Scroll to navigation

PERL5255DELTA(1) Perl Programmers Reference Guide PERL5255DELTA(1)


perl5255delta - what is new for perl v5.25.5


This document describes differences between the 5.25.4 release and the 5.25.5 release.

If you are upgrading from an earlier release such as 5.25.3, first read perl5254delta, which describes differences between 5.25.3 and 5.25.4.


"Escaped" colons and relative paths in PATH

On Unix systems, Perl treats any relative paths in the PATH environment variable as tainted when starting a new process. Previously, it was allowing a backslash to escape a colon (unlike the OS), consequently allowing relative paths to be considered safe if the PATH was set to something like "/\:.". The check has been fixed to treat "." as tainted in that example.

Modules and Pragmata

Updated Modules and Pragmata

  • Filter::Simple has been upgraded from version 0.92 to 0.93.

    It no longer treats "no MyFilter" immediately following "use MyFilter" as end-of-file. [perl #107726]

  • Locale::Codes has been upgraded from 3.39 to 3.40.
  • Module::CoreList has been upgraded from version 5.20160820 to 5.20160920.
  • POSIX has been upgraded from version 1.71 to 1.72.
  • Sys::Syslog has been upgraded from version 0.34_01 to 0.35.
  • Test::Simple has been upgraded from version 1.302052 to 1.302056.
  • Thread::Semaphore has been upgraded from 2.12 to 2.13.

    Added the "down_timed" method.

  • XSLoader has been upgraded from version 0.22 to 0.24.


Changes to Existing Documentation

perlinterp has been expanded to give a more detailed example of how to hunt around in the parser for how a given operator is handled.


t/re/regexp_nonull.t has been added to test that the regular expression engine can handle scalars that do not have a null byte just past the end of the string.

Platform Support

Platform-Specific Notes

  • The path separator for the "PERL5LIB" and "PERLLIB" environment entries is now a colon (":") when running under a Unix shell. There is no change when running under DCL (it's still "|").
  • Remove some VMS-specific hacks from "showlex.t". These were added 15 years ago, and are no longer necessary for any VMS version now supported.
Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses the uninit CCTYPE var. Also fix else vs .ELSE in

Internal Changes

  • Several macros and functions have been added to the public API for dealing with Unicode and UTF-8-encoded strings. See "Unicode Support" in perlapi.
  • Use "my_strlcat()" in "locale.c". While "strcat()" is safe in this context, some compilers were optimizing this to "strcpy()" causing a porting test to fail that looks for unsafe code. Rather than fighting this, we just use "my_strlcat()" instead.

Selected Bug Fixes

  • Invalid assignments to a reference constructor (e.g., "\eval=time") could sometimes crash in addition to giving a syntax error. [perl #125679]
  • The parser could sometimes crash if a bareword came after "evalbytes". [perl #129196]
  • Autoloading via a method call would warn erroneously ("Use of inherited AUTOLOAD for non-method") if there was a stub present in the package into which the invocant had been blessed. The warning is no longer emitted in such circumstances. [perl #47047]
  • A sub containing with a "forward" declaration with the same name (e.g., "sub c { sub c; }") could sometimes crash or loop infinitely. [perl #129090]
  • The use of "splice" on arrays with nonexistent elements could cause other operators to crash. [perl #129164]
  • Fixed case where "re_untuit_start" will overshoot the length of a utf8 string. [perl #129012]
  • Handle "CXt_SUBST" better in "Perl_deb_stack_all", previously it wasn't checking that the current "cx" is the right type, and instead was always checking the base "cx" (effectively a noop). [perl #129029]
  • Fixed two possible use-after-free bugs in "Perl_yylex". "Perl_yylex" maintains up to two pointers into the parser buffer, one of which can become stale under the right conditions. [perl #129069]
  • Fixed a crash with "s///l" where it thought it was dealing with UTF-8 when it wasn't. [perl #129038]
  • Fixed place where regex was not setting the syntax error correctly. [perl #129122]
  • The "&." operator (and the "&" operator, when it treats its arguments as strings) were failing to append a trailing null byte if at least one string was marked as utf8 internally. Many code paths (system calls, regexp compilation) still expect there to be a null byte in the string buffer just past the end of the logical string. An assertion failure was the result. [perl #129287]
  • Check "pack_sockaddr_un()"'s return value because "pack_sockaddr_un()" silently truncates the supplied path if it won't fit into the "sun_path" member of "sockaddr_un". This may change in the future, but for now check the path in the"sockaddr" matches the desired path, and skip if it doesn't. [perl #128095]
  • Make sure "PL_oldoldbufptr" is preserved in "scan_heredoc()". In some cases this is used in building error messages. [perl #128988]
  • Check for null PL_curcop in IN_LC() [perl #129106]
  • Fixed the parser error handling for an '":attr(foo"' that does not have an ending '")"'.
  • Fix "Perl_delimcpy()" to handle a backslash as last char, this actually fixed two bugs, [perl #129064] and [perl #129176].
  • [perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to prevent possible string overrun with invalid len in gv.c


Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community member, has passed away on August 10, 2016. He will be remembered and missed by all those with which he came in contact and enriched with his intellect, wit, and spirit.


Perl 5.25.5 represents approximately 4 weeks of development since Perl 5.25.4 and contains approximately 67,000 lines of changes across 230 files from 25 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 62,000 lines of changes to 160 .pm, .t, .c and .h files.

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 5.25.5:

Aaron Crane, Aristotle Pagaltzis, Chris 'BinGOs' Williams, Craig A. Berry, Dagfinn Ilmari Mannsåker, Dan Collins, Daniel Dragan, Dave Cross, David Mitchell, E. Choroba, Father Chrysostomos, James E Keenan, Jerry D. Hedden, Karl Williamson, Lukas Mai, Ricardo Signes, Rick Delaney, Sawyer X, Stevan Little, Steve Hay, Sullivan Beck, Theo Buehler, Tony Cook, Yaroslav Kuzmin, Yves Orton.

The list above is almost certainly incomplete as it is automatically generated from version control history. In particular, it does not include the names of the (very much appreciated) contributors who reported issues to the Perl bug tracker.

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.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the Perl source distribution.

Reporting Bugs

If you find what you think is a bug, you might check 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 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 see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of how to report the issue.


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.

2017-05-20 perl v5.26.0