NAME¶
perl5136delta - what is new for perl v5.13.6
DESCRIPTION¶
This document describes differences between the 5.13.5 release and the 5.13.6
release.
If you are upgrading from an earlier release such as 5.13.4, first read
perl5135delta, which describes differences between 5.13.4 and 5.13.5.
Core Enhancements¶
"(?^...)" regex construct added to signify default
modifiers¶
A caret (also called a "circumflex accent") "^" immediately
following a "(?" in a regular expression now means that the
subexpression is to not inherit the surrounding modifiers such as
"/i", but to revert to the Perl defaults. Any modifiers following
the caret override the defaults.
The stringification of regular expressions now uses this notation. E.g., before,
"qr/hlagh/i" would be stringified as "(?i-xsm:hlagh)", but
now it's stringified as "(?^i:hlagh)".
The main purpose of this is to allow tests that rely on the stringification to
not have to change when new modifiers are added. See "Extended
Patterns" in perlre.
"d", "l", and "u" regex modifiers
added¶
These modifiers are currently only available within a "(?...)"
construct.
The "l" modifier says to compile the regular expression as if it were
in the scope of "use locale", even if it is not.
The "u" modifier says to compile the regular expression as if it were
in the scope of a "use feature "unicode_strings"" pragma.
The "d" modifier is used to override any "use locale" and
"use feature "unicode_strings"" pragmas that are in effect
at the time of compiling the regular expression.
See just below and "(?dlupimsx-imsx)" in perlre.
"use feature "unicode_strings"" now applies
to some regex matching¶
Another chunk of the "The "Unicode Bug"" in perlunicode is
fixed in this release. Now, regular expressions compiled within the scope of
the "unicode_strings" feature will match the same whether or not the
target string is encoded in utf8, with regard to "\s",
"\w", "\b", and their complements. Work is underway to add
the "[[:posix:]]" character classes and case sensitive matching to
the control of this feature, but was not complete in time for this dot
release.
"\N{...}" now handles Unicode named character
sequences¶
Unicode has a number of named character sequences, in which particular sequences
of code points are given names. "\N{...}" now recognizes these. See
charnames.
New function "charnames::string_vianame()"¶
This function is a run-time version of "\N{...}", returning the string
of characters whose Unicode name is its parameter. It can handle Unicode named
character sequences, whereas the pre-existing "charnames::vianame()"
cannot, as the latter returns a single code point. See charnames.
Reentrant regular expression engine¶
It is now safe to use regular expressions within "(?{...})" and
"(??{...})" code blocks inside regular expressions.
These block are still experimental, however, and still have problems with
lexical ("my") variables, lexical pragmata and abnormal exiting.
Custom per-subroutine check hooks¶
XS code in an extension module can now annotate a subroutine (whether
implemented in XS or in Perl) so that nominated XS code will be called at
compile time (specifically as part of op checking) to change the op tree of
that subroutine. The compile-time check function (supplied by the extension
module) can implement argument processing that can't be expressed as a
prototype, generate customised compile-time warnings, perform constant folding
for a pure function, inline a subroutine consisting of sufficiently simple
ops, replace the whole call with a custom op, and so on. This was previously
all possible by hooking the "entersub" op checker, but the new
mechanism makes it easy to tie the hook to a specific subroutine. See
"cv_set_call_checker" in perlapi.
To help in writing custom check hooks, several subtasks within standard
"entersub" op checking have been separated out and exposed in the
API.
Return value of "delete $+{...}"¶
Custom regular expression engines can now determine the return value of
"delete" on an entry of "%+" or "%-".
"keys", "values" work on arrays¶
You can now use the "keys", "values", "each"
builtin functions on arrays (previously you could only use them on hashes).
See perlfunc for details. This is actually a change introduced in perl 5.12.0,
but it was missed from that release's perldelta.
Incompatible Changes¶
Stringification of regexes has changed¶
Default regular expression modifiers are now notated by using
"(?^...)". Code relying on the old stringification will fail. The
purpose of this is so that when new modifiers are added, such code will not
have to change (after this one time), as the stringification will
automatically incorporate the new modifiers.
