This document describes differences between the 5.8.4 release and the
There are no changes incompatible with 5.8.4.
Perl's regular expression engine now contains support for matching on
the intersection of two Unicode character classes. You can also now
refer to user-defined character classes from within other user defined
Modules and Pragmata
o Carp improved to work nicely with Safe. Carp's message reporting
should now be anomaly free - it will always print out line number
o CGI upgraded to version 3.05
o charnames now avoids clobbering $_
o Digest upgraded to version 1.08
o Encode upgraded to version 2.01
o FileCache upgraded to version 1.04
o libnet upgraded to version 1.19
o Pod::Parser upgraded to version 1.28
o Pod::Perldoc upgraded to version 3.13
o Pod::LaTeX upgraded to version 0.57
o Safe now works properly with Carp
o Scalar-List-Utils upgraded to version 1.14
o Shell's documentation has been re-written, and its historical
partial auto-quoting of command arguments can now be disabled.
o Test upgraded to version 1.25
o Test::Harness upgraded to version 2.42
o Time::Local upgraded to version 1.10
o Unicode::Collate upgraded to version 0.40
o Unicode::Normalize upgraded to version 0.30
Selected Bug Fixes
o The in-place sort optimisation introduced in 5.8.4 had a bug. For
example, in code such as
@a = sort ($b, @a)
the result would omit the value $b. This is now fixed.
o The optimisation for unnecessary assignments introduced in 5.8.4
could give spurious warnings. This has been fixed.
o Perl should now correctly detect and read BOM-marked and (BOMless)
UTF-16 scripts of either endianness.
o Creating a new thread when weak references exist was buggy, and
would often cause warnings at interpreter destruction time. The
known bug is now fixed.
o Several obscure bugs involving manipulating Unicode strings with
"substr" have been fixed.
o Previously if Perl's file globbing function encountered a directory
that it did not have permission to open it would return
immediately, leading to unexpected truncation of the list of
results. This has been fixed, to be consistent with Unix shells'
o Thread creation time could vary wildly between identical runs. This
was caused by a poor hashing algorithm in the thread cloning
routines, which has now been fixed.
o The internals of the ithreads implementation were not checking if
OS-level thread creation had failed. threads->create() now returns
"undef" in if thread creation fails instead of crashing perl.
New or Changed Diagnostics
o Perl -V has several improvements
o correctly outputs local patch names that contain embedded code
snippets or other characters that used to confuse it.
o arguments to -V that look like regexps will give multiple lines
o a trailing colon suppresses the linefeed and ';' terminator,
allowing embedding of queries into shell commands.
o a leading colon removes the 'name=' part of the response,
allowing mapping to any name.
o When perl fails to find the specified script, it now outputs a
second line suggesting that the user use the "-S" flag:
The regression test t/uni/class.t is now performing considerably more
tests, and can take several minutes to run even on a fast machine.
Platform Specific Problems
This release is known not to build on Windows 95.
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 http://bugs.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 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 email@example.com to be analysed by
the Perl porting team. You can browse and search the Perl 5 bugs at
The Changes file for 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.
perl v5.22.1 2018-11-19 PERL585DELTA(1)
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