1PERL5280DELTA(1) Perl Programmers Reference Guide PERL5280DELTA(1)
2
6 perl5280delta - what is new for perl v5.28.0
7
9 This document describes differences between the 5.26.0 release and the
10 5.28.0 release.
11 If you are upgrading from an earlier release such as 5.24.0, first read
13 perl5260delta, which describes differences between 5.24.0 and 5.26.0.
14
16 Unicode 10.0 is supported
17 A list of changes is at
18 <http://www.unicode.org/versions/Unicode10.0.0>.
19 "delete" on key/value hash slices
21 "delete" can now be used on key/value hash slices, returning the keys
22 along with the deleted values. [perl #131328]
23 <https://rt.perl.org/Ticket/Display.html?id=131328>
24 Experimentally, there are now alphabetic synonyms for some regular
26 expression assertions
27 If you find it difficult to remember how to write certain of the
28 pattern assertions, there are now alphabetic synonyms.
29 CURRENT NEW SYNONYMS
31 ------ ------------
32 (?=...) (*pla:...) or (*positive_lookahead:...)
33 (?!...) (*nla:...) or (*negative_lookahead:...)
34 (?<=...) (*plb:...) or (*positive_lookbehind:...)
35 (?<!...) (*nlb:...) or (*negative_lookbehind:...)
36 (?>...) (*atomic:...)
37 These are considered experimental, so using any of these will raise
39 (unless turned off) a warning in the "experimental::alpha_assertions"
40 category.
41 Mixed Unicode scripts are now detectable
43 A mixture of scripts, such as Cyrillic and Latin, in a string is often
44 the sign of a spoofing attack. A new regular expression construct now
45 allows for easy detection of these. For example, you can say
46 qr/(*script_run: \d+ \b )/x
48 And the digits matched will all be from the same set of 10. You won't
50 get a look-alike digit from a different script that has a different
51 value than what it appears to be.
52 Or:
54 qr/(*sr: \b \w+ \b )/x
56 makes sure that all the characters come from the same script.
58 You can also combine script runs with "(?>...)" (or "*atomic:...)").
60 Instead of writing:
62 (*sr:(?<...))
64 you can now run:
66 (*asr:...)
68 # or
69 (*atomic_script_run:...)
70 This is considered experimental, so using it will raise (unless turned
72 off) a warning in the "experimental::script_run" category.
73 See "Script Runs" in perlre.
75 In-place editing with "perl -i" is now safer
77 Previously in-place editing ("perl -i") would delete or rename the
78 input file as soon as you started working on a new file.
79 Without backups this would result in loss of data if there was an
81 error, such as a full disk, when writing to the output file.
82 This has changed so that the input file isn't replaced until the output
84 file has been completely written and successfully closed.
85 This works by creating a work file in the same directory, which is
87 renamed over the input file once the output file is complete.
88 Incompatibilities:
90 · Since this renaming needs to only happen once, if you create a
92 thread or child process, that renaming will only happen in the
93 original thread or process.
94 · If you change directories while processing a file, and your
96 operating system doesn't provide the "unlinkat()", "renameat()" and
97 "fchmodat()" functions, the final rename step may fail.
98 [perl #127663] <https://rt.perl.org/Public/Bug/Display.html?id=127663>
100 Initialisation of aggregate state variables
102 A persistent lexical array or hash variable can now be initialized, by
103 an expression such as "state @a = qw(x y z)". Initialization of a list
104 of persistent lexical variables is still not possible.
105 Full-size inode numbers
107 On platforms where inode numbers are of a type larger than perl's
108 native integer numerical types, stat will preserve the full content of
109 large inode numbers by returning them in the form of strings of decimal
110 digits. Exact comparison of inode numbers can thus be achieved by
111 comparing with "eq" rather than "==". Comparison with "==", and other
112 numerical operations (which are usually meaningless on inode numbers),
113 work as well as they did before, which is to say they fall back to
114 floating point, and ultimately operate on a fairly useless rounded
115 inode number if the real inode number is too big for the floating point
116 format.
117 The "sprintf" %j format size modifier is now available with pre-C99
119 compilers
120 The actual size used depends on the platform, so remains unportable.
121 Close-on-exec flag set atomically
123 When opening a file descriptor, perl now generally opens it with its
124 close-on-exec flag already set, on platforms that support doing so.
125 This improves thread safety, because it means that an "exec" initiated
126 by one thread can no longer cause a file descriptor in the process of
127 being opened by another thread to be accidentally passed to the
128 executed program.
129 Additionally, perl now sets the close-on-exec flag more reliably,
131 whether it does so atomically or not. Most file descriptors were
132 getting the flag set, but some were being missed.
133 String- and number-specific bitwise ops are no longer experimental
135 The new string-specific ("&. |. ^. ~.") and number-specific ("& | ^ ~")
136 bitwise operators introduced in Perl 5.22 that are available within the
137 scope of "use feature 'bitwise'" are no longer experimental. Because
138 the number-specific ops are spelled the same way as the existing
139 operators that choose their behaviour based on their operands, these
140 operators must still be enabled via the "bitwise" feature, in either of
141 these two ways:
142 use feature "bitwise";
144 use v5.28; # "bitwise" now included
146 They are also now enabled by the -E command-line switch.
148 The "bitwise" feature no longer emits a warning. Existing code that
150 disables the "experimental::bitwise" warning category that the feature
151 previously used will continue to work.
152 One caveat that module authors ought to be aware of is that the numeric
154 operators now pass a fifth TRUE argument to overload methods. Any
155 methods that check the number of operands may croak if they do not
156 expect so many. XS authors in particular should be aware that this:
157 SV *
159 bitop_handler (lobj, robj, swap)
160 may need to be changed to this:
162 SV *
164 bitop_handler (lobj, robj, swap, ...)
165 Locales are now thread-safe on systems that support them
167 These systems include Windows starting with Visual Studio 2005, and in
168 POSIX 2008 systems.
169 The implication is that you are now free to use locales and change them
171 in a threaded environment. Your changes affect only your thread. See
172 "Multi-threaded operation" in perllocale
173 New read-only predefined variable "${^SAFE_LOCALES}"
175 This variable is 1 if the Perl interpreter is operating in an
176 environment where it is safe to use and change locales (see
177 perllocale.) This variable is true when the perl is unthreaded, or
178 compiled in a platform that supports thread-safe locale operation (see
179 previous item).
180
182 [CVE-2017-12837] Heap buffer overflow in regular expression compiler
183 Compiling certain regular expression patterns with the case-insensitive
184 modifier could cause a heap buffer overflow and crash perl. This has
185 now been fixed. [perl #131582]
186 <https://rt.perl.org/Public/Bug/Display.html?id=131582>
187 [CVE-2017-12883] Buffer over-read in regular expression parser
189 For certain types of syntax error in a regular expression pattern, the
190 error message could either contain the contents of a random, possibly
191 large, chunk of memory, or could crash perl. This has now been fixed.
192 [perl #131598] <https://rt.perl.org/Public/Bug/Display.html?id=131598>
193 [CVE-2017-12814] $ENV{$key} stack buffer overflow on Windows
195 A possible stack buffer overflow in the %ENV code on Windows has been
196 fixed by removing the buffer completely since it was superfluous
197 anyway. [perl #131665]
198 <https://rt.perl.org/Public/Bug/Display.html?id=131665>
199 Default Hash Function Change
201 Perl 5.28.0 retires various older hash functions which are not viewed
202 as sufficiently secure for use in Perl. We now support four general
203 purpose hash functions, Siphash (2-4 and 1-3 variants), and Zaphod32,
204 and StadtX hash. In addition we support SBOX32 (a form of tabular
205 hashing) for hashing short strings, in conjunction with any of the
206 other hash functions provided.
207 By default Perl is configured to support SBOX hashing of strings up to
209 24 characters, in conjunction with StadtX hashing on 64 bit builds, and
210 Zaphod32 hashing for 32 bit builds.
211 You may control these settings with the following options to Configure:
213 -DPERL_HASH_FUNC_SIPHASH
215 -DPERL_HASH_FUNC_SIPHASH13
216 -DPERL_HASH_FUNC_STADTX
217 -DPERL_HASH_FUNC_ZAPHOD32
218 To disable SBOX hashing you can use
220 -DPERL_HASH_USE_SBOX32_ALSO=0
222 And to set the maximum length to use SBOX32 hashing on with:
224 -DSBOX32_MAX_LEN=16
226 The maximum length allowed is 256. There probably isn't much point in
228 setting it higher than the default.
