NAME

DESCRIPTION

If you are upgrading from an earlier release such as 5.10.1, first read perl5120delta, which describes differences between 5.10.0 and 5.12.0.

Incompatible Changes

Core Enhancements

Modules and Pragmata

Changes to Existing Documentation

• We added the new maintenance release policy to perlpolicy
• We've clarified the multiple-angle-bracket construct in the spec for POD in perlpodspec
• We added a missing explanation for a warning about ":=" to perldiag
• We removed a false claim in perlunitut that all text strings are Unicode strings in Perl.
• We updated the GitHub mirror link in perlrepository to mirrors/perl, not github/perl
• We fixed a minor error in perl5114delta.
• We replaced a mention of the now-obsolete Switch with given/when.
• We improved documentation about $sitelibexp/sitecustomize.pl in perlrun.
• We corrected perlmodlib which had unintentionally omitted a number of modules.
• We updated the documentation for 'require' in perlfunc relating to putting Perl code in @INC.
• We reinstated some erroneously-removed documentation about quotemeta in perlfunc.
• We fixed an a2p example in perlutil.
• We filled in a blank in perlport with the release date of Perl 5.12.
• We fixed broken links in a number of perldelta files.
• The documentation for Carp incorrectly stated that the $Carp::Verbose variable makes cluck generate stack backtraces.
• We fixed a number of typos in Pod::Functions
• We improved documentation of case-changing functions in perlfunc
• We corrected perlgpl to contain the correct version of the GNU General Public License.

Testing

Installation and Configuration Improvements

Bug Fixes

• A bug in how we process filetest operations could cause a segfault. Filetests don't always expect an op on the stack, so we now use TOPs only if we're sure that we're not stat'ing the _ filehandle. This is indicated by OPf_KIDS (as checked in ck_ftst).

  See also: <https://github.com/Perl/perl5/issues/10335>

• When deparsing a nextstate op that has both a change of package (relative to the previous nextstate) and a label, the package declaration is now emitted first, because it is syntactically impermissible for a label to prefix a package declaration.
• XSUB.h now correctly redefines fgets under PERL_IMPLICIT_SYS

  See also: <http://rt.cpan.org/Public/Bug/Display.html?id=55049>

• utf8::is_utf8 now respects GMAGIC (e.g. $1)
• XS code using "fputc()" or "fputs()": on Windows could cause an error due to their arguments being swapped.

  See also: <https://github.com/Perl/perl5/issues/10156>

• We fixed a small bug in lex_stuff_pvn() that caused spurious syntax errors in an obscure situation. It happened when stuffing was performed on the last line of a file and the line ended with a statement that lacked a terminating semicolon.

  See also: <https://github.com/Perl/perl5/issues/10273>

• We fixed a bug that could cause \N{} constructs followed by a single . to be parsed incorrectly.

  See also: <https://github.com/Perl/perl5/issues/10367>

• We fixed a bug that caused when(scalar) without an argument not to be treated as a syntax error.

  See also: <https://github.com/Perl/perl5/issues/10287>

• We fixed a regression in the handling of labels immediately before string evals that was introduced in Perl 5.12.0.

  See also: <https://github.com/Perl/perl5/issues/10301>

• We fixed a regression in case-insensitive matching of folded characters in regular expressions introduced in Perl 5.10.1.

  See also: <https://github.com/Perl/perl5/issues/10193>

Platform Specific Notes

Known Problems

• "List::Util::first" misbehaves in the presence of a lexical $_ (typically introduced by "my $_" or implicitly by "given"). The variable which gets set for each iteration is the package variable $_, not the lexical $_.

  A similar issue may occur in other modules that provide functions which take a block as their first argument, like

      foo { ... $_ ...} list
      

  See also: <https://github.com/Perl/perl5/issues/9798>

• "Module::Load::Conditional" and "version" have an unfortunate interaction which can cause "CPANPLUS" to crash when it encounters an unparseable version string. Upgrading to "CPANPLUS" 0.9004 or "Module::Load::Conditional" 0.38 from CPAN will resolve this issue.

Acknowledgements

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.12.1:

AEvar Arnfjoerd` Bjarmason, Chris Williams, chromatic, Craig A. Berry, David Golden, Father Chrysostomos, Florian Ragwitz, Frank Wiegand, Gene Sullivan, Goro Fuji, H.Merijn Brand, James E Keenan, Jan Dubois, Jesse Vincent, Josh ben Jore, Karl Williamson, Leon Brocard, Michael Schwern, Nga Tang Chan, Nicholas Clark, Niko Tyni, Philippe Bruhat, Rafael Garcia-Suarez, Ricardo Signes, Steffen Mueller, Todd Rinaldo, Vincent Pit and Zefram.

Reporting Bugs

If you believe you have an unreported bug, please run the perlbug 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 "perl -V", 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.

SEE ALSO

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.