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 unpack_str()
331 have changed from "I32" to "SSize_t", in order to accommodate datasets
332 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 deprecated,
372 but didn't have a removal date. This has now been scheduled for Perl
373 5.32. [GH #14662] <https://github.com/Perl/perl5/issues/14662>
374 Module removals
376 The following modules will be removed from the core distribution in a
377 future release, and will at that time need to be installed from CPAN.
378 Distributions on CPAN which require these modules will need to list
379 them as prerequisites.
380 The core versions of these modules will now issue "deprecated"-category
382 warnings to alert you to this fact. To silence these deprecation
383 warnings, install the modules in question from CPAN.
384 Note that these are (with rare exceptions) fine modules that you are
386 encouraged to continue to use. Their disinclusion from core primarily
387 hinges on their necessity to bootstrapping a fully functional, CPAN-
388 capable Perl installation, not usually on concerns over their design.
389 B::Debug
391 Locale::Codes and its associated Country, Currency and Language modules
392
394 • The start up overhead for creating regular expression patterns with
395 Unicode properties ("\p{...}") has been greatly reduced in most
396 cases.
397 • Many string concatenation expressions are now considerably faster,
399 due to the introduction internally of a "multiconcat" opcode which
400 combines multiple concatenations, and optionally a "=" or ".=",
401 into a single action. For example, apart from retrieving $s, $a and
402 $b, this whole expression is now handled as a single op:
403 $s .= "a=$a b=$b\n"
405 As a special case, if the LHS of an assignment is a lexical
407 variable or "my $s", the op itself handles retrieving the lexical
408 variable, which is faster.
409 In general, the more the expression includes a mix of constant
411 strings and variable expressions, the longer the expression, and
412 the more it mixes together non-utf8 and utf8 strings, the more
413 marked the performance improvement. For example on a "x86_64"
414 system, this code has been benchmarked running four times faster:
415 my $s;
417 my $a = "ab\x{100}cde";
418 my $b = "fghij";
419 my $c = "\x{101}klmn";
420 for my $i (1..10_000_000) {
422 $s = "\x{100}wxyz";
423 $s .= "foo=$a bar=$b baz=$c";
424 }
425 In addition, "sprintf" expressions which have a constant format
427 containing only %s and "%%" format elements, and which have a fixed
428 number of arguments, are now also optimised into a "multiconcat"
429 op.
430 • The ref() builtin is now much faster in boolean context, since it
432 no longer bothers to construct a temporary string like
433 "Foo=ARRAY(0x134af48)".
434 • keys() in void and scalar contexts is now more efficient.
436 • The common idiom of comparing the result of index() with -1 is now
438 specifically optimised, e.g.
439 if (index(...) != -1) { ... }
441 • for() loops and similar constructs are now more efficient in most
443 cases.
444 • File::Glob has been modified to remove unnecessary backtracking and
446 recursion, thanks to Russ Cox. See
447 <https://research.swtch.com/glob> for more details.
448 • The XS-level SvTRUE() API function is now more efficient.
450 • Various integer-returning ops are now more efficient in
452 scalar/boolean context.
453 • Slightly improved performance when parsing stash names. [GH
455 #15689] <https://github.com/Perl/perl5/issues/15689>
456 • Calls to "require" for an already loaded module are now slightly
458 faster. [GH #16175] <https://github.com/Perl/perl5/issues/16175>
459 • The performance of pattern matching "[[:ascii:]]" and
461 "[[:^ascii:]]" has been improved significantly except on EBCDIC
462 platforms.
463 • Various optimizations have been applied to matching regular
465 expression patterns, so under the right circumstances, significant
466 performance gains may be noticed. But in an application with many
467 varied patterns, little overall improvement likely will be seen.
468 • Other optimizations have been applied to UTF-8 handling, but these
470 are not typically a major factor in most applications.
471
473 Key highlights in this release across several modules:
474 Removal of use vars
476 The usage of "use vars" has been discouraged since the introduction of
477 "our" in Perl 5.6.0. Where possible the usage of this pragma has now
478 been removed from the Perl source code.
479 This had a slight effect (for the better) on the output of WARNING_BITS
481 in B::Deparse.
482 Use of DynaLoader changed to XSLoader in many modules
484 XSLoader is more modern, and most modules already require perl 5.6 or
485 greater, so no functionality is lost by switching. In some cases, we
486 have also made changes to the local implementation that may not be
487 reflected in the version on CPAN due to a desire to maintain more
488 backwards compatibility.
489 Updated Modules and Pragmata
491 • Archive::Tar has been upgraded from version 2.24 to 2.30.
492 This update also handled CVE-2018-12015: directory traversal
494 vulnerability. [cpan #125523]
495 <https://rt.cpan.org/Ticket/Display.html?id=125523>
496 • arybase has been upgraded from version 0.12 to 0.15.
498 • Attribute::Handlers has been upgraded from version 0.99 to 1.01.
500 • attributes has been upgraded from version 0.29 to 0.33.
502 • B has been upgraded from version 1.68 to 1.74.
504 • B::Concise has been upgraded from version 0.999 to 1.003.
506 • B::Debug has been upgraded from version 1.24 to 1.26.
508 NOTE: B::Debug is deprecated and may be removed from a future
510 version of Perl.
511 • B::Deparse has been upgraded from version 1.40 to 1.48.
513 It includes many bug fixes, and in particular, it now deparses
515 variable attributes correctly:
516 my $x :foo; # used to deparse as
518 # 'attributes'->import('main', \$x, 'foo'), my $x;
519 • base has been upgraded from version 2.25 to 2.27.
521 • bignum has been upgraded from version 0.47 to 0.49.
523 • blib has been upgraded from version 1.06 to 1.07.
525 • bytes has been upgraded from version 1.05 to 1.06.
527 • Carp has been upgraded from version 1.42 to 1.50.
529 If a package on the call stack contains a constant named "ISA",
531 Carp no longer throws a "Not a GLOB reference" error.
532 Carp, when generating stack traces, now attempts to work around
534 longstanding bugs resulting from Perl's non-reference-counted
535 stack. [GH #9282] <https://github.com/Perl/perl5/issues/9282>
536 Carp has been modified to avoid assuming that objects cannot be
538 overloaded without the overload module loaded (this can happen with
539 objects created by XS modules). Previously, infinite recursion
540 would result if an XS-defined overload method itself called Carp.
541 [GH #16407] <https://github.com/Perl/perl5/issues/16407>
542 Carp now avoids using "overload::StrVal", partly because older
544 versions of overload (included with perl 5.14 and earlier) load
545 Scalar::Util at run time, which will fail if Carp has been invoked
546 after a syntax error.
547 • charnames has been upgraded from version 1.44 to 1.45.
549 • Compress::Raw::Zlib has been upgraded from version 2.074 to 2.076.
