=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 v5.23.1 =head1 DESCRIPTION This document describes differences between the 5.23.0 release and the 5.23.1 release. If you are upgrading from an earlier release such as 5.22.0, first read L, which describes differences between 5.22.0 and 5.23.0. =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 Integer shift (C<< << >> and C<< >> >>) now explicitly defined Negative shifts are reverse shifts: left shift becomes right shift, and right shift becomes left shift. Shifting by the number of bits in a native integer (or more) is zero, except when the "overshift" is right shifting a negative value under C, in which case the result is -1 (arithmetic shift). Until now negative shifting and overshifting have been undefined because they have relied on whatever the C implementation happens to do. For example, for the "overshift" a common behavior C is "modulo shift": 1 >> 64 == 1 >> (64 % 64) == 1 >> 0 == 1 # Common C behavior. # And the same for <<, while Perl now produces 0 for both. Now these behaviors are well-defined under Perl, regardless of what the underlying C implementation does. Note, however, that you cannot escape the native integer width. If you need more bits on the left shift, you could use the C pragma. =head2 Postfix dereferencing is no longer experimental Using the C and C features no longer emits a warning. Existing code that disables the C warning category that they previously used will continue to work. The C feature has no effect; all Perl code can use postfix dereferencing, regardless of what feature declarations are in scope. The C<5.24> feature bundle now includes the C feature. =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 =head2 ASCII characters in variable names must now be all visible It was legal until now on ASCII platforms for variable names to contain non-graphical ASCII control characters (ordinals 0 through 31, and 127, which are the C0 controls and C). This usage has been deprecated since v5.20, and as of now causes a syntax error. The variables these names referred to are special, reserved by Perl for whatever use it may choose, now, or in the future. Each such variable has an alternative way of spelling it. Instead of the single non-graphic control character, a two character sequence beginning with a caret is used, like C<$^]> and C<${^GLOBAL_PHASE}>. Details are at L. It remains legal, though unwise and deprecated (raising a deprecation warning), to use certain non-graphic non-ASCII characters in variables names when not under S>. No code should do this, as all such variables are reserved by Perl, and Perl doesn't currently define any of them (but could at any time, without notice). =head2 The C feature has been removed The experimental C feature (which allowed calling C, C, C, C, C, C, C, and C on a scalar argument) has been deemed unsuccessful. It has now been removed; trying to use the feature (or to disable the C warning it previously triggered) now yields an exception. =head1 Deprecations XXX Any deprecated features, syntax, modules etc. should be listed here. =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 * XXX =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 2.28 to 2.29. =item * L has been upgraded from version 1.18 to 1.19. If a Perl exception was thrown from inside this module, the exception C threw to the callers of C would have an irrelevant message derived from C<$!> which was in an undefined state, instead of the C<$@> message which triggers the failure path inside C. =item * L has been upgraded from version 1.12 to 1.14. =item * L has been upgraded from version 1.18 to 1.19. =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 * XXX Description of the change here =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 * XXX L =back =head2 Changes to Existing Diagnostics XXX Changes (i.e. rewording) of diagnostic messages go here =over 4 =item * XXX Describe change here =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 L =over 4 =item * XXX =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 * XXX =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 XXX-some-platform XXX =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 VMS =over =item * The minimum supported version of VMS is now v7.3-2, released in 2003. As a side effect of this change, VAX is no longer supported as the terminal release of OpenVMS VAX was v7.3 in 2001. =back =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. [ List each change as a =item entry ] =over 4 =item * XXX =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 * A leak in the XS typemap caused one scalar to be leaked each time a C or a C was Ced or imported to Perl, since perl 5.000. These particular typemap entries are thought to be extremely rarely used by XS modules. [perl #124181] =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 v5.23.1..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 L . There may also be information at L , 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