=encoding utf8 =head1 NAME [ this is a template for a new perldelta file. Any text flagged as XXX needs to be processed before release. ] perldelta - what is new for perl v5.21.1 =head1 DESCRIPTION This document describes differences between the 5.21.0 release and the 5.21.1 release. If you are upgrading from an earlier release such as 5.20.0, first read L, which describes differences between 5.20.0 and 5.21.0. =head1 Notice XXX Any important notices here =head1 Core Enhancements XXX New core language features go here. Summarize user-visible core language enhancements. Particularly prominent performance optimisations could go here, but most should go in the L section. [ List each enhancement as a =head2 entry ] =head2 Experimental C Backtrace API Starting from Perl 5.21.1, on some platforms Perl supports retrieving the C level backtrace (similar to what symbolic debuggers like gdb do). The backtrace returns the stack trace of the C call frames, with the symbol names (function names), the object names (like "perl"), and if it can, also the source code locations (file:line). The supported platforms are Linux and OS X (some *BSD might work at least partly, but they have not yet been tested). The feature needs to be enabled with C. Also included is a C API to retrieve backtraces. See L for more information. =head2 C now ignores any Unicode pattern white space The C regular expression modifier allows the pattern to contain white space and comments, both of which are ignored, for improved readability. Until now, not all the white space characters that Unicode designates for this purpose were handled. The additional ones now recognized are U+0085 NEXT LINE, U+200E LEFT-TO-RIGHT MARK, U+200F RIGHT-TO-LEFT MARK, U+2028 LINE SEPARATOR, and U+2029 PARAGRAPH SEPARATOR. =head2 S> can restrict which locale categories are affected It is now possible to pass a parameter to S> to specify a subset of locale categories to be locale-aware, with the remaining ones unaffected. See L for details. =head1 Security XXX Any security-related notices go here. In particular, any security vulnerabilities closed should be noted here rather than in the L section. [ List each security issue as a =head2 entry ] =head1 Incompatible Changes XXX For a release on a stable branch, this section aspires to be: There are no changes intentionally incompatible with 5.XXX.XXX If any exist, they are bugs, and we request that you submit a report. See L below. =head2 C<\N{}> with a sequence of multiple spaces is now a fatal error. This has been deprecated since v5.18. =head2 In double-quotish C<\cI>, I must now be a printable ASCII character In prior releases, failure to do this raised a deprecation warning. =head2 Splitting the tokens C<(?> and C<(*> in regular expressions is now a fatal compilation error. These had been deprecated since v5.18. =head2 5 additional characters are treated as white space under C in regex patterns (unless escaped) The use of these characters with C outside bracketed character classes and when not preceeded by a backslash has raised a deprecation warning since v5.18. Now they will be ignored. See LfooEx> for the list of the five characters. =head2 Comment lines within S> now are ended only by a C<\n> S> is an experimental feature, introduced in v5.18. It operates as if C is always enabled. But there was a difference, comment lines (following a C<#> character) were terminated by anything matching C<\R> which includes all vertical whitespace, such as form feeds. For consistency, this is now changed to match what terminates comment lines outside S>, namely a C<\n> (even if escaped), which is the same as what terminates a heredoc string and formats. =head2 Omitting % and @ on hash and array names is no longer permitted Really old Perl let you omit the @ on array names and the % on hash names in some spots. This has issued a deprecation warning since Perl 5.0, and is no longer permitted. =head2 C<"$!"> text is now in English outside C<"use locale"> scope Previously, the text, unlike almost everything else, always came out based on the current underlying locale of the program. (Also affected on some systems is C<"$^E>".) For programs that are unprepared to handle locale, this can cause garbage text to be displayed. It's better to display text that is translatable via some tool than garbage text which is much harder to figure out. =head2 C<"$!"> text will be returned in UTF-8 when appropriate The stringification of C<$!> and C<$^E> will have the UTF-8 flag set when the text is actually non-ASCII UTF-8. This will enable programs that are set up to be locale-aware to properly output messages in the user's native language. Code that needs to continue the 5.20 and earlier behavior can do the stringification within the scopes of both 'use bytes' and 'use locale ":messages". No other Perl operations will be affected by locale; only C<$!