551 This addresses a security vulnerability in older versions of the
553 'zlib' library (which is bundled with Compress-Raw-Zlib).
554 • Config::Extensions has been upgraded from version 0.01 to 0.02.
556 • Config::Perl::V has been upgraded from version 0.28 to 0.29.
558 • CPAN has been upgraded from version 2.18 to 2.20.
560 • Data::Dumper has been upgraded from version 2.167 to 2.170.
562 Quoting of glob names now obeys the Useqq option [GH #13274]
564 <https://github.com/Perl/perl5/issues/13274>.
565 Attempts to set an option to "undef" through a combined
567 getter/setter method are no longer mistaken for getter calls [GH
568 #12135] <https://github.com/Perl/perl5/issues/12135>.
569 • Devel::Peek has been upgraded from version 1.26 to 1.27.
571 • Devel::PPPort has been upgraded from version 3.35 to 3.40.
573 Devel::PPPort has moved from cpan-first to perl-first maintenance
575 Primary responsibility for the code in Devel::PPPort has moved into
577 core perl. In a practical sense there should be no change except
578 that hopefully it will stay more up to date with changes made to
579 symbols in perl, rather than needing to be updated after the fact.
580 • Digest::SHA has been upgraded from version 5.96 to 6.01.
582 • DirHandle has been upgraded from version 1.04 to 1.05.
584 • DynaLoader has been upgraded from version 1.42 to 1.45.
586 Its documentation now shows the use of "__PACKAGE__" and direct
588 object syntax [GH #16190]
589 <https://github.com/Perl/perl5/issues/16190>.
590 • Encode has been upgraded from version 2.88 to 2.97.
592 • encoding has been upgraded from version 2.19 to 2.22.
594 • Errno has been upgraded from version 1.28 to 1.29.
596 • experimental has been upgraded from version 0.016 to 0.019.
598 • Exporter has been upgraded from version 5.72 to 5.73.
600 • ExtUtils::CBuilder has been upgraded from version 0.280225 to
602 0.280230.
603 • ExtUtils::Constant has been upgraded from version 0.23 to 0.25.
605 • ExtUtils::Embed has been upgraded from version 1.34 to 1.35.
607 • ExtUtils::Install has been upgraded from version 2.04 to 2.14.
609 • ExtUtils::MakeMaker has been upgraded from version 7.24 to 7.34.
611 • ExtUtils::Miniperl has been upgraded from version 1.06 to 1.08.
613 • ExtUtils::ParseXS has been upgraded from version 3.34 to 3.39.
615 • ExtUtils::Typemaps has been upgraded from version 3.34 to 3.38.
617 • ExtUtils::XSSymSet has been upgraded from version 1.3 to 1.4.
619 • feature has been upgraded from version 1.47 to 1.52.
621 • fields has been upgraded from version 2.23 to 2.24.
623 • File::Copy has been upgraded from version 2.32 to 2.33.
625 It will now use the sub-second precision variant of utime()
627 supplied by Time::HiRes where available. [GH #16225]
628 <https://github.com/Perl/perl5/issues/16225>.
629 • File::Fetch has been upgraded from version 0.52 to 0.56.
631 • File::Glob has been upgraded from version 1.28 to 1.31.
633 • File::Path has been upgraded from version 2.12_01 to 2.15.
635 • File::Spec and Cwd have been upgraded from version 3.67 to 3.74.
637 • File::stat has been upgraded from version 1.07 to 1.08.
639 • FileCache has been upgraded from version 1.09 to 1.10.
641 • Filter::Simple has been upgraded from version 0.93 to 0.95.
643 • Filter::Util::Call has been upgraded from version 1.55 to 1.58.
645 • GDBM_File has been upgraded from version 1.15 to 1.17.
647 Its documentation now explains that "each" and "delete" don't mix
649 in hashes tied to this module [GH #12894]
650 <https://github.com/Perl/perl5/issues/12894>.
651 It will now retry opening with an acceptable block size if asking
653 gdbm to default the block size failed [GH #13232]
654 <https://github.com/Perl/perl5/issues/13232>.
655 • Getopt::Long has been upgraded from version 2.49 to 2.5.
657 • Hash::Util::FieldHash has been upgraded from version 1.19 to 1.20.
659 • I18N::Langinfo has been upgraded from version 0.13 to 0.17.
661 This module is now available on all platforms, emulating the system
663 nl_langinfo(3) on systems that lack it. Some caveats apply, as
664 detailed in its documentation, the most severe being that, except
665 for MS Windows, the "CODESET" item is not implemented on those
666 systems, always returning "".
667 It now sets the UTF-8 flag in its returned scalar if the string
669 contains legal non-ASCII UTF-8, and the locale is UTF-8 [GH #15131]
670 <https://github.com/Perl/perl5/issues/15131>.
671 This update also fixes a bug in which the underlying locale was
673 ignored for the "RADIXCHAR" (always was returned as a dot) and the
674 "THOUSEP" (always empty). Now the locale-appropriate values are
675 returned.
676 • I18N::LangTags has been upgraded from version 0.42 to 0.43.
678 • if has been upgraded from version 0.0606 to 0.0608.
680 • IO has been upgraded from version 1.38 to 1.39.
682 • IO::Socket::IP has been upgraded from version 0.38 to 0.39.
684 • IPC::Cmd has been upgraded from version 0.96 to 1.00.
686 • JSON::PP has been upgraded from version 2.27400_02 to 2.97001.
688 • The "libnet" distribution has been upgraded from version 3.10 to
690 3.11.
691 • List::Util has been upgraded from version 1.46_02 to 1.49.
693 • Locale::Codes has been upgraded from version 3.42 to 3.56.
695 NOTE: Locale::Codes scheduled to be removed from core in Perl 5.30.
697 • Locale::Maketext has been upgraded from version 1.28 to 1.29.
699 • Math::BigInt has been upgraded from version 1.999806 to 1.999811.
701 • Math::BigInt::FastCalc has been upgraded from version 0.5005 to
703 0.5006.
704 • Math::BigRat has been upgraded from version 0.2611 to 0.2613.
706 • Module::CoreList has been upgraded from version 5.20170530 to
708 5.20180622.
709 • mro has been upgraded from version 1.20 to 1.22.
711 • Net::Ping has been upgraded from version 2.55 to 2.62.
713 • NEXT has been upgraded from version 0.67 to 0.67_01.
715 • ODBM_File has been upgraded from version 1.14 to 1.15.
717 • Opcode has been upgraded from version 1.39 to 1.43.
719 • overload has been upgraded from version 1.28 to 1.30.
721 • PerlIO::encoding has been upgraded from version 0.25 to 0.26.
723 • PerlIO::scalar has been upgraded from version 0.26 to 0.29.
725 • PerlIO::via has been upgraded from version 0.16 to 0.17.
727 • Pod::Functions has been upgraded from version 1.11 to 1.13.