Code that needs to work properly with both old- and new-style regexes can avoid
the whole issue by using (for Perls since 5.9.5):
use re qw(regexp_pattern);
my ($pat, $mods) = regexp_pattern($re_ref);
where $re_ref is a reference to a compiled regular expression. Upon return,
$mods will be a string containing all the non-default modifiers used when the
regular expression was compiled, and $pattern the actual pattern.
If the actual stringification is important, or older Perls need to be supported,
you can use something like the following:
# Accept both old and new-style stringification
my $modifiers = (qr/foobar/ =~ /\Q(?^/) ? '^' : '-xism';
And then use $modifiers instead of "-xism".
Regular expressions retain their localeness when
interpolated¶
Regular expressions compiled under "use locale" now retain this when
interpolated into a new regular expression compiled outside a "use
locale", and vice-versa.
Previously, a regular expression interpolated into another one inherited the
localeness of the surrounding one, losing whatever state it originally had.
This is considered a bug fix, but may trip up code that has come to rely on
the incorrect behavior.
Directory handles not copied to threads¶
On systems that do not have a "fchdir" function, newly-created threads
no longer inherit directory handles from their parent threads. Such programs
would probably have crashed anyway [perl #75154]
<
http://rt.perl.org/rt3/Public/Bug/Display.html?id=75154>.
Negation treats strings differently from before¶
The unary negation operator "-" now treats strings that look like
numbers as numbers [perl #57706]
<
http://rt.perl.org/rt3/Public/Bug/Display.html?id=57706>.
Negative zero¶
Negative zero (-0.0), when converted to a string, now becomes "0" on
all platforms. It used to become "-0" on some, but "0" on
others.
If you still need to determine whether a zero is negative, use
"sprintf("%g", $zero) =~ /^-/" or the Data::Float module
on CPAN.
- •
- The bulk of the "Tie::Hash::NamedCapture" module
used to be in the perl core. It has now been moved to an XS module, to
reduce the overhead for programs that do not use "%+" or
"%-".
- •
- Eliminate "PL_*" accessor functions under
ithreads.
When "MULTIPLICITY" was first developed, and interpreter state
moved into an interpreter struct, thread and interpreter local
"PL_*" variables were defined as macros that called accessor
functions, returning the address of the value, outside of the perl core.
The intent was to allow members within the interpreter struct to change
size without breaking binary compatibility, so that bug fixes could be
merged to a maintenance branch that necessitated such a size change.
However, some non-core code defines "PERL_CORE", sometimes
intentionally to bypass this mechanism for speed reasons, sometimes for
other reasons but with the inadvertent side effect of bypassing this
mechanism. As some of this code is widespread in production use, the
result is that the core can't change the size of members of the
interpreter struct, as it will break such modules compiled against a
previous release on that maintenance branch. The upshot is that this
mechanism is redundant, and well-behaved code is penalised by it. Hence it
can and should be removed.
Modules and Pragmata¶
Updated Modules and Pragmata¶
- •
- "Archive::Extract" has been upgraded from version
0.42 to 0.44
- •
- "Carp" has been upgraded from version 1.18 to
1.19.
It no longer autovivifies the *CORE::GLOBAL::caller glob, something it
started doing in 1.18, which was released with perl 5.13.4 [perl #78082]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=78082>
- •
- "Compress::Raw::Bzip2" has been upgraded from
version 2.030 to 2.031
Updated to use bzip2 1.0.6
- •
- "CPAN" has been upgraded from version 1.94_57 to
1.94_61
- •
- "Data::Dumper" has been upgraded from version
2.128 to 2.129.
"Dumpxs" no longer crashes with globs returned by *$io_ref [perl
#72332]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=72332>.
- •
- "Digest::MD5" has been upgraded from version 2.40
to 2.51.
It is now safe to use this module in combination with threads.
- •
- "File::DosGlob" has been upgraded from version
1.02 to 1.03.
It allows patterns containing literal parentheses (they no longer need to be
escaped). On Windows, it no longer adds an extra ./ to the file
names returned when the pattern is a relative glob with a drive
specification, like c:*.pl [perl #71712]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=71712>.
