4 This has been completed up to b2ef6d44, except for:
5 d9a4b459f94297889956ac3adc42707365f274c2
6 bf5522a13a381257966e7ed6b731195a873b153e
7 9cef83062267e94311e1fd8744396e440642738e
8 8e88cfee26d866223a6b3bfffce6270271de00db
12 [ this is a template for a new perldelta file. Any text flagged as
13 XXX needs to be processed before release. ]
15 perldelta - what is new for perl v5.13.8
19 This document describes differences between the 5.13.8 release and
22 If you are upgrading from an earlier release such as 5.13.6, first read
23 L<perl5137delta>, which describes differences between 5.13.6 and
28 XXX Any important notices here
30 =head1 Core Enhancements
32 XXX New core language features go here. Summarise user-visible core language
33 enhancements. Particularly prominent performance optimisations could go
34 here, but most should go in the L</Performance Enhancements> section.
36 [ List each enhancement as a =head2 entry ]
38 =head2 C<-d:-foo> calls C<Devel::foo::unimport>
40 The syntax C<-dI<B<:>foo>> was extended in 5.6.1 to make C<-dI<:fooB<=bar>>>
41 equivalent to C<-MDevel::foo=bar>, which expands
42 internally to C<use Devel::foo 'bar';>.
43 F<perl> now allows prefixing the module name with C<->, with the same
44 semantics as C<-M>, I<i.e.>
50 Equivalent to C<-M-Devel::foo>, expands to
51 C<no Devel::foo;>, calls C<< Devel::foo->unimport() >>
56 Equivalent to C<-M-Devel::foo=bar>, expands to C<no Devel::foo 'bar';>,
57 calls C<< Devel::foo->unimport('bar') >> if the method exists.
61 This is particularly useful to suppresses the default actions of a
62 C<Devel::*> module's C<import> method whilst still loading it for debugging.
64 =head2 Filehandle method calls load IO::File on demand
66 When a method call on a filehandle would die because the method can not
67 be resolved and L<IO::File> has not been loaded, Perl now loads IO::File
68 via C<require> and attempts method resolution again:
70 open my $fh, ">", $file;
71 $fh->binmode(":raw"); # loads IO::File and succeeds
73 This also works for globs like STDOUT, STDERR and STDIN:
77 Because this on-demand load only happens if method resolution fails, the
78 legacy approach of manually loading an IO::File parent class for partial
79 method support still works as expected:
82 open my $fh, ">", $file;
83 $fh->autoflush(1); # IO::File not loaded
85 =head2 Full functionality for C<use feature 'unicode_strings'>
87 This release provides full functionality for C<use feature
88 'unicode_strings'>. Under its scope, all string operations executed and
89 regular expressions compiled (even if executed outside its scope) have
90 Unicode semantics. See L<feature>.
92 This feature avoids the "Unicode Bug" (See
93 L<perlunicode/The "Unicode Bug"> for details.) If their is a
94 possibility that your code will process Unicode strings, you are
95 B<strongly> encouraged to use this subpragma to avoid nasty surprises.
97 This availability of this should strongly affect the whole tone of
98 various documents, such as L<perlunicode> and L<perluniintro>, but this
99 work has not been done yet.
101 =head2 Exception Handling Backcompat Hack
103 When an exception is thrown in an C<eval BLOCK>, C<$@> is now set before
104 unwinding, as well as being set after unwinding as the eval block exits. This
105 early setting supports code that has historically treated C<$@> during unwinding
106 as an indicator of whether the unwinding was due to an exception. These modules
107 had been broken by 5.13.1's change from setting C<$@> early to setting it late.
108 This double setting arrangement is a stopgap until the reason for unwinding can
109 be made properly introspectable. C<$@> has never been a reliable indicator of
114 XXX Any security-related notices go here. In particular, any security
115 vulnerabilities closed should be noted here rather than in the
116 L</Selected Bug Fixes> section.
118 [ List each security issue as a =head2 entry ]
120 =head1 Incompatible Changes
122 =head2 Attempting to use C<:=> as an empty attribute list is now a syntax error
124 Previously C<my $pi := 4;> was exactly equivalent to C<my $pi : = 4;>,
125 with the C<:> being treated as the start of an attribute list, ending before
126 the C<=>. The use of C<:=> to mean C<: => was deprecated in 5.12.0, and is now
127 a syntax error. This will allow the future use of C<:=> as a new token.
129 We find no Perl 5 code on CPAN using this construction, outside the core's
130 tests for it, so we believe that this change will have very little impact on
131 real-world codebases.
