NAME¶
perl5135delta - what is new for perl v5.13.5
DESCRIPTION¶
This document describes differences between the 5.13.4 release and the 5.13.5
release.
If you are upgrading from an earlier release such as 5.13.3, first read
perl5134delta, which describes differences between 5.13.3 and 5.13.4.
Core Enhancements¶
Adjacent pairs of nextstate opcodes are now optimized away¶
Previously, in code such as
use constant DEBUG => 0;
sub GAK {
warn if DEBUG;
print "stuff\n";
}
the ops for "warn if DEBUG;" would be folded to a "null" op
("ex-const"), but the "nextstate" op would remain,
resulting in a runtime op dispatch of "nextstate",
"nextstate", ...
The execution of a sequence of "nextstate" ops is indistinguishable
from just the last "nextstate" op so the peephole optimizer now
eliminates the first of a pair of "nextstate" ops, except where the
first carries a label, since labels must not be eliminated by the optimizer
and label usage isn't conclusively known at compile time.
API function to parse statements¶
The "parse_fullstmt" function has been added to allow parsing of a
single complete Perl statement. See perlapi for details.
API functions for accessing the runtime hinthash¶
A new C API for introspecting the hinthash "%^H" at runtime has been
added. See "cop_hints_2hv", "cop_hints_fetchpvn",
"cop_hints_fetchpvs", "cop_hints_fetchsv", and
"hv_copy_hints_hv" in perlapi for details.
C interface to "caller()"¶
The "caller_cx" function has been added as an XSUB-writer's equivalent
of "caller()". See perlapi for details.
Incompatible Changes¶
Magic variables outside the main package¶
In previous versions of Perl, magic variables like $!, %SIG, etc. would 'leak'
into other packages. So %foo::SIG could be used to access signals,
"${"foo::!"}" (with strict mode off) to access C's
"errno", etc.
This was a bug, or an 'unintentional' feature, which caused various ill effects,
such as signal handlers being wiped when modules were loaded, etc.
This has been fixed (or the feature has been removed, depending on how you see
it).
Smart-matching against array slices¶
Previously, the following code resulted in a successful match:
my @a = qw(a y0 z);
my @b = qw(a x0 z);
@a[0 .. $#b] ~~ @b;
This odd behaviour has now been fixed [perl #77468]
<
http://rt.perl.org/rt3//Public/Bug/Display.html?id=77468>.
C API changes¶
The first argument of the C API function "Perl_fetch_cop_label" has
changed from "struct refcounted he *" to "COP *", to
better insulate the user from implementation details.
This API function was marked as "may change", and likely isn't in use
outside the core. (Neither an unpacked CPAN, nor Google's codesearch, finds
any other references to it.)
Deprecations¶
Use of qw(...) as parentheses¶
Historically the parser fooled itself into thinking that "qw(...)"
literals were always enclosed in parentheses, and as a result you could
sometimes omit parentheses around them:
for $x qw(a b c) { ... }
The parser no longer lies to itself in this way. Wrap the list literal in
parentheses, like:
for $x (qw(a b c)) { ... }
- •
- Scalars containing regular expressions now only allocate
the part of the "SV" body they actually use, saving some
space.
- •
- Compiling regular expressions has been made faster for the
case where upgrading the regex to utf8 is necessary but that isn't known
when the compilation begins.
Modules and Pragmata¶
Updated Modules and Pragmata¶
- "bignum"
- Upgraded from version 0.23 to 0.25.
- "blib"
- Upgraded from version 1.05 to 1.06.
- "open"
- Upgraded from version 1.07 to 1.08.
- "threads-shared"
- Upgraded from version 1.33_02 to 1.33_03.
- "warnings" and
"warnings::register"
- Upgraded from version 1.10 to 1.11 and from version 1.01 to
1.02 respectively.
It is now possible to register warning categories other than the names of
packages using "warnings::register". See perllexwarn for more
information.
- "B::Debug"
- Upgraded from version 1.12 to 1.16.
- "CPANPLUS::Dist::Build"
- Upgraded from version 0.46 to 0.48.
- "Data::Dumper"
- Upgraded from version 2.126 to 2.128.
This fixes a crash when using custom sort functions that might cause the
stack to change.
- "Encode"
- Upgraded from version 2.39 to 2.40.
- "Errno"
- Upgraded from version 1.12 to 1.13.