> and C<$^E> stringification. The 'bytes' pragma causes the UTF-8 flag to not be set, just as in previous Perl releases. This resolves [perl #112208]. =head1 Deprecations XXX Any deprecated features, syntax, modules etc. should be listed here. =head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now deprecated This non-graphic character is essentially indistinguishable from a regular space, and so should not be allowed. See L. =head2 Module removals XXX Remove this section if inapplicable. The following modules will be removed from the core distribution in a future release, and will at that time need to be installed from CPAN. Distributions on CPAN which require these modules will need to list them as prerequisites. The core versions of these modules will now issue C<"deprecated">-category warnings to alert you to this fact. To silence these deprecation warnings, install the modules in question from CPAN. Note that these are (with rare exceptions) fine modules that you are encouraged to continue to use. Their disinclusion from core primarily hinges on their necessity to bootstrapping a fully functional, CPAN-capable Perl installation, not usually on concerns over their design. =over =item XXX XXX Note that deprecated modules should be listed here even if they are listed as an updated module in the L section. =back [ List each other deprecation as a =head2 entry ] =head1 Performance Enhancements XXX Changes which enhance performance without changing behaviour go here. There may well be none in a stable release. [ List each enhancement as a =item entry ] =over 4 =item * Many internal functions have been refactored to improve performance and reduce their memory footprints. L<[perl #121436]|https://rt.perl.org/Ticket/Display.html?id=121436> L<[perl #121906]|https://rt.perl.org/Ticket/Display.html?id=121906> L<[perl #121969]|https://rt.perl.org/Ticket/Display.html?id=121969> =item * C<-T> and C<-B> filetests will return sooner when an empty file is detected. L =back =head1 Modules and Pragmata XXX All changes to installed files in F, F, F and F go here. If Module::CoreList is updated, generate an initial draft of the following sections using F. A paragraph summary for important changes should then be added by hand. In an ideal world, dual-life modules would have a F file that could be cribbed. [ Within each section, list entries as a =item entry ] =head2 New Modules and Pragmata =over 4 =item * XXX =back =head2 Updated Modules and Pragmata =over 4 =item * L has been upgraded from version 1.3301 to 1.34. Carp::Heavy now ignores version mismatches with Carp if Carp is newer than 1.12, since Carp::Heavy's guts were merged into Carp at that point. L<[perl #121574]|https://rt.perl.org/Ticket/Display.html?id=121574> =item * L has been upgraded from version 2.151 to 2.152. Changes to resolve Coverity issues. XS dumps incorrectly stored the name of code references stored in a GLOB. L<[perl #122070]|https://rt.perl.org/Ticket/Display.html?id=122070> =item * L has been upgraded from version 2.60_01 to 2.62. B now has better error handling when the encoding name is nonexistent, and a build breakage when upgrading L in perl-5.8.2 and earlier has been fixed. =item * L has been upgraded from version 0.16 to 0.17. Minor bug fixes and documentation fixes to Hash::Util::hash_stats() =item * The libnet collection of modules has been upgraded from version 1.25 to 1.27. There are only whitespace changes to the installed files. =item * The Locale-Codes collection of modules has been upgraded from vesion 3.30 to 3.31. Fixed a bug in the scripts used to extract data from spreadsheets that prevented the SHP currency code from being found. L<[cpan #94229]|https://rt.cpan.org/Ticket/Display.html?id=94229> =item * L has been upgraded from version 1.9993 to 1.9994. Synchronize POD changes from the CPAN release. C<< Math::BigFloat->blog(x) >> would sometimes return blog(2*x) when the accuracy was greater than 70 digits. The result of C<< Math::BigFloat->bdiv() >> in list context now satisfies C<< x = quotient * divisor + remainder >>. =item * L has been upgraded from version 0.2606 to 0.2607. Synchronize POD changes from the CPAN release. =item * L has been upgraded from version 1.000022 to 1.000024. Support installations on older perls with an L earlier than 6.63_03 =item * L has been upgraded from version 1.09 to 1.10. =item * L has been upgraded from version 1.44 to 1.45. fork() in the debugger under C will now create a new window for the forked process. L<[perl #121333]|https://rt.perl.org/Ticket/Display.html?id=121333> The debugger now saves the current working directory on startup and restores it when you restart your program with C or . L<[perl #121509]|https://rt.perl.org/Ticket/Display.html?id=121509> =item * L has been upgraded from version 0.18 to 0.19. No changes in behaviour. =item * L has been upgraded from version 0.012 to 0.013. No changes in behaviour. =item * L has been upgraded from version 0.18 to 0.19. No changes in behaviour. =item * L has been upgraded from version 1.04 to 1.07. Version 0.67's improved discontiguous contractions is invalidated by default and is supported as a parameter 'long_contraction'. =item * L has been upgraded from version 1.17 to 1.18. The XSUB implementation has been removed in favour of pure Perl. =item * A mismatch between the documentation and the code in utf8::downgrade() was fixed in favour of the documentation. The optional second argument is now correctly