133 If it is absolutely necessary to have empty attribute lists (for example,
134 because of a code generator) then avoid the error by adding a space before
137 =head2 Run-time code block in regular expressions
139 Code blocks in regular expressions (C<(?{...})> and C<(??{...})>) used not
140 to inherit any pragmata (strict, warnings, etc.) if the regular expression
141 was compiled at run time as happens in cases like these two:
144 $foo =~ $bar; # when $bar contains (?{...})
145 $foo =~ /$bar(?{ $finished = 1 })/;
147 This was a bug, which has now been fixed. But it has the potential to break
148 any code that was relying on this bug.
152 XXX Any deprecated features, syntax, modules etc. should be listed here.
153 In particular, deprecated modules should be listed here even if they are
154 listed as an updated module in the L</Modules and Pragmata> section.
156 [ List each deprecation as a =head2 entry ]
158 =head2 C<?PATTERN?> is deprecated
160 C<?PATTERN?> (without the initial m) has been deprecated and now produces
163 =head2 C<sv_compile_2op> is now deprecated
165 The C<sv_compile_2op> is now deprecated, and will be removed. Searches suggest
166 that nothing on CPAN is using it, so this should have zero impact.
168 It attempted to provide an API to compile code down to an optree, but failed
169 to bind correctly to lexicals in the enclosing scope. It's not possible to
170 fix this problem within the constraints of its parameters and return value.
172 =head2 Tie functions on scalars holding typeglobs
174 Calling a tie function (C<tie>, C<tied>, C<untie>) with a scalar argument
175 acts on a file handle if the scalar happens to hold a typeglob.
177 This is a long-standing bug that will be removed in Perl 5.16, as
178 there is currently no way to tie the scalar itself when it holds
179 a typeglob, and no way to untie a scalar that has had a typeglob
182 This bug was fixed in 5.13.7 but, because of the breakage it caused, the
183 fix has been reverted. Now there is a deprecation warning whenever a tie
184 function is used on a handle without an explicit C<*>.
186 =head1 Performance Enhancements
188 XXX Changes which enhance performance without changing behaviour go here. There
189 may well be none in a stable release.
191 [ List each enhancement as a =item entry ]
201 =head1 Modules and Pragmata
203 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
204 go here. If Module::CoreList is updated, generate an initial draft of the
205 following sections using F<Porting/corelist-perldelta.pl>, which prints stub
206 entries to STDOUT. Results can be pasted in place of the '=head2' entries
207 below. A paragraph summary for important changes should then be added by hand.
208 In an ideal world, dual-life modules would have a F<Changes> file that could be
211 [ Within each section, list entries as a =item entry ]
213 =head2 New Modules and Pragmata
223 =head2 Updated Modules and Pragmata
229 C<Digest::SHA> has been upgraded from 5.48 to 5.49
231 shasum now more closely mimics sha1sum/md5sum and Addfile
232 accepts all POSIX filenames.
236 C<ExtUtils::CBuilder> has been upgraded from 0.2703 to 0.2802
240 C<if> has been upgraded from 0.06 to 0.0601.
244 C<Devel::SelfStubber> has been upgraded from version 1.03 to 1.04.
248 C<IPC::Cmd> has been upgraded from 0.64 to 0.66
250 Resolves an issue with splitting Win32 command lines
251 and documentation enhancements.
255 C<Locale::Codes> has been upgraded from version 3.14 to 3.15
259 C<Memoize> has been upgraded from version 1.01_03 to 1.02.
263 C<MIME::Base64> has been upgraded from 3.10 to 3.13
265 Now provides encode_base64url and decode_base64url functions to process
266 the base64 scheme for "URL applications".
270 C<mro> has been upgraded from version 1.05 to 1.06.
272 C<next::method> I<et al.> now take into account that every class inherits
274 L<[perl #68654]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68654>.
278 C<overload> has been upgraded from 1.11 to 1.12.
282 C<PerlIO::scalar> has been upgraded from 0.10 to 0.11.
284 A C<read> after a C<seek> beyond the end of the string no longer thinks it
286 L<[perl #78716]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=78716>.
290 C<re> has been upgraded from 0.14 to 0.15.
294 C<Socket> has been upgraded from 1.91 to 1.92.
296 It has several new functions for handling IPv6 addresses.
300 C<Storable> has been upgraded from 2.24 to 2.25.
302 This adds support for serialising code references that contain UTF-8 strings
303 correctly. The Storable minor version number changed as a result -- this means
304 Storable users that set C<$Storable::accept_future_minor> to a C<FALSE> value
305 will see errors (see L<Storable/FORWARD COMPATIBILITY> for more details).