229
231 Subroutine attribute and signature order
232 The experimental subroutine signatures feature has been changed so that
233 subroutine attributes must now come before the signature rather than
234 after. This is because attributes like ":lvalue" can affect the
235 compilation of code within the signature, for example:
236 sub f :lvalue ($a = do { $x = "abc"; return substr($x,0,1)}) { ...}
238 Note that this the second time they have been flipped:
240 sub f :lvalue ($a, $b) { ... }; # 5.20; 5.28 onwards
242 sub f ($a, $b) :lvalue { ... }; # 5.22 - 5.26
243 Comma-less variable lists in formats are no longer allowed
245 Omitting the commas between variables passed to formats is no longer
246 allowed. This has been deprecated since Perl 5.000.
247 The ":locked" and ":unique" attributes have been removed
249 These have been no-ops and deprecated since Perl 5.12 and 5.10,
250 respectively.
251 "\N{}" with nothing between the braces is now illegal
253 This has been deprecated since Perl 5.24.
254 Opening the same symbol as both a file and directory handle is no longer
256 allowed
257 Using "open()" and "opendir()" to associate both a filehandle and a
258 dirhandle to the same symbol (glob or scalar) has been deprecated since
259 Perl 5.10.
260 Use of bare "<<" to mean "<<""" is no longer allowed
262 Use of a bare terminator has been deprecated since Perl 5.000.
263 Setting $/ to a reference to a non-positive integer no longer allowed
265 This used to work like setting it to "undef", but has been deprecated
266 since Perl 5.20.
267 Unicode code points with values exceeding "IV_MAX" are now fatal
269 This was deprecated since Perl 5.24.
270 The "B::OP::terse" method has been removed
272 Use "B::Concise::b_terse" instead.
273 Use of inherited AUTOLOAD for non-methods is no longer allowed
275 This was deprecated in Perl 5.004.
276 Use of strings with code points over 0xFF is not allowed for bitwise string
278 operators
279 Code points over 0xFF do not make sense for bitwise operators and such
280 an operation will now croak, except for a few remaining cases. See
281 perldeprecation.
282 This was deprecated in Perl 5.24.
284 Setting "${^ENCODING}" to a defined value is now illegal
286 This has been deprecated since Perl 5.22 and a no-op since Perl 5.26.
287 Backslash no longer escapes colon in PATH for the "-S" switch
289 Previously the "-S" switch incorrectly treated backslash ("\") as an
290 escape for colon when traversing the "PATH" environment variable.
291 [perl #129183] <https://rt.perl.org/Ticket/Display.html?id=129183>
292 the -DH (DEBUG_H) misfeature has been removed
294 On a perl built with debugging support, the "H" flag to the "-D"
295 debugging option has been removed. This was supposed to dump hash
296 values, but has been broken for many years.
297 Yada-yada is now strictly a statement
299 By the time of its initial stable release in Perl 5.12, the "..."
300 (yada-yada) operator was explicitly intended to serve as a statement,
301 not an expression. However, the original implementation was confused
302 on this point, leading to inconsistent parsing. The operator was
303 accidentally accepted in a few situations where it did not serve as a
304 complete statement, such as
305 ... . "foo";
307 ... if $a < $b;
308 The parsing has now been made consistent, permitting yada-yada only as
310 a statement. Affected code can use "do{...}" to put a yada-yada into
311 an arbitrary expression context.
312 Sort algorithm can no longer be specified
314 Since Perl 5.8, the sort pragma has had subpragmata "_mergesort",
315 "_quicksort", and "_qsort" that can be used to specify which algorithm
316 perl should use to implement the sort builtin. This was always
317 considered a dubious feature that might not last, hence the underscore
318 spellings, and they were documented as not being portable beyond Perl
319 5.8. These subpragmata have now been deleted, and any attempt to use
320 them is an error. The sort pragma otherwise remains, and the
321 algorithm-neutral "stable" subpragma can be used to control sorting
322 behaviour. [perl #119635]
323 <https://rt.perl.org/Ticket/Display.html?id=119635>
324 Over-radix digits in floating point literals
326 Octal and binary floating point literals used to permit any hexadecimal
327 digit to appear after the radix point. The digits are now restricted
328 to those appropriate for the radix, as digits before the radix point
329 always were.
330 Return type of "unpackstring()"
332 The return types of the C API functions "unpackstring()" and
333 "unpack_str()" have changed from "I32" to "SSize_t", in order to
334 accommodate datasets of more than two billion items.
335
337 Use of "vec" on strings with code points above 0xFF is deprecated
338 Such strings are represented internally in UTF-8, and "vec" is a bit-
339 oriented operation that will likely give unexpected results on those
340 strings.
341 Some uses of unescaped "{" in regexes are no longer fatal
343 Perl 5.26.0 fatalized some uses of an unescaped left brace, but an
344 exception was made at the last minute, specifically crafted to be a
345 minimal change to allow GNU Autoconf to work. That tool is heavily
346 depended upon, and continues to use the deprecated usage. Its use of
347 an unescaped left brace is one where we have no intention of
348 repurposing "{" to be something other than itself.
349 That exception is now generalized to include various other such cases
351 where the "{" will not be repurposed.
352 Note that these uses continue to raise a deprecation message.
354 Use of unescaped "{" immediately after a "(" in regular expression patterns
356 is deprecated
357 Using unescaped left braces is officially deprecated everywhere, but it
358 is not enforced in contexts where their use does not interfere with
359 expected extensions to the language. A deprecation is added in this
360 release when the brace appears immediately after an opening
361 parenthesis. Before this, even if the brace was part of a legal
362 quantifier, it was not interpreted as such, but as the literal
363 characters, unlike other quantifiers that follow a "(" which are
364 considered errors. Now, their use will raise a deprecation message,
365 unless turned off.
366 Assignment to $[ will be fatal in Perl 5.30
368 Assigning a non-zero value to $[ has been deprecated since Perl 5.12,
369 but was never given a deadline for removal. This has now been
370 scheduled for Perl 5.30.
371 hostname() won't accept arguments in Perl 5.32
373 Passing arguments to "Sys::Hostname::hostname()" was already
374 deprecated, but didn't have a removal date. This has now been
375 scheduled for Perl 5.32. [perl #124349]
376 <https://rt.perl.org/Ticket/Display.html?id=124349>
377 Module removals
379 The following modules will be removed from the core distribution in a
380 future release, and will at that time need to be installed from CPAN.
381 Distributions on CPAN which require these modules will need to list
382 them as prerequisites.
383 The core versions of these modules will now issue "deprecated"-category
385 warnings to alert you to this fact. To silence these deprecation
386 warnings, install the modules in question from CPAN.
387 Note that these are (with rare exceptions) fine modules that you are
389 encouraged to continue to use. Their disinclusion from core primarily
390 hinges on their necessity to bootstrapping a fully functional, CPAN-
391 capable Perl installation, not usually on concerns over their design.
392 B::Debug
394 Locale::Codes and its associated Country, Currency and Language modules
395
397 · The start up overhead for creating regular expression patterns with
398 Unicode properties ("\p{...}") has been greatly reduced in most
399 cases.
400 · Many string concatenation expressions are now considerably faster,
402 due to the introduction internally of a "multiconcat" opcode which
403 combines multiple concatenations, and optionally a "=" or ".=",
404 into a single action. For example, apart from retrieving $s, $a and
405 $b, this whole expression is now handled as a single op:
406 $s .= "a=$a b=$b\n"
408 As a special case, if the LHS of an assignment is a lexical
410 variable or "my $s", the op itself handles retrieving the lexical
411 variable, which is faster.
412 In general, the more the expression includes a mix of constant
414 strings and variable expressions, the longer the expression, and
415 the more it mixes together non-utf8 and utf8 strings, the more
416 marked the performance improvement. For example on a "x86_64"
417 system, this code has been benchmarked running four times faster:
418 my $s;
420 my $a = "ab\x{100}cde";
421 my $b = "fghij";
422 my $c = "\x{101}klmn";
423 for my $i (1..10_000_000) {
425 $s = "\x{100}wxyz";
426 $s .= "foo=$a bar=$b baz=$c";
427 }
428 In addition, "sprintf" expressions which have a constant format
430 containing only %s and "%%" format elements, and which have a fixed
431 number of arguments, are now also optimised into a "multiconcat"
432 op.
433 · The "ref()" builtin is now much faster in boolean context, since it
435 no longer bothers to construct a temporary string like
436 "Foo=ARRAY(0x134af48)".
437 · "keys()" in void and scalar contexts is now more efficient.
439 · The common idiom of comparing the result of index() with -1 is now
441 specifically optimised, e.g.
442 if (index(...) != -1) { ... }
444 · "for()" loops and similar constructs are now more efficient in most
446 cases.
447 · File::Glob has been modified to remove unnecessary backtracking and
449 recursion, thanks to Russ Cox. See
450 <https://research.swtch.com/glob> for more details.
451 · The XS-level "SvTRUE()" API function is now more efficient.
453 · Various integer-returning ops are now more efficient in
455 scalar/boolean context.
