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Perl 5 version 12.5 documentation
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perl5115delta - what is new for perl v5.11.5


This document describes differences between the 5.11.4 release and the 5.11.5 release.

If you are upgrading from an earlier release such as 5.11.3, first read perl5114delta, which describes differences between 5.11.3 and 5.11.4.

Core Enhancements

32-bit limit on substr arguments removed

The 32-bit limit on substr arguments has now been removed. The full range of the system's signed and unsigned integers is now available for the pos and len arguments.

Modules and Pragmata

Pragmata Changes

  • version

    Upgraded from version 0.81 to 0.82.

    The is_lax and is_strict functions can now be optionally exported to the caller's namespace and are also now documented.

    Undefined version objects are now uninitialized with zero rather than undef.

Updated Modules

  • B::Debug

    Upgraded from version 1.11 to 1.12.

  • CPAN

    Upgraded from version 1.94_53 to 1.94_56.

    This resolves RT #72362, in which CPAN was ignoring configure_requires , and RT #72348, in which the command o conf init in the CPAN shell could cause an exception to be thrown.

    This module is also now built in a less specialized way, which resolves a problem that caused make after make clean to fail, fixing RT #72218.

  • CPANPLUS::Dist::Build

    Upgraded from version 0.44 to 0.46.

    This makes the prereq resolving fall back to _build/ querying if the prereq_data action fails.

  • Pod::Perldoc

    Upgraded from version 3.15_01 to 3.15_02.

  • Pod::Plainer

    Upgraded from version 1.01 to 1.02.

  • Safe

    Upgraded from version 2.21 to 2.22.

    This resolves RT #72700, in which an exception thrown from a closure was getting lost.

  • Socket

    Upgraded from version 1.85 to 1.86.

    This makes the new Socket implementation of inet_pton consistent with the existing Socket6 implementation of inet_pton , fixing RT #72884.

  • podlators

    Upgraded from version 2.2.2 to 2.3.1.

Changes to Existing Documentation

The syntax unless (EXPR) BLOCK else BLOCK is now documented as valid, as is the syntax unless (EXPR) BLOCK elsif (EXPR) BLOCK ... else BLOCK, although actually using the latter may not be the best idea for the readability of your source code.

Installation and Configuration Improvements

Configuration improvements

Support for SystemTap's dtrace compatibility layer has been added and an issue with linking miniperl has been fixed in the process.

less -R is now used instead of less for groff 's new usage of ANSI escape codes by setting $Config{less} (and thereby $Config{pager} , which fixes RT #72156.

USE_PERL_ATOF is now reported in the compile-time options listed by the -V switch.

Selected Bug Fixes

  • Arbitrary whitespace is now allowed between NAME and VERSION in package NAME VERSION; statements. (Fixes RT #72432)

  • A panic caused by trying to load charnames when the parser is already in error (e.g. by a missing my under use strict; ) is now averted. This was a regression since Perl 5.10.0. (Fixes RT #72590)

  • Reading $! no longer causes a SEGV for out of range errno values. (Fixes RT #72850)

  • A possible SEGV in /\N{...}/ has been fixed. This was a regression since Perl 5.10.

  • A possible SEGV when freeing a scalar that was upgraded to an SVt_REGEXP type from a simple(r) scalar has been fixed.

  • A type conversion bug in gmtime64 that caused it to break around 2**48 has been fixed.

  • Interpolating a regex that makes use of the charnames pragma will no longer cause a run-time error. (Fixes RT #56444)

  • Array references assigned to *Foo::ISA now have the necessary magic added to them to catch any further updates to the new @ISA . (Fixes RT #72866)

  • Filehandles are now always blessed into IO::File , which, together with some suitable manipulation of @IO::File::ISA , fixes a breakage introduced in Perl 5.11.3 by a change that always blessed filehandles into IO::Handle rather than checking for FileHandle first.