729 • Pod::Html has been upgraded from version 1.2202 to 1.24.
731 A title for the HTML document will now be automatically generated
733 by default from a "NAME" section in the POD document, as it used to
734 be before the module was rewritten to use Pod::Simple::XHTML to do
735 the core of its job [GH #11954]
736 <https://github.com/Perl/perl5/issues/11954>.
737 • Pod::Perldoc has been upgraded from version 3.28 to 3.2801.
739 • The "podlators" distribution has been upgraded from version 4.09 to
741 4.10.
742 Man page references and function names now follow the Linux man
744 page formatting standards, instead of the Solaris standard.
745 • POSIX has been upgraded from version 1.76 to 1.84.
747 Some more cautions were added about using locale-specific functions
749 in threaded applications.
750 • re has been upgraded from version 0.34 to 0.36.
752 • Scalar::Util has been upgraded from version 1.46_02 to 1.50.
754 • SelfLoader has been upgraded from version 1.23 to 1.25.
756 • Socket has been upgraded from version 2.020_03 to 2.027.
758 • sort has been upgraded from version 2.02 to 2.04.
760 • Storable has been upgraded from version 2.62 to 3.08.
762 • Sub::Util has been upgraded from version 1.48 to 1.49.
764 • subs has been upgraded from version 1.02 to 1.03.
766 • Sys::Hostname has been upgraded from version 1.20 to 1.22.
768 • Term::ReadLine has been upgraded from version 1.16 to 1.17.
770 • Test has been upgraded from version 1.30 to 1.31.
772 • Test::Harness has been upgraded from version 3.38 to 3.42.
774 • Test::Simple has been upgraded from version 1.302073 to 1.302133.
776 • threads has been upgraded from version 2.15 to 2.22.
778 The documentation now better describes the problems that arise when
780 returning values from threads, and no longer warns about creating
781 threads in "BEGIN" blocks. [GH #11563]
782 <https://github.com/Perl/perl5/issues/11563>
783 • threads::shared has been upgraded from version 1.56 to 1.58.
785 • Tie::Array has been upgraded from version 1.06 to 1.07.
787 • Tie::StdHandle has been upgraded from version 4.4 to 4.5.
789 • Time::gmtime has been upgraded from version 1.03 to 1.04.
791 • Time::HiRes has been upgraded from version 1.9741 to 1.9759.
793 • Time::localtime has been upgraded from version 1.02 to 1.03.
795 • Time::Piece has been upgraded from version 1.31 to 1.3204.
797 • Unicode::Collate has been upgraded from version 1.19 to 1.25.
799 • Unicode::Normalize has been upgraded from version 1.25 to 1.26.
801 • Unicode::UCD has been upgraded from version 0.68 to 0.70.
803 The function "num" now accepts an optional parameter to help in
805 diagnosing error returns.
806 • User::grent has been upgraded from version 1.01 to 1.02.
808 • User::pwent has been upgraded from version 1.00 to 1.01.
810 • utf8 has been upgraded from version 1.19 to 1.21.
812 • vars has been upgraded from version 1.03 to 1.04.
814 • version has been upgraded from version 0.9917 to 0.9923.
816 • VMS::DCLsym has been upgraded from version 1.08 to 1.09.
818 • VMS::Stdio has been upgraded from version 2.41 to 2.44.
820 • warnings has been upgraded from version 1.37 to 1.42.
822 It now includes new functions with names ending in "_at_level",
824 allowing callers to specify the exact call frame. [GH #16257]
825 <https://github.com/Perl/perl5/issues/16257>
826 • XS::Typemap has been upgraded from version 0.15 to 0.16.
828 • XSLoader has been upgraded from version 0.27 to 0.30.
830 Its documentation now shows the use of "__PACKAGE__", and direct
832 object syntax for example "DynaLoader" usage [GH #16190]
833 <https://github.com/Perl/perl5/issues/16190>.
834 Platforms that use "mod2fname" to edit the names of loadable
836 libraries now look for bootstrap (.bs) files under the correct,
837 non-edited name.
838 Removed Modules and Pragmata
840 • The "VMS::stdio" compatibility shim has been removed.
841
843 Changes to Existing Documentation
844 We have attempted to update the documentation to reflect the changes
845 listed in this document. If you find any we have missed, send email to
846 perlbug@perl.org <mailto:perlbug@perl.org>.
847 Additionally, the following selected changes have been made:
849 perlapi
851 • The API functions perl_parse(), perl_run(), and perl_destruct() are
853 now documented comprehensively, where previously the only
854 documentation was a reference to the perlembed tutorial.
855 • The documentation of newGIVENOP() has been belatedly updated to
857 account for the removal of lexical $_.
858 • The API functions newCONSTSUB() and newCONSTSUB_flags() are
860 documented much more comprehensively than before.
861 perldata
863 • The section "Truth and Falsehood" in perlsyn has been moved into
865 perldata.
866 perldebguts
868 • The description of the conditions under which DB::sub() will be
870 called has been clarified. [GH #16055]
871 <https://github.com/Perl/perl5/issues/16055>
872 perldiag
874 • "Variable length lookbehind not implemented in regex m/%s/" in
876 perldiag
877 This now gives more ideas as to workarounds to the issue that was
879 introduced in Perl 5.18 (but not documented explicitly in its
880 perldelta) for the fact that some Unicode "/i" rules cause a few
881 sequences such as
882 (?<!st)
884 to be considered variable length, and hence disallowed.
886 • "Use of state $_ is experimental" in perldiag
888 This entry has been removed, as the experimental support of this
890 construct was removed in perl 5.24.0.
891 • The diagnostic "Initialization of state variables in list context
893 currently forbidden" has changed to "Initialization of state
894 variables in list currently forbidden", because list-context
895 initialization of single aggregate state variables is now
896 permitted.
897 perlembed
899 • The examples in perlembed have been made more portable in the way
901 they exit, and the example that gets an exit code from the embedded
902 Perl interpreter now gets it from the right place. The examples
903 that pass a constructed argv to Perl now show the mandatory null
904 "argv[argc]".
905 • An example in perlembed used the string value of "ERRSV" as a
907 format string when calling croak(). If that string contains format
908 codes such as %s this could crash the program.
909 This has been changed to a call to croak_sv().
911 An alternative could have been to supply a trivial format string:
913 croak("%s", SvPV_nolen(ERRSV));
915 or as a special case for "ERRSV" simply:
917 croak(NULL);
919 perlfunc
921 • There is now a note that warnings generated by built-in functions
923 are documented in perldiag and warnings. [GH #12642]
924 <https://github.com/Perl/perl5/issues/12642>
925 • The documentation for the "exists" operator no longer says that
927 autovivification behaviour "may be fixed in a future release".
