path: root/pod/perl51911delta.pod

=encoding utf8

=head1 NAME

perl51911delta - what is new for perl v5.19.11

=head1 DESCRIPTION

This document describes differences between the 5.19.10 release and the 5.19.11
release.

If you are upgrading from an earlier release such as 5.19.9, first read
L<perl51910delta>, which describes differences between 5.19.9 and 5.19.10.

=head1 Modules and Pragmata

=head2 New Modules and Pragmata

=over 4

=item *

L<experimental> version 0.007 has been added.

This pragma provides an easy and convenient way to enable or disable
experimental features.

=back

=head2 Updated Modules and Pragmata

=over 4

=item *

L<Carp> has been upgraded from version 1.33 to 1.3301.

No changes have been made to the installed code other than the version bump to
keep in sync with the latest CPAN release.

=item *

L<CPAN> has been upgraded from version 2.04-TRIAL to 2.05.

This fixes L<local::lib> shell variable string output and prevents an endless
loop when running "notest test Module" for some Module having dependencies.

=item *

L<DB> has been upgraded from version 1.43 to 1.44.

The debugger now correctly restores its input and output filehandles after
using the pager command.
[L<perl #121456|https://rt.perl.org/Public/Bug/Display.html?id=121456>]

=item *

L<ExtUtils::Install> has been upgraded from version 1.63 to 1.67.

When upgrading an already-installed file, L<ExtUtils::Install> could mess up
the permissions of files if the old versions of files were hard or symbolic
links.  This has now been fixed.
[L<perl #72028|https://rt.perl.org/Public/Bug/Display.html?id=72028>]

The MM_TEST_ROOT feature has been removed from the tests.

=item *

L<ExtUtils::MakeMaker> has been upgraded from version 6.92 to 6.94.

A regression in MM_Unix.pm has been resolved.
[L<Issue #96|https://github.com/Perl-Toolchain-Gang/ExtUtils-MakeMaker/issues/96>]

=item *

L<Module::CoreList> has been upgraded from version 3.09 to 3.10.

The list of Perl versions covered has been updated.

=item *

L<PerlIO> has been upgraded from version 1.08 to 1.09.

The warning about the use of the C<:utf8> layer has been made more prominent.

=item *

L<Storable> has been upgraded from version 2.48 to 2.49.

Recognition of tied SVs has been tightened up.

=item *

L<Win32> has been upgraded from version 0.48 to 0.49.

This fixes a problem when building with B<gcc> version 4.8.1 from
L<http://www.mingw.org>.
[L<cpan #94730|https://rt.cpan.org/Public/Bug/Display.html?id=94730>]

=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<perldiag>.

=head2 Changes to Existing Diagnostics

=over 4

=item *

The now fatal error message C<Character following "\c" must be ASCII> has been
reworded as C<Character following "\c" must be printable ASCII> to emphasize
that in C<\cI<X>>, I<X> must be a I<printable (non-control)> ASCII character.

=back

=head1 Utility Changes

=head2 L<perlbug>

=over 4

=item *

L<perlbug> has been modified to supply the report template with CRLF line
endings on Windows.
[L<perl #121277|https://rt.perl.org/Public/Bug/Display.html?id=121277>]

=item *

L<perlbug> now makes as few assumptions as possible about the encoding of the
report.  This will likely change in the future to assume UTF-8 by default but
allow a user override.

=back

=head1 Configuration and Compilation

=over 4

=item *

By default, B<gcc> 4.9 does some optimizations that break perl.  The B<-fwrapv>
option disables those optimizations (and probably others), so for B<gcc> 4.9
(and later, since the optimizations probably won't go away), F<Configure> now
adds B<-fwrapv> unless the user requests B<-fno-wrapv>, which disables
B<-fwrapv>, or B<-fsanitize=undefined>, which turns the overflows B<-fwrapv>
ignores into runtime errors.  (This is not done prior to B<gcc> 4.3, since
B<-fwrapv> was broken then.)
[L<perl #121505|https://rt.perl.org/Public/Bug/Display.html?id=121505>]

=back

=head1 Platform Support

=head2 Platform-Specific Notes

=over 4

=item VMS

On VMS only, a check for glob metacharacters in a path returned by the
L<C<glob()>|perlfunc/glob> operator has been replaced with a check for VMS
wildcard characters.  This saves a significant number of unnecessary
L<C<lstat()>|perlfunc/lstat> calls such that some simple glob operations become
60-80% faster.

=item Win32

The time taken to build perl on Windows has been reduced quite significantly
(time savings in the region of 30-40% are typically seen) by reducing the
number of, usually failing, I/O calls for each L<C<require()>|perlfunc/require>
(for B<miniperl.exe> only).
[L<perl #121119|https://rt.perl.org/Public/Bug/Display.html?id=121119>]

About 15 minutes of idle sleeping was removed from running C<make test> due to
a bug in which the timeout monitor used for tests could not be cancelled once
the test completes, and the full timeout period elapsed before running the next
test file.
[L<perl #121395|https://rt.perl.org/Public/Bug/Display.html?id=121395>]