  • A change in the behaviour of warnings::enabled and warnings::warnif in Perl 5.10.0 that wasn't documented at the time is now documented in perl5100delta. (Fixes RT #62522)

  • RT #71504 is now fixed by simply skipping the tests that failed on OpenBSD with ithreads and perlio.

New or Changed Diagnostics

  • The fatal error Malformed UTF-8 returned by \N is now produced if the charnames handler returns malformed UTF-8.

  • If an unresolved named character or sequence was encountered when compiling a regex pattern then the fatal error \\N{NAME} must be resolved by the lexer is now produced. This can happen, for example, when using a single-quotish context like $re = '\N{SPACE}'; $re; . See perldiag for more examples of how the lexer can get bypassed.

  • The fatal error Invalid hexadecimal number in \\N{U+...} will be produced if the character constant represented by ... is not a valid hexadecimal number.

  • The new meaning of \N as [^\n] is not valid in a bracketed character class, just like . in a character class loses its special meaning, and will cause the fatal error \\N in a character class must be a named character: \\N{...}.

  • The rules on what is legal for the ... in \N{...} have been tightened up so that unless the ... begins with an alphabetic character and continues with a combination of alphanumerics, dashes, spaces, parentheses or colons then the warning Deprecated character(s) in \\N{...} starting at '%s' is now issued.

  • The warning Using just the first characters returned by \N{} will be issued if the charnames handler returns a sequence of characters which exceeds the limit of the number of characters that can be used. The message will indicate which characters were used and which were discarded.

  • Currently, all but the first of the several characters that the charnames handler may return are discarded when used in a regular expression pattern bracketed character class. If this happens then the warning Using just the first character returned by \N{} in character class will be issued.

  • The warning Missing right brace on \\N{} or unescaped left brace after \\N. Assuming the latter will be issued if Perl encounters a \N{ but doesn't find a matching }. In this case Perl doesn't know if it was mistakenly omitted, or if "match non-newline" followed by "match a {" was desired. It assumes the latter because that is actually a valid interpretation as written, unlike the other case. If you meant the former, you need to add the matching right brace. If you did mean the latter, you can silence this warning by writing instead \N\{.

  • gmtime and localtime called with numbers smaller than they can reliably handle will now issue the warnings gmtime(%.0f) too small and localtime(%.0f) too small.

New Tests

  • t/op/filehandle.t

    Tests some suitably portable filetest operators to check that they work as expected, particularly in the light of some internal changes made in how filehandles are blessed.

  • t/op/time_loop.t

    Tests that times greater than 2**63 , which can now be handed to gmtime and localtime, do not cause an internal overflow or an excessively long loop.

Known Problems

Perl 5.11.5 is a development release leading up to Perl 5.12.0. Some notable known problems found in 5.11.5 are listed as dependencies of RT #69710, the Perl 5 version 12 meta-ticket.


Perl 5.11.5 represents approximately one month of development since Perl 5.11.4 and contains 9618 lines of changes across 151 files from 33 authors and committers:

Ævar Arnfjörð Bjarmason, Abigail, brian d foy, Chris Williams, David Golden, David Mitchell, Eric Brine, Frank Wiegand, Gisle Aas, H.Merijn Brand, Jan Dubois, Jesse Vincent, Jim Cromie, John Peacock, Josh ben Jore, Karl Williamson, Marcus Holland-Moritz, Michael G Schwern, Nicholas Clark, Offer Kaye, Philippe Bruhat (BooK), Rafael Garcia-Suarez, Reini Urban, Ricardo Signes, Robin Barker, Slaven Rezic, Steffen Mueller, Steve Hay, Steve Peters, Tim Bunce, Todd Rinaldo, Tony Cook and Vincent Pit.

Many of the changes included in this version originated in the CPAN modules included in Perl's core. We're grateful to the entire CPAN community for helping Perl to flourish.

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 . There may also be information at , the Perl Home Page.

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 to be analyzed 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 This points to a closed subscription unarchived mailing list, which includes all the core committers, who 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.


The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.