::ISA = ();
6960
6961           to silence the warnings, otherwise you should correct the package
6962           name, or ensure that the package is loaded prior to the method
6963           call.
6964
6965       %s() with negative argument
6966           (S misc) Certain operations make no sense with negative arguments.
6967           Warning is given and the operation is not done.
6968
6969       write() on closed filehandle %s
6970           (W closed) The filehandle you're writing to got itself closed
6971           sometime before now.  Check your control flow.
6972
6973       %s "\x%X" does not map to Unicode
6974           (S utf8) When reading in different encodings, Perl tries to map
6975           everything into Unicode characters.  The bytes you read in are not
6976           legal in this encoding.  For example
6977
6978               utf8 "\xE4" does not map to Unicode
6979
6980           if you try to read in the a-diaereses Latin-1 as UTF-8.
6981
6982       'X' outside of string
6983           (F) You had a (un)pack template that specified a relative position
6984           before the beginning of the string being (un)packed.  See "pack" in
6985           perlfunc.
6986
6987       'x' outside of string in unpack
6988           (F) You had a pack template that specified a relative position
6989           after the end of the string being unpacked.  See "pack" in
6990           perlfunc.
6991
6992       YOU HAVEN'T DISABLED SET-ID SCRIPTS IN THE KERNEL YET!
6993           (F) And you probably never will, because you probably don't have
6994           the sources to your kernel, and your vendor probably doesn't give a
6995           rip about what you want.  There is a vulnerability anywhere that
6996           you have a set-id script, and to close it you need to remove the
6997           set-id bit from the script that you're attempting to run.  To
6998           actually run the script set-id, your best bet is to put a set-id C
6999           wrapper around your script.
7000
7001       You need to quote "%s"
7002           (W syntax) You assigned a bareword as a signal handler name.
7003           Unfortunately, you already have a subroutine of that name declared,
7004           which means that Perl 5 will try to call the subroutine when the
7005           assignment is executed, which is probably not what you want.  (If
7006           it IS what you want, put an & in front.)
7007
7008       Your random numbers are not that random
7009           (F) When trying to initialize the random seed for hashes, Perl
7010           could not get any randomness out of your system.  This usually
7011           indicates Something Very Wrong.
7012
7013       Zero length \N{} in regex; marked by <-- HERE in m/%s/
7014           (F) Named Unicode character escapes ("\N{...}") may return a zero-
7015           length sequence.  Such an escape was used in an extended character
7016           class, i.e.  "(?[...])", or under "use re 'strict'", which is not
7017           permitted.  Check that the correct escape has been used, and the
7018           correct charnames handler is in scope.  The <-- HERE shows
7019           whereabouts in the regular expression the problem was discovered.
7020

SEE ALSO

7022       warnings, diagnostics.
7023
7024
7025
7026perl v5.32.1                      2021-03-31                       PERLDIAG(1)
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