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. [GH #15982]
23 <https://github.com/Perl/perl5/issues/15982>
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 [GH #15216] <https://github.com/Perl/perl5/issues/15216>
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. [GH #16021]
186 <https://github.com/Perl/perl5/issues/16021>
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 [GH #16025] <https://github.com/Perl/perl5/issues/16025>
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. [GH #16051] <https://github.com/Perl/perl5/issues/16051>
198 Default Hash Function Change
200 Perl 5.28.0 retires various older hash functions which are not viewed
201 as sufficiently secure for use in Perl. We now support four general
202 purpose hash functions, Siphash (2-4 and 1-3 variants), and Zaphod32,
203 and StadtX hash. In addition we support SBOX32 (a form of tabular
204 hashing) for hashing short strings, in conjunction with any of the
205 other hash functions provided.
206 By default Perl is configured to support SBOX hashing of strings up to
208 24 characters, in conjunction with StadtX hashing on 64 bit builds, and
209 Zaphod32 hashing for 32 bit builds.
210 You may control these settings with the following options to Configure:
212 -DPERL_HASH_FUNC_SIPHASH
214 -DPERL_HASH_FUNC_SIPHASH13
215 -DPERL_HASH_FUNC_STADTX
216 -DPERL_HASH_FUNC_ZAPHOD32
217 To disable SBOX hashing you can use
219 -DPERL_HASH_USE_SBOX32_ALSO=0
221 And to set the maximum length to use SBOX32 hashing on with:
223 -DSBOX32_MAX_LEN=16
225 The maximum length allowed is 256. There probably isn't much point in
227 setting it higher than the default.
228
230 Subroutine attribute and signature order
231 The experimental subroutine signatures feature has been changed so that
232 subroutine attributes must now come before the signature rather than
233 after. This is because attributes like ":lvalue" can affect the
234 compilation of code within the signature, for example:
235 sub f :lvalue ($a = do { $x = "abc"; return substr($x,0,1)}) { ...}
237 Note that this the second time they have been flipped:
239 sub f :lvalue ($a, $b) { ... }; # 5.20; 5.28 onwards
241 sub f ($a, $b) :lvalue { ... }; # 5.22 - 5.26
242 Comma-less variable lists in formats are no longer allowed
244 Omitting the commas between variables passed to formats is no longer
245 allowed. This has been deprecated since Perl 5.000.
246 The ":locked" and ":unique" attributes have been removed
248 These have been no-ops and deprecated since Perl 5.12 and 5.10,
249 respectively.
250 "\N{}" with nothing between the braces is now illegal
252 This has been deprecated since Perl 5.24.
253 Opening the same symbol as both a file and directory handle is no longer
255 allowed
256 Using "open()" and "opendir()" to associate both a filehandle and a
257 dirhandle to the same symbol (glob or scalar) has been deprecated since
258 Perl 5.10.
259 Use of bare "<<" to mean "<<""" is no longer allowed
261 Use of a bare terminator has been deprecated since Perl 5.000.
262 Setting $/ to a reference to a non-positive integer no longer allowed
264 This used to work like setting it to "undef", but has been deprecated
265 since Perl 5.20.
266 Unicode code points with values exceeding "IV_MAX" are now fatal
268 This was deprecated since Perl 5.24.
269 The "B::OP::terse" method has been removed
271 Use "B::Concise::b_terse" instead.
272 Use of inherited AUTOLOAD for non-methods is no longer allowed
274 This was deprecated in Perl 5.004.
275 Use of strings with code points over 0xFF is not allowed for bitwise string
277 operators
278 Code points over 0xFF do not make sense for bitwise operators and such
279 an operation will now croak, except for a few remaining cases. See
280 perldeprecation.
281 This was deprecated in Perl 5.24.
283 Setting "${^ENCODING}" to a defined value is now illegal
285 This has been deprecated since Perl 5.22 and a no-op since Perl 5.26.
286 Backslash no longer escapes colon in PATH for the "-S" switch
288 Previously the "-S" switch incorrectly treated backslash ("\") as an
289 escape for colon when traversing the "PATH" environment variable. [GH
290 #15584] <https://github.com/Perl/perl5/issues/15584>
291 the -DH (DEBUG_H) misfeature has been removed
293 On a perl built with debugging support, the "H" flag to the "-D"
294 debugging option has been removed. This was supposed to dump hash
295 values, but has been broken for many years.
296 Yada-yada is now strictly a statement
298 By the time of its initial stable release in Perl 5.12, the "..."
299 (yada-yada) operator was explicitly intended to serve as a statement,
300 not an expression. However, the original implementation was confused
301 on this point, leading to inconsistent parsing. The operator was
302 accidentally accepted in a few situations where it did not serve as a
303 complete statement, such as
304 ... . "foo";
306 ... if $a < $b;
307 The parsing has now been made consistent, permitting yada-yada only as
309 a statement. Affected code can use "do{...}" to put a yada-yada into
310 an arbitrary expression context.
311 Sort algorithm can no longer be specified
313 Since Perl 5.8, the sort pragma has had subpragmata "_mergesort",
314 "_quicksort", and "_qsort" that can be used to specify which algorithm
315 perl should use to implement the sort builtin. This was always
316 considered a dubious feature that might not last, hence the underscore
317 spellings, and they were documented as not being portable beyond Perl
318 5.8. These subpragmata have now been deleted, and any attempt to use
319 them is an error. The sort pragma otherwise remains, and the
320 algorithm-neutral "stable" subpragma can be used to control sorting
321 behaviour. [GH #13234] <https://github.com/Perl/perl5/issues/13234>
322 Over-radix digits in floating point literals
324 Octal and binary floating point literals used to permit any hexadecimal
325 digit to appear after the radix point. The digits are now restricted
326 to those appropriate for the radix, as digits before the radix point
327 always were.
328 Return type of "unpackstring()"
330 The return types of the C API functions "unpackstring()" and
331 "unpack_str()" have changed from "I32" to "SSize_t", in order to
332 accommodate datasets of more than two billion items.
333
335 Use of "vec" on strings with code points above 0xFF is deprecated
336 Such strings are represented internally in UTF-8, and "vec" is a bit-
337 oriented operation that will likely give unexpected results on those
338 strings.
339 Some uses of unescaped "{" in regexes are no longer fatal
341 Perl 5.26.0 fatalized some uses of an unescaped left brace, but an
342 exception was made at the last minute, specifically crafted to be a
343 minimal change to allow GNU Autoconf to work. That tool is heavily
344 depended upon, and continues to use the deprecated usage. Its use of
345 an unescaped left brace is one where we have no intention of
346 repurposing "{" to be something other than itself.
347 That exception is now generalized to include various other such cases
349 where the "{" will not be repurposed.
350 Note that these uses continue to raise a deprecation message.
352 Use of unescaped "{" immediately after a "(" in regular expression patterns
354 is deprecated
355 Using unescaped left braces is officially deprecated everywhere, but it
356 is not enforced in contexts where their use does not interfere with
357 expected extensions to the language. A deprecation is added in this
358 release when the brace appears immediately after an opening
359 parenthesis. Before this, even if the brace was part of a legal
360 quantifier, it was not interpreted as such, but as the literal
361 characters, unlike other quantifiers that follow a "(" which are
362 considered errors. Now, their use will raise a deprecation message,
363 unless turned off.
364 Assignment to $[ will be fatal in Perl 5.30
366 Assigning a non-zero value to $[ has been deprecated since Perl 5.12,
367 but was never given a deadline for removal. This has now been
368 scheduled for Perl 5.30.
369 hostname() won't accept arguments in Perl 5.32
371 Passing arguments to "Sys::Hostname::hostname()" was already
372 deprecated, but didn't have a removal date. This has now been
373 scheduled for Perl 5.32. [GH #14662]
374 <https://github.com/Perl/perl5/issues/14662>
375 Module removals
377 The following modules will be removed from the core distribution in a
378 future release, and will at that time need to be installed from CPAN.