928 We've determined that we're not going to change the default
929 behaviour. [GH #15231]
930 <https://github.com/Perl/perl5/issues/15231>
931 • A couple of small details in the documentation for the "bless"
933 operator have been clarified. [GH #14684]
934 <https://github.com/Perl/perl5/issues/14684>
935 • The description of @INC hooks in the documentation for "require"
937 has been corrected to say that filter subroutines receive a useless
938 first argument. [GH #12569]
939 <https://github.com/Perl/perl5/issues/12569>
940 • The documentation of "ref" has been rewritten for clarity.
942 • The documentation of "use" now explains what syntactically
944 qualifies as a version number for its module version checking
945 feature.
946 • The documentation of "warn" has been updated to reflect that since
948 Perl 5.14 it has treated complex exception objects in a manner
949 equivalent to "die". [GH #13641]
950 <https://github.com/Perl/perl5/issues/13641>
951 • The documentation of "die" and "warn" has been revised for clarity.
953 • The documentation of "each" has been improved, with a slightly more
955 explicit description of the sharing of iterator state, and with
956 caveats regarding the fragility of while-each loops. [GH #16334]
957 <https://github.com/Perl/perl5/issues/16334>
958 • Clarification to "require" was added to explain the differences
960 between
961 require Foo::Bar;
963 require "Foo/Bar.pm";
964 perlgit
966 • The precise rules for identifying "smoke-me" branches are now
968 stated.
969 perlguts
971 • The section on reference counting in perlguts has been heavily
973 revised, to describe references in the way a programmer needs to
974 think about them rather than in terms of the physical data
975 structures.
976 • Improve documentation related to UTF-8 multibytes.
978 perlintern
980 • The internal functions newXS_len_flags() and newATTRSUB_x() are now
982 documented.
983 perlobj
985 • The documentation about "DESTROY" methods has been corrected,
987 updated, and revised, especially in regard to how they interact
988 with exceptions. [GH #14083]
989 <https://github.com/Perl/perl5/issues/14083>
990 perlop
992 • The description of the "x" operator in perlop has been clarified.
994 [GH #16253] <https://github.com/Perl/perl5/issues/16253>
995 • perlop has been updated to note that "qw"'s whitespace rules differ
997 from that of "split"'s in that only ASCII whitespace is used.
998 • The general explanation of operator precedence and associativity
1000 has been corrected and clarified. [GH #15153]
1001 <https://github.com/Perl/perl5/issues/15153>
1002 • The documentation for the "\" referencing operator now explains the
1004 unusual context that it supplies to its operand. [GH #15932]
1005 <https://github.com/Perl/perl5/issues/15932>
1006 perlrequick
1008 • Clarifications on metacharacters and character classes
1010 perlretut
1012 • Clarify metacharacters.
1014 perlrun
1016 • Clarify the differences between -M and -m. [GH #15998]
1018 <https://github.com/Perl/perl5/issues/15998>
1019 perlsec
1021 • The documentation about set-id scripts has been updated and
1023 revised. [GH #10289] <https://github.com/Perl/perl5/issues/10289>
1024 • A section about using "sudo" to run Perl scripts has been added.
1026 perlsyn
1028 • The section "Truth and Falsehood" in perlsyn has been removed from
1030 that document, where it didn't belong, and merged into the existing
1031 paragraph on the same topic in perldata.
1032 • The means to disambiguate between code blocks and hash
1034 constructors, already documented in perlref, are now documented in
1035 perlsyn too. [GH #15918]
1036 <https://github.com/Perl/perl5/issues/15918>
1037 perluniprops
1039 • perluniprops has been updated to note that "\p{Word}" now includes
1041 code points matching the "\p{Join_Control}" property. The change
1042 to the property was made in Perl 5.18, but not documented until
1043 now. There are currently only two code points that match this
1044 property U+200C (ZERO WIDTH NON-JOINER) and U+200D (ZERO WIDTH
1045 JOINER).
1046 • For each binary table or property, the documentation now includes
1048 which characters in the range "\x00-\xFF" it matches, as well as a
1049 list of the first few ranges of code points matched above that.
1050 perlvar
1052 • The entry for $+ in perlvar has been expanded upon to describe
1054 handling of multiply-named capturing groups.
1055 perlfunc, perlop, perlsyn
1057 • In various places, improve the documentation of the special cases
1059 in the condition expression of a while loop, such as implicit
1060 "defined" and assignment to $_. [GH #16334]
1061 <https://github.com/Perl/perl5/issues/16334>
1062
1064 The following additions or changes have been made to diagnostic output,
1065 including warnings and fatal error messages. For the complete list of
1066 diagnostic messages, see perldiag.
1067 New Diagnostics
1069 New Errors
1070 • Can't "goto" into a "given" block
1072 (F) A "goto" statement was executed to jump into the middle of a
1074 "given" block. You can't get there from here. See "goto" in
1075 perlfunc.
1076 • Can't "goto" into a binary or list expression
1078 Use of "goto" to jump into the parameter of a binary or list
1080 operator has been prohibited, to prevent crashes and stack
1081 corruption. [GH #15914]
1082 <https://github.com/Perl/perl5/issues/15914>
1083 You may only enter the first argument of an operator that takes a
1085 fixed number of arguments, since this is a case that will not cause
1086 stack corruption. [GH #16415]
1087 <https://github.com/Perl/perl5/issues/16415>
1088 New Warnings
1090 • Old package separator used in string
1092 (W syntax) You used the old package separator, "'", in a variable
1094 named inside a double-quoted string; e.g., "In $name's house".
1095 This is equivalent to "In $name::s house". If you meant the
1096 former, put a backslash before the apostrophe ("In $name\'s
1097 house").
1098 • "Locale '%s' contains (at least) the following characters which
1100 have unexpected meanings: %s The Perl program will use the
1101 expected meanings" in perldiag
1102 Changes to Existing Diagnostics
1104 • A false-positive warning that was issued when using a numerically-
1105 quantified sub-pattern in a recursive regex has been silenced. [GH
1106 #16106] <https://github.com/Perl/perl5/issues/16106>
1107 • The warning about useless use of a concatenation operator in void
1109 context is now generated for expressions with multiple
1110 concatenations, such as "$a.$b.$c", which used to mistakenly not
1111 warn. [GH #3990] <https://github.com/Perl/perl5/issues/3990>
1112 • Warnings that a variable or subroutine "masks earlier declaration
1114 in same ...", or that an "our" variable has been redeclared, have
1115 been moved to a new warnings category "shadow". Previously they
1116 were in category "misc".
1117 • The deprecation warning from Sys::Hostname::hostname() saying that
1119 it doesn't accept arguments now states the Perl version in which
1120 the warning will be upgraded to an error. [GH #14662]
1121 <https://github.com/Perl/perl5/issues/14662>
1122 • The perldiag entry for the error regarding a set-id script has been
1124 expanded to make clear that the error is reporting a specific
1125 security vulnerability, and to advise how to fix it.
