2 35e037e846 Commit 1735f6f started to escape all...
3 9b4bdfd44e fix chop formats with non PV vars
9 [ this is a template for a new perldelta file. Any text flagged as XXX needs
10 to be processed before release. ]
12 perldelta - what is new for perl v5.19.6
16 This document describes differences between the 5.19.5 release and the 5.19.6
19 If you are upgrading from an earlier release such as 5.19.4, first read
20 L<perl5195delta>, which describes differences between 5.19.4 and 5.19.5.
24 XXX Any important notices here
26 =head1 Core Enhancements
28 XXX New core language features go here. Summarize user-visible core language
29 enhancements. Particularly prominent performance optimisations could go
30 here, but most should go in the L</Performance Enhancements> section.
32 [ List each enhancement as a =head2 entry ]
34 =head2 $a and $b warnings exemption
36 The special variables $a and $b, used in C<sort>, are now exempt from "used
37 once" warnings, even where C<sort> is not used. This makes it easier for
38 CPAN modules to provide functions using $a and $b for similar purposes.
43 XXX Any security-related notices go here. In particular, any security
44 vulnerabilities closed should be noted here rather than in the
45 L</Selected Bug Fixes> section.
47 [ List each security issue as a =head2 entry ]
49 =head1 Incompatible Changes
51 XXX For a release on a stable branch, this section aspires to be:
53 There are no changes intentionally incompatible with 5.XXX.XXX
54 If any exist, they are bugs, and we request that you submit a
55 report. See L</Reporting Bugs> below.
57 [ List each incompatible change as a =head2 entry ]
61 XXX Any deprecated features, syntax, modules etc. should be listed here.
63 =head2 Module removals
65 XXX Remove this section if inapplicable.
67 The following modules will be removed from the core distribution in a
68 future release, and will at that time need to be installed from CPAN.
69 Distributions on CPAN which require these modules will need to list them as
72 The core versions of these modules will now issue C<"deprecated">-category
73 warnings to alert you to this fact. To silence these deprecation warnings,
74 install the modules in question from CPAN.
76 Note that these are (with rare exceptions) fine modules that you are encouraged
77 to continue to use. Their disinclusion from core primarily hinges on their
78 necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
79 not usually on concerns over their design.
83 =item L<Package::Constants>
87 [ List each other deprecation as a =head2 entry ]
89 =head1 Performance Enhancements
91 XXX Changes which enhance performance without changing behaviour go here.
92 There may well be none in a stable release.
94 [ List each enhancement as a =item entry ]
100 Constant hash key lookups (C<$hash{key}> as opposed to C<$hash{$key}>) have
101 long had the internal hash value computed at compile time, to speed up
102 lookup. This optimisation has only now been applied to hash slices as
107 Combined C<and> and C<or> operators in void context, like those
108 generated for C<< unless ($a && $b) >> and C<< if ($a || b) >> now
109 short circuit directly to the end of the statement. [perl #120128]
113 =head1 Modules and Pragmata
115 XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
116 go here. If Module::CoreList is updated, generate an initial draft of the
117 following sections using F<Porting/corelist-perldelta.pl>, which prints stub
118 entries to STDOUT. Results can be pasted in place of the '=head2' entries
119 below. A paragraph summary for important changes should then be added by hand.
120 In an ideal world, dual-life modules would have a F<Changes> file that could be
123 [ Within each section, list entries as a =item entry ]
125 =head2 New Modules and Pragmata
135 =head2 Updated Modules and Pragmata
141 L<B> has been upgraded from version 1.46 to 1.47.
143 C<< B::PMOP->precomp >> now preserves the internal UTF8 flag correctly, so
144 chr 256 remains chr 256, instead of turning into "\xc4\x80". This allows
145 L<B::Deparse> to deparse Unicode regular expression correctly.
148 C<< B::HV->ARRAY >> now preserves the UTF8 flag on returned hash keys.
153 L<B::Concise> has been upgraded from version 0.99 to 0.991.
155 B<-debug> output now includes C<op_other> pointers.
159 L<B::Deparse> has been upgraded from version 1.23 to 1.24.
161 C<s//\(3)/e> is now deparsed in a way that does not issue warnings when
162 parsed again. [perl #119807]
164 C<glob(my $x)> is now deparsed correctly, rather than as C<< <my $x> >> or
167 C<CORE::glob> is now deparsed correctly with the CORE:: prefix when there
168 is a subroutine named "glob".
172 L<IO::Select> has been upgraded from version 1.21 to 1.22.
174 Removing a closed file handle from an IO::Select object now correctly
175 updates its internal state and returns the correct value. [perl #75156]
179 L<Module::CoreList> has been upgraded from version 3.00 to 3.01.
181 The list of Perl versions covered has been updated.
185 L<PerlIO::scalar> has been upgraded from version 0.17 to 0.18.
187 A bug fix in 0.17 caused references to be stringified as soon as a handle
188 to it was opened, even if it was opened only for reading. It also croaked
189 on read-only references. This has been fixed. [perl #119529]
193 L<Tie::StdHandle> has been upgraded from version 4.3 to 4.4.
195 It no longer prints C<$\> twice. [perl #120202]
197 It no longer ignores the offset passed to C<syswrite>.
201 =head2 Removed Modules and Pragmata
213 XXX Changes to files in F<pod/> go here. Consider grouping entries by
214 file and be sure to link to the appropriate page, e.g. L<perlfunc>.