On some platforms with unusual header files, like Win32/gcc using mingw64
headers, some constants which weren't actually error numbers have been
exposed by "Errno". This has been fixed [perl #77416]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=77416>.
- "ExtUtils::MakeMaker"
- Upgraded from version 6.5601 to 6.57_05.
- "Filter::Simple"
- Upgraded from version 0.84 to 0.85.
- "Hash::Util"
- Upgraded from version 0.08 to 0.09.
- "Math::BigInt"
- Upgraded from version 1.89_01 to 1.95.
This fixes, among other things, incorrect results when computing binomial
coefficients [perl #77640]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77640>.
- "Math::BigInt::FastCalc"
- Upgraded from version 0.19 to 0.22.
- "Math::BigRat"
- Upgraded from version 0.24 to 0.26.
- "Module::CoreList"
- Upgraded from version 2.37 to 2.38.
- "PerlIO::scalar"
- Upgraded from version 0.08 to 0.09.
- "POSIX"
- Upgraded from version 1.19 to 1.20.
It now includes constants for POSIX signal constants.
- "Safe"
- Upgraded from version 2.27 to 2.28.
This fixes a possible infinite loop when looking for coderefs.
- "Test::Simple"
- Upgraded from version 0.96 to 0.97_01.
- "Tie::Hash"
- Upgraded from version 1.03 to 1.04.
Calling "Tie::Hash->TIEHASH()" used to loop forever. Now it
"croak"s.
- "Unicode::Collate"
- Upgraded from version 0.56 to 0.59.
- "XSLoader"
- Upgraded from version 0.10 to 0.11.
Documentation¶
Changes to Existing Documentation¶
perlapi
- •
- Many of the optree construction functions are now
documented.
perlbook
- •
- Expanded to cover many more popular books.
perlfaq
- •
- perlfaq, perlfaq2, perlfaq4, perlfaq5, perlfaq6, perlfaq8,
and perlfaq9 have seen various updates and modernizations.
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 perldiag.
New Diagnostics¶
- •
- Parsing code internal error (%s)
New fatal error produced when parsing code supplied by an extension violated
the parser's API in a detectable way.
- •
- Use of qw(...) as parentheses is deprecated
See "Use of qw(...) as parentheses" for details.
Changes to Existing Diagnostics¶
- •
- "warn" and "die" now produce 'Wide
character' warnings when fed a character outside the byte range if STDERR
is a byte-sized handle.
Utility Changes¶
h2ph
- •
- The use of a deprecated "goto" construct has been
removed [perl #74404]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=74404>.
Testing¶
- •
- The new t/lib/universal.t script tests the
Internal::* functions and other things in universal.c.
- •
- A rare race condition in t/op/while_readdir.t has
been fixed, stopping it from failing randomly when running tests in
parallel.
- •
- The new t/op/leaky-magic.t script tests that magic
applied to variables in the main packages does not affect other
packages.
- VMS
- •
- Make "PerlIOUnix_open" honour default permissions
on VMS.
When "perlio" became the default and "unixio" became the
default bottom layer, the most common path for creating files from Perl
became "PerlIOUnix_open", which has always explicitly used 0666
as the permission mask.
To avoid this, 0777 is now passed as the permissions to "open()".
In the VMS CRTL, 0777 has a special meaning over and above intersecting
with the current umask; specifically, it allows Unix syscalls to preserve
native default permissions.
Internal Changes¶
- •
- "CALL_FPTR" and "CPERLscope" have been
deprecated.
Those are left from an old implementation of "MULTIPLICITY" using
C++ objects, which was removed in Perl 5.8. Nowadays these macros do
exactly nothing, so they shouldn't be used anymore.
For compatibility, they are still defined for external "XS" code.
Only extensions defining "PERL_CORE" must be updated now.
- •
- "lex_stuff_pvs()" has been added as a convenience
macro wrapping "lex_stuff_pvn()" for literal strings.
- •
- The recursive part of the peephole optimizer is now
hookable.
In addition to "PL_peepp", for hooking into the toplevel peephole
optimizer, a "PL_rpeepp" is now available to hook into the
optimizer recursing into side-chains of the optree.
Selected Bug Fixes¶
- •
- A regression introduced in Perl 5.12.0, making "my $x
= 3; $x = length(undef)" result in $x set to 3 has been fixed. $x
will now be "undef".
- •
- A fatal error in regular expressions when processing UTF-8
data has been fixed [perl #75680]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=75680>.
