5 perl5201delta - what is new for perl v5.20.1
9 This document describes differences between the 5.20.0 release and the 5.20.1
12 If you are upgrading from an earlier release such as 5.18.0, first read
13 L<perl5200delta>, which describes differences between 5.18.0 and 5.20.0.
15 =head1 Incompatible Changes
17 There are no changes intentionally incompatible with 5.20.0. If any exist,
18 they are bugs, and we request that you submit a report. See L</Reporting Bugs>
21 =head1 Performance Enhancements
27 An optimization to avoid problems with COW and deliberately overallocated PVs
28 has been disabled because it interfered with another, more important,
29 optimization, causing a slowdown on some platforms.
30 L<[GH #13878]|https://github.com/Perl/perl5/issues/13878>
34 Returning a string from a lexical variable could be slow in some cases. This
36 L<[GH #13880]|https://github.com/Perl/perl5/issues/13880>
40 =head1 Modules and Pragmata
42 =head2 Updated Modules and Pragmata
48 L<Config::Perl::V> has been upgraded from version 0.20 to 0.22.
50 The list of Perl versions covered has been updated and some flaws in the
51 parsing have been fixed.
55 L<Exporter> has been upgraded from version 5.70 to 5.71.
57 Illegal POD syntax in the documentation has been corrected.
61 L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280217.
63 Android builds now link to both B<-lperl> and C<$Config::Config{perllibs}>.
67 L<File::Copy> has been upgraded from version 2.29 to 2.30.
69 The documentation now notes that C<copy> will not overwrite read-only files.
73 L<Module::CoreList> has been upgraded from version 3.11 to 5.020001.
75 The list of Perl versions covered has been updated.
79 The PathTools module collection has been upgraded from version 3.47 to 3.48.
81 Fallbacks are now in place when cross-compiling for Android and
82 C<$Config::Config{sh}> is not yet defined.
83 L<[GH #13872]|https://github.com/Perl/perl5/issues/13872>
87 L<PerlIO::via> has been upgraded from version 0.14 to 0.15.
89 A minor portability improvement has been made to the XS implementation.
93 L<Unicode::UCD> has been upgraded from version 0.57 to 0.58.
95 The documentation includes many clarifications and fixes.
99 L<utf8> has been upgraded from version 1.13 to 1.13_01.
101 The documentation has some minor formatting improvements.
105 L<version> has been upgraded from version 0.9908 to 0.9909.
107 External libraries and Perl may have different ideas of what the locale is.
108 This is problematic when parsing version strings if the locale's numeric
109 separator has been changed. Version parsing has been patched to ensure it
110 handles the locales correctly.
111 L<[GH #13863]|https://github.com/Perl/perl5/issues/13863>
117 =head2 Changes to Existing Documentation
125 C<av_len> - Emphasize that this returns the highest index in the array, not the
127 L<[GH #13377]|https://github.com/Perl/perl5/issues/13377>
131 Note that C<SvSetSV> doesn't do set magic.
135 C<sv_usepvn_flags> - Fix documentation to mention the use of C<NewX> instead of
137 L<[GH #13835]|https://github.com/Perl/perl5/issues/13835>
141 Clarify where C<NUL> may be embedded or is required to terminate a string.
151 Clarify the meaning of C<-B> and C<-T>.
155 C<-l> now notes that it will return false if symlinks aren't supported by the
157 L<[GH #13695]|https://github.com/Perl/perl5/issues/13695>
161 Note that C<each>, C<keys> and C<values> may produce different orderings for
162 tied hashes compared to other perl hashes.
163 L<[GH #13650]|https://github.com/Perl/perl5/issues/13650>
167 Note that C<exec LIST> and C<system LIST> may fall back to the shell on Win32.
168 Only C<exec PROGRAM LIST> and C<system PROGRAM LIST> indirect object syntax
169 will reliably avoid using the shell. This has also been noted in L<perlport>.
170 L<[GH #13907]|https://github.com/Perl/perl5/issues/13907>
174 Clarify the meaning of C<our>.
175 L<[GH #13938]|https://github.com/Perl/perl5/issues/13938>
185 Explain various ways of modifying an existing SV's buffer.
186 L<[GH #12813]|https://github.com/Perl/perl5/issues/12813>
196 We now have a code of conduct for the I<< p5p >> mailing list, as documented in
197 L<< perlpolicy/STANDARDS OF CONDUCT >>.
207 The C</x> modifier has been clarified to note that comments cannot be continued
208 onto the next line by escaping them.
218 Mention the use of empty conditionals in C<for>/C<while> loops for infinite
229 Added a discussion of locale issues in XS code.
235 The following additions or changes have been made to diagnostic output,
236 including warnings and fatal error messages. For the complete list of
237 diagnostic messages, see L<perldiag>.
