5 perl5256delta - what is new for perl v5.25.6
9 This document describes differences between the 5.25.5 release and the 5.25.6
12 If you are upgrading from an earlier release such as 5.25.4, first read
13 L<perl5255delta>, which describes differences between 5.25.4 and 5.25.5.
15 =head1 Performance Enhancements
21 Converting a single-digit string to a number is now substantially faster.
25 The internal op implementing the C<split> builtin has been simplified and
26 sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
27 to do its work. Secondly, code of the form C<my @x = split(...)> is now
28 optimised in the same way as C<@x = split(...)>, and is therefore a few
33 =head1 Modules and Pragmata
35 =head2 Updated Modules and Pragmata
41 L<Archive::Tar> has been upgraded from version 2.10 to 2.14.
45 L<attributes> has been upgraded from version 0.27 to 0.28.
49 L<B> has been upgraded from version 1.63 to 1.64.
53 L<B::Concise> has been upgraded from version 0.998 to 0.999.
55 Its output is now more descriptive for C<op_private> flags.
59 L<B::Deparse> has been upgraded from version 1.38 to 1.39.
63 L<Data::Dumper> has been upgraded from version 2.161 to 2.162.
67 L<Devel::Peek> has been upgraded from version 1.24 to 1.25.
71 L<HTTP::Tiny> has been upgraded from version 0.064 to 0.070.
73 Internal 599-series errors now include the redirect history.
77 L<List::Util> has been upgraded from version 1.45_01 to 1.46.
81 L<Module::CoreList> has been upgraded from version 5.20160920 to 5.20161020.
85 L<mro> has been upgraded from version 1.18 to 1.19.
89 L<Net::Ping> has been upgraded from version 2.44 to 2.51.
91 IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
96 L<Opcode> has been upgraded from version 1.37 to 1.38.
100 L<overload> has been upgraded from version 1.26 to 1.27.
102 Its compilation speed has been improved slightly.
106 L<parent> has been upgraded from version 0.234 to 0.236.
110 L<PerlIO::encoding> has been upgraded from version 0.24 to 0.25.
114 podlators has been upgraded from version 4.07 to 4.08.
118 L<POSIX> has been upgraded from version 1.72 to 1.73.
122 L<Scalar::Util> has been upgraded from version 1.45_01 to 1.46.
126 L<Storable> has been upgraded from version 2.57 to 2.58.
130 L<Test::Simple> has been upgraded from version 1.302056 to 1.302059.
134 L<Time::HiRes> has been upgraded from version 1.9739 to 1.9740_01.
136 It now builds on systems with C++11 compilers (such as G++ 6 and Clang++
141 L<VMS::Stdio> has been upgraded from version 2.41 to 2.42.
147 The following additions or changes have been made to diagnostic output,
148 including warnings and fatal error messages. For the complete list of
149 diagnostic messages, see L<perldiag>.
151 =head2 New Diagnostics
159 Using the empty pattern (which re-executes the last successfully-matched
160 pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
161 always previously yielded a segfault. It now produces an error: L<Use of the
162 empty pattern inside of a regex code block is forbidden|perldiag/"Use of the
163 empty pattern inside of a regex code block is forbidden">.
167 =head2 Changes to Existing Diagnostics
173 Details as to the exact problem have been added to the diagnostics that
174 occur when malformed UTF-8 is encountered when trying to convert to a
179 Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
180 blames the variable for an uninitialized-value warning encountered by the
185 =head1 Configuration and Compilation
191 Builds using C<USE_PAD_RESET> now work again; this configuration had
202 Some parts of the test suite that try to exhaustively test edge cases in the
203 regex implementation have been restricted to running for a maximum of five
204 minutes. On slow systems they could otherwise take several hours, without
205 significantly improving our understanding of the correctness of the code
208 In addition, some of those test cases have been split into more files, to
209 allow them to be run in parallel on suitable systems.
213 A new internal facility allows analysing the time taken by the individual
214 tests in Perl's own test suite; see F<Porting/harness-timer-report.pl>.
218 =head1 Platform Support
226 Perl now compiles under NetBSD on VAX machines. However, it's not
227 possible for that platform to implement floating-point infinities and
228 NaNs compatibly with most modern systems, which implement the IEEE-754
229 floating point standard. The hexadecimal floating point (C<0x...p[+-]n>
230 literals, C<printf %a>) is not implemented, either.
231 The C<make test> passes 98% of tests.
235 =head1 Internal Changes
241 The C<PADOFFSET> type has changed from being unsigned to signed, and
242 several pad-related variables such as C<PL_padix> have changed from being
243 of type C<I32> to type C<PADOFFSET>.