456 · Slightly improved performance when parsing stash names. [perl
458 #129990] <https://rt.perl.org/Public/Bug/Display.html?id=129990>
459 · Calls to "require" for an already loaded module are now slightly
461 faster. [perl #132171]
462 <https://rt.perl.org/Public/Bug/Display.html?id=132171>
463 · The performance of pattern matching "[[:ascii:]]" and
465 "[[:^ascii:]]" has been improved significantly except on EBCDIC
466 platforms.
467 · Various optimizations have been applied to matching regular
469 expression patterns, so under the right circumstances, significant
470 performance gains may be noticed. But in an application with many
471 varied patterns, little overall improvement likely will be seen.
472 · Other optimizations have been applied to UTF-8 handling, but these
474 are not typically a major factor in most applications.
475
477 Key highlights in this release across several modules:
478 Removal of use vars
480 The usage of "use vars" has been discouraged since the introduction of
481 "our" in Perl 5.6.0. Where possible the usage of this pragma has now
482 been removed from the Perl source code.
483 This had a slight effect (for the better) on the output of WARNING_BITS
485 in B::Deparse.
486 Use of DynaLoader changed to XSLoader in many modules
488 XSLoader is more modern, and most modules already require perl 5.6 or
489 greater, so no functionality is lost by switching. In some cases, we
490 have also made changes to the local implementation that may not be
491 reflected in the version on CPAN due to a desire to maintain more
492 backwards compatibility.
493 Updated Modules and Pragmata
495 · Archive::Tar has been upgraded from version 2.24 to 2.30.
496 This update also handled CVE-2018-12015: directory traversal
498 vulnerability. [cpan #125523]
499 <https://rt.cpan.org/Ticket/Display.html?id=125523>
500 · arybase has been upgraded from version 0.12 to 0.15.
502 · Attribute::Handlers has been upgraded from version 0.99 to 1.01.
504 · attributes has been upgraded from version 0.29 to 0.33.
506 · B has been upgraded from version 1.68 to 1.74.
508 · B::Concise has been upgraded from version 0.999 to 1.003.
510 · B::Debug has been upgraded from version 1.24 to 1.26.
512 NOTE: B::Debug is deprecated and may be removed from a future
514 version of Perl.
515 · B::Deparse has been upgraded from version 1.40 to 1.48.
517 It includes many bug fixes, and in particular, it now deparses
519 variable attributes correctly:
520 my $x :foo; # used to deparse as
522 # 'attributes'->import('main', \$x, 'foo'), my $x;
523 · base has been upgraded from version 2.25 to 2.27.
525 · bignum has been upgraded from version 0.47 to 0.49.
527 · blib has been upgraded from version 1.06 to 1.07.
529 · bytes has been upgraded from version 1.05 to 1.06.
531 · Carp has been upgraded from version 1.42 to 1.50.
533 If a package on the call stack contains a constant named "ISA",
535 Carp no longer throws a "Not a GLOB reference" error.
536 Carp, when generating stack traces, now attempts to work around
538 longstanding bugs resulting from Perl's non-reference-counted
539 stack. [perl #52610]
540 <https://rt.perl.org/Ticket/Display.html?id=52610>
541 Carp has been modified to avoid assuming that objects cannot be
543 overloaded without the overload module loaded (this can happen with
544 objects created by XS modules). Previously, infinite recursion
545 would result if an XS-defined overload method itself called Carp.
546 [perl #132828] <https://rt.perl.org/Ticket/Display.html?id=132828>
547 Carp now avoids using "overload::StrVal", partly because older
549 versions of overload (included with perl 5.14 and earlier) load
550 Scalar::Util at run time, which will fail if Carp has been invoked
551 after a syntax error.
552 · charnames has been upgraded from version 1.44 to 1.45.
554 · Compress::Raw::Zlib has been upgraded from version 2.074 to 2.076.
556 This addresses a security vulnerability in older versions of the
558 'zlib' library (which is bundled with Compress-Raw-Zlib).
559 · Config::Extensions has been upgraded from version 0.01 to 0.02.
561 · Config::Perl::V has been upgraded from version 0.28 to 0.29.
563 · CPAN has been upgraded from version 2.18 to 2.20.
565 · Data::Dumper has been upgraded from version 2.167 to 2.170.
567 Quoting of glob names now obeys the Useqq option [perl #119831]
569 <https://rt.perl.org/Ticket/Display.html?id=119831>.
570 Attempts to set an option to "undef" through a combined
572 getter/setter method are no longer mistaken for getter calls [perl
573 #113090] <https://rt.perl.org/Ticket/Display.html?id=113090>.
574 · Devel::Peek has been upgraded from version 1.26 to 1.27.
576 · Devel::PPPort has been upgraded from version 3.35 to 3.40.
578 Devel::PPPort has moved from cpan-first to perl-first maintenance
580 Primary responsibility for the code in Devel::PPPort has moved into
582 core perl. In a practical sense there should be no change except
583 that hopefully it will stay more up to date with changes made to
584 symbols in perl, rather than needing to be updated after the fact.
585 · Digest::SHA has been upgraded from version 5.96 to 6.01.
587 · DirHandle has been upgraded from version 1.04 to 1.05.
589 · DynaLoader has been upgraded from version 1.42 to 1.45.
591 Its documentation now shows the use of "__PACKAGE__" and direct
593 object syntax [perl #132247]
594 <https://rt.perl.org/Ticket/Display.html?id=132247>.
595 · Encode has been upgraded from version 2.88 to 2.97.
597 · encoding has been upgraded from version 2.19 to 2.22.
599 · Errno has been upgraded from version 1.28 to 1.29.
601 · experimental has been upgraded from version 0.016 to 0.019.
603 · Exporter has been upgraded from version 5.72 to 5.73.
605 · ExtUtils::CBuilder has been upgraded from version 0.280225 to
607 0.280230.
608 · ExtUtils::Constant has been upgraded from version 0.23 to 0.25.
610 · ExtUtils::Embed has been upgraded from version 1.34 to 1.35.
612 · ExtUtils::Install has been upgraded from version 2.04 to 2.14.
614 · ExtUtils::MakeMaker has been upgraded from version 7.24 to 7.34.
616 · ExtUtils::Miniperl has been upgraded from version 1.06 to 1.08.
618 · ExtUtils::ParseXS has been upgraded from version 3.34 to 3.39.
620 · ExtUtils::Typemaps has been upgraded from version 3.34 to 3.38.
622 · ExtUtils::XSSymSet has been upgraded from version 1.3 to 1.4.
624 · feature has been upgraded from version 1.47 to 1.52.
626 · fields has been upgraded from version 2.23 to 2.24.
628 · File::Copy has been upgraded from version 2.32 to 2.33.
630 It will now use the sub-second precision variant of utime()
632 supplied by Time::HiRes where available. [perl #132401]
633 <https://rt.perl.org/Ticket/Display.html?id=132401>.
634 · File::Fetch has been upgraded from version 0.52 to 0.56.
636 · File::Glob has been upgraded from version 1.28 to 1.31.
638 · File::Path has been upgraded from version 2.12_01 to 2.15.
640 · File::Spec and Cwd have been upgraded from version 3.67 to 3.74.
642 · File::stat has been upgraded from version 1.07 to 1.08.
644 · FileCache has been upgraded from version 1.09 to 1.10.
646 · Filter::Simple has been upgraded from version 0.93 to 0.95.
648 · Filter::Util::Call has been upgraded from version 1.55 to 1.58.
650 · GDBM_File has been upgraded from version 1.15 to 1.17.
652 Its documentation now explains that "each" and "delete" don't mix
654 in hashes tied to this module [perl #117449]
655 <https://rt.perl.org/Ticket/Display.html?id=117449>.
656 It will now retry opening with an acceptable block size if asking
658 gdbm to default the block size failed [perl #119623]
659 <https://rt.perl.org/Ticket/Display.html?id=119623>.
660 · Getopt::Long has been upgraded from version 2.49 to 2.5.
662 · Hash::Util::FieldHash has been upgraded from version 1.19 to 1.20.
664 · I18N::Langinfo has been upgraded from version 0.13 to 0.17.
666 This module is now available on all platforms, emulating the system
668 nl_langinfo(3) on systems that lack it. Some caveats apply, as
669 detailed in its documentation, the most severe being that, except
670 for MS Windows, the "CODESET" item is not implemented on those
671 systems, always returning "".
672 It now sets the UTF-8 flag in its returned scalar if the string
674 contains legal non-ASCII UTF-8, and the locale is UTF-8 [perl
675 #127288] <https://rt.perl.org/Ticket/Display.html?id=127288>.
676 This update also fixes a bug in which the underlying locale was
678 ignored for the "RADIXCHAR" (always was returned as a dot) and the
679 "THOUSEP" (always empty). Now the locale-appropriate values are
680 returned.