- •
- "File::Find" has been upgraded from version 1.17
to 1.18.
It improves handling of backslashes on Windows, so that paths such as
c:\dir\/file are no longer generated [perl #71710]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=71710>.
- •
- "if" has been upgraded from version 0.05 to
0.06
- •
- "IPC::Cmd" has been upgraded from version 0.60 to
0.64
- •
- "IPC::Open3" has been upgraded from version 1.06
to 1.07.
The internal "xclose" routine now knows how to handle file
descriptors, as documented, so duplicating STDIN in a child process using
its file descriptor now works [perl #76474]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=71710>.
- •
- "Locale::Codes" has been upgraded from version
3.13 to 3.14.
- •
- "Locale::Maketext" has been upgraded from version
1.15 to 1.16.
It fixes an infinite loop in "Locale::Maketext::Guts::_compile()"
when working with tainted values (CPAN RT #40727
<https://rt.cpan.org/Public/Bug/Display.html?id=40727>).
"->maketext" calls will now backup and restore $@ so that error
messages are not suppressed (CPAN RT #34182
<https://rt.cpan.org/Public/Bug/Display.html?id=34182>).
- •
- "Math::BigInt" has been upgraded from version
1.95 to 1.97.
This prevents "sqrt($int)" from crashing under "use
bigrat;" [perl #73534]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=73534>.
- •
- "NEXT" has been upgraded from version 0.64 to
0.65.
- •
- "overload" has been upgraded from version 1.10 to
1.11.
"overload::Method" can now handle subroutines that are themselves
blessed into overloaded classes [perl #71998]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=71998>.
- •
- "PathTools" has been upgraded from version
3.31_01 to 3.34.
- •
- "podlators" has been upgraded from version 2.3.1
to 2.4.0
- •
- "sigtrap" has been upgraded from version 1.04 to
1.05.
It no longer tries to modify read-only arguments when generating a backtrace
[perl #72340]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=72340>.
- •
- "threads" has been upgraded from version 1.77_03
to 1.81_01.
- •
- "threads::shared" has been upgrade from version
1.33_03 to 1.34
- •
- "Unicode::Collate" has been upgraded from version
0.59 to 0.63
U::C::Locale newly supports locales: ar, be, bg, de__phonebook, hu, hy, kk,
mk, nso, om, tn, vi, hr, ig, ru, sq, se, sr, to and uk
- •
- "Unicode::Normalize" has been upgraded from
version 1.06 to 1.07
- •
- "B::Deparse" has been upgraded from version 0.98
to 0.99
B::Deparse now properly handles the code that applies a conditional pattern
match against implicit $_ as it was fixed in [perl #20444]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=20444>.
- •
- "GDBM_File" has been upgraded from version 1.10
to 1.11
Documentation¶
Changes to Existing Documentation¶
perlapi
- •
- The documentation for the "SvTRUE" macro was
simply wrong in stating that get-magic is not processed. It has been
corrected.
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.
Changes to Existing Diagnostics¶
- •
- The 'Layer does not match this perl' error message has been
replaced with these more helpful messages:
- •
- PerlIO layer function table size (%d) does not match size
expected by this perl (%d)
- •
- PerlIO layer instance size (%d) does not match size
expected by this perl (%d)
Testing¶
- •
- The script t/op/threads-dirh.t has been added, which
tests interaction of threads and directory handles.
- IRIX
- Conversion of strings to floating-point numbers is now more
accurate on IRIX systems [perl #32380]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=32380>.
- Mac OS X
- Early versions of Mac OS X (Darwin) had buggy
implementations of the "setregid", "setreuid",
"setrgid" and "setruid" functions, so perl would
pretend they did not exist.
These functions are now recognised on Mac OS 10.5 (Leopard; Darwin 9) and
higher, as they have been fixed [perl #72990]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=72990>.
- OpenVOS
- perl now builds again with OpenVOS (formerly known as
Stratus VOS) [perl #78132]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=78132>.
- VMS
- The shortening of symbols longer than 31 characters in the
C sources is now done by the compiler rather than by xsubpp (which could
only do so for generated symbols in XS code).