247 The function C<L<perlapi/utf8n_to_uvchr>> has been changed to not
248 abandon searching for other malformations when the first one is
249 encountered. A call to it thus can generate multiple diagnostics,
254 A new function, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
255 use by modules that need to know the details of UTF-8 malformations
256 beyond pass/fail. Previously, the only ways to know why a sequence was
257 ill-formed was to capture and parse the generated diagnostics, or to do
262 Several new functions for handling Unicode have been added to the API:
263 C<L<perlapi/is_strict_utf8_string>>,
264 C<L<perlapi/is_c9strict_utf8_string>>,
265 C<L<perlapi/is_utf8_string_flags>>,
266 C<L<perlapi/is_strict_utf8_string_loc>>,
267 C<L<perlapi/is_strict_utf8_string_loclen>>,
268 C<L<perlapi/is_c9strict_utf8_string_loc>>,
269 C<L<perlapi/is_c9strict_utf8_string_loclen>>,
270 C<L<perlapi/is_utf8_string_loc_flags>>,
271 C<L<perlapi/is_utf8_string_loclen_flags>>,
272 C<L<perlapi/is_utf8_fixed_width_buf_flags>>,
273 C<L<perlapi/is_utf8_fixed_width_buf_loc_flags>>,
274 C<L<perlapi/is_utf8_fixed_width_buf_loclen_flags>>.
276 These functions are all extensions of the C<is_utf8_string_*()> functions,
277 that apply various restrictions to the UTF-8 recognized as valid.
281 A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
282 length and allocated size of the buffer in an C<SV>, growing the buffer if
287 A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
288 like Perl-space C<$x = ''>, but with several optimisations.
292 All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
293 previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
294 that several parts of the internals had to be special-cased to accommodate
295 it. This oddity's original motivation was to handle code like C<$x ||= 1>;
296 that is now handled in a simpler way.
300 Several new internal C macros have been added that take a string literal as
301 arguments, alongside existing routines that take the equivalent value as two
302 arguments, a character pointer and a length. The advantage of this is that
303 the length of the string is calculated automatically, rather than having to
304 be done manually. These routines are now used where appropriate across the
309 The code in F<gv.c> that determines whether a variable has a special meaning
310 to Perl has been simplified.
314 The C<DEBUGGING>-mode output for regex compilation and execution has been
319 =head1 Selected Bug Fixes
325 A sub containing a "forward" declaration with the same name (e.g.,
326 C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
331 A crash in executing a regex with a floating UTF-8 substring against a
332 target string that also used UTF-8 has been fixed. [perl #129350]
336 Previously, a shebang line like C<#!perl -i u> could be erroneously
337 interpreted as requesting the C<-u> option. This has been fixed. [perl
342 The regex engine was previously producing incorrect results in some rare
343 situations when backtracking past a trie that matches only one thing; this
344 showed up as capture buffers (C<$1>, C<$2>, etc) erroneously containing data
345 from regex execution paths that weren't actually executed for the final
346 match. [perl #129897]
350 Certain regexes making use of the experimental C<regex_sets> feature could
351 trigger an assertion failure. This has been fixed. [perl #129322]
355 =head1 Acknowledgements
357 Perl 5.25.6 represents approximately 4 weeks of development since Perl 5.25.5
358 and contains approximately 16,000 lines of changes across 300 files from 23
361 Excluding auto-generated files, documentation and release tools, there were
362 approximately 10,000 lines of changes to 190 .pm, .t, .c and .h files.
364 Perl continues to flourish into its third decade thanks to a vibrant community
365 of users and developers. The following people are known to have contributed the
366 improvements that became Perl 5.25.6:
368 Aaron Crane, Andy Lester, Chris 'BinGOs' Williams, Dagfinn Ilmari Mannsåker,
369 Dan Collins, David Mitchell, François Perrad, Hugo van der Sanden, James E
370 Keenan, James Raspass, Jarkko Hietaniemi, Karl Williamson, Lukas Mai, Nicolas
371 R., Reini Urban, Sawyer X, Sergey Aleynikov, Stevan Little, Steve Hay, Steven
372 Humphrey, Thomas Sibley, Tony Cook, Yves Orton.
374 The list above is almost certainly incomplete as it is automatically generated
375 from version control history. In particular, it does not include the names of
376 the (very much appreciated) contributors who reported issues to the Perl bug
379 Many of the changes included in this version originated in the CPAN modules
380 included in Perl's core. We're grateful to the entire CPAN community for
381 helping Perl to flourish.
383 For a more complete list of all of Perl's historical contributors, please see
384 the F<AUTHORS> file in the Perl source distribution.
386 =head1 Reporting Bugs
388 If you find what you think is a bug, you might check the perl bug database
389 at L<https://rt.perl.org/> . There may also be information at
390 L<http://www.perl.org/> , the Perl Home Page.
392 If you believe you have an unreported bug, please run the L<perlbug> program
393 included with your release. Be sure to trim your bug down to a tiny but
394 sufficient test case. Your bug report, along with the output of C<perl -V>,
395 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
397 If the bug you are reporting has security implications which make it
398 inappropriate to send to a publicly archived mailing list, then see
399 L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
400 for details of how to report the issue.
404 The F<Changes> file for an explanation of how to view exhaustive details on
407 The F<INSTALL> file for how to build Perl.
409 The F<README> file for general stuff.
411 The F<Artistic> and F<Copying> files for copyright information.