On a perl built without pseudo-fork (pseudo-fork builds were not affected by
this bug), killing a process tree with L<C<kill()>|perlfunc/kill> and a negative
signal resulted in C<kill()> inverting the returned value.  For example, if
C<kill()> killed 1 process tree PID then it returned 0 instead of 1, and if
C<kill()> was passed 2 invalid PIDs then it returned 2 instead of 0.  This has
probably been the case since the process tree kill feature was implemented on
Win32.  It has now been corrected to follow the documented behaviour.
[L<perl #121230|https://rt.perl.org/Public/Bug/Display.html?id=121230>]

When building a 64-bit perl, an uninitialized memory read in B<miniperl.exe>,
used during the build process, could lead to a 4GB B<wperl.exe> being created.
This has now been fixed.  (Note that B<perl.exe> itself was unaffected, but
obviously B<wperl.exe> would have been completely broken.)
[L<perl #121471|https://rt.perl.org/Public/Bug/Display.html?id=121471>]

Perl can now be built with B<gcc> version 4.8.1 from L<http://www.mingw.org>.
This was previously broken due to an incorrect definition of DllMain() in one
of perl's source files.  Earlier B<gcc> versions were also affected when using
version 4 of the w32api package.  Versions of B<gcc> available from
L<http://mingw-w64.sourceforge.net/> were not affected.
[L<perl #121643|https://rt.perl.org/Public/Bug/Display.html?id=121643>]

The test harness now has no failures when perl is built on a FAT drive with the
Windows OS on an NTFS drive.
[L<perl #21442|https://rt.perl.org/Public/Bug/Display.html?id=21442>]

=back

=head1 Internal Changes

=over 4

=item *

C<LC_NUMERIC> is now initialized to the C locale.  This affects only XS
modules, as the Perl core usages always make sure this locale category is
correctly set for their purposes.  XS code remains vulnerable to other code
changing this category's locale.  Further fixes are planned in Perl 5.22 to
reduce these long-standing vulnerabilities.
[L<perl #121317|https://rt.perl.org/Public/Bug/Display.html?id=121317>]

=back

=head1 Selected Bug Fixes

=over 4

=item *

A regression involving the string value of L<C<$!>|perlvar/$!> introduced in
Perl 5.19.2 has been reverted for Perl 5.20.
[L<perl #119499|https://rt.perl.org/Public/Bug/Display.html?id=119499>]

This re-breaks the bugs it fixed,
L<perl #112208|https://rt.perl.org/Public/Bug/Display.html?id=112208>, so an
alternative fix is planned for Perl 5.22

=item *

A regression was introduced in Perl 5.19.10 that under some circumstances
caused C<//m> matches to falsely fail.  Now fixed.
[L<perl #121484|https://rt.perl.org/Public/Bug/Display.html?id=121484>]

=item *

A regression was introduced in the fix for
L<perl #116192|https://rt.perl.org/Public/Bug/Display.html?id=116192> that
prevented C<perl -I /somedir/> (with a trailing slash) from finding .pmc files.
This has been fixed.
[L<perl #121512|https://rt.perl.org/Public/Bug/Display.html?id=121512>].

=item *

Fixed a bug detected by valgrind where sv_pvn_force_flags() would check SvPVX()
even when the SV hadn't been upgraded to a SVt_PV.  SvPVX() is only initialized
when the SV is upgraded to a SVt_PV or higher.
[L<perl #121366|https://rt.perl.org/Public/Bug/Display.html?id=121366>]

=item *

Fixed a bug in L<C<caller()>|perlfunc/caller> introduced in Perl 5.18.0.  In
some circumstances when C<caller()> was called on an C<eval STRING> stack frame
it would attempt to allocate the limit of the address space minus one, which
would croak with an out of memory error, which would be caught by the eval.  A
change in Perl 5.19.1 which increased allocation sizes to allow COW to operate
more often rounded that allocation size up and wrapped to a zero allocation
size, resulting in a crash when the source string was copied over.
[L<perl #120998|https://rt.perl.org/Public/Bug/Display.html?id=120998>].

=back

=head1 Known Problems

=over 4

=item *

One test in F<ext/POSIX/t/time.t> is known to fail on Windows when building
with certain versions of B<gcc> from L<http://www.mingw.org> due to a known bug
in the MinGW build, which is logged here:
L<http://sourceforge.net/p/mingw/bugs/2152/>.

=back

=head1 Acknowledgements

Perl 5.19.11 represents approximately 4 weeks of development since Perl 5.19.10
and contains approximately 3,600 lines of changes across 140 files from 18
authors.

Excluding auto-generated files, documentation and release tools, there were
approximately 850 lines of changes to 72 .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 5.19.11:

Aaron Crane, Chris 'BinGOs' Williams, Craig A. Berry, Daniel Dragan, David
Golden, David Mitchell, H.Merijn Brand, Hiroo Hayashi, Karl Williamson, Matthew
Horsfall, Ricardo Signes, Shirakata Kentaro, Smylers, Steve Hay, Thomas Sibley,
Tony Cook, Zefram, Ævar Arnfjörð Bjarmason.

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 F<AUTHORS> file in the Perl source distribution.

=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
https://rt.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 L<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 C<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.

=head1 SEE ALSO

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

The F<INSTALL> file for how to build Perl.

The F<README> file for general stuff.

The F<Artistic> and F<Copying> files for copyright information.

=cut