681 · I18N::LangTags has been upgraded from version 0.42 to 0.43.
683 · if has been upgraded from version 0.0606 to 0.0608.
685 · IO has been upgraded from version 1.38 to 1.39.
687 · IO::Socket::IP has been upgraded from version 0.38 to 0.39.
689 · IPC::Cmd has been upgraded from version 0.96 to 1.00.
691 · JSON::PP has been upgraded from version 2.27400_02 to 2.97001.
693 · The "libnet" distribution has been upgraded from version 3.10 to
695 3.11.
696 · List::Util has been upgraded from version 1.46_02 to 1.49.
698 · Locale::Codes has been upgraded from version 3.42 to 3.56.
700 NOTE: Locale::Codes scheduled to be removed from core in Perl 5.30.
702 · Locale::Maketext has been upgraded from version 1.28 to 1.29.
704 · Math::BigInt has been upgraded from version 1.999806 to 1.999811.
706 · Math::BigInt::FastCalc has been upgraded from version 0.5005 to
708 0.5006.
709 · Math::BigRat has been upgraded from version 0.2611 to 0.2613.
711 · Module::CoreList has been upgraded from version 5.20170530 to
713 5.20180622.
714 · mro has been upgraded from version 1.20 to 1.22.
716 · Net::Ping has been upgraded from version 2.55 to 2.62.
718 · NEXT has been upgraded from version 0.67 to 0.67_01.
720 · ODBM_File has been upgraded from version 1.14 to 1.15.
722 · Opcode has been upgraded from version 1.39 to 1.43.
724 · overload has been upgraded from version 1.28 to 1.30.
726 · PerlIO::encoding has been upgraded from version 0.25 to 0.26.
728 · PerlIO::scalar has been upgraded from version 0.26 to 0.29.
730 · PerlIO::via has been upgraded from version 0.16 to 0.17.
732 · Pod::Functions has been upgraded from version 1.11 to 1.13.
734 · Pod::Html has been upgraded from version 1.2202 to 1.24.
736 A title for the HTML document will now be automatically generated
738 by default from a "NAME" section in the POD document, as it used to
739 be before the module was rewritten to use Pod::Simple::XHTML to do
740 the core of its job [perl #110520]
741 <https://rt.perl.org/Ticket/Display.html?id=110520>.
742 · Pod::Perldoc has been upgraded from version 3.28 to 3.2801.
744 · The "podlators" distribution has been upgraded from version 4.09 to
746 4.10.
747 Man page references and function names now follow the Linux man
749 page formatting standards, instead of the Solaris standard.
750 · POSIX has been upgraded from version 1.76 to 1.84.
752 Some more cautions were added about using locale-specific functions
754 in threaded applications.
755 · re has been upgraded from version 0.34 to 0.36.
757 · Scalar::Util has been upgraded from version 1.46_02 to 1.50.
759 · SelfLoader has been upgraded from version 1.23 to 1.25.
761 · Socket has been upgraded from version 2.020_03 to 2.027.
763 · sort has been upgraded from version 2.02 to 2.04.
765 · Storable has been upgraded from version 2.62 to 3.08.
767 · Sub::Util has been upgraded from version 1.48 to 1.49.
769 · subs has been upgraded from version 1.02 to 1.03.
771 · Sys::Hostname has been upgraded from version 1.20 to 1.22.
773 · Term::ReadLine has been upgraded from version 1.16 to 1.17.
775 · Test has been upgraded from version 1.30 to 1.31.
777 · Test::Harness has been upgraded from version 3.38 to 3.42.
779 · Test::Simple has been upgraded from version 1.302073 to 1.302133.
781 · threads has been upgraded from version 2.15 to 2.22.
783 The documentation now better describes the problems that arise when
785 returning values from threads, and no longer warns about creating
786 threads in "BEGIN" blocks. [perl #96538]
787 <https://rt.perl.org/Ticket/Display.html?id=96538>
788 · threads::shared has been upgraded from version 1.56 to 1.58.
790 · Tie::Array has been upgraded from version 1.06 to 1.07.
792 · Tie::StdHandle has been upgraded from version 4.4 to 4.5.
794 · Time::gmtime has been upgraded from version 1.03 to 1.04.
796 · Time::HiRes has been upgraded from version 1.9741 to 1.9759.
798 · Time::localtime has been upgraded from version 1.02 to 1.03.
800 · Time::Piece has been upgraded from version 1.31 to 1.3204.
802 · Unicode::Collate has been upgraded from version 1.19 to 1.25.
804 · Unicode::Normalize has been upgraded from version 1.25 to 1.26.
806 · Unicode::UCD has been upgraded from version 0.68 to 0.70.
808 The function "num" now accepts an optional parameter to help in
810 diagnosing error returns.
811 · User::grent has been upgraded from version 1.01 to 1.02.
813 · User::pwent has been upgraded from version 1.00 to 1.01.
815 · utf8 has been upgraded from version 1.19 to 1.21.
817 · vars has been upgraded from version 1.03 to 1.04.
819 · version has been upgraded from version 0.9917 to 0.9923.
821 · VMS::DCLsym has been upgraded from version 1.08 to 1.09.
823 · VMS::Stdio has been upgraded from version 2.41 to 2.44.
825 · warnings has been upgraded from version 1.37 to 1.42.
827 It now includes new functions with names ending in "_at_level",
829 allowing callers to specify the exact call frame. [perl #132468]
830 <https://rt.perl.org/Ticket/Display.html?id=132468>
831 · XS::Typemap has been upgraded from version 0.15 to 0.16.
833 · XSLoader has been upgraded from version 0.27 to 0.30.
835 Its documentation now shows the use of "__PACKAGE__", and direct
837 object syntax for example "DynaLoader" usage [perl #132247]
838 <https://rt.perl.org/Ticket/Display.html?id=132247>.
839 Platforms that use "mod2fname" to edit the names of loadable
841 libraries now look for bootstrap (.bs) files under the correct,
842 non-edited name.
843 Removed Modules and Pragmata
845 · The "VMS::stdio" compatibility shim has been removed.
846
848 Changes to Existing Documentation
849 We have attempted to update the documentation to reflect the changes
850 listed in this document. If you find any we have missed, send email to
851 perlbug@perl.org <mailto:perlbug@perl.org>.
852 Additionally, the following selected changes have been made:
854 perlapi
856 · The API functions "perl_parse()", "perl_run()", and
858 "perl_destruct()" are now documented comprehensively, where
859 previously the only documentation was a reference to the perlembed
860 tutorial.
861 · The documentation of "newGIVENOP()" has been belatedly updated to
863 account for the removal of lexical $_.
864 · The API functions "newCONSTSUB()" and "newCONSTSUB_flags()" are
866 documented much more comprehensively than before.
867 perldata
869 · The section "Truth and Falsehood" in perlsyn has been moved into
871 perldata.
872 perldebguts
874 · The description of the conditions under which "DB::sub()" will be
876 called has been clarified. [perl #131672]
877 <https://rt.perl.org/Ticket/Display.html?id=131672>
878 perldiag
880 · "Variable length lookbehind not implemented in regex m/%s/" in
882 perldiag
883 This now gives more ideas as to workarounds to the issue that was
885 introduced in Perl 5.18 (but not documented explicitly in its
886 perldelta) for the fact that some Unicode "/i" rules cause a few
887 sequences such as
888 (?<!st)
890 to be considered variable length, and hence disallowed.
892 · "Use of state $_ is experimental" in perldiag
894 This entry has been removed, as the experimental support of this
896 construct was removed in perl 5.24.0.
897 · The diagnostic "Initialization of state variables in list context
899 currently forbidden" has changed to "Initialization of state
900 variables in list currently forbidden", because list-context
901 initialization of single aggregate state variables is now
902 permitted.
903 perlembed
905 · The examples in perlembed have been made more portable in the way
907 they exit, and the example that gets an exit code from the embedded
908 Perl interpreter now gets it from the right place. The examples
909 that pass a constructed argv to Perl now show the mandatory null
910 "argv[argc]".
911 · An example in perlembed used the string value of "ERRSV" as a
913 format string when calling croak(). If that string contains format
914 codes such as %s this could crash the program.
915 This has been changed to a call to croak_sv().
917 An alternative could have been to supply a trivial format string:
919 croak("%s", SvPV_nolen(ERRSV));
921 or as a special case for "ERRSV" simply:
923 croak(NULL);
925 perlfunc
927 · There is now a note that warnings generated by built-in functions
929 are documented in perldiag and warnings. [perl #116080]
930 <https://rt.perl.org/Ticket/Display.html?id=116080>
931 · The documentation for the "exists" operator no longer says that
933 autovivification behaviour "may be fixed in a future release".