309 C<Time::HiRes> has been upgraded from 1.9721 to 1.9721_01.
313 C<Unicode::Collate> has been upgraded from 0.67 to 0.68
317 C<Unicode::UCD> has been upgraded from 0.29 to 0.30.
321 C<version> has been upgraded from 0.82 to 0.86.
325 C<Win32> has been upgraded from 0.039 to 0.040.
329 =head2 Removed Modules and Pragmata
341 XXX Changes to files in F<pod/> go here. Consider grouping entries by
342 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
344 =head2 New Documentation
346 XXX Changes which create B<new> files in F<pod/> go here.
350 XXX Description of the purpose of the new file here
352 =head2 Changes to Existing Documentation
354 XXX Changes which significantly change existing files in F<pod/> go here.
355 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
364 XXX Description of the change here
370 The following additions or changes have been made to diagnostic output,
371 including warnings and fatal error messages. For the complete list of
372 diagnostic messages, see L<perldiag>.
374 XXX New or changed warnings emitted by the core's C<C> code go here. Also
375 include any changes in L<perldiag> that reconcile it to the C<C> code.
377 [ Within each section, list entries as a =item entry ]
379 =head2 New Diagnostics
381 XXX Newly added diagnostic messages go here
387 There is a new "Closure prototype called" error.
391 =head2 Changes to Existing Diagnostics
393 XXX Changes (i.e. rewording) of diagnostic messages go here
399 The "Found = in conditional" warning that is emitted when a constant is
400 assigned to a variable in a condition is now withheld if the constant is
401 actually a subroutine or one generated by C<use constant>, since the value
402 of the constant may not be known at the time the program is written
403 L<[perl #77762]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=77762>.
407 =head1 Utility Changes
409 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
410 here. Most of these are built within the directories F<utils> and F<x2p>.
412 [ List utility changes as a =head3 entry for each utility and =item
413 entries for each change
414 Use L<XXX> with program names to get proper documentation linking. ]
426 =head1 Configuration and Compilation
428 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
429 go here. Any other changes to the Perl build process should be listed here.
430 However, any platform-specific changes should be listed in the
431 L</Platform Support> section, instead.
433 [ List changes as a =item entry ].
445 XXX Any significant changes to the testing of a freshly built perl should be
446 listed here. Changes which create B<new> files in F<t/> go here as do any
447 large changes to the testing harness (e.g. when parallel testing was added).
448 Changes to existing files in F<t/> aren't worth summarising, although the bugs
449 that they represent may be covered elsewhere.
451 [ List each test improvement as a =item entry ]
461 =head1 Platform Support
463 XXX Any changes to platform support should be listed in the sections below.
465 [ Within the sections, list each platform as a =item entry with specific
466 changes as paragraphs below it. ]
470 XXX List any platforms that this version of perl compiles on, that previous
471 versions did not. These will either be enabled by new files in the F<hints/>
472 directories, or new subdirectories and F<README> files at the top level of the
477 =item XXX-some-platform
483 =head2 Discontinued Platforms
485 XXX List any platforms that this version of perl no longer compiles on.
489 =item XXX-some-platform
495 =head2 Platform-Specific Notes
497 XXX List any changes for specific platforms. This could include configuration
498 and compilation changes or changes in portability/compatibility. However,
499 changes within modules for platforms should generally be listed in the
500 L</Modules and Pragmata> section.
506 The NetBSD hints file has been changed to make the system's malloc the
511 =head1 Internal Changes
513 XXX Changes which affect the interface available to C<XS> code go here.
514 Other significant internal changes for future core maintainers should
517 [ List each test improvement as a =item entry ]
523 C<mg_findext> and C<sv_unmagicext> have been added.
525 These new functions allow extension authors to find and remove magic attached to
526 scalars based on both the magic type and the magic virtual table, similar to how
527 C<sv_magicext> attaches magic of a certain type and with a given virtual table
528 to a scalar. This eliminates the need for extensions to walk the list of
529 C<MAGIC> pointers of an C<SV> to find the magic that belongs to them.
533 =head1 Selected Bug Fixes
535 XXX Important bug fixes in the core language are summarised here.
536 Bug fixes in files in F<ext/> and F<lib/> are best summarised in
537 L</Modules and Pragmata>.
539 [ List each fix as a =item entry ]