treated as a perl boolean (true/false semantics) and not as an integer. =back =head2 Removed Modules and Pragmata =over 4 =item * XXX =back =head1 Documentation XXX Changes to files in F go here. Consider grouping entries by file and be sure to link to the appropriate page, e.g. L. =head2 New Documentation XXX Changes which create B files in F go here. =head3 L XXX Description of the purpose of the new file here =head2 Changes to Existing Documentation XXX Changes which significantly change existing files in F go here. However, any changes to F should go in the L section. =head3 L =over 4 =item * C<-l> now notes that it will return false if symlinks aren't supported by the file system. L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523> =item * Note that C and C may fall back to the shell on Win32. Only C and C indirect object syntax will reliably avoid using the shell. This has also been noted in L. L<[perl #122046]|https://rt.perl.org/Ticket/Display.html?id=122046> =back =head3 L =over 4 =item * C - Fix documentation to mention the use of C instead of C. L<[perl #121869]|https://rt.perl.org/Ticket/Display.html?id=121869> =item * Clarify where C may be embedded or is required to terminate a string. =item * Previously missing documentation due to formatting errors are now included. =item * Entries are now organized into groups rather than by file where they are found. =item * Alphabetical sorting of entries is now handled by the POD generator to make entries easier to find when scanning. =back =head3 L =over 4 =item * Updated documentation for the C C target. L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431> =back =head3 L =over 4 =item * The C modifier has been clarified to note that comments cannot be continued onto the next line by escaping them. =back =head3 L =over 4 =item * The documentation includes many clarifications and fixes. =back =head1 Diagnostics The following additions or changes have been made to diagnostic output, including warnings and fatal error messages. For the complete list of diagnostic messages, see L. XXX New or changed warnings emitted by the core's C code go here. Also include any changes in L that reconcile it to the C code. =head2 New Diagnostics XXX Newly added diagnostic messages go under here, separated into New Errors and New Warnings =head3 New Errors =over 4 =item * XXX L =back =head3 New Warnings =over 4 =item * L: (S experimental::win32_perlio) The C<:win32> PerlIO layer is experimental. If you want to take the risk of using this layer, simply disable this warning: no warnings "experimental::win32_perlio"; =back =head2 Changes to Existing Diagnostics XXX Changes (i.e. rewording) of diagnostic messages go here =over 4 =item * <> should be quotes This warning has been changed to L<< <> at require-statement should be quotes|perldiag/"<> at require-statement should be quotes" >> to make the issue more identifiable. =item * L This warning is now only produced when the newline is at the end of the filename. =back =head1 Utility Changes XXX Changes to installed programs such as F and F go here. Most of these are built within the directory F. [ List utility changes as a =head2 entry for each utility and =item entries for each change Use L with program names to get proper documentation linking. ] =head2 F =over 4 =item * The F directory has been removed from the Perl core. This removes find2perl, s2p and a2p. They have all been released to CPAN as separate distributions (App::find2perl, App::s2p, App::a2p). =back =head1 Configuration and Compilation XXX Changes to F, F, F, and analogous tools go here. Any other changes to the Perl build process should be listed here. However, any platform-specific changes should be listed in the L section, instead. [ List changes as a =item entry ]. =over 4 =item * C now supports parallel testing. For example: TEST_JOBS=9 make test.valgrind See L for more information. L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431> =back =head1 Testing XXX Any significant changes to the testing of a freshly built perl should be listed here. Changes which create B files in F go here as do any large changes to the testing harness (e.g. when parallel testing was added). Changes to existing files in F aren't worth summarizing, although the bugs that they represent may be covered elsewhere. [ List each test improvement as a =item entry ] =over 4 =item * XXX =back =head1 Platform Support XXX Any changes to platform support should be listed in the sections below. [ Within the sections, list each platform as a =item entry with specific changes as paragraphs below it. ] =head2 New Platforms XXX List any platforms that this version of perl compiles on, that previous versions did not. These will either be enabled by new files in the F directories, or new subdirectories and F files at the top level of the source tree. =over 4 =item XXX-some-platform XXX =back =head2 Discontinued Platforms XXX List any platforms that this version of perl no longer compiles on. =over 4 =item NeXTSTEP/OPENSTEP NeXTSTEP was proprietary OS bundled with NeXT's workstations in the early to mid 90's; OPENSTEP was an API specification that provided a NeXTSTEP-like