1126 • The "Unable to flush stdout" error message was missing a trailing
1128 newline. [debian #875361]
1129
1131 perlbug
1132 • "--help" and "--version" options have been added.
1133
1135 • C89 requirement
1136 Perl has been documented as requiring a C89 compiler to build since
1138 October 1998. A variety of simplifications have now been made to
1139 Perl's internals to rely on the features specified by the C89
1140 standard. We believe that this internal change hasn't altered the
1141 set of platforms that Perl builds on, but please report a bug if
1142 Perl now has new problems building on your platform.
1143 • On GCC, "-Werror=pointer-arith" is now enabled by default,
1145 disallowing arithmetic on void and function pointers.
1146 • Where an HTML version of the documentation is installed, the HTML
1148 documents now use relative links to refer to each other. Links
1149 from the index page of perlipc to the individual section documents
1150 are now correct. [GH #11941]
1151 <https://github.com/Perl/perl5/issues/11941>
1152 • lib/unicore/mktables now correctly canonicalizes the names of the
1154 dependencies stored in the files it generates.
1155 regen/mk_invlists.pl, unlike the other regen/*.pl scripts, used $0
1157 to name itself in the dependencies stored in the files it
1158 generates. It now uses a literal so that the path stored in the
1159 generated files doesn't depend on how regen/mk_invlists.pl is
1160 invoked.
1161 This lack of canonical names could cause test failures in
1163 t/porting/regen.t. [GH #16446]
1164 <https://github.com/Perl/perl5/issues/16446>
1165 • New probes
1167 HAS_BUILTIN_ADD_OVERFLOW
1169 HAS_BUILTIN_MUL_OVERFLOW
1170 HAS_BUILTIN_SUB_OVERFLOW
1171 HAS_THREAD_SAFE_NL_LANGINFO_L
1172 HAS_LOCALECONV_L
1173 HAS_MBRLEN
1174 HAS_MBRTOWC
1175 HAS_MEMRCHR
1176 HAS_NANOSLEEP
1177 HAS_STRNLEN
1178 HAS_STRTOLD_L
1179 I_WCHAR
1180
1182 • Testing of the XS-APItest directory is now done in parallel, where
1183 applicable.
1184 • Perl now includes a default .travis.yml file for Travis CI testing
1186 on github mirrors. [GH #14558]
1187 <https://github.com/Perl/perl5/issues/14558>
1188 • The watchdog timer count in re/pat_psycho.t can now be overridden.
1190 This test can take a long time to run, so there is a timer to keep
1192 this in check (currently, 5 minutes). This commit adds checking the
1193 environment variable "PERL_TEST_TIME_OUT_FACTOR"; if set, the time
1194 out setting is multiplied by its value.
1195 • harness no longer waits for 30 seconds when running t/io/openpid.t.
1197 [GH #13535] <https://github.com/Perl/perl5/issues/13535> [GH
1198 #16420] <https://github.com/Perl/perl5/issues/16420>
1199
1201 For the past few years we have released perl using three different
1202 archive formats: bzip (".bz2"), LZMA2 (".xz") and gzip (".gz"). Since
1203 xz compresses better and decompresses faster, and gzip is more
1204 compatible and uses less memory, we have dropped the ".bz2" archive
1205 format with this release. (If this poses a problem, do let us know;
1206 see "Reporting Bugs", below.)
1207
1209 Discontinued Platforms
1210 PowerUX / Power MAX OS
1211 Compiler hints and other support for these apparently long-defunct
1212 platforms has been removed.
1213 Platform-Specific Notes
1215 CentOS
1216 Compilation on CentOS 5 is now fixed.
1217 Cygwin
1219 A build with the quadmath library can now be done on Cygwin.
1220 Darwin
1222 Perl now correctly uses reentrant functions, like "asctime_r", on
1223 versions of Darwin that have support for them.
1224 FreeBSD
1226 FreeBSD's /usr/share/mk/sys.mk specifies "-O2" for architectures
1227 other than ARM and MIPS. By default, perl is now compiled with the
1228 same optimization levels.
1229 VMS Several fix-ups for configure.com, marking function VMS has (or
1231 doesn't have).
1232 CRTL features can now be set by embedders before invoking Perl by
1234 using the "decc$feature_set" and "decc$feature_set_value"
1235 functions. Previously any attempt to set features after image
1236 initialization were ignored.
1237 Windows
1239 • Support for compiling perl on Windows using Microsoft Visual
1240 Studio 2017 (containing Visual C++ 14.1) has been added.
1241 • Visual C++ compiler version detection has been improved to work
1243 on non-English language systems.
1244 • We now set $Config{libpth} correctly for 64-bit builds using
1246 Visual C++ versions earlier than 14.1.
1247
1249 • A new optimisation phase has been added to the compiler,
1250 optimize_optree(), which does a top-down scan of a complete optree
1251 just before the peephole optimiser is run. This phase is not
1252 currently hookable.
1253 • An "OP_MULTICONCAT" op has been added. At optimize_optree() time, a
1255 chain of "OP_CONCAT" and "OP_CONST" ops, together optionally with
1256 an "OP_STRINGIFY" and/or "OP_SASSIGN", are combined into a single
1257 "OP_MULTICONCAT" op. The op is of type "UNOP_AUX", and the aux
1258 array contains the argument count, plus a pointer to a constant
1259 string and a set of segment lengths. For example with
1260 my $x = "foo=$foo, bar=$bar\n";
1262 the constant string would be "foo=, bar=\n" and the segment lengths
1264 would be (4,6,1). If the string contains characters such as "\x80",
1265 whose representation changes under utf8, two sets of strings plus
1266 lengths are precomputed and stored.
1267 • Direct access to "PL_keyword_plugin" is not safe in the presence of
1269 multithreading. A new "wrap_keyword_plugin" function has been added
1270 to allow XS modules to safely define custom keywords even when
1271 loaded from a thread, analogous to "PL_check" / "wrap_op_checker".
1272 • The "PL_statbuf" interpreter variable has been removed.
1274 • The deprecated function to_utf8_case(), accessible from XS code,
1276 has been removed.
1277 • A new function is_utf8_invariant_string_loc() has been added that
1279 is like is_utf8_invariant_string() but takes an extra pointer
1280 parameter into which is stored the location of the first variant
1281 character, if any are found.
1282 • A new function, Perl_langinfo() has been added. It is an (almost)
1284 drop-in replacement for the system nl_langinfo(3), but works on
1285 platforms that lack that; as well as being more thread-safe, and
1286 hiding some gotchas with locale handling from the caller. Code
1287 that uses this, needn't use localeconv(3) (and be affected by the
1288 gotchas) to find the decimal point, thousands separator, or
1289 currency symbol. See "Perl_langinfo" in perlapi.