934 We've determined that we're not going to change the default
935 behaviour. [perl #127712]
936 <https://rt.perl.org/Ticket/Display.html?id=127712>
937 · A couple of small details in the documentation for the "bless"
939 operator have been clarified. [perl #124428]
940 <https://rt.perl.org/Ticket/Display.html?id=124428>
941 · The description of @INC hooks in the documentation for "require"
943 has been corrected to say that filter subroutines receive a useless
944 first argument. [perl #115754]
945 <https://rt.perl.org/Ticket/Display.html?id=115754>
946 · The documentation of "ref" has been rewritten for clarity.
948 · The documentation of "use" now explains what syntactically
950 qualifies as a version number for its module version checking
951 feature.
952 · The documentation of "warn" has been updated to reflect that since
954 Perl 5.14 it has treated complex exception objects in a manner
955 equivalent to "die". [perl #121372]
956 <https://rt.perl.org/Ticket/Display.html?id=121372>
957 · The documentation of "die" and "warn" has been revised for clarity.
959 · The documentation of "each" has been improved, with a slightly more
961 explicit description of the sharing of iterator state, and with
962 caveats regarding the fragility of while-each loops. [perl
963 #132644] <https://rt.perl.org/Ticket/Display.html?id=132644>
964 · Clarification to "require" was added to explain the differences
966 between
967 require Foo::Bar;
969 require "Foo/Bar.pm";
970 perlgit
972 · The precise rules for identifying "smoke-me" branches are now
974 stated.
975 perlguts
977 · The section on reference counting in perlguts has been heavily
979 revised, to describe references in the way a programmer needs to
980 think about them rather than in terms of the physical data
981 structures.
982 · Improve documentation related to UTF-8 multibytes.
984 perlintern
986 · The internal functions "newXS_len_flags()" and "newATTRSUB_x()" are
988 now documented.
989 perlobj
991 · The documentation about "DESTROY" methods has been corrected,
993 updated, and revised, especially in regard to how they interact
994 with exceptions. [perl #122753]
995 <https://rt.perl.org/Ticket/Display.html?id=122753>
996 perlop
998 · The description of the "x" operator in perlop has been clarified.
1000 [perl #132460] <https://rt.perl.org/Ticket/Display.html?id=132460>
1001 · perlop has been updated to note that "qw"'s whitespace rules differ
1003 from that of "split"'s in that only ASCII whitespace is used.
1004 · The general explanation of operator precedence and associativity
1006 has been corrected and clarified. [perl #127391]
1007 <https://rt.perl.org/Ticket/Display.html?id=127391>
1008 · The documentation for the "\" referencing operator now explains the
1010 unusual context that it supplies to its operand. [perl #131061]
1011 <https://rt.perl.org/Ticket/Display.html?id=131061>
1012 perlrequick
1014 · Clarifications on metacharacters and character classes
1016 perlretut
1018 · Clarify metacharacters.
1020 perlrun
1022 · Clarify the differences between -M and -m. [perl #131518]
1024 <https://rt.perl.org/Ticket/Display.html?id=131518>
1025 perlsec
1027 · The documentation about set-id scripts has been updated and
1029 revised. [perl #74142]
1030 <https://rt.perl.org/Ticket/Display.html?id=74142>
1031 · A section about using "sudo" to run Perl scripts has been added.
1033 perlsyn
1035 · The section "Truth and Falsehood" in perlsyn has been removed from
1037 that document, where it didn't belong, and merged into the existing
1038 paragraph on the same topic in perldata.
1039 · The means to disambiguate between code blocks and hash
1041 constructors, already documented in perlref, are now documented in
1042 perlsyn too. [perl #130958]
1043 <https://rt.perl.org/Ticket/Display.html?id=130958>
1044 perluniprops
1046 · perluniprops has been updated to note that "\p{Word}" now includes
1048 code points matching the "\p{Join_Control}" property. The change
1049 to the property was made in Perl 5.18, but not documented until
1050 now. There are currently only two code points that match this
1051 property U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH
1052 JOINER).
1053 · For each binary table or property, the documentation now includes
1055 which characters in the range "\x00-\xFF" it matches, as well as a
1056 list of the first few ranges of code points matched above that.
1057 perlvar
1059 · The entry for $+ in perlvar has been expanded upon to describe
1061 handling of multiply-named capturing groups.
1062 perlfunc, perlop, perlsyn
1064 · In various places, improve the documentation of the special cases
1066 in the condition expression of a while loop, such as implicit
1067 "defined" and assignment to $_. [perl #132644]
1068 <https://rt.perl.org/Ticket/Display.html?id=132644>
1069
1071 The following additions or changes have been made to diagnostic output,
1072 including warnings and fatal error messages. For the complete list of
1073 diagnostic messages, see perldiag.
1074 New Diagnostics
1076 New Errors
1077 · Can't "goto" into a "given" block
1079 (F) A "goto" statement was executed to jump into the middle of a
1081 "given" block. You can't get there from here. See "goto" in
1082 perlfunc.
1083 · Can't "goto" into a binary or list expression
1085 Use of "goto" to jump into the parameter of a binary or list
1087 operator has been prohibited, to prevent crashes and stack
1088 corruption. [perl #130936]
1089 <https://rt.perl.org/Ticket/Display.html?id=130936>
1090 You may only enter the first argument of an operator that takes a
1092 fixed number of arguments, since this is a case that will not cause
1093 stack corruption. [perl #132854]
1094 <https://rt.perl.org/Ticket/Display.html?id=132854>
1095 New Warnings
1097 · Old package separator used in string
1099 (W syntax) You used the old package separator, "'", in a variable
1101 named inside a double-quoted string; e.g., "In $name's house".
1102 This is equivalent to "In $name::s house". If you meant the
1103 former, put a backslash before the apostrophe ("In $name\'s
1104 house").
1105 · "Locale '%s' contains (at least) the following characters which
1107 have unexpected meanings: %s The Perl program will use the
1108 expected meanings" in perldiag
1109 Changes to Existing Diagnostics
1111 · A false-positive warning that was issued when using a numerically-
1112 quantified sub-pattern in a recursive regex has been silenced.
1113 [perl #131868]
1114 <https://rt.perl.org/Public/Bug/Display.html?id=131868>
1115 · The warning about useless use of a concatenation operator in void
1117 context is now generated for expressions with multiple
1118 concatenations, such as "$a.$b.$c", which used to mistakenly not
1119 warn. [perl #6997]
1120 <https://rt.perl.org/Ticket/Display.html?id=6997>
1121 · Warnings that a variable or subroutine "masks earlier declaration
1123 in same ...", or that an "our" variable has been redeclared, have
1124 been moved to a new warnings category "shadow". Previously they
1125 were in category "misc".
1126 · The deprecation warning from "Sys::Hostname::hostname()" saying
1128 that it doesn't accept arguments now states the Perl version in
1129 which the warning will be upgraded to an error. [perl #124349]
1130 <https://rt.perl.org/Ticket/Display.html?id=124349>
1131 · The perldiag entry for the error regarding a set-id script has been
1133 expanded to make clear that the error is reporting a specific
1134 security vulnerability, and to advise how to fix it.
1135 · The "Unable to flush stdout" error message was missing a trailing
1137 newline. [debian #875361]
1138
1140 perlbug
1141 · "--help" and "--version" options have been added.
1142
1144 · C89 requirement
1145 Perl has been documented as requiring a C89 compiler to build since
1147 October 1998. A variety of simplifications have now been made to
1148 Perl's internals to rely on the features specified by the C89
1149 standard. We believe that this internal change hasn't altered the
1150 set of platforms that Perl builds on, but please report a bug if
1151 Perl now has new problems building on your platform.
1152 · On GCC, "-Werror=pointer-arith" is now enabled by default,
1154 disallowing arithmetic on void and function pointers.
1155 · Where an HTML version of the documentation is installed, the HTML
1157 documents now use relative links to refer to each other. Links
1158 from the index page of perlipc to the individual section documents
1159 are now correct. [perl #110056]
1160 <https://rt.perl.org/Ticket/Display.html?id=110056>
1161 · lib/unicore/mktables now correctly canonicalizes the names of the
1163 dependencies stored in the files it generates.
1164 regen/mk_invlists.pl, unlike the other regen/*.pl scripts, used $0
1166 to name itself in the dependencies stored in the files it
1167 generates. It now uses a literal so that the path stored in the
1168 generated files doesn't depend on how regen/mk_invlists.pl is
1169 invoked.