environment on a non-NeXTSTEP system. Both are now long dead, so support for building Perl on them has been removed. =back =head2 Platform-Specific Notes XXX List any changes for specific platforms. This could include configuration and compilation changes or changes in portability/compatibility. However, changes within modules for platforms should generally be listed in the L section. =over 4 =item XXX-some-platform XXX =item OpenBSD On OpenBSD, Perl will now default to using the system C due to the security features it provides. Perl's own malloc wrapper has been in use since v5.14 due to performance reasons, but the OpenBSD project believes the tradeoff is worth it and would prefer that users who need the speed specifically ask for it. L<[perl #122000]|https://rt.perl.org/Ticket/Display.html?id=122000>. =back =head1 Internal Changes XXX Changes which affect the interface available to C code go here. Other significant internal changes for future core maintainers should be noted as well. =over 4 =item * The deprecated variable C has been removed. =item * Perl now tries to keep the locale category C set to "C" except around operations that need it to be set to the program's underlying locale. This protects the many XS modules that cannot cope with the decimal radix character not being a dot. Prior to this release, Perl initialized this category to "C", but a call to C would change it. Now such a call will change the underlying locale of the C category for the program, but the locale exposed to XS code will remain "C". There is an API under development for those relatively few modules that need to use the underlying locale. This API will be nailed down during the course of developing v5.21. Send email to L for guidance. =back =head1 Selected Bug Fixes XXX Important bug fixes in the core language are summarized here. Bug fixes in files in F and F are best summarized in L. [ List each fix as a =item entry ] =over 4 =item * index() and rindex() no longer crash when used on strings over 2GB in size. L<[perl #121562]|https://rt.perl.org/Ticket/Display.html?id=121562>. =item * A small previously intentional memory leak in PERL_SYS_INIT/PERL_SYS_INIT3 on Win32 builds was fixed. This might affect embedders who repeatedly create and destroy perl engines within the same process. =item * C now returns the data for the program's underlying locale even when called from outside the scope of S>. =item * C now works properly on platforms which don't have C and/or C, or for which Perl has been compiled to disregard either or both of these locale categories. In such circumstances, there are now no entries for the corresponding values in the hash returned by C. =item * C now marks appropriately the values it returns as UTF-8 or not. Previously they were always returned as a bytes, even if they were supposed to be encoded as UTF-8. =item * On Microsoft Windows, within the scope of C>, the following POSIX character classes gave results for many locales that did not conform to the POSIX standard: C<[[:alnum:]]>, C<[[:alpha:]]>, C<[[:blank:]]>, C<[[:digit:]]>, C<[[:graph:]]>, C<[[:lower:]]>, C<[[:print:]]>, C<[[:punct:]]>, C<[[:upper:]]>, C<[[:word:]]>, and C<[[:xdigit:]]>. These are because the underlying Microsoft implementation does not follow the standard. Perl now takes special precautions to correct for this. =item * Many issues have been detected by L and fixed. =item * system() and friends should now work properly on more Android builds. Due to an oversight, the value specified through -Dtargetsh to Configure would end up being ignored by some of the build process. This caused perls cross-compiled for Android to end up with defective versions of system(), exec() and backticks: the commands would end up looking for C instead of C, and so would fail for the vast majority of devices, leaving C<$!> as C. =back =head1 Known Problems XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any tests that had to be Ced for the release would be noted here. Unfixed platform specific bugs also go here. [ List each fix as a =item entry ] =over 4 =item * XXX =back =head1 Errata From Previous Releases =over 4 =item * XXX Add anything here that we forgot to add, or were mistaken about, in the perldelta of a previous release. =back =head1 Obituary XXX If any significant core contributor has died, we've added a short obituary here. =head1 Acknowledgements XXX Generate this with: perl Porting/acknowledgements.pl v5.21.1..HEAD =head1 Reporting Bugs If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at https://rt.perl.org/ . There may also be information at http://www.perl.org/ , the Perl Home Page. If you believe you have an unreported bug, please run the L program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of C, will be sent off to perlbug@perl.org to be analysed by the Perl porting team. If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who will be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN. =head1 SEE ALSO The F file for an explanation of how to view exhaustive details on what changed. The F file for how to build Perl. The F file for general stuff. The F and F files for copyright information. =cut