- •
- An erroneous regular expression engine optimization that
caused regex verbs like *COMMIT to sometimes be ignored has been
removed.
- •
- The Perl debugger now also works in taint mode [perl
#76872]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=76872>.
- •
- Several memory leaks in cloning and freeing threaded Perl
interpreters have been fixed [perl #77352]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77352>.
- •
- A possible string corruption when doing regular expression
matches on overloaded objects has been fixed [perl #77084]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77084>.
- •
- Magic applied to variables in the main package no longer
affects other packages. See "Magic variables outside the main
package" above [perl #76138]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=76138>.
- •
- Opening a glob reference via "open $fh,
">", \*glob" will no longer cause the glob to be
corrupted when the filehandle is printed to. This would cause perl to
crash whenever the glob's contents were accessed [perl #77492]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77492>.
- •
- The postincrement and postdecrement operators,
"++" and "--", used to cause leaks when being used on
references. This has now been fixed.
- •
- A bug when replacing the glob of a loop variable within the
loop has been fixed [perl #21469]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=21469>. This
means the following code will no longer crash:
for $x (...) {
*x = *y;
}
- •
- Perl would segfault if the undocumented
"Internals" functions that used reference prototypes were called
with the "&foo()" syntax, e.g.
"&Internals::SvREADONLY(undef)" [perl #77776]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77776>.
These functions now call "SvROK" on their arguments before
dereferencing them with "SvRV", and we test for this case in
t/lib/universal.t.
- •
- When assigning a list with duplicated keys to a hash, the
assignment used to return garbage and/or freed values:
@a = %h = (list with some duplicate keys);
This has now been fixed [perl #31865]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=31865>.
- •
- An earlier release of the 5.13 series of Perl changed the
semantics of opening a reference to a copy of a glob:
my $var = *STDOUT;
open my $fh, '>', \$var;
This was a mistake, and the previous behaviour from Perl 5.10 and 5.12,
which is to treat \$var as a scalar reference, has now been restored.
- •
- The regular expression bracketed character class
"[\8\9]" was effectively the same as "[89\000]",
incorrectly matching a NULL character. It also gave incorrect warnings
that the 8 and 9 were ignored. Now "[\8\9]" is the same as
"[89]" and gives legitimate warnings that "\8" and
"\9" are unrecognized escape sequences, passed-through.
- •
- "warn()" and "die()" now respect
utf8-encoded scalars [perl #45549]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=45549>.
Known Problems¶
- •
- The upgrade to Encode-2.40 has caused some tests in the
libwww-perl distribution on CPAN to fail. (Specifically,
base/message-charset.t tests 33-36 in version 5.836 of that
distribution now fail.)
- •
- The upgrade to ExtUtils-MakeMaker-6.57_05 has caused some
tests in the Module-Install distribution on CPAN to fail. (Specifically,
02_mymeta.t tests 5 and 21, 18_all_from.t tests 6 and 15,
19_authors.t tests 5, 13, 21 and 29, and
20_authors_with_special_characters.t tests 6, 15 and 23 in version
1.00 of that distribution now fail.)
Acknowledgements¶
Perl 5.13.5 represents approximately one month of development since Perl 5.13.4
and contains 74558 lines of changes across 549 files from 45 authors and
committers:
Abigail, Alexander Alekseev, Aristotle Pagaltzis, Ben Morrow, Bram, brian d foy,
Chas. Owens, Chris 'BinGOs' Williams, Craig A. Berry, Curtis Jewell, Dagfinn
Ilmari Mannsaaker, David Golden, David Leadbeater, David Mitchell, Eric Brine,
Father Chrysostomos, Florian Ragwitz, Gisle Aas, Jan Dubois, Jerry D. Hedden,
Jesse Vincent, Jim Cromie, Jirka HruXka, Karl Williamson, Michael G. Schwern,
Nicholas Clark, Paul Johnson, Philippe Bruhat (BooK), Piotr Fusik, Rafael
Garcia-Suarez, Rainer Tammer, Reini Urban, Ricardo Signes, Rob Hoelz, Robin
Barker, Steffen Mueller, Steve Hay, Steve Peters, Todd Rinaldo, Tony Cook,
Vincent Pit, Yves Orton, Zefram, Zsban Ambrus, AEvar Arnfjoerd` Bjarmason.
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
http://rt.perl.org/perlbug/ . 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 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 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
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.