379 Distributions on CPAN which require these modules will need to list
380 them as prerequisites.
381 The core versions of these modules will now issue "deprecated"-category
383 warnings to alert you to this fact. To silence these deprecation
384 warnings, install the modules in question from CPAN.
385 Note that these are (with rare exceptions) fine modules that you are
387 encouraged to continue to use. Their disinclusion from core primarily
388 hinges on their necessity to bootstrapping a fully functional, CPAN-
389 capable Perl installation, not usually on concerns over their design.
390 B::Debug
392 Locale::Codes and its associated Country, Currency and Language modules
393
395 • The start up overhead for creating regular expression patterns with
396 Unicode properties ("\p{...}") has been greatly reduced in most
397 cases.
398 • Many string concatenation expressions are now considerably faster,
400 due to the introduction internally of a "multiconcat" opcode which
401 combines multiple concatenations, and optionally a "=" or ".=",
402 into a single action. For example, apart from retrieving $s, $a and
403 $b, this whole expression is now handled as a single op:
404 $s .= "a=$a b=$b\n"
406 As a special case, if the LHS of an assignment is a lexical
408 variable or "my $s", the op itself handles retrieving the lexical
409 variable, which is faster.
410 In general, the more the expression includes a mix of constant
412 strings and variable expressions, the longer the expression, and
413 the more it mixes together non-utf8 and utf8 strings, the more
414 marked the performance improvement. For example on a "x86_64"
415 system, this code has been benchmarked running four times faster:
416 my $s;
418 my $a = "ab\x{100}cde";
419 my $b = "fghij";
420 my $c = "\x{101}klmn";
421 for my $i (1..10_000_000) {
423 $s = "\x{100}wxyz";
424 $s .= "foo=$a bar=$b baz=$c";
425 }
426 In addition, "sprintf" expressions which have a constant format
428 containing only %s and "%%" format elements, and which have a fixed
429 number of arguments, are now also optimised into a "multiconcat"
430 op.
431 • The "ref()" builtin is now much faster in boolean context, since it
433 no longer bothers to construct a temporary string like
434 "Foo=ARRAY(0x134af48)".
435 • "keys()" in void and scalar contexts is now more efficient.
437 • The common idiom of comparing the result of index() with -1 is now
439 specifically optimised, e.g.
440 if (index(...) != -1) { ... }
442 • "for()" loops and similar constructs are now more efficient in most
444 cases.
445 • File::Glob has been modified to remove unnecessary backtracking and
447 recursion, thanks to Russ Cox. See
448 <https://research.swtch.com/glob> for more details.
449 • The XS-level "SvTRUE()" API function is now more efficient.
451 • Various integer-returning ops are now more efficient in
453 scalar/boolean context.
454 • Slightly improved performance when parsing stash names. [GH
456 #15689] <https://github.com/Perl/perl5/issues/15689>
457 • Calls to "require" for an already loaded module are now slightly
459 faster. [GH #16175] <https://github.com/Perl/perl5/issues/16175>
460 • The performance of pattern matching "[[:ascii:]]" and
462 "[[:^ascii:]]" has been improved significantly except on EBCDIC
463 platforms.
464 • Various optimizations have been applied to matching regular
466 expression patterns, so under the right circumstances, significant
467 performance gains may be noticed. But in an application with many
468 varied patterns, little overall improvement likely will be seen.
469 • Other optimizations have been applied to UTF-8 handling, but these
471 are not typically a major factor in most applications.
472
474 Key highlights in this release across several modules:
475 Removal of use vars
477 The usage of "use vars" has been discouraged since the introduction of
478 "our" in Perl 5.6.0. Where possible the usage of this pragma has now
479 been removed from the Perl source code.
480 This had a slight effect (for the better) on the output of WARNING_BITS
482 in B::Deparse.
483 Use of DynaLoader changed to XSLoader in many modules
485 XSLoader is more modern, and most modules already require perl 5.6 or
486 greater, so no functionality is lost by switching. In some cases, we
487 have also made changes to the local implementation that may not be
488 reflected in the version on CPAN due to a desire to maintain more
489 backwards compatibility.
490 Updated Modules and Pragmata
492 • Archive::Tar has been upgraded from version 2.24 to 2.30.
493 This update also handled CVE-2018-12015: directory traversal
495 vulnerability. [cpan #125523]
496 <https://rt.cpan.org/Ticket/Display.html?id=125523>
497 • arybase has been upgraded from version 0.12 to 0.15.
499 • Attribute::Handlers has been upgraded from version 0.99 to 1.01.
501 • attributes has been upgraded from version 0.29 to 0.33.
503 • B has been upgraded from version 1.68 to 1.74.
505 • B::Concise has been upgraded from version 0.999 to 1.003.
507 • B::Debug has been upgraded from version 1.24 to 1.26.
509 NOTE: B::Debug is deprecated and may be removed from a future
511 version of Perl.
512 • B::Deparse has been upgraded from version 1.40 to 1.48.
514 It includes many bug fixes, and in particular, it now deparses
516 variable attributes correctly:
517 my $x :foo; # used to deparse as
519 # 'attributes'->import('main', \$x, 'foo'), my $x;
520 • base has been upgraded from version 2.25 to 2.27.
522 • bignum has been upgraded from version 0.47 to 0.49.
524 • blib has been upgraded from version 1.06 to 1.07.
526 • bytes has been upgraded from version 1.05 to 1.06.
528 • Carp has been upgraded from version 1.42 to 1.50.
530 If a package on the call stack contains a constant named "ISA",
532 Carp no longer throws a "Not a GLOB reference" error.
533 Carp, when generating stack traces, now attempts to work around
535 longstanding bugs resulting from Perl's non-reference-counted
536 stack. [GH #9282] <https://github.com/Perl/perl5/issues/9282>
537 Carp has been modified to avoid assuming that objects cannot be
539 overloaded without the overload module loaded (this can happen with
540 objects created by XS modules). Previously, infinite recursion
541 would result if an XS-defined overload method itself called Carp.
542 [GH #16407] <https://github.com/Perl/perl5/issues/16407>
543 Carp now avoids using "overload::StrVal", partly because older
545 versions of overload (included with perl 5.14 and earlier) load
546 Scalar::Util at run time, which will fail if Carp has been invoked
547 after a syntax error.
548 • charnames has been upgraded from version 1.44 to 1.45.
550 • Compress::Raw::Zlib has been upgraded from version 2.074 to 2.076.
552 This addresses a security vulnerability in older versions of the
554 'zlib' library (which is bundled with Compress-Raw-Zlib).
555 • Config::Extensions has been upgraded from version 0.01 to 0.02.
557 • Config::Perl::V has been upgraded from version 0.28 to 0.29.
559 • CPAN has been upgraded from version 2.18 to 2.20.
561 • Data::Dumper has been upgraded from version 2.167 to 2.170.
563 Quoting of glob names now obeys the Useqq option [GH #13274]
565 <https://github.com/Perl/perl5/issues/13274>.
566 Attempts to set an option to "undef" through a combined
568 getter/setter method are no longer mistaken for getter calls [GH
569 #12135] <https://github.com/Perl/perl5/issues/12135>.
570 • Devel::Peek has been upgraded from version 1.26 to 1.27.
572 • Devel::PPPort has been upgraded from version 3.35 to 3.40.
574 Devel::PPPort has moved from cpan-first to perl-first maintenance
576 Primary responsibility for the code in Devel::PPPort has moved into
578 core perl. In a practical sense there should be no change except
579 that hopefully it will stay more up to date with changes made to
580 symbols in perl, rather than needing to be updated after the fact.