- Windows
- $Config{gccversion} is now set correctly when perl is built
using the mingw64 compiler from <http://mingw64.org> [perl #73754]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=73754>.
The build process proceeds more smoothly with mingw and dmake when
C:\MSYS\bin is in the PATH, due to a "Cwd" fix.
Internal Changes¶
- •
- See "Regular expressions retain their localeness when
interpolated", above.
- •
- The "sv_cmp_flags",
"sv_cmp_locale_flags", "sv_eq_flags" and
"sv_collxfrm_flags" functions have been added. These are like
their non-_flags counterparts, but allow one to specify whether get-magic
is processed.
The "sv_cmp", "sv_cmp_locale", "sv_eq" and
"sv_collxfrm" functions have been replaced with wrappers around
the new functions.
- •
- A new "sv_2bool_flags" function has been added.
This is like "sv_2bool", but it lets the calling code decide
whether get-magic is handled. "sv_2bool" is now a macro that
calls the new function.
- •
- A new macro, "SvTRUE_nomg", has been added.
This is like "SvTRUE", except that it does not process magic. It
uses the new "sv_2bool_flags" function.
- •
- "sv_catsv_flags" no longer calls
"mg_get" on its second argument (the source string) if the flags
passed to it do not include SV_GMAGIC. So it now matches the
documentation.
- •
- A new interface has been added for custom check hooks on
subroutines. See "Custom per-subroutine check hooks",
above.
- •
- List op building functions have been added to the API. See
op_append_elem, op_append_list, and op_prepend_elem.
- •
- The LINKLIST macro, part of op building that constructs the
execution-order op chain, has been added to the API.
- •
- Many functions ending with pvn now have equivalent
pv/pvs/sv versions.
- •
- The "save_freeop", "save_op",
"save_pushi32ptr" and "save_pushptrptr" functions have
been added to the API.
- •
- The new API function "parse_stmtseq()" parses a
sequence of statements, up to closing brace or EOF.
Selected Bug Fixes¶
- •
- A regular expression match in the right-hand side of a
global substitution ("s///g") that is in the same scope will no
longer cause match variables to have the wrong values on subsequent
iterations. This can happen when an array or hash subscript is
interpolated in the right-hand side, as in "s|(.)|@a{ print($1), /./
}|g" [perl #19078]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=19078>.
- •
- Constant-folding used to cause
$text =~ ( 1 ? /phoo/ : /bear/)
to turn into
$text =~ /phoo/
at compile time. Now it correctly matches against $_ [perl #20444]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=20444>.
- •
- Parsing Perl code (either with string "eval" or
by loading modules) from within a "UNITCHECK" block no longer
causes the interpreter to crash [perl #70614]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=70614>.
- •
- When "-d" is used on the shebang ("#!")
line, the debugger now has access to the lines of the main program. In the
past, this sometimes worked and sometimes did not, depending on what order
things happened to be arranged in memory [perl #71806]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=71806>.
- •
- The "y///" or "tr///" operator now
calls get-magic (e.g., the "FETCH" method of a tie) on its
left-hand side just once, not twice [perl #76814]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
- •
- String comparison ("eq", "ne",
"lt", "gt", "le", "ge" and
"cmp") and logical not ("not" and "!")
operators no longer call magic (e.g., tie methods) twice on their operands
[perl #76814]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
This bug was introduced in an earlier 5.13 release, and does not affect perl
5.12.
- •
- When a tied (or other magic) variable is used as, or in, a
regular expression, it no longer has its "FETCH" method called
twice [perl #76814]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=76814>.
This bug was introduced in an earlier 5.13 release, and does not affect perl
5.12.
- •
- The "-C" command line option can now be followed
by other options [perl #72434]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=72434>.
- •
- Assigning a glob to a PVLV used to convert it to a plain
string. Now it works correctly, and a PVLV can hold a glob. This would
happen when a nonexistent hash or array element was passed to a
subroutine:
sub { $_[0] = *foo }->($hash{key});
# $_[0] would have been the string "*main::foo"
It also happened when a glob was assigned to, or returned from, an element
of a tied array or hash [perl #36051]
<http://rt.perl.org/rt3//Public/Bug/Display.html?id=36051>.