1290 • A new API function sv_rvunweaken() has been added to complement
1292 sv_rvweaken(). The implementation was taken from "unweaken" in
1293 Scalar::Util.
1294 • A new flag, "SORTf_UNSTABLE", has been added. This will allow a
1296 future commit to make mergesort unstable when the user specifies
1297 ‘no sort stable’, since it has been decided that mergesort should
1298 remain stable by default.
1299 • XS modules can now automatically get reentrant versions of system
1301 functions on threaded perls.
1302 By adding
1304 #define PERL_REENTRANT
1306 near the beginning of an "XS" file, it will be compiled so that
1308 whatever reentrant functions perl knows about on that system will
1309 automatically and invisibly be used instead of the plain, non-
1310 reentrant versions. For example, if you write getpwnam() in your
1311 code, on a system that has getpwnam_r() all calls to the former
1312 will be translated invisibly into the latter. This does not happen
1313 except on threaded perls, as they aren't needed otherwise. Be
1314 aware that which functions have reentrant versions varies from
1315 system to system.
1316 • The "PERL_NO_OP_PARENT" build define is no longer supported, which
1318 means that perl is now always built with "PERL_OP_PARENT" enabled.
1319 • The format and content of the non-utf8 transliteration table
1321 attached to the "op_pv" field of "OP_TRANS"/"OP_TRANSR" ops has
1322 changed. It's now a "struct OPtrans_map".
1323 • A new compiler "#define", "dTHX_DEBUGGING". has been added. This
1325 is useful for XS or C code that only need the thread context
1326 because their debugging statements that get compiled only under
1327 "-DDEBUGGING" need one.
1328 • A new API function "Perl_setlocale" in perlapi has been added.
1330 • "sync_locale" in perlapi has been revised to return a boolean as to
1332 whether the system was using the global locale or not.
1333 • A new kind of magic scalar, called a "nonelem" scalar, has been
1335 introduced. It is stored in an array to denote a non-existent
1336 element, whenever such an element is accessed in a potential lvalue
1337 context. It replaces the existing "defelem" (deferred element)
1338 magic wherever this is possible, being significantly more
1339 efficient. This means that some_sub($sparse_array[$nonelem]) no
1340 longer has to create a new magic defelem scalar each time, as long
1341 as the element is within the array.
1342 It partially fixes the rare bug of deferred elements getting out of
1344 synch with their arrays when the array is shifted or unshifted.
1345 [GH #16364] <https://github.com/Perl/perl5/issues/16364>
1346
1348 • List assignment ("aassign") could in some rare cases allocate an
1349 entry on the mortals stack and leave the entry uninitialized,
1350 leading to possible crashes. [GH #16017]
1351 <https://github.com/Perl/perl5/issues/16017>
1352 • Attempting to apply an attribute to an "our" variable where a
1354 function of that name already exists could result in a NULL pointer
1355 being supplied where an SV was expected, crashing perl. [perl
1356 #131597] <https://rt.perl.org/Ticket/Display.html?id=131597>
1357 • "split ' '" now correctly handles the argument being split when in
1359 the scope of the "unicode_strings" feature. Previously, when a
1360 string using the single-byte internal representation contained
1361 characters that are whitespace by Unicode rules but not by ASCII
1362 rules, it treated those characters as part of fields rather than as
1363 field separators. [GH #15904]
1364 <https://github.com/Perl/perl5/issues/15904>
1365 • Several built-in functions previously had bugs that could cause
1367 them to write to the internal stack without allocating room for the
1368 item being written. In rare situations, this could have led to a
1369 crash. These bugs have now been fixed, and if any similar bugs are
1370 introduced in future, they will be detected automatically in
1371 debugging builds.
1372 These internal stack usage checks introduced are also done by the
1374 "entersub" operator when calling XSUBs. This means we can report
1375 which XSUB failed to allocate enough stack space. [GH #16126]
1376 <https://github.com/Perl/perl5/issues/16126>
1377 • Using a symbolic ref with postderef syntax as the key in a hash
1379 lookup was yielding an assertion failure on debugging builds. [GH
1380 #16029] <https://github.com/Perl/perl5/issues/16029>
1381 • Array and hash variables whose names begin with a caret now admit
1383 indexing inside their curlies when interpolated into strings, as in
1384 "${^CAPTURE[0]}" to index "@{^CAPTURE}". [GH #16050]
1385 <https://github.com/Perl/perl5/issues/16050>
1386 • Fetching the name of a glob that was previously UTF-8 but wasn't
1388 any longer would return that name flagged as UTF-8. [GH #15971]
1389 <https://github.com/Perl/perl5/issues/15971>
1390 • The perl sprintf() function (via the underlying C function
1392 Perl_sv_vcatpvfn_flags()) has been heavily reworked to fix many
1393 minor bugs, including the integer wrapping of large width and
1394 precision specifiers and potential buffer overruns. It has also
1395 been made faster in many cases.
1396 • Exiting from an "eval", whether normally or via an exception, now
1398 always frees temporary values (possibly calling destructors) before
1399 setting $@. For example:
1400 sub DESTROY { eval { die "died in DESTROY"; } }
1402 eval { bless []; };
1403 # $@ used to be equal to "died in DESTROY" here; it's now "".
1404 • Fixed a duplicate symbol failure with "-flto -mieee-fp" builds.
1406 pp.c defined "_LIB_VERSION" which "-lieee" already defines. [GH
1407 #16086] <https://github.com/Perl/perl5/issues/16086>
1408 • The tokenizer no longer consumes the exponent part of a floating
1410 point number if it's incomplete. [GH #16073]
1411 <https://github.com/Perl/perl5/issues/16073>
1412 • On non-threaded builds, for "m/$null/" where $null is an empty
1414 string is no longer treated as if the "/o" flag was present when
1415 the previous matching match operator included the "/o" flag. The
1416 rewriting used to implement this behavior could confuse the
1417 interpreter. This matches the behaviour of threaded builds. [GH
1418 #14668] <https://github.com/Perl/perl5/issues/14668>
1419 • Parsing a "sub" definition could cause a use after free if the
1421 "sub" keyword was followed by whitespace including newlines (and
1422 comments.) [GH #16097]
1423 <https://github.com/Perl/perl5/issues/16097>
1424 • The tokenizer now correctly adjusts a parse pointer when skipping
1426 whitespace in a "${identifier}" construct. [perl #131949]
1427 <https://rt.perl.org/Public/Bug/Display.html?id=131949>
1428 • Accesses to "${^LAST_FH}" no longer assert after using any of a
1430 variety of I/O operations on a non-glob. [GH #15372]
1431 <https://github.com/Perl/perl5/issues/15372>
1432 • The XS-level Copy(), Move(), Zero() macros and their variants now
1434 assert if the pointers supplied are "NULL". ISO C considers
1435 supplying NULL pointers to the functions these macros are built
1436 upon as undefined behaviour even when their count parameters are
1437 zero. Based on these assertions and the original bug report three
1438 macro calls were made conditional. [GH #16079]
1439 <https://github.com/Perl/perl5/issues/16079> [GH #16112]
1440 <https://github.com/Perl/perl5/issues/16112>
1441 • Only the "=" operator is permitted for defining defaults for
1443 parameters in subroutine signatures. Previously other assignment
1444 operators, e.g. "+=", were also accidentally permitted. [GH
1445 #16084] <https://github.com/Perl/perl5/issues/16084>
1446 • Package names are now always included in ":prototype" warnings
1448 [perl #131833]
1449 <https://rt.perl.org/Public/Bug/Display.html?id=131833>
1450 • The "je_old_stack_hwm" field, previously only found in the "jmpenv"
1452 structure on debugging builds, has been added to non-debug builds
1453 as well. This fixes an issue with some CPAN modules caused by the
1454 size of this structure varying between debugging and non-debugging
1455 builds. [GH #16122] <https://github.com/Perl/perl5/issues/16122>
1456 • The arguments to the ninstr() macro are now correctly
1458 parenthesized.