581 • Digest::SHA has been upgraded from version 5.96 to 6.01.
583 • DirHandle has been upgraded from version 1.04 to 1.05.
585 • DynaLoader has been upgraded from version 1.42 to 1.45.
587 Its documentation now shows the use of "__PACKAGE__" and direct
589 object syntax [GH #16190]
590 <https://github.com/Perl/perl5/issues/16190>.
591 • Encode has been upgraded from version 2.88 to 2.97.
593 • encoding has been upgraded from version 2.19 to 2.22.
595 • Errno has been upgraded from version 1.28 to 1.29.
597 • experimental has been upgraded from version 0.016 to 0.019.
599 • Exporter has been upgraded from version 5.72 to 5.73.
601 • ExtUtils::CBuilder has been upgraded from version 0.280225 to
603 0.280230.
604 • ExtUtils::Constant has been upgraded from version 0.23 to 0.25.
606 • ExtUtils::Embed has been upgraded from version 1.34 to 1.35.
608 • ExtUtils::Install has been upgraded from version 2.04 to 2.14.
610 • ExtUtils::MakeMaker has been upgraded from version 7.24 to 7.34.
612 • ExtUtils::Miniperl has been upgraded from version 1.06 to 1.08.
614 • ExtUtils::ParseXS has been upgraded from version 3.34 to 3.39.
616 • ExtUtils::Typemaps has been upgraded from version 3.34 to 3.38.
618 • ExtUtils::XSSymSet has been upgraded from version 1.3 to 1.4.
620 • feature has been upgraded from version 1.47 to 1.52.
622 • fields has been upgraded from version 2.23 to 2.24.
624 • File::Copy has been upgraded from version 2.32 to 2.33.
626 It will now use the sub-second precision variant of utime()
628 supplied by Time::HiRes where available. [GH #16225]
629 <https://github.com/Perl/perl5/issues/16225>.
630 • File::Fetch has been upgraded from version 0.52 to 0.56.
632 • File::Glob has been upgraded from version 1.28 to 1.31.
634 • File::Path has been upgraded from version 2.12_01 to 2.15.
636 • File::Spec and Cwd have been upgraded from version 3.67 to 3.74.
638 • File::stat has been upgraded from version 1.07 to 1.08.
640 • FileCache has been upgraded from version 1.09 to 1.10.
642 • Filter::Simple has been upgraded from version 0.93 to 0.95.
644 • Filter::Util::Call has been upgraded from version 1.55 to 1.58.
646 • GDBM_File has been upgraded from version 1.15 to 1.17.
648 Its documentation now explains that "each" and "delete" don't mix
650 in hashes tied to this module [GH #12894]
651 <https://github.com/Perl/perl5/issues/12894>.
652 It will now retry opening with an acceptable block size if asking
654 gdbm to default the block size failed [GH #13232]
655 <https://github.com/Perl/perl5/issues/13232>.
656 • Getopt::Long has been upgraded from version 2.49 to 2.5.
658 • Hash::Util::FieldHash has been upgraded from version 1.19 to 1.20.
660 • I18N::Langinfo has been upgraded from version 0.13 to 0.17.
662 This module is now available on all platforms, emulating the system
664 nl_langinfo(3) on systems that lack it. Some caveats apply, as
665 detailed in its documentation, the most severe being that, except
666 for MS Windows, the "CODESET" item is not implemented on those
667 systems, always returning "".
668 It now sets the UTF-8 flag in its returned scalar if the string
670 contains legal non-ASCII UTF-8, and the locale is UTF-8 [GH #15131]
671 <https://github.com/Perl/perl5/issues/15131>.
672 This update also fixes a bug in which the underlying locale was
674 ignored for the "RADIXCHAR" (always was returned as a dot) and the
675 "THOUSEP" (always empty). Now the locale-appropriate values are
676 returned.
677 • I18N::LangTags has been upgraded from version 0.42 to 0.43.
679 • if has been upgraded from version 0.0606 to 0.0608.
681 • IO has been upgraded from version 1.38 to 1.39.
683 • IO::Socket::IP has been upgraded from version 0.38 to 0.39.
685 • IPC::Cmd has been upgraded from version 0.96 to 1.00.
687 • JSON::PP has been upgraded from version 2.27400_02 to 2.97001.
689 • The "libnet" distribution has been upgraded from version 3.10 to
691 3.11.
692 • List::Util has been upgraded from version 1.46_02 to 1.49.
694 • Locale::Codes has been upgraded from version 3.42 to 3.56.
696 NOTE: Locale::Codes scheduled to be removed from core in Perl 5.30.
698 • Locale::Maketext has been upgraded from version 1.28 to 1.29.
700 • Math::BigInt has been upgraded from version 1.999806 to 1.999811.
702 • Math::BigInt::FastCalc has been upgraded from version 0.5005 to
704 0.5006.
705 • Math::BigRat has been upgraded from version 0.2611 to 0.2613.
707 • Module::CoreList has been upgraded from version 5.20170530 to
709 5.20180622.
710 • mro has been upgraded from version 1.20 to 1.22.
712 • Net::Ping has been upgraded from version 2.55 to 2.62.
714 • NEXT has been upgraded from version 0.67 to 0.67_01.
716 • ODBM_File has been upgraded from version 1.14 to 1.15.
718 • Opcode has been upgraded from version 1.39 to 1.43.
720 • overload has been upgraded from version 1.28 to 1.30.
722 • PerlIO::encoding has been upgraded from version 0.25 to 0.26.
724 • PerlIO::scalar has been upgraded from version 0.26 to 0.29.
726 • PerlIO::via has been upgraded from version 0.16 to 0.17.
728 • Pod::Functions has been upgraded from version 1.11 to 1.13.
730 • Pod::Html has been upgraded from version 1.2202 to 1.24.
732 A title for the HTML document will now be automatically generated
734 by default from a "NAME" section in the POD document, as it used to
735 be before the module was rewritten to use Pod::Simple::XHTML to do
736 the core of its job [GH #11954]
737 <https://github.com/Perl/perl5/issues/11954>.
738 • Pod::Perldoc has been upgraded from version 3.28 to 3.2801.
740 • The "podlators" distribution has been upgraded from version 4.09 to
742 4.10.
743 Man page references and function names now follow the Linux man
745 page formatting standards, instead of the Solaris standard.
746 • POSIX has been upgraded from version 1.76 to 1.84.
748 Some more cautions were added about using locale-specific functions
750 in threaded applications.
751 • re has been upgraded from version 0.34 to 0.36.
753 • Scalar::Util has been upgraded from version 1.46_02 to 1.50.
755 • SelfLoader has been upgraded from version 1.23 to 1.25.
757 • Socket has been upgraded from version 2.020_03 to 2.027.
759 • sort has been upgraded from version 2.02 to 2.04.
761 • Storable has been upgraded from version 2.62 to 3.08.
763 • Sub::Util has been upgraded from version 1.48 to 1.49.
765 • subs has been upgraded from version 1.02 to 1.03.
767 • Sys::Hostname has been upgraded from version 1.20 to 1.22.
769 • Term::ReadLine has been upgraded from version 1.16 to 1.17.
771 • Test has been upgraded from version 1.30 to 1.31.
773 • Test::Harness has been upgraded from version 3.38 to 3.42.
775 • Test::Simple has been upgraded from version 1.302073 to 1.302133.
777 • threads has been upgraded from version 2.15 to 2.22.
779 The documentation now better describes the problems that arise when
781 returning values from threads, and no longer warns about creating
782 threads in "BEGIN" blocks. [GH #11563]
783 <https://github.com/Perl/perl5/issues/11563>
784 • threads::shared has been upgraded from version 1.56 to 1.58.
786 • Tie::Array has been upgraded from version 1.06 to 1.07.
788 • Tie::StdHandle has been upgraded from version 4.4 to 4.5.