1170 This lack of canonical names could cause test failures in
1172 t/porting/regen.t. [perl #132925]
1173 <https://rt.perl.org/Ticket/Display.html?id=132925>
1174 · New probes
1176 HAS_BUILTIN_ADD_OVERFLOW
1178 HAS_BUILTIN_MUL_OVERFLOW
1179 HAS_BUILTIN_SUB_OVERFLOW
1180 HAS_THREAD_SAFE_NL_LANGINFO_L
1181 HAS_LOCALECONV_L
1182 HAS_MBRLEN
1183 HAS_MBRTOWC
1184 HAS_MEMRCHR
1185 HAS_NANOSLEEP
1186 HAS_STRNLEN
1187 HAS_STRTOLD_L
1188 I_WCHAR
1189
1191 · Testing of the XS-APItest directory is now done in parallel, where
1192 applicable.
1193 · Perl now includes a default .travis.yml file for Travis CI testing
1195 on github mirrors. [perl #123981]
1196 <https://rt.perl.org/Ticket/Display.html?id=123981>
1197 · The watchdog timer count in re/pat_psycho.t can now be overridden.
1199 This test can take a long time to run, so there is a timer to keep
1201 this in check (currently, 5 minutes). This commit adds checking the
1202 environment variable "PERL_TEST_TIME_OUT_FACTOR"; if set, the time
1203 out setting is multiplied by its value.
1204 · harness no longer waits for 30 seconds when running t/io/openpid.t.
1206 [perl #121028] <https://rt.perl.org/Ticket/Display.html?id=121028>
1207 [perl #132867] <https://rt.perl.org/Ticket/Display.html?id=132867>
1208
1210 For the past few years we have released perl using three different
1211 archive formats: bzip (".bz2"), LZMA2 (".xz") and gzip (".gz"). Since
1212 xz compresses better and decompresses faster, and gzip is more
1213 compatible and uses less memory, we have dropped the ".bz2" archive
1214 format with this release. (If this poses a problem, do let us know;
1215 see "Reporting Bugs", below.)
1216
1218 Discontinued Platforms
1219 PowerUX / Power MAX OS
1220 Compiler hints and other support for these apparently long-defunct
1221 platforms has been removed.
1222 Platform-Specific Notes
1224 CentOS
1225 Compilation on CentOS 5 is now fixed.
1226 Cygwin
1228 A build with the quadmath library can now be done on Cygwin.
1229 Darwin
1231 Perl now correctly uses reentrant functions, like "asctime_r", on
1232 versions of Darwin that have support for them.
1233 FreeBSD
1235 FreeBSD's /usr/share/mk/sys.mk specifies "-O2" for architectures
1236 other than ARM and MIPS. By default, perl is now compiled with the
1237 same optimization levels.
1238 VMS Several fix-ups for configure.com, marking function VMS has (or
1240 doesn't have).
1241 CRTL features can now be set by embedders before invoking Perl by
1243 using the "decc$feature_set" and "decc$feature_set_value"
1244 functions. Previously any attempt to set features after image
1245 initialization were ignored.
1246 Windows
1248 · Support for compiling perl on Windows using Microsoft Visual
1249 Studio 2017 (containing Visual C++ 14.1) has been added.
1250 · Visual C++ compiler version detection has been improved to work
1252 on non-English language systems.
1253 · We now set $Config{libpth} correctly for 64-bit builds using
1255 Visual C++ versions earlier than 14.1.
1256
1258 · A new optimisation phase has been added to the compiler,
1259 "optimize_optree()", which does a top-down scan of a complete
1260 optree just before the peephole optimiser is run. This phase is not
1261 currently hookable.
1262 · An "OP_MULTICONCAT" op has been added. At "optimize_optree()" time,
1264 a chain of "OP_CONCAT" and "OP_CONST" ops, together optionally with
1265 an "OP_STRINGIFY" and/or "OP_SASSIGN", are combined into a single
1266 "OP_MULTICONCAT" op. The op is of type "UNOP_AUX", and the aux
1267 array contains the argument count, plus a pointer to a constant
1268 string and a set of segment lengths. For example with
1269 my $x = "foo=$foo, bar=$bar\n";
1271 the constant string would be "foo=, bar=\n" and the segment lengths
1273 would be (4,6,1). If the string contains characters such as "\x80",
1274 whose representation changes under utf8, two sets of strings plus
1275 lengths are precomputed and stored.
1276 · Direct access to "PL_keyword_plugin" is not safe in the presence of
1278 multithreading. A new "wrap_keyword_plugin" function has been added
1279 to allow XS modules to safely define custom keywords even when
1280 loaded from a thread, analogous to "PL_check" / "wrap_op_checker".
1281 · The "PL_statbuf" interpreter variable has been removed.
1283 · The deprecated function "to_utf8_case()", accessible from XS code,
1285 has been removed.
1286 · A new function "is_utf8_invariant_string_loc()" has been added that
1288 is like "is_utf8_invariant_string()" but takes an extra pointer
1289 parameter into which is stored the location of the first variant
1290 character, if any are found.
1291 · A new function, "Perl_langinfo()" has been added. It is an
1293 (almost) drop-in replacement for the system nl_langinfo(3), but
1294 works on platforms that lack that; as well as being more thread-
1295 safe, and hiding some gotchas with locale handling from the caller.
1296 Code that uses this, needn't use localeconv(3) (and be affected by
1297 the gotchas) to find the decimal point, thousands separator, or
1298 currency symbol. See "Perl_langinfo" in perlapi.
1299 · A new API function "sv_rvunweaken()" has been added to complement
1301 "sv_rvweaken()". The implementation was taken from "unweaken" in
1302 Scalar::Util.
1303 · A new flag, "SORTf_UNSTABLE", has been added. This will allow a
1305 future commit to make mergesort unstable when the user specifies
1306 Xno sort stableX, since it has been decided that mergesort should
1307 remain stable by default.
1308 · XS modules can now automatically get reentrant versions of system
1310 functions on threaded perls.
1311 By adding
1313 #define PERL_REENTRANT
1315 near the beginning of an "XS" file, it will be compiled so that
1317 whatever reentrant functions perl knows about on that system will
1318 automatically and invisibly be used instead of the plain, non-
1319 reentrant versions. For example, if you write "getpwnam()" in your
1320 code, on a system that has "getpwnam_r()" all calls to the former
1321 will be translated invisibly into the latter. This does not happen
1322 except on threaded perls, as they aren't needed otherwise. Be
1323 aware that which functions have reentrant versions varies from
1324 system to system.
1325 · The "PERL_NO_OP_PARENT" build define is no longer supported, which
1327 means that perl is now always built with "PERL_OP_PARENT" enabled.
1328 · The format and content of the non-utf8 transliteration table
1330 attached to the "op_pv" field of "OP_TRANS"/"OP_TRANSR" ops has
1331 changed. It's now a "struct OPtrans_map".
1332 · A new compiler "#define", "dTHX_DEBUGGING". has been added. This
1334 is useful for XS or C code that only need the thread context
1335 because their debugging statements that get compiled only under
1336 "-DDEBUGGING" need one.
1337 · A new API function "Perl_setlocale" in perlapi has been added.
1339 · "sync_locale" in perlapi has been revised to return a boolean as to
1341 whether the system was using the global locale or not.
1342 · A new kind of magic scalar, called a "nonelem" scalar, has been
1344 introduced. It is stored in an array to denote a non-existent
1345 element, whenever such an element is accessed in a potential lvalue
1346 context. It replaces the existing "defelem" (deferred element)
1347 magic wherever this is possible, being significantly more
1348 efficient. This means that "some_sub($sparse_array[$nonelem])" no
1349 longer has to create a new magic defelem scalar each time, as long
1350 as the element is within the array.
1351 It partially fixes the rare bug of deferred elements getting out of
1353 synch with their arrays when the array is shifted or unshifted.
1354 [perl #132729] <https://rt.perl.org/Ticket/Display.html?id=132729>
1355
1357 · List assignment ("aassign") could in some rare cases allocate an
1358 entry on the mortals stack and leave the entry uninitialized,
1359 leading to possible crashes. [perl #131570]
1360 <https://rt.perl.org/Ticket/Display.html?id=131570>
1361 · Attempting to apply an attribute to an "our" variable where a
1363 function of that name already exists could result in a NULL pointer
1364 being supplied where an SV was expected, crashing perl. [perl
1365 #131597] <https://rt.perl.org/Ticket/Display.html?id=131597>
1366 · "split ' '" now correctly handles the argument being split when in
1368 the scope of the "unicode_strings" feature. Previously, when a
1369 string using the single-byte internal representation contained
1370 characters that are whitespace by Unicode rules but not by ASCII
1371 rules, it treated those characters as part of fields rather than as
1372 field separators. [perl #130907]
1373 <https://rt.perl.org/Ticket/Display.html?id=130907>
1374 · Several built-in functions previously had bugs that could cause
1376 them to write to the internal stack without allocating room for the
1377 item being written. In rare situations, this could have led to a
1378 crash. These bugs have now been fixed, and if any similar bugs are
1379 introduced in future, they will be detected automatically in
1380 debugging builds.