239 =head2 Changes to Existing Diagnostics
245 L<Variable length lookbehind not implemented in regex mE<sol>%sE<sol>|perldiag/"Variable length lookbehind not implemented in regex m/%s/">
247 Information about Unicode behaviour has been added.
251 =head1 Configuration and Compilation
257 Building Perl no longer writes to the source tree when configured with
258 F<Configure>'s B<-Dmksymlinks> option.
259 L<[GH #13712]|https://github.com/Perl/perl5/issues/13712>
263 =head1 Platform Support
265 =head2 Platform-Specific Notes
271 Build support has been improved for cross-compiling in general and for Android
276 Corrected architectures and version numbers used in configuration hints when
281 B<c99> options have been cleaned up, hints look for B<solstudio> as well as
282 B<SUNWspro>, and support for native C<setenv> has been added.
286 An old bug in feature checking, mainly affecting pre-7.3 systems, has been
291 C<%I64d> is now being used instead of C<%lld> for MinGW.
295 =head1 Internal Changes
301 Added L<perlapi/sync_locale>.
302 Changing the program's locale should be avoided by XS code. Nevertheless,
303 certain non-Perl libraries called from XS, such as C<Gtk> do so. When this
304 happens, Perl needs to be told that the locale has changed. Use this function
305 to do so, before returning to Perl.
309 =head1 Selected Bug Fixes
315 A bug has been fixed where zero-length assertions and code blocks inside of a
316 regex could cause C<pos> to see an incorrect value.
317 L<[GH #14016]|https://github.com/Perl/perl5/issues/14016>
321 Using C<s///e> on tainted utf8 strings could issue bogus "Malformed UTF-8
322 character (unexpected end of string)" warnings. This has now been fixed.
323 L<[GH #13948]|https://github.com/Perl/perl5/issues/13948>
327 C<system> and friends should now work properly on more Android builds.
329 Due to an oversight, the value specified through B<-Dtargetsh> to F<Configure>
330 would end up being ignored by some of the build process. This caused perls
331 cross-compiled for Android to end up with defective versions of C<system>,
332 C<exec> and backticks: the commands would end up looking for F</bin/sh> instead
333 of F</system/bin/sh>, and so would fail for the vast majority of devices,
334 leaving C<$!> as C<ENOENT>.
338 Many issues have been detected by L<Coverity|http://www.coverity.com/> and
343 =head1 Acknowledgements
345 Perl 5.20.1 represents approximately 4 months of development since Perl 5.20.0
346 and contains approximately 12,000 lines of changes across 170 files from 36
349 Excluding auto-generated files, documentation and release tools, there were
350 approximately 2,600 lines of changes to 110 .pm, .t, .c and .h files.
352 Perl continues to flourish into its third decade thanks to a vibrant community
353 of users and developers. The following people are known to have contributed
354 the improvements that became Perl 5.20.1:
356 Aaron Crane, Abigail, Alberto Simões, Alexandr Ciornii, Alexandre (Midnite)
357 Jousset, Andrew Fresh, Andy Dougherty, Brian Fraser, Chris 'BinGOs' Williams,
358 Craig A. Berry, Daniel Dragan, David Golden, David Mitchell, H.Merijn Brand,
359 James E Keenan, Jan Dubois, Jarkko Hietaniemi, John Peacock, kafka, Karen
360 Etheridge, Karl Williamson, Lukas Mai, Matthew Horsfall, Michael Bunk, Peter
361 Martini, Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Shirakata Kentaro,
362 Smylers, Steve Hay, Thomas Sibley, Todd Rinaldo, Tony Cook, Vladimir Marek,
365 The list above is almost certainly incomplete as it is automatically generated
366 from version control history. In particular, it does not include the names of
367 the (very much appreciated) contributors who reported issues to the Perl bug
370 Many of the changes included in this version originated in the CPAN modules
371 included in Perl's core. We're grateful to the entire CPAN community for
372 helping Perl to flourish.
374 For a more complete list of all of Perl's historical contributors, please see
375 the F<AUTHORS> file in the Perl source distribution.
377 =head1 Reporting Bugs
379 If you find what you think is a bug, you might check the articles recently
380 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
381 https://rt.perl.org/ . There may also be information at http://www.perl.org/ ,
384 If you believe you have an unreported bug, please run the L<perlbug> program
385 included with your release. Be sure to trim your bug down to a tiny but
386 sufficient test case. Your bug report, along with the output of C<perl -V>,
387 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
389 If the bug you are reporting has security implications, which make it
390 inappropriate to send to a publicly archived mailing list, then please send it
391 to perl5-security-report@perl.org. This points to a closed subscription
392 unarchived mailing list, which includes all the core committers, who will be
393 able to help assess the impact of issues, figure out a resolution, and help
394 co-ordinate the release of patches to mitigate or fix the problem across all
395 platforms on which Perl is supported. Please only use this address for
396 security issues in the Perl core, not for modules independently distributed on
401 The F<Changes> file for an explanation of how to view exhaustive details on
404 The F<INSTALL> file for how to build Perl.
406 The F<README> file for general stuff.
408 The F<Artistic> and F<Copying> files for copyright information.