790 • Time::gmtime has been upgraded from version 1.03 to 1.04.
792 • Time::HiRes has been upgraded from version 1.9741 to 1.9759.
794 • Time::localtime has been upgraded from version 1.02 to 1.03.
796 • Time::Piece has been upgraded from version 1.31 to 1.3204.
798 • Unicode::Collate has been upgraded from version 1.19 to 1.25.
800 • Unicode::Normalize has been upgraded from version 1.25 to 1.26.
802 • Unicode::UCD has been upgraded from version 0.68 to 0.70.
804 The function "num" now accepts an optional parameter to help in
806 diagnosing error returns.
807 • User::grent has been upgraded from version 1.01 to 1.02.
809 • User::pwent has been upgraded from version 1.00 to 1.01.
811 • utf8 has been upgraded from version 1.19 to 1.21.
813 • vars has been upgraded from version 1.03 to 1.04.
815 • version has been upgraded from version 0.9917 to 0.9923.
817 • VMS::DCLsym has been upgraded from version 1.08 to 1.09.
819 • VMS::Stdio has been upgraded from version 2.41 to 2.44.
821 • warnings has been upgraded from version 1.37 to 1.42.
823 It now includes new functions with names ending in "_at_level",
825 allowing callers to specify the exact call frame. [GH #16257]
826 <https://github.com/Perl/perl5/issues/16257>
827 • XS::Typemap has been upgraded from version 0.15 to 0.16.
829 • XSLoader has been upgraded from version 0.27 to 0.30.
831 Its documentation now shows the use of "__PACKAGE__", and direct
833 object syntax for example "DynaLoader" usage [GH #16190]
834 <https://github.com/Perl/perl5/issues/16190>.
835 Platforms that use "mod2fname" to edit the names of loadable
837 libraries now look for bootstrap (.bs) files under the correct,
838 non-edited name.
839 Removed Modules and Pragmata
841 • The "VMS::stdio" compatibility shim has been removed.
842
844 Changes to Existing Documentation
845 We have attempted to update the documentation to reflect the changes
846 listed in this document. If you find any we have missed, send email to
847 perlbug@perl.org <mailto:perlbug@perl.org>.
848 Additionally, the following selected changes have been made:
850 perlapi
852 • The API functions "perl_parse()", "perl_run()", and
854 "perl_destruct()" are now documented comprehensively, where
855 previously the only documentation was a reference to the perlembed
856 tutorial.
857 • The documentation of "newGIVENOP()" has been belatedly updated to
859 account for the removal of lexical $_.
860 • The API functions "newCONSTSUB()" and "newCONSTSUB_flags()" are
862 documented much more comprehensively than before.
863 perldata
865 • The section "Truth and Falsehood" in perlsyn has been moved into
867 perldata.
868 perldebguts
870 • The description of the conditions under which "DB::sub()" will be
872 called has been clarified. [GH #16055]
873 <https://github.com/Perl/perl5/issues/16055>
874 perldiag
876 • "Variable length lookbehind not implemented in regex m/%s/" in
878 perldiag
879 This now gives more ideas as to workarounds to the issue that was
881 introduced in Perl 5.18 (but not documented explicitly in its
882 perldelta) for the fact that some Unicode "/i" rules cause a few
883 sequences such as
884 (?<!st)
886 to be considered variable length, and hence disallowed.
888 • "Use of state $_ is experimental" in perldiag
890 This entry has been removed, as the experimental support of this
892 construct was removed in perl 5.24.0.
893 • The diagnostic "Initialization of state variables in list context
895 currently forbidden" has changed to "Initialization of state
896 variables in list currently forbidden", because list-context
897 initialization of single aggregate state variables is now
898 permitted.
899 perlembed
901 • The examples in perlembed have been made more portable in the way
903 they exit, and the example that gets an exit code from the embedded
904 Perl interpreter now gets it from the right place. The examples
905 that pass a constructed argv to Perl now show the mandatory null
906 "argv[argc]".
907 • An example in perlembed used the string value of "ERRSV" as a
909 format string when calling croak(). If that string contains format
910 codes such as %s this could crash the program.
911 This has been changed to a call to croak_sv().
913 An alternative could have been to supply a trivial format string:
915 croak("%s", SvPV_nolen(ERRSV));
917 or as a special case for "ERRSV" simply:
919 croak(NULL);
921 perlfunc
923 • There is now a note that warnings generated by built-in functions
925 are documented in perldiag and warnings. [GH #12642]
926 <https://github.com/Perl/perl5/issues/12642>
927 • The documentation for the "exists" operator no longer says that
929 autovivification behaviour "may be fixed in a future release".
930 We've determined that we're not going to change the default
931 behaviour. [GH #15231]
932 <https://github.com/Perl/perl5/issues/15231>
933 • A couple of small details in the documentation for the "bless"
935 operator have been clarified. [GH #14684]
936 <https://github.com/Perl/perl5/issues/14684>
937 • The description of @INC hooks in the documentation for "require"
939 has been corrected to say that filter subroutines receive a useless
940 first argument. [GH #12569]
941 <https://github.com/Perl/perl5/issues/12569>
942 • The documentation of "ref" has been rewritten for clarity.
944 • The documentation of "use" now explains what syntactically
946 qualifies as a version number for its module version checking
947 feature.
948 • The documentation of "warn" has been updated to reflect that since
950 Perl 5.14 it has treated complex exception objects in a manner
951 equivalent to "die". [GH #13641]
952 <https://github.com/Perl/perl5/issues/13641>
953 • The documentation of "die" and "warn" has been revised for clarity.
955 • The documentation of "each" has been improved, with a slightly more
957 explicit description of the sharing of iterator state, and with
958 caveats regarding the fragility of while-each loops. [GH #16334]
959 <https://github.com/Perl/perl5/issues/16334>
960 • Clarification to "require" was added to explain the differences
962 between
963 require Foo::Bar;
965 require "Foo/Bar.pm";
966 perlgit
968 • The precise rules for identifying "smoke-me" branches are now
970 stated.
971 perlguts
973 • The section on reference counting in perlguts has been heavily
975 revised, to describe references in the way a programmer needs to
976 think about them rather than in terms of the physical data
977 structures.
978 • Improve documentation related to UTF-8 multibytes.
980 perlintern
982 • The internal functions "newXS_len_flags()" and "newATTRSUB_x()" are
984 now documented.
985 perlobj
987 • The documentation about "DESTROY" methods has been corrected,
989 updated, and revised, especially in regard to how they interact
990 with exceptions. [GH #14083]
991 <https://github.com/Perl/perl5/issues/14083>
992 perlop
994 • The description of the "x" operator in perlop has been clarified.
996 [GH #16253] <https://github.com/Perl/perl5/issues/16253>
997 • perlop has been updated to note that "qw"'s whitespace rules differ
999 from that of "split"'s in that only ASCII whitespace is used.
1000 • The general explanation of operator precedence and associativity
1002 has been corrected and clarified. [GH #15153]
1003 <https://github.com/Perl/perl5/issues/15153>
1004 • The documentation for the "\" referencing operator now explains the
1006 unusual context that it supplies to its operand. [GH #15932]
1007 <https://github.com/Perl/perl5/issues/15932>
1008 perlrequick
1010 • Clarifications on metacharacters and character classes
1012 perlretut
1014 • Clarify metacharacters.
1016 perlrun
1018 • Clarify the differences between -M and -m. [GH #15998]
1020 <https://github.com/Perl/perl5/issues/15998>
1021 perlsec
1023 • The documentation about set-id scripts has been updated and
1025 revised. [GH #10289] <https://github.com/Perl/perl5/issues/10289>
1026 • A section about using "sudo" to run Perl scripts has been added.