1381 These internal stack usage checks introduced are also done by the
1383 "entersub" operator when calling XSUBs. This means we can report
1384 which XSUB failed to allocate enough stack space. [perl #131975]
1385 <https://rt.perl.org/Public/Bug/Display.html?id=131975>
1386 · Using a symbolic ref with postderef syntax as the key in a hash
1388 lookup was yielding an assertion failure on debugging builds.
1389 [perl #131627] <https://rt.perl.org/Ticket/Display.html?id=131627>
1390 · Array and hash variables whose names begin with a caret now admit
1392 indexing inside their curlies when interpolated into strings, as in
1393 "${^CAPTURE[0]}" to index "@{^CAPTURE}". [perl #131664]
1394 <https://rt.perl.org/Ticket/Display.html?id=131664>
1395 · Fetching the name of a glob that was previously UTF-8 but wasn't
1397 any longer would return that name flagged as UTF-8. [perl #131263]
1398 <https://rt.perl.org/Ticket/Display.html?id=131263>
1399 · The perl "sprintf()" function (via the underlying C function
1401 "Perl_sv_vcatpvfn_flags()") has been heavily reworked to fix many
1402 minor bugs, including the integer wrapping of large width and
1403 precision specifiers and potential buffer overruns. It has also
1404 been made faster in many cases.
1405 · Exiting from an "eval", whether normally or via an exception, now
1407 always frees temporary values (possibly calling destructors) before
1408 setting $@. For example:
1409 sub DESTROY { eval { die "died in DESTROY"; } }
1411 eval { bless []; };
1412 # $@ used to be equal to "died in DESTROY" here; it's now "".
1413 · Fixed a duplicate symbol failure with "-flto -mieee-fp" builds.
1415 pp.c defined "_LIB_VERSION" which "-lieee" already defines. [perl
1416 #131786] <https://rt.perl.org/Ticket/Display.html?id=131786>
1417 · The tokenizer no longer consumes the exponent part of a floating
1419 point number if it's incomplete. [perl #131725]
1420 <https://rt.perl.org/Ticket/Display.html?id=131725>
1421 · On non-threaded builds, for "m/$null/" where $null is an empty
1423 string is no longer treated as if the "/o" flag was present when
1424 the previous matching match operator included the "/o" flag. The
1425 rewriting used to implement this behavior could confuse the
1426 interpreter. This matches the behaviour of threaded builds. [perl
1427 #124368] <https://rt.perl.org/Ticket/Display.html?id=124368>
1428 · Parsing a "sub" definition could cause a use after free if the
1430 "sub" keyword was followed by whitespace including newlines (and
1431 comments.) [perl #131836]
1432 <https://rt.perl.org/Public/Bug/Display.html?id=131836>
1433 · The tokenizer now correctly adjusts a parse pointer when skipping
1435 whitespace in a "${identifier}" construct. [perl #131949]
1436 <https://rt.perl.org/Public/Bug/Display.html?id=131949>
1437 · Accesses to "${^LAST_FH}" no longer assert after using any of a
1439 variety of I/O operations on a non-glob. [perl #128263]
1440 <https://rt.perl.org/Public/Bug/Display.html?id=128263>
1441 · The XS-level "Copy()", "Move()", "Zero()" macros and their variants
1443 now assert if the pointers supplied are "NULL". ISO C considers
1444 supplying NULL pointers to the functions these macros are built
1445 upon as undefined behaviour even when their count parameters are
1446 zero. Based on these assertions and the original bug report three
1447 macro calls were made conditional. [perl #131746]
1448 <https://rt.perl.org/Public/Bug/Display.html?id=131746> [perl
1449 #131892] <https://rt.perl.org/Public/Bug/Display.html?id=131892>
1450 · Only the "=" operator is permitted for defining defaults for
1452 parameters in subroutine signatures. Previously other assignment
1453 operators, e.g. "+=", were also accidentally permitted. [perl
1454 #131777] <https://rt.perl.org/Public/Bug/Display.html?id=131777>
1455 · Package names are now always included in ":prototype" warnings
1457 [perl #131833]
1458 <https://rt.perl.org/Public/Bug/Display.html?id=131833>
1459 · The "je_old_stack_hwm" field, previously only found in the "jmpenv"
1461 structure on debugging builds, has been added to non-debug builds
1462 as well. This fixes an issue with some CPAN modules caused by the
1463 size of this structure varying between debugging and non-debugging
1464 builds. [perl #131942]
1465 <https://rt.perl.org/Public/Bug/Display.html?id=131942>
1466 · The arguments to the "ninstr()" macro are now correctly
1468 parenthesized.
1469 · A NULL pointer dereference in the "S_regmatch()" function has been
1471 fixed. [perl #132017]
1472 <https://rt.perl.org/Public/Bug/Display.html?id=132017>
1473 · Calling exec PROGRAM LIST with an empty "LIST" has been fixed.
1475 This should call "execvp()" with an empty "argv" array (containing
1476 only the terminating "NULL" pointer), but was instead just
1477 returning false (and not setting $!). [perl #131730]
1478 <https://rt.perl.org/Public/Bug/Display.html?id=131730>
1479 · The "gv_fetchmeth_sv" C function stopped working properly in Perl
1481 5.22 when fetching a constant with a UTF-8 name if that constant
1482 subroutine was stored in the stash as a simple scalar reference,
1483 rather than a full typeglob. This has been corrected.
1484 · Single-letter debugger commands followed by an argument which
1486 starts with punctuation (e.g. "p$^V" and "x@ARGV") now work again.
1487 They had been wrongly requiring a space between the command and the
1488 argument. [perl #120174]
1489 <https://rt.perl.org/Public/Bug/Display.html?id=120174>
1490 · splice now throws an exception ("Modification of a read-only value
1492 attempted") when modifying a read-only array. Until now it had
1493 been silently modifying the array. The new behaviour is consistent
1494 with the behaviour of push and unshift. [perl #131000]
1495 <https://rt.perl.org/Public/Bug/Display.html?id=131000>
1496 · "stat()", "lstat()", and file test operators now fail if given a
1498 filename containing a nul character, in the same way that "open()"
1499 already fails.
1500 · "stat()", "lstat()", and file test operators now reliably set $!
1502 when failing due to being applied to a closed or otherwise invalid
1503 file handle.
1504 · File test operators for Unix permission bits that don't exist on a
1506 particular platform, such as "-k" (sticky bit) on Windows, now
1507 check that the file being tested exists before returning the
1508 blanket false result, and yield the appropriate errors if the
1509 argument doesn't refer to a file.
1510 · Fixed a 'read before buffer' overrun when parsing a range starting
1512 with "\N{}" at the beginning of the character set for the
1513 transliteration operator. [perl #132245]
1514 <https://rt.perl.org/Ticket/Display.html?id=132245>
1515 · Fixed a leaked scalar when parsing an empty "\N{}" at compile-time.
1517 [perl #132245] <https://rt.perl.org/Ticket/Display.html?id=132245>
1518 · Calling "do $path" on a directory or block device now yields a
1520 meaningful error code in $!. [perl #125774]
1521 <https://rt.perl.org/Ticket/Display.html?id=125774>
1522 · Regexp substitution using an overloaded replacement value that
1524 provides a tainted stringification now correctly taints the
1525 resulting string. [perl #115266]
1526 <https://rt.perl.org/Ticket/Display.html?id=115266>
1527 · Lexical sub declarations in "do" blocks such as "do { my sub lex;
1529 123 }" could corrupt the stack, erasing items already on the stack
1530 in the enclosing statement. This has been fixed. [perl #132442]
1531 <https://rt.perl.org/Ticket/Display.html?id=132442>
1532 · "pack" and "unpack" can now handle repeat counts and lengths that
1534 exceed two billion. [perl #119367]
1535 <https://rt.perl.org/Ticket/Display.html?id=119367>
1536 · Digits past the radix point in octal and binary floating point
1538 literals now have the correct weight on platforms where a floating
1539 point significand doesn't fit into an integer type.