1459 • A NULL pointer dereference in the S_regmatch() function has been
1461 fixed. [perl #132017]
1462 <https://rt.perl.org/Public/Bug/Display.html?id=132017>
1463 • Calling exec PROGRAM LIST with an empty "LIST" has been fixed.
1465 This should call execvp() with an empty "argv" array (containing
1466 only the terminating "NULL" pointer), but was instead just
1467 returning false (and not setting $!). [GH #16075]
1468 <https://github.com/Perl/perl5/issues/16075>
1469 • The "gv_fetchmeth_sv" C function stopped working properly in Perl
1471 5.22 when fetching a constant with a UTF-8 name if that constant
1472 subroutine was stored in the stash as a simple scalar reference,
1473 rather than a full typeglob. This has been corrected.
1474 • Single-letter debugger commands followed by an argument which
1476 starts with punctuation (e.g. "p$^V" and "x@ARGV") now work again.
1477 They had been wrongly requiring a space between the command and the
1478 argument. [GH #13342] <https://github.com/Perl/perl5/issues/13342>
1479 • splice now throws an exception ("Modification of a read-only value
1481 attempted") when modifying a read-only array. Until now it had
1482 been silently modifying the array. The new behaviour is consistent
1483 with the behaviour of push and unshift. [GH #15923]
1484 <https://github.com/Perl/perl5/issues/15923>
1485 • stat(), lstat(), and file test operators now fail if given a
1487 filename containing a nul character, in the same way that open()
1488 already fails.
1489 • stat(), lstat(), and file test operators now reliably set $! when
1491 failing due to being applied to a closed or otherwise invalid file
1492 handle.
1493 • File test operators for Unix permission bits that don't exist on a
1495 particular platform, such as "-k" (sticky bit) on Windows, now
1496 check that the file being tested exists before returning the
1497 blanket false result, and yield the appropriate errors if the
1498 argument doesn't refer to a file.
1499 • Fixed a 'read before buffer' overrun when parsing a range starting
1501 with "\N{}" at the beginning of the character set for the
1502 transliteration operator. [GH #16189]
1503 <https://github.com/Perl/perl5/issues/16189>
1504 • Fixed a leaked scalar when parsing an empty "\N{}" at compile-time.
1506 [GH #16189] <https://github.com/Perl/perl5/issues/16189>
1507 • Calling "do $path" on a directory or block device now yields a
1509 meaningful error code in $!. [GH #14841]
1510 <https://github.com/Perl/perl5/issues/14841>
1511 • Regexp substitution using an overloaded replacement value that
1513 provides a tainted stringification now correctly taints the
1514 resulting string. [GH #12495]
1515 <https://github.com/Perl/perl5/issues/12495>
1516 • Lexical sub declarations in "do" blocks such as "do { my sub lex;
1518 123 }" could corrupt the stack, erasing items already on the stack
1519 in the enclosing statement. This has been fixed. [GH #16243]
1520 <https://github.com/Perl/perl5/issues/16243>
1521 • "pack" and "unpack" can now handle repeat counts and lengths that
1523 exceed two billion. [GH #13179]
1524 <https://github.com/Perl/perl5/issues/13179>
1525 • Digits past the radix point in octal and binary floating point
1527 literals now have the correct weight on platforms where a floating
1528 point significand doesn't fit into an integer type.
1529 • The canonical truth value no longer has a spurious special meaning
1531 as a callable subroutine. It used to be a magic placeholder for a
1532 missing "import" or "unimport" method, but is now treated like any
1533 other string 1. [GH #14902]
1534 <https://github.com/Perl/perl5/issues/14902>
1535 • "system" now reduces its arguments to strings in the parent
1537 process, so any effects of stringifying them (such as overload
1538 methods being called or warnings being emitted) are visible in the
1539 way the program expects. [GH #13561]
1540 <https://github.com/Perl/perl5/issues/13561>
1541 • The readpipe() built-in function now checks at compile time that it
1543 has only one parameter expression, and puts it in scalar context,
1544 thus ensuring that it doesn't corrupt the stack at runtime. [GH
1545 #2793] <https://github.com/Perl/perl5/issues/2793>
1546 • "sort" now performs correct reference counting when aliasing $a and
1548 $b, thus avoiding premature destruction and leakage of scalars if
1549 they are re-aliased during execution of the sort comparator. [GH
1550 #11422] <https://github.com/Perl/perl5/issues/11422>
1551 • "reverse" with no operand, reversing $_ by default, is no longer in
1553 danger of corrupting the stack. [GH #16291]
1554 <https://github.com/Perl/perl5/issues/16291>
1555 • "exec", "system", et al are no longer liable to have their argument
1557 lists corrupted by reentrant calls and by magic such as tied
1558 scalars. [GH #15660] <https://github.com/Perl/perl5/issues/15660>
1559 • Perl's own "malloc" no longer gets confused by attempts to allocate
1561 more than a gigabyte on a 64-bit platform. [GH #13273]
1562 <https://github.com/Perl/perl5/issues/13273>
1563 • Stacked file test operators in a sort comparator expression no
1565 longer cause a crash. [GH #15626]
1566 <https://github.com/Perl/perl5/issues/15626>
1567 • An identity "tr///" transformation on a reference is no longer
1569 mistaken for that reference for the purposes of deciding whether it
1570 can be assigned to. [GH #15812]
1571 <https://github.com/Perl/perl5/issues/15812>
1572 • Lengthy hexadecimal, octal, or binary floating point literals no
1574 longer cause undefined behaviour when parsing digits that are of
1575 such low significance that they can't affect the floating point
1576 value. [GH #16114] <https://github.com/Perl/perl5/issues/16114>
1577 • "open $$scalarref..." and similar invocations no longer leak the
1579 file handle. [GH #12593]
1580 <https://github.com/Perl/perl5/issues/12593>
1581 • Some convoluted kinds of regexp no longer cause an arithmetic
1583 overflow when compiled. [GH #16113]
1584 <https://github.com/Perl/perl5/issues/16113>
1585 • The default typemap, by avoiding "newGVgen", now no longer leaks
1587 when XSUBs return file handles ("PerlIO *" or "FILE *"). [GH
1588 #12593] <https://github.com/Perl/perl5/issues/12593>
1589 • Creating a "BEGIN" block as an XS subroutine with a prototype no
1591 longer crashes because of the early freeing of the subroutine.