1028 perlsyn
1030 • The section "Truth and Falsehood" in perlsyn has been removed from
1032 that document, where it didn't belong, and merged into the existing
1033 paragraph on the same topic in perldata.
1034 • The means to disambiguate between code blocks and hash
1036 constructors, already documented in perlref, are now documented in
1037 perlsyn too. [GH #15918]
1038 <https://github.com/Perl/perl5/issues/15918>
1039 perluniprops
1041 • perluniprops has been updated to note that "\p{Word}" now includes
1043 code points matching the "\p{Join_Control}" property. The change
1044 to the property was made in Perl 5.18, but not documented until
1045 now. There are currently only two code points that match this
1046 property U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH
1047 JOINER).
1048 • For each binary table or property, the documentation now includes
1050 which characters in the range "\x00-\xFF" it matches, as well as a
1051 list of the first few ranges of code points matched above that.
1052 perlvar
1054 • The entry for $+ in perlvar has been expanded upon to describe
1056 handling of multiply-named capturing groups.
1057 perlfunc, perlop, perlsyn
1059 • In various places, improve the documentation of the special cases
1061 in the condition expression of a while loop, such as implicit
1062 "defined" and assignment to $_. [GH #16334]
1063 <https://github.com/Perl/perl5/issues/16334>
1064
1066 The following additions or changes have been made to diagnostic output,
1067 including warnings and fatal error messages. For the complete list of
1068 diagnostic messages, see perldiag.
1069 New Diagnostics
1071 New Errors
1072 • Can't "goto" into a "given" block
1074 (F) A "goto" statement was executed to jump into the middle of a
1076 "given" block. You can't get there from here. See "goto" in
1077 perlfunc.
1078 • Can't "goto" into a binary or list expression
1080 Use of "goto" to jump into the parameter of a binary or list
1082 operator has been prohibited, to prevent crashes and stack
1083 corruption. [GH #15914]
1084 <https://github.com/Perl/perl5/issues/15914>
1085 You may only enter the first argument of an operator that takes a
1087 fixed number of arguments, since this is a case that will not cause
1088 stack corruption. [GH #16415]
1089 <https://github.com/Perl/perl5/issues/16415>
1090 New Warnings
1092 • Old package separator used in string
1094 (W syntax) You used the old package separator, "'", in a variable
1096 named inside a double-quoted string; e.g., "In $name's house".
1097 This is equivalent to "In $name::s house". If you meant the
1098 former, put a backslash before the apostrophe ("In $name\'s
1099 house").
1100 • "Locale '%s' contains (at least) the following characters which
1102 have unexpected meanings: %s The Perl program will use the
1103 expected meanings" in perldiag
1104 Changes to Existing Diagnostics
1106 • A false-positive warning that was issued when using a numerically-
1107 quantified sub-pattern in a recursive regex has been silenced. [GH
1108 #16106] <https://github.com/Perl/perl5/issues/16106>
1109 • The warning about useless use of a concatenation operator in void
1111 context is now generated for expressions with multiple
1112 concatenations, such as "$a.$b.$c", which used to mistakenly not
1113 warn. [GH #3990] <https://github.com/Perl/perl5/issues/3990>
1114 • Warnings that a variable or subroutine "masks earlier declaration
1116 in same ...", or that an "our" variable has been redeclared, have
1117 been moved to a new warnings category "shadow". Previously they
1118 were in category "misc".
1119 • The deprecation warning from "Sys::Hostname::hostname()" saying
1121 that it doesn't accept arguments now states the Perl version in
1122 which the warning will be upgraded to an error. [GH #14662]
1123 <https://github.com/Perl/perl5/issues/14662>
1124 • The perldiag entry for the error regarding a set-id script has been
1126 expanded to make clear that the error is reporting a specific
1127 security vulnerability, and to advise how to fix it.
1128 • The "Unable to flush stdout" error message was missing a trailing
1130 newline. [debian #875361]
1131
1133 perlbug
1134 • "--help" and "--version" options have been added.
1135
1137 • C89 requirement
1138 Perl has been documented as requiring a C89 compiler to build since
1140 October 1998. A variety of simplifications have now been made to
1141 Perl's internals to rely on the features specified by the C89
1142 standard. We believe that this internal change hasn't altered the
1143 set of platforms that Perl builds on, but please report a bug if
1144 Perl now has new problems building on your platform.
1145 • On GCC, "-Werror=pointer-arith" is now enabled by default,
1147 disallowing arithmetic on void and function pointers.
1148 • Where an HTML version of the documentation is installed, the HTML
1150 documents now use relative links to refer to each other. Links
1151 from the index page of perlipc to the individual section documents
1152 are now correct. [GH #11941]
1153 <https://github.com/Perl/perl5/issues/11941>
1154 • lib/unicore/mktables now correctly canonicalizes the names of the
1156 dependencies stored in the files it generates.
1157 regen/mk_invlists.pl, unlike the other regen/*.pl scripts, used $0
1159 to name itself in the dependencies stored in the files it
1160 generates. It now uses a literal so that the path stored in the
1161 generated files doesn't depend on how regen/mk_invlists.pl is
1162 invoked.
1163 This lack of canonical names could cause test failures in
1165 t/porting/regen.t. [GH #16446]
1166 <https://github.com/Perl/perl5/issues/16446>
1167 • New probes
1169 HAS_BUILTIN_ADD_OVERFLOW
1171 HAS_BUILTIN_MUL_OVERFLOW
1172 HAS_BUILTIN_SUB_OVERFLOW
1173 HAS_THREAD_SAFE_NL_LANGINFO_L
1174 HAS_LOCALECONV_L
1175 HAS_MBRLEN
1176 HAS_MBRTOWC
1177 HAS_MEMRCHR
1178 HAS_NANOSLEEP
1179 HAS_STRNLEN
1180 HAS_STRTOLD_L
1181 I_WCHAR
1182
1184 • Testing of the XS-APItest directory is now done in parallel, where
1185 applicable.
1186 • Perl now includes a default .travis.yml file for Travis CI testing
1188 on github mirrors. [GH #14558]
1189 <https://github.com/Perl/perl5/issues/14558>
1190 • The watchdog timer count in re/pat_psycho.t can now be overridden.
1192 This test can take a long time to run, so there is a timer to keep
1194 this in check (currently, 5 minutes). This commit adds checking the
1195 environment variable "PERL_TEST_TIME_OUT_FACTOR"; if set, the time
1196 out setting is multiplied by its value.
1197 • harness no longer waits for 30 seconds when running t/io/openpid.t.
1199 [GH #13535] <https://github.com/Perl/perl5/issues/13535> [GH
1200 #16420] <https://github.com/Perl/perl5/issues/16420>
1201
1203 For the past few years we have released perl using three different
1204 archive formats: bzip (".bz2"), LZMA2 (".xz") and gzip (".gz"). Since
1205 xz compresses better and decompresses faster, and gzip is more
1206 compatible and uses less memory, we have dropped the ".bz2" archive
1207 format with this release. (If this poses a problem, do let us know;
1208 see "Reporting Bugs", below.)
1209
1211 Discontinued Platforms
1212 PowerUX / Power MAX OS
1213 Compiler hints and other support for these apparently long-defunct
1214 platforms has been removed.
1215 Platform-Specific Notes
1217 CentOS
1218 Compilation on CentOS 5 is now fixed.
1219 Cygwin
1221 A build with the quadmath library can now be done on Cygwin.
1222 Darwin
1224 Perl now correctly uses reentrant functions, like "asctime_r", on
1225 versions of Darwin that have support for them.
1226 FreeBSD
1228 FreeBSD's /usr/share/mk/sys.mk specifies "-O2" for architectures
1229 other than ARM and MIPS. By default, perl is now compiled with the
1230 same optimization levels.
1231 VMS Several fix-ups for configure.com, marking function VMS has (or
1233 doesn't have).