545 C<BEGIN {require 5.12.0}> now behaves as documented, rather than behaving
546 identically to C<use 5.12.0;>. Previously, C<require> in a C<BEGIN> block
547 was erroneously executing the C<use feature ':5.12.0'> and
548 C<use strict; use warnings;> behaviour, which only C<use> was documented to
550 L<[perl #69050]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=69050>.
555 L<[perl #69050]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=69050>,
556 C<use 6> and C<no 5> no longer leak memory.
560 C<eval "BEGIN{die}"> no longer leaks memory on non-threaded builds.
564 PerlIO no longer crashes when called recursively, e.g., from a signal
565 handler. Now it just leaks memory
566 L<[perl #75556]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=75556>.
570 Defining a constant with the same name as one of perl's special blocks
571 (e.g., INIT) stopped working in 5.12.0, but has now been fixed
572 L<[perl #78634]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=78634>.
576 A reference to a literal value used as a hash key (C<$hash{\"foo"}>) used
577 to be stringified, even if the hash was tied
578 L<[perl #79178]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=79178>.
582 A closure containing an C<if> statement followed by a constant or variable
583 is no longer treated as a constant
584 L<[perl #63540]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=63540>.
588 Calling a closure prototype (what is passed to an attribute handler for a
589 closure) now results in a "Closure prototype called" error message
590 L<[perl #68560]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68560>.
594 A regular expression optimisation would sometimes cause a match with a
595 C<{n,m}> quantifier to fail when it should match
596 L<[perl #79152]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=79152>.
600 What has become known as the "Unicode Bug" is resolved in this release.
601 Under C<use feature 'unicode_strings'>, the internal storage format of a
602 string no longer affects the external semantics. There are two known
603 exceptions. User-defined case changing functions, which are planned to
604 be deprecated in 5.14, require utf8-encoded strings to function; and the
605 character C<LATIN SMALL LETTER SHARP S> in regular expression
606 case-insensitive matching has a somewhat different set of bugs depending
607 on the internal storage format. Case-insensitive matching of all
608 characters that have multi-character matches, as this one does, is
609 problematical in Perl.
610 L<[perl #58182]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=58182>.
614 Mentioning a read-only lexical variable from the enclosing scope in a
615 string C<eval> would cause the variable to become writable
616 L<[perl #19135]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=19135>.
620 C<state> can now be used with attributes. It used to mean the same thing as
621 C<my> if attributes were present
622 L<[perl #68658]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68658>.
626 Expressions like C<< @$a > 3 >> no longer cause C<$a> to be mentioned in
627 the "Use of uninitialized value in numeric gt" warning when C<$a> is
628 undefined (since it is not part of the C<E<gt>> expression, but the operand
630 L<[perl #72090]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=72090>.
634 C<require> no longer causes C<caller> to return the wrong file name for
635 the scope that called C<require> and other scopes higher up that had the
637 L<[perl #68712]|http://rt.perl.org/rt3/Public/Bug/Display.html?id=68712>.
641 =head1 Known Problems
643 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
644 tests that had to be C<TODO>ed for the release would be noted here, unless
645 they were specific to a particular platform (see below).
647 This is a list of some significant unfixed bugs, which are regressions
648 from either 5.XXX.XXX or 5.XXX.XXX.
650 [ List each fix as a =item entry ]
662 XXX If any significant core contributor has died, we've added a short obituary
665 =head1 Acknowledgements
667 XXX The list of people to thank goes here.
669 =head1 Reporting Bugs
671 If you find what you think is a bug, you might check the articles
672 recently posted to the comp.lang.perl.misc newsgroup and the perl
673 bug database at http://rt.perl.org/perlbug/ . There may also be
674 information at http://www.perl.org/ , the Perl Home Page.
676 If you believe you have an unreported bug, please run the L<perlbug>
677 program included with your release. Be sure to trim your bug down
678 to a tiny but sufficient test case. Your bug report, along with the
679 output of C<perl -V>, will be sent off to perlbug@perl.org to be
680 analysed by the Perl porting team.
682 If the bug you are reporting has security implications, which make it
683 inappropriate to send to a publicly archived mailing list, then please send
684 it to perl5-security-report@perl.org. This points to a closed subscription
685 unarchived mailing list, which includes all the core committers, who be able
686 to help assess the impact of issues, figure out a resolution, and help
687 co-ordinate the release of patches to mitigate or fix the problem across all
688 platforms on which Perl is supported. Please only use this address for
689 security issues in the Perl core, not for modules independently
694 The F<Changes> file for an explanation of how to view exhaustive details
697 The F<INSTALL> file for how to build Perl.
699 The F<README> file for general stuff.
701 The F<Artistic> and F<Copying> files for copyright information.