1592 • The "printf" format specifier "%.0f" no longer rounds incorrectly
1594 [GH #9125] <https://github.com/Perl/perl5/issues/9125>, and now
1595 shows the correct sign for a negative zero.
1596 • Fixed an issue where the error "Scalar value @arrayname[0] better
1598 written as $arrayname" would give an error "Cannot printf Inf with
1599 'c'" when arrayname starts with "Inf". [GH #16335]
1600 <https://github.com/Perl/perl5/issues/16335>
1601 • The Perl implementation of getcwd() in "Cwd" in the PathTools
1603 distribution now behaves the same as XS implementation on errors:
1604 it returns an error, and sets $!. [GH #16338]
1605 <https://github.com/Perl/perl5/issues/16338>
1606 • Vivify array elements when putting them on the stack. Fixes [GH
1608 #5310] <https://github.com/Perl/perl5/issues/5310> (reported in
1609 April 2002).
1610 • Fixed parsing of braced subscript after parens. Fixes [GH #4688]
1612 <https://github.com/Perl/perl5/issues/4688> (reported in December
1613 2001).
1614 • "tr/non_utf8/long_non_utf8/c" could give the wrong results when the
1616 length of the replacement character list was greater than 0x7fff.
1617 • "tr/non_utf8/non_utf8/cd" failed to add the implied
1619 "\x{100}-\x{7fffffff}" to the search character list.
1620 • Compilation failures within "perl-within-perl" constructs, such as
1622 with string interpolation and the right part of "s///e", now cause
1623 compilation to abort earlier.
1624 Previously compilation could continue in order to report other
1626 errors, but the failed sub-parse could leave partly parsed
1627 constructs on the parser shift-reduce stack, confusing the parser,
1628 leading to perl crashes. [GH #14739]
1629 <https://github.com/Perl/perl5/issues/14739>
1630 • On threaded perls where the decimal point (radix) character is not
1632 a dot, it has been possible for a race to occur between threads
1633 when one needs to use the real radix character (such as with
1634 "sprintf"). This has now been fixed by use of a mutex on systems
1635 without thread-safe locales, and the problem just doesn't come up
1636 on those with thread-safe locales.
1637 • Errors while compiling a regex character class could sometime
1639 trigger an assertion failure. [GH #16172]
1640 <https://github.com/Perl/perl5/issues/16172>
1641
1643 Perl 5.28.0 represents approximately 13 months of development since
1644 Perl 5.26.0 and contains approximately 730,000 lines of changes across
1645 2,200 files from 77 authors.
1646 Excluding auto-generated files, documentation and release tools, there
1648 were approximately 580,000 lines of changes to 1,300 .pm, .t, .c and .h
1649 files.
1650 Perl continues to flourish into its fourth decade thanks to a vibrant
1652 community of users and developers. The following people are known to
1653 have contributed the improvements that became Perl 5.28.0:
1654 Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alberto Simões, Alexandr
1656 Savca, Andrew Fresh, Andy Dougherty, Andy Lester, Aristotle Pagaltzis,
1657 Ask Bjørn Hansen, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn
1658 Ilmari Mannsåker, Dan Collins, Daniel Dragan, David Cantrell, David
1659 Mitchell, Dmitry Ulanov, Dominic Hargreaves, E. Choroba, Eric Herman,
1660 Eugen Konkov, Father Chrysostomos, Gene Sullivan, George Hartzell,
1661 Graham Knop, Harald Jörg, H.Merijn Brand, Hugo van der Sanden, Jacques
1662 Germishuys, James E Keenan, Jarkko Hietaniemi, Jerry D. Hedden, J. Nick
1663 Koston, John Lightsey, John Peacock, John P. Linderman, John SJ
1664 Anderson, Karen Etheridge, Karl Williamson, Ken Brown, Ken Cotterill,
1665 Leon Timmermans, Lukas Mai, Marco Fontani, Marc-Philip Werner, Matthew
1666 Horsfall, Neil Bowers, Nicholas Clark, Nicolas R., Niko Tyni, Pali,
1667 Paul Marquess, Peter John Acklam, Reini Urban, Renee Baecker, Ricardo
1668 Signes, Robin Barker, Sawyer X, Scott Lanning, Sergey Aleynikov,
1669 Shirakata Kentaro, Shoichi Kaji, Slaven Rezic, Smylers, Steffen Müller,
1670 Steve Hay, Sullivan Beck, Thomas Sibley, Todd Rinaldo, Tomasz
1671 Konojacki, Tom Hukins, Tom Wyant, Tony Cook, Vitali Peil, Yves Orton,
1672 Zefram.
1673 The list above is almost certainly incomplete as it is automatically
1675 generated from version control history. In particular, it does not
1676 include the names of the (very much appreciated) contributors who
1677 reported issues to the Perl bug tracker.
1678 Many of the changes included in this version originated in the CPAN
1680 modules included in Perl's core. We're grateful to the entire CPAN
1681 community for helping Perl to flourish.
1682 For a more complete list of all of Perl's historical contributors,
1684 please see the AUTHORS file in the Perl source distribution.
1685
1687 If you find what you think is a bug, you might check the perl bug
1688 database at <https://rt.perl.org/> . There may also be information at
1689 <http://www.perl.org/> , the Perl Home Page.
1690 If you believe you have an unreported bug, please run the perlbug
1692 program included with your release. Be sure to trim your bug down to a
1693 tiny but sufficient test case. Your bug report, along with the output
1694 of "perl -V", will be sent off to perlbug@perl.org to be analysed by
1695 the Perl porting team.
1696 If the bug you are reporting has security implications which make it
1698 inappropriate to send to a publicly archived mailing list, then see
1699 "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of
1700 how to report the issue.
1701
1703 If you wish to thank the Perl 5 Porters for the work we had done in
1704 Perl 5, you can do so by running the "perlthanks" program:
1705 perlthanks
1707 This will send an email to the Perl 5 Porters list with your show of
1709 thanks.
1710
1712 The Changes file for an explanation of how to view exhaustive details
1713 on what changed.
1714 The INSTALL file for how to build Perl.
1716 The README file for general stuff.
1718 The Artistic and Copying files for copyright information.
1720perl v5.38.2 2023-11-30 PERL5280DELTA(1)