1234 CRTL features can now be set by embedders before invoking Perl by
1236 using the "decc$feature_set" and "decc$feature_set_value"
1237 functions. Previously any attempt to set features after image
1238 initialization were ignored.
1239 Windows
1241 • Support for compiling perl on Windows using Microsoft Visual
1242 Studio 2017 (containing Visual C++ 14.1) has been added.
1243 • Visual C++ compiler version detection has been improved to work
1245 on non-English language systems.
1246 • We now set $Config{libpth} correctly for 64-bit builds using
1248 Visual C++ versions earlier than 14.1.
1249
1251 • A new optimisation phase has been added to the compiler,
1252 "optimize_optree()", which does a top-down scan of a complete
1253 optree just before the peephole optimiser is run. This phase is not
1254 currently hookable.
1255 • An "OP_MULTICONCAT" op has been added. At "optimize_optree()" time,
1257 a chain of "OP_CONCAT" and "OP_CONST" ops, together optionally with
1258 an "OP_STRINGIFY" and/or "OP_SASSIGN", are combined into a single
1259 "OP_MULTICONCAT" op. The op is of type "UNOP_AUX", and the aux
1260 array contains the argument count, plus a pointer to a constant
1261 string and a set of segment lengths. For example with
1262 my $x = "foo=$foo, bar=$bar\n";
1264 the constant string would be "foo=, bar=\n" and the segment lengths
1266 would be (4,6,1). If the string contains characters such as "\x80",
1267 whose representation changes under utf8, two sets of strings plus
1268 lengths are precomputed and stored.
1269 • Direct access to "PL_keyword_plugin" is not safe in the presence of
1271 multithreading. A new "wrap_keyword_plugin" function has been added
1272 to allow XS modules to safely define custom keywords even when
1273 loaded from a thread, analogous to "PL_check" / "wrap_op_checker".
1274 • The "PL_statbuf" interpreter variable has been removed.
1276 • The deprecated function "to_utf8_case()", accessible from XS code,
1278 has been removed.
1279 • A new function "is_utf8_invariant_string_loc()" has been added that
1281 is like "is_utf8_invariant_string()" but takes an extra pointer
1282 parameter into which is stored the location of the first variant
1283 character, if any are found.
1284 • A new function, "Perl_langinfo()" has been added. It is an
1286 (almost) drop-in replacement for the system nl_langinfo(3), but
1287 works on platforms that lack that; as well as being more thread-
1288 safe, and hiding some gotchas with locale handling from the caller.
1289 Code that uses this, needn't use localeconv(3) (and be affected by
1290 the gotchas) to find the decimal point, thousands separator, or
1291 currency symbol. See "Perl_langinfo" in perlapi.
1292 • A new API function "sv_rvunweaken()" has been added to complement
1294 "sv_rvweaken()". The implementation was taken from "unweaken" in
1295 Scalar::Util.
1296 • A new flag, "SORTf_UNSTABLE", has been added. This will allow a
1298 future commit to make mergesort unstable when the user specifies
1299 Xno sort stableX, since it has been decided that mergesort should
1300 remain stable by default.
1301 • XS modules can now automatically get reentrant versions of system
1303 functions on threaded perls.
1304 By adding
1306 #define PERL_REENTRANT
1308 near the beginning of an "XS" file, it will be compiled so that
1310 whatever reentrant functions perl knows about on that system will
1311 automatically and invisibly be used instead of the plain, non-
1312 reentrant versions. For example, if you write "getpwnam()" in your
1313 code, on a system that has "getpwnam_r()" all calls to the former
1314 will be translated invisibly into the latter. This does not happen
1315 except on threaded perls, as they aren't needed otherwise. Be
1316 aware that which functions have reentrant versions varies from
1317 system to system.
1318 • The "PERL_NO_OP_PARENT" build define is no longer supported, which
1320 means that perl is now always built with "PERL_OP_PARENT" enabled.
1321 • The format and content of the non-utf8 transliteration table
1323 attached to the "op_pv" field of "OP_TRANS"/"OP_TRANSR" ops has
1324 changed. It's now a "struct OPtrans_map".
1325 • A new compiler "#define", "dTHX_DEBUGGING". has been added. This
1327 is useful for XS or C code that only need the thread context
1328 because their debugging statements that get compiled only under
1329 "-DDEBUGGING" need one.
1330 • A new API function "Perl_setlocale" in perlapi has been added.
1332 • "sync_locale" in perlapi has been revised to return a boolean as to
1334 whether the system was using the global locale or not.
1335 • A new kind of magic scalar, called a "nonelem" scalar, has been
1337 introduced. It is stored in an array to denote a non-existent
1338 element, whenever such an element is accessed in a potential lvalue
1339 context. It replaces the existing "defelem" (deferred element)
1340 magic wherever this is possible, being significantly more
1341 efficient. This means that "some_sub($sparse_array[$nonelem])" no
1342 longer has to create a new magic defelem scalar each time, as long
1343 as the element is within the array.
1344 It partially fixes the rare bug of deferred elements getting out of
1346 synch with their arrays when the array is shifted or unshifted.
1347 [GH #16364] <https://github.com/Perl/perl5/issues/16364>
1348
1350 • List assignment ("aassign") could in some rare cases allocate an
1351 entry on the mortals stack and leave the entry uninitialized,
1352 leading to possible crashes. [GH #16017]
1353 <https://github.com/Perl/perl5/issues/16017>
1354 • Attempting to apply an attribute to an "our" variable where a
1356 function of that name already exists could result in a NULL pointer
1357 being supplied where an SV was expected, crashing perl. [perl
1358 #131597] <https://rt.perl.org/Ticket/Display.html?id=131597>
1359 • "split ' '" now correctly handles the argument being split when in
1361 the scope of the "unicode_strings" feature. Previously, when a
1362 string using the single-byte internal representation contained
1363 characters that are whitespace by Unicode rules but not by ASCII
1364 rules, it treated those characters as part of fields rather than as
1365 field separators. [GH #15904]
1366 <https://github.com/Perl/perl5/issues/15904>
1367 • Several built-in functions previously had bugs that could cause
1369 them to write to the internal stack without allocating room for the
1370 item being written. In rare situations, this could have led to a
1371 crash. These bugs have now been fixed, and if any similar bugs are
1372 introduced in future, they will be detected automatically in
1373 debugging builds.
1374 These internal stack usage checks introduced are also done by the
1376 "entersub" operator when calling XSUBs. This means we can report
1377 which XSUB failed to allocate enough stack space. [GH #16126]
1378 <https://github.com/Perl/perl5/issues/16126>
1379 • Using a symbolic ref with postderef syntax as the key in a hash
1381 lookup was yielding an assertion failure on debugging builds. [GH
1382 #16029] <https://github.com/Perl/perl5/issues/16029>
1383 • Array and hash variables whose names begin with a caret now admit
1385 indexing inside their curlies when interpolated into strings, as in
1386 "${^CAPTURE[0]}" to index "@{^CAPTURE}". [GH #16050]
1387 <https://github.com/Perl/perl5/issues/16050>
1388 • Fetching the name of a glob that was previously UTF-8 but wasn't
1390 any longer would return that name flagged as UTF-8. [GH #15971]
1391 <https://github.com/Perl/perl5/issues/15971>
1392 • The perl "sprintf()" function (via the underlying C function
1394 "Perl_sv_vcatpvfn_flags()") has been heavily reworked to fix many
1395 minor bugs, including the integer wrapping of large width and
1396 precision specifiers and potential buffer overruns. It has also
1397 been made faster in many cases.
1398 • Exiting from an "eval", whether normally or via an exception, now
1400 always frees temporary values (possibly calling destructors) before
1401 setting $@. For example:
1402 sub DESTROY { eval { die "died in DESTROY"; } }
1404 eval { bless []; };
1405 # $@ used to be equal to "died in DESTROY" here; it's now "".