- •
- Creating a new thread when directory handles were open used
to cause a crash, because the handles were not cloned, but simply passed
to the new thread, resulting in a double free.
Now directory handles are cloned properly, on systems that have a
"fchdir" function. On other systems, new threads simply do not
inherit directory handles from their parent threads [perl #75154]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=75154>.
- •
- The regular expression parser no longer hangs when parsing
"\18" and "\88".
This bug was introduced in version 5.13.5 and did not affect earlier
versions [perl #78058]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=78058>.
- •
- Subroutine redefinition works once more in the debugger
[perl #48332]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=48332>.
- •
- The "&" "|" "^" bitwise
operators no longer coerce read-only arguments [perl #20661]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=20661>.
- •
- Stringifying a scalar containing -0.0 no longer has the
affect of turning false into true [perl #45133]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=45133>.
- •
- Aliasing packages by assigning to globs or deleting
packages by deleting their containing stash elements used to have erratic
effects on method resolution, because the internal 'isa' caches were not
reset. This has been fixed.
- •
- "sort" with a custom sort routine could crash if
too many nested subroutine calls occurred from within the sort routine
[perl #77930]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=77930>.
This bug was introduced in an earlier 5.13 release, and did not affect perl
5.12.
- •
- The "eval_sv" and "eval_pv" C functions
now set $@ correctly when there is a syntax error and no
"G_KEEPERR" flag, and never set it if the "G_KEEPERR"
flag is present [perl #3719]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=3719>.
- •
- Nested "map" and "grep" blocks no
longer leak memory when processing large lists [perl #48004]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=48004>.
- •
- Malformed "version" objects no longer cause
crashes [perl #78286]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=78286>.
- •
- The interpreter no longer crashes when freeing
deeply-nested arrays of arrays. Hashes have not been fixed yet [perl
#44225]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=44225>.
- •
- The mechanism for freeing objects in globs used to leave
dangling pointers to freed SVs, meaning Perl users could see corrupted
state during destruction.
Perl now only frees the affected slots of the GV, rather than freeing the GV
itself. This makes sure that there are no dangling refs or corrupted state
during destruction.
- •
- The typeglob "*,", which holds the scalar
variable $, (output field separator), had the wrong reference count in
child threads.
- •
- "splice" now calls set-magic. This means that,
for instance, changes made by "splice @ISA" are respected by
method calls [perl #78400]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=78400>.
- •
- "use v5.8" no longer leaks memory [perl #78436]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=78436>.
- •
- The XS multicall API no longer causes subroutines to lose
reference counts if called via the multicall interface from within those
very subroutines. This affects modules like List::Util. Calling one of its
functions with an active subroutine as the first argument could cause a
crash [perl #78070]
<http://rt.perl.org/rt3/Public/Bug/Display.html?id=78070>.
Errata¶
- •
- Fixed a typo in perl5135delta regarding array slices and
smart matching
Acknowledgements¶
Perl 5.13.6 represents approximately one month of development since Perl 5.13.5
and contains 67920 lines of changes across 566 files from 47 authors and
committers:
A. Sinan Unur, Aaron Crane, Alex Davies, Ali Polatel, Allen Smith, Andrew
Rodland, Andy Dougherty, Ben Morrow, brian d foy, Casey West, Chip Salzenberg,
Chris 'BinGOs' Williams, Craig A. Berry, David Golden, David Mitchell, Eric
Brine, Father Chrysostomos, Florian Ragwitz, George Greer, gregor herrmann,
Jan Dubois, Jerry D. Hedden, Jesse Vincent, Joshua Pritikin, Karl Williamson,
kmx, Michael G Schwern, Mike Kelly, Nicholas Clark, Paul Green, Rafael
Garcia-Suarez, Renee Baecker, Ricardo Signes, Sisyphus, Slaven Rezic, Steffen
Mueller, Steve Hay, Sullivan Beck, Tatsuhiko Miyagawa, Todd Rinaldo, Tony
Cook, Tye McQueen, Vernon Lyon, Walt Mankowski, 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.