1540 · The canonical truth value no longer has a spurious special meaning
1542 as a callable subroutine. It used to be a magic placeholder for a
1543 missing "import" or "unimport" method, but is now treated like any
1544 other string 1. [perl #126042]
1545 <https://rt.perl.org/Ticket/Display.html?id=126042>
1546 · "system" now reduces its arguments to strings in the parent
1548 process, so any effects of stringifying them (such as overload
1549 methods being called or warnings being emitted) are visible in the
1550 way the program expects. [perl #121105]
1551 <https://rt.perl.org/Ticket/Display.html?id=121105>
1552 · The "readpipe()" built-in function now checks at compile time that
1554 it has only one parameter expression, and puts it in scalar
1555 context, thus ensuring that it doesn't corrupt the stack at
1556 runtime. [perl #4574]
1557 <https://rt.perl.org/Ticket/Display.html?id=4574>
1558 · "sort" now performs correct reference counting when aliasing $a and
1560 $b, thus avoiding premature destruction and leakage of scalars if
1561 they are re-aliased during execution of the sort comparator. [perl
1562 #92264] <https://rt.perl.org/Ticket/Display.html?id=92264>
1563 · "reverse" with no operand, reversing $_ by default, is no longer in
1565 danger of corrupting the stack. [perl #132544]
1566 <https://rt.perl.org/Ticket/Display.html?id=132544>
1567 · "exec", "system", et al are no longer liable to have their argument
1569 lists corrupted by reentrant calls and by magic such as tied
1570 scalars. [perl #129888]
1571 <https://rt.perl.org/Ticket/Display.html?id=129888>
1572 · Perl's own "malloc" no longer gets confused by attempts to allocate
1574 more than a gigabyte on a 64-bit platform. [perl #119829]
1575 <https://rt.perl.org/Ticket/Display.html?id=119829>
1576 · Stacked file test operators in a sort comparator expression no
1578 longer cause a crash. [perl #129347]
1579 <https://rt.perl.org/Ticket/Display.html?id=129347>
1580 · An identity "tr///" transformation on a reference is no longer
1582 mistaken for that reference for the purposes of deciding whether it
1583 can be assigned to. [perl #130578]
1584 <https://rt.perl.org/Ticket/Display.html?id=130578>
1585 · Lengthy hexadecimal, octal, or binary floating point literals no
1587 longer cause undefined behaviour when parsing digits that are of
1588 such low significance that they can't affect the floating point
1589 value. [perl #131894]
1590 <https://rt.perl.org/Ticket/Display.html?id=131894>
1591 · "open $$scalarref..." and similar invocations no longer leak the
1593 file handle. [perl #115814]
1594 <https://rt.perl.org/Ticket/Display.html?id=115814>
1595 · Some convoluted kinds of regexp no longer cause an arithmetic
1597 overflow when compiled. [perl #131893]
1598 <https://rt.perl.org/Ticket/Display.html?id=131893>
1599 · The default typemap, by avoiding "newGVgen", now no longer leaks
1601 when XSUBs return file handles ("PerlIO *" or "FILE *"). [perl
1602 #115814] <https://rt.perl.org/Ticket/Display.html?id=115814>
1603 · Creating a "BEGIN" block as an XS subroutine with a prototype no
1605 longer crashes because of the early freeing of the subroutine.
1606 · The "printf" format specifier "%.0f" no longer rounds incorrectly
1608 [perl #47602] <https://rt.perl.org/Ticket/Display.html?id=47602>,
1609 and now shows the correct sign for a negative zero.
1610 · Fixed an issue where the error "Scalar value @arrayname[0] better
1612 written as $arrayname" would give an error "Cannot printf Inf with
1613 'c'" when arrayname starts with "Inf". [perl #132645]
1614 <https://rt.perl.org/Ticket/Display.html?id=132645>
1615 · The Perl implementation of "getcwd()" in "Cwd" in the PathTools
1617 distribution now behaves the same as XS implementation on errors:
1618 it returns an error, and sets $!. [perl #132648]
1619 <https://rt.perl.org/Ticket/Display.html?id=132648>
1620 · Vivify array elements when putting them on the stack. Fixes [perl
1622 #8910] <https://rt.perl.org/Ticket/Display.html?id=8910> (reported
1623 in April 2002).
1624 · Fixed parsing of braced subscript after parens. Fixes [perl #8045]
1626 <https://rt.perl.org/Ticket/Display.html?id=8045> (reported in
1627 December 2001).
1628 · "tr/non_utf8/long_non_utf8/c" could give the wrong results when the
1630 length of the replacement character list was greater than 0x7fff.
1631 · "tr/non_utf8/non_utf8/cd" failed to add the implied
1633 "\x{100}-\x{7fffffff}" to the search character list.
1634 · Compilation failures within "perl-within-perl" constructs, such as
1636 with string interpolation and the right part of "s///e", now cause
1637 compilation to abort earlier.
1638 Previously compilation could continue in order to report other
1640 errors, but the failed sub-parse could leave partly parsed
1641 constructs on the parser shift-reduce stack, confusing the parser,
1642 leading to perl crashes. [perl #125351]
1643 <https://rt.perl.org/Ticket/Display.html?id=125351>
1644 · On threaded perls where the decimal point (radix) character is not
1646 a dot, it has been possible for a race to occur between threads
1647 when one needs to use the real radix character (such as with
1648 "sprintf"). This has now been fixed by use of a mutex on systems
1649 without thread-safe locales, and the problem just doesn't come up
1650 on those with thread-safe locales.
1651 · Errors while compiling a regex character class could sometime
1653 trigger an assertion failure. [perl #132163]
1654 <https://rt.perl.org/Ticket/Display.html?id=132163>
1655
1657 Perl 5.28.0 represents approximately 13 months of development since
1658 Perl 5.26.0 and contains approximately 730,000 lines of changes across
1659 2,200 files from 77 authors.
1660 Excluding auto-generated files, documentation and release tools, there
1662 were approximately 580,000 lines of changes to 1,300 .pm, .t, .c and .h
1663 files.
1664 Perl continues to flourish into its fourth decade thanks to a vibrant
1666 community of users and developers. The following people are known to
1667 have contributed the improvements that became Perl 5.28.0:
1668 Aaron Crane, Abigail, AEvar Arnfjoerd` Bjarmason, Alberto Simo~es,
1670 Alexandr Savca, Andrew Fresh, Andy Dougherty, Andy Lester, Aristotle
1671 Pagaltzis, Ask Bjorn Hansen, Chris 'BinGOs' Williams, Craig A. Berry,
1672 Dagfinn Ilmari Mannsaaker, Dan Collins, Daniel Dragan, David Cantrell,
1673 David Mitchell, Dmitry Ulanov, Dominic Hargreaves, E. Choroba, Eric
1674 Herman, Eugen Konkov, Father Chrysostomos, Gene Sullivan, George
1675 Hartzell, Graham Knop, Harald Joerg, H.Merijn Brand, Hugo van der
1676 Sanden, Jacques Germishuys, James E Keenan, Jarkko Hietaniemi, Jerry D.
1677 Hedden, J. Nick Koston, John Lightsey, John Peacock, John P. Linderman,
1678 John SJ Anderson, Karen Etheridge, Karl Williamson, Ken Brown, Ken
1679 Cotterill, Leon Timmermans, Lukas Mai, Marco Fontani, Marc-Philip
1680 Werner, Matthew Horsfall, Neil Bowers, Nicholas Clark, Nicolas R., Niko
1681 Tyni, Pali, Paul Marquess, Peter John Acklam, Reini Urban, Renee
1682 Baecker, Ricardo Signes, Robin Barker, Sawyer X, Scott Lanning, Sergey
1683 Aleynikov, Shirakata Kentaro, Shoichi Kaji, Slaven Rezic, Smylers,
1684 Steffen Mueller, Steve Hay, Sullivan Beck, Thomas Sibley, Todd Rinaldo,
1685 Tomasz Konojacki, Tom Hukins, Tom Wyant, Tony Cook, Vitali Peil, Yves
1686 Orton, Zefram.
1687 The list above is almost certainly incomplete as it is automatically
1689 generated from version control history. In particular, it does not
1690 include the names of the (very much appreciated) contributors who
1691 reported issues to the Perl bug tracker.
1692 Many of the changes included in this version originated in the CPAN
1694 modules included in Perl's core. We're grateful to the entire CPAN
1695 community for helping Perl to flourish.
1696 For a more complete list of all of Perl's historical contributors,
1698 please see the AUTHORS file in the Perl source distribution.
1699
1701 If you find what you think is a bug, you might check the perl bug
1702 database at <https://rt.perl.org/> . There may also be information at
1703 <http://www.perl.org/> , the Perl Home Page.
1704 If you believe you have an unreported bug, please run the perlbug
1706 program included with your release. Be sure to trim your bug down to a
1707 tiny but sufficient test case. Your bug report, along with the output
1708 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
1709 the Perl porting team.
1710 If the bug you are reporting has security implications which make it
1712 inappropriate to send to a publicly archived mailing list, then see
1713 "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of
1714 how to report the issue.
1715
1717 If you wish to thank the Perl 5 Porters for the work we had done in
1718 Perl 5, you can do so by running the "perlthanks" program:
1719 perlthanks
1721 This will send an email to the Perl 5 Porters list with your show of
1723 thanks.
1724
1726 The Changes file for an explanation of how to view exhaustive details
1727 on what changed.
1728 The INSTALL file for how to build Perl.
1730 The README file for general stuff.
1732 The Artistic and Copying files for copyright information.
1734perl v5.28.2 2018-11-04 PERL5280DELTA(1)