1406 • Fixed a duplicate symbol failure with "-flto -mieee-fp" builds.
1408 pp.c defined "_LIB_VERSION" which "-lieee" already defines. [GH
1409 #16086] <https://github.com/Perl/perl5/issues/16086>
1410 • The tokenizer no longer consumes the exponent part of a floating
1412 point number if it's incomplete. [GH #16073]
1413 <https://github.com/Perl/perl5/issues/16073>
1414 • On non-threaded builds, for "m/$null/" where $null is an empty
1416 string is no longer treated as if the "/o" flag was present when
1417 the previous matching match operator included the "/o" flag. The
1418 rewriting used to implement this behavior could confuse the
1419 interpreter. This matches the behaviour of threaded builds. [GH
1420 #14668] <https://github.com/Perl/perl5/issues/14668>
1421 • Parsing a "sub" definition could cause a use after free if the
1423 "sub" keyword was followed by whitespace including newlines (and
1424 comments.) [GH #16097]
1425 <https://github.com/Perl/perl5/issues/16097>
1426 • The tokenizer now correctly adjusts a parse pointer when skipping
1428 whitespace in a "${identifier}" construct. [perl #131949]
1429 <https://rt.perl.org/Public/Bug/Display.html?id=131949>
1430 • Accesses to "${^LAST_FH}" no longer assert after using any of a
1432 variety of I/O operations on a non-glob. [GH #15372]
1433 <https://github.com/Perl/perl5/issues/15372>
1434 • The XS-level "Copy()", "Move()", "Zero()" macros and their variants
1436 now assert if the pointers supplied are "NULL". ISO C considers
1437 supplying NULL pointers to the functions these macros are built
1438 upon as undefined behaviour even when their count parameters are
1439 zero. Based on these assertions and the original bug report three
1440 macro calls were made conditional. [GH #16079]
1441 <https://github.com/Perl/perl5/issues/16079> [GH #16112]
1442 <https://github.com/Perl/perl5/issues/16112>
1443 • Only the "=" operator is permitted for defining defaults for
1445 parameters in subroutine signatures. Previously other assignment
1446 operators, e.g. "+=", were also accidentally permitted. [GH
1447 #16084] <https://github.com/Perl/perl5/issues/16084>
1448 • Package names are now always included in ":prototype" warnings
1450 [perl #131833]
1451 <https://rt.perl.org/Public/Bug/Display.html?id=131833>
1452 • The "je_old_stack_hwm" field, previously only found in the "jmpenv"
1454 structure on debugging builds, has been added to non-debug builds
1455 as well. This fixes an issue with some CPAN modules caused by the
1456 size of this structure varying between debugging and non-debugging
1457 builds. [GH #16122] <https://github.com/Perl/perl5/issues/16122>
1458 • The arguments to the "ninstr()" macro are now correctly
1460 parenthesized.
1461 • A NULL pointer dereference in the "S_regmatch()" function has been
1463 fixed. [perl #132017]
1464 <https://rt.perl.org/Public/Bug/Display.html?id=132017>
1465 • Calling exec PROGRAM LIST with an empty "LIST" has been fixed.
1467 This should call "execvp()" with an empty "argv" array (containing
1468 only the terminating "NULL" pointer), but was instead just
1469 returning false (and not setting $!). [GH #16075]
1470 <https://github.com/Perl/perl5/issues/16075>
1471 • The "gv_fetchmeth_sv" C function stopped working properly in Perl
1473 5.22 when fetching a constant with a UTF-8 name if that constant
1474 subroutine was stored in the stash as a simple scalar reference,
1475 rather than a full typeglob. This has been corrected.
1476 • Single-letter debugger commands followed by an argument which
1478 starts with punctuation (e.g. "p$^V" and "x@ARGV") now work again.
1479 They had been wrongly requiring a space between the command and the
1480 argument. [GH #13342] <https://github.com/Perl/perl5/issues/13342>
1481 • splice now throws an exception ("Modification of a read-only value
1483 attempted") when modifying a read-only array. Until now it had
1484 been silently modifying the array. The new behaviour is consistent
1485 with the behaviour of push and unshift. [GH #15923]
1486 <https://github.com/Perl/perl5/issues/15923>
1487 • "stat()", "lstat()", and file test operators now fail if given a
1489 filename containing a nul character, in the same way that "open()"
1490 already fails.
1491 • "stat()", "lstat()", and file test operators now reliably set $!
1493 when failing due to being applied to a closed or otherwise invalid
1494 file handle.
1495 • File test operators for Unix permission bits that don't exist on a
1497 particular platform, such as "-k" (sticky bit) on Windows, now
1498 check that the file being tested exists before returning the
1499 blanket false result, and yield the appropriate errors if the
1500 argument doesn't refer to a file.
1501 • Fixed a 'read before buffer' overrun when parsing a range starting
1503 with "\N{}" at the beginning of the character set for the
1504 transliteration operator. [GH #16189]
1505 <https://github.com/Perl/perl5/issues/16189>
1506 • Fixed a leaked scalar when parsing an empty "\N{}" at compile-time.
1508 [GH #16189] <https://github.com/Perl/perl5/issues/16189>
1509 • Calling "do $path" on a directory or block device now yields a
1511 meaningful error code in $!. [GH #14841]
1512 <https://github.com/Perl/perl5/issues/14841>
1513 • Regexp substitution using an overloaded replacement value that
1515 provides a tainted stringification now correctly taints the
1516 resulting string. [GH #12495]
1517 <https://github.com/Perl/perl5/issues/12495>
1518 • Lexical sub declarations in "do" blocks such as "do { my sub lex;
1520 123 }" could corrupt the stack, erasing items already on the stack
1521 in the enclosing statement. This has been fixed. [GH #16243]
1522 <https://github.com/Perl/perl5/issues/16243>
1523 • "pack" and "unpack" can now handle repeat counts and lengths that
1525 exceed two billion. [GH #13179]
1526 <https://github.com/Perl/perl5/issues/13179>
1527 • Digits past the radix point in octal and binary floating point
1529 literals now have the correct weight on platforms where a floating
1530 point significand doesn't fit into an integer type.
1531 • The canonical truth value no longer has a spurious special meaning
1533 as a callable subroutine. It used to be a magic placeholder for a
1534 missing "import" or "unimport" method, but is now treated like any
1535 other string 1. [GH #14902]
1536 <https://github.com/Perl/perl5/issues/14902>
1537 • "system" now reduces its arguments to strings in the parent
1539 process, so any effects of stringifying them (such as overload
1540 methods being called or warnings being emitted) are visible in the
1541 way the program expects. [GH #13561]
1542 <https://github.com/Perl/perl5/issues/13561>
1543 • The "readpipe()" built-in function now checks at compile time that
1545 it has only one parameter expression, and puts it in scalar
1546 context, thus ensuring that it doesn't corrupt the stack at
1547 runtime. [GH #2793] <https://github.com/Perl/perl5/issues/2793>
1548 • "sort" now performs correct reference counting when aliasing $a and
1550 $b, thus avoiding premature destruction and leakage of scalars if
1551 they are re-aliased during execution of the sort comparator. [GH
1552 #11422] <https://github.com/Perl/perl5/issues/11422>
1553 • "reverse" with no operand, reversing $_ by default, is no longer in
1555 danger of corrupting the stack. [GH #16291]
1556 <https://github.com/Perl/perl5/issues/16291>
1557 • "exec", "system", et al are no longer liable to have their argument
1559 lists corrupted by reentrant calls and by magic such as tied
1560 scalars. [GH #15660] <https://github.com/Perl/perl5/issues/15660>
1561 • Perl's own "malloc" no longer gets confused by attempts to allocate
1563 more than a gigabyte on a 64-bit platform. [GH #13273]
1564 <https://github.com/Perl/perl5/issues/13273>
1565 • Stacked file test operators in a sort comparator expression no
1567 longer cause a crash. [GH #15626]
1568 <https://github.com/Perl/perl5/issues/15626>
1569 • An identity "tr///" transformation on a reference is no longer
1571 mistaken for that reference for the purposes of deciding whether it
1572 can be assigned to. [GH #15812]
1573 <https://github.com/Perl/perl5/issues/15812>
1574 • Lengthy hexadecimal, octal, or binary floating point literals no
1576 longer cause undefined behaviour when parsing digits that are of
1577 such low significance that they can't affect the floating point
1578 value. [GH #16114] <https://github.com/Perl/perl5/issues/16114>
1579 • "open $$scalarref..." and similar invocations no longer leak the
1581 file handle. [GH #12593]
1582 <https://github.com/Perl/perl5/issues/12593>
1583 • Some convoluted kinds of regexp no longer cause an arithmetic
1585 overflow when compiled. [GH #16113]
1586 <https://github.com/Perl/perl5/issues/16113>
1587 • The default typemap, by avoiding "newGVgen", now no longer leaks
1589 when XSUBs return file handles ("PerlIO *" or "FILE *"). [GH
1590 #12593] <https://github.com/Perl/perl5/issues/12593>
1591 • Creating a "BEGIN" block as an XS subroutine with a prototype no
1593 longer crashes because of the early freeing of the subroutine.
1594 • The "printf" format specifier "%.0f" no longer rounds incorrectly
1596 [GH #9125] <https://github.com/Perl/perl5/issues/9125>, and now
1597 shows the correct sign for a negative zero.
1598 • Fixed an issue where the error "Scalar value @arrayname[0] better
1600 written as $arrayname" would give an error "Cannot printf Inf with
1601 'c'" when arrayname starts with "Inf". [GH #16335]
1602 <https://github.com/Perl/perl5/issues/16335>
1603 • The Perl implementation of "getcwd()" in "Cwd" in the PathTools
1605 distribution now behaves the same as XS implementation on errors:
1606 it returns an error, and sets $!. [GH #16338]
1607 <https://github.com/Perl/perl5/issues/16338>
1608 • Vivify array elements when putting them on the stack. Fixes [GH
1610 #5310] <https://github.com/Perl/perl5/issues/5310> (reported in
1611 April 2002).
1612 • Fixed parsing of braced subscript after parens. Fixes [GH #4688]
1614 <https://github.com/Perl/perl5/issues/4688> (reported in December
1615 2001).
1616 • "tr/non_utf8/long_non_utf8/c" could give the wrong results when the
1618 length of the replacement character list was greater than 0x7fff.
1619 • "tr/non_utf8/non_utf8/cd" failed to add the implied
1621 "\x{100}-\x{7fffffff}" to the search character list.
1622 • Compilation failures within "perl-within-perl" constructs, such as
1624 with string interpolation and the right part of "s///e", now cause
1625 compilation to abort earlier.
1626 Previously compilation could continue in order to report other
1628 errors, but the failed sub-parse could leave partly parsed
1629 constructs on the parser shift-reduce stack, confusing the parser,
1630 leading to perl crashes. [GH #14739]
1631 <https://github.com/Perl/perl5/issues/14739>
1632 • On threaded perls where the decimal point (radix) character is not
1634 a dot, it has been possible for a race to occur between threads
1635 when one needs to use the real radix character (such as with
1636 "sprintf"). This has now been fixed by use of a mutex on systems
1637 without thread-safe locales, and the problem just doesn't come up
1638 on those with thread-safe locales.
1639 • Errors while compiling a regex character class could sometime
1641 trigger an assertion failure. [GH #16172]
1642 <https://github.com/Perl/perl5/issues/16172>
1643
1645 Perl 5.28.0 represents approximately 13 months of development since
1646 Perl 5.26.0 and contains approximately 730,000 lines of changes across
1647 2,200 files from 77 authors.
1648 Excluding auto-generated files, documentation and release tools, there
1650 were approximately 580,000 lines of changes to 1,300 .pm, .t, .c and .h
1651 files.
1652 Perl continues to flourish into its fourth decade thanks to a vibrant
1654 community of users and developers. The following people are known to
1655 have contributed the improvements that became Perl 5.28.0:
1656 Aaron Crane, Abigail, AEvar Arnfjoerd` Bjarmason, Alberto Simo~es,
1658 Alexandr Savca, Andrew Fresh, Andy Dougherty, Andy Lester, Aristotle
1659 Pagaltzis, Ask Bjorn Hansen, Chris 'BinGOs' Williams, Craig A. Berry,
1660 Dagfinn Ilmari Mannsaaker, Dan Collins, Daniel Dragan, David Cantrell,
1661 David Mitchell, Dmitry Ulanov, Dominic Hargreaves, E. Choroba, Eric
1662 Herman, Eugen Konkov, Father Chrysostomos, Gene Sullivan, George
1663 Hartzell, Graham Knop, Harald Joerg, H.Merijn Brand, Hugo van der
1664 Sanden, Jacques Germishuys, James E Keenan, Jarkko Hietaniemi, Jerry D.
1665 Hedden, J. Nick Koston, John Lightsey, John Peacock, John P. Linderman,
1666 John SJ Anderson, Karen Etheridge, Karl Williamson, Ken Brown, Ken
1667 Cotterill, Leon Timmermans, Lukas Mai, Marco Fontani, Marc-Philip
1668 Werner, Matthew Horsfall, Neil Bowers, Nicholas Clark, Nicolas R., Niko
1669 Tyni, Pali, Paul Marquess, Peter John Acklam, Reini Urban, Renee
1670 Baecker, Ricardo Signes, Robin Barker, Sawyer X, Scott Lanning, Sergey
1671 Aleynikov, Shirakata Kentaro, Shoichi Kaji, Slaven Rezic, Smylers,
1672 Steffen Mueller, Steve Hay, Sullivan Beck, Thomas Sibley, Todd Rinaldo,
1673 Tomasz Konojacki, Tom Hukins, Tom Wyant, Tony Cook, Vitali Peil, Yves
1674 Orton, Zefram.
1675 The list above is almost certainly incomplete as it is automatically
1677 generated from version control history. In particular, it does not
1678 include the names of the (very much appreciated) contributors who
1679 reported issues to the Perl bug tracker.
1680 Many of the changes included in this version originated in the CPAN
1682 modules included in Perl's core. We're grateful to the entire CPAN
1683 community for helping Perl to flourish.
1684 For a more complete list of all of Perl's historical contributors,
1686 please see the AUTHORS file in the Perl source distribution.
1687
1689 If you find what you think is a bug, you might check the perl bug
1690 database at <https://rt.perl.org/> . There may also be information at
1691 <http://www.perl.org/> , the Perl Home Page.
1692 If you believe you have an unreported bug, please run the perlbug
1694 program included with your release. Be sure to trim your bug down to a
1695 tiny but sufficient test case. Your bug report, along with the output
1696 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
1697 the Perl porting team.
1698 If the bug you are reporting has security implications which make it
1700 inappropriate to send to a publicly archived mailing list, then see
1701 "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of
1702 how to report the issue.
1703
1705 If you wish to thank the Perl 5 Porters for the work we had done in
1706 Perl 5, you can do so by running the "perlthanks" program:
1707 perlthanks
1709 This will send an email to the Perl 5 Porters list with your show of
1711 thanks.
1712
1714 The Changes file for an explanation of how to view exhaustive details
1715 on what changed.
1716 The INSTALL file for how to build Perl.
1718 The README file for general stuff.
1720 The Artistic and Copying files for copyright information.
1722perl v5.36.0 2022-08-30 PERL5280DELTA(1)