216 =head2 New Documentation
218 XXX Changes which create B<new> files in F<pod/> go here.
222 XXX Description of the purpose of the new file here
224 =head2 Changes to Existing Documentation
226 XXX Changes which significantly change existing files in F<pod/> go here.
227 However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
236 XXX Description of the change here
242 The following additions or changes have been made to diagnostic output,
243 including warnings and fatal error messages. For the complete list of
244 diagnostic messages, see L<perldiag>.
246 XXX New or changed warnings emitted by the core's C<C> code go here. Also
247 include any changes in L<perldiag> that reconcile it to the C<C> code.
249 =head2 New Diagnostics
251 XXX Newly added diagnostic messages go under here, separated into New Errors
260 XXX L<message|perldiag/"message">
270 XXX L<message|perldiag/"message">
274 =head2 Changes to Existing Diagnostics
276 XXX Changes (i.e. rewording) of diagnostic messages go here
282 L<%%s[%s] in scalar context better written as $%s[%s]|perldiag/"%%s[%s] in scalar context better written as $%s[%s]">:
284 This warning now occurs for any C<%array[$index]> or C<%hash{key}> known to
285 be in scalar context at compile time. Previously it was worded "Scalar
286 value %%s[%s] better written as $%s[%s]".
290 =head1 Utility Changes
292 XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
293 Most of these are built within the directories F<utils> and F<x2p>.
295 [ List utility changes as a =head3 entry for each utility and =item
296 entries for each change
297 Use L<XXX> with program names to get proper documentation linking. ]
309 =head1 Configuration and Compilation
311 XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
312 go here. Any other changes to the Perl build process should be listed here.
313 However, any platform-specific changes should be listed in the
314 L</Platform Support> section, instead.
316 [ List changes as a =item entry ].
328 XXX Any significant changes to the testing of a freshly built perl should be
329 listed here. Changes which create B<new> files in F<t/> go here as do any
330 large changes to the testing harness (e.g. when parallel testing was added).
331 Changes to existing files in F<t/> aren't worth summarizing, although the bugs
332 that they represent may be covered elsewhere.
334 [ List each test improvement as a =item entry ]
340 F<ext/File-Find/t/find.t> has been converted from manual C<print>
341 statements to Test::More functions. Each test now has a description.
346 =head1 Platform Support
354 Synology ships its NAS boxes with a lean Linux distribution (DSM) on relative
355 cheap CPU's (like the Marvell Kirkwood mv6282 - ARMv5tel or Freescale QorIQ
356 P1022 ppc - e500v2) not meant for workstations or development. These boxes
357 should build now. The basic problems are the non-standard location for tools.
361 =head2 Discontinued Platforms
363 XXX List any platforms that this version of perl no longer compiles on.
367 =item XXX-some-platform
373 =head2 Platform-Specific Notes
375 XXX List any changes for specific platforms. This could include configuration
376 and compilation changes or changes in portability/compatibility. However,
377 changes within modules for platforms should generally be listed in the
378 L</Modules and Pragmata> section.
384 Support for building with Visual C++ 2013 has been added. There are currently
385 two possible test failures (see L<perlwin32/"Testing Perl on Windows">) which
386 will hopefully be resolved soon.
390 Perl can now be built in one shot with no user intervention on WinCE by running
391 C<nmake -f Makefile.ce all>.
393 Support for building with EVC (Embedded Visual C++) 4 has been restored. Perl
394 can also be built using Smart Devices for Visual C++ 2005 or 2008.
398 =head1 Internal Changes
400 XXX Changes which affect the interface available to C<XS> code go here. Other
401 significant internal changes for future core maintainers should be noted as
404 [ List each change as a =item entry ]
410 Compiling with C<-Accflags=-PERL_BOOL_AS_CHAR> now allows C99 and C++
411 compilers to emulate the aliasing of C<bool> to C<char> that perl does for
412 C89 compilers. [perl #120314]
416 =head1 Selected Bug Fixes
418 XXX Important bug fixes in the core language are summarized here. Bug fixes in
419 files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
421 [ List each fix as a =item entry ]
427 Perl 5.18.0 accidentally disallowed C<-bareword> under C<use strict> and
428 C<use integer>. This has been fixed. [perl #120288]
432 C<-a> at the start of a line (or a hyphen with any single letter that is
433 not a filetest operator) no longer produces an erroneous 'Use of "-a"
434 without parentheses is ambiguous' warning. [perl #120288]
438 Lvalue context is now properly propagated into bare blocks and C<if> and
439 C<else> blocks in lvalue subroutines. Previously, arrays and hashes would
440 sometimes incorrectly be flattened when returned in lvalue list context, or
441 "Bizarre copy" errors could occur. [perl #119797]
445 Lvalue context is now propagated to the branches of C<||> and C<&&> (and
446 their alphabetic equivalents, C<or> and C<and>). This means
447 C<foreach (pos $x || pos $y) {...}> now allows C<pos> to be modified
452 C<*DB::DB = sub {} if 0> no longer stops Perl's debugging mode from finding
453 C<DB::DB> subs declared thereafter.
457 C<stat> and C<readline> remember the last handle used; the former
458 for the special C<_> filehandle, the latter for C<${^LAST_FH}>.
459 C<eval "*foo if 0"> where *foo was the last handle passed to C<stat>
460 or C<readline> could cause that handle to be forgotten if the
461 handle were not opened yet. This has been fixed.
465 Various cases of C<delete $::{a}>, C<delete $::{ENV}> etc. causing a crash
466 have been fixed. [perl #54044]
470 Assigning another typeglob to C<*^R> no longer makes the regular expression
475 C<%{'_<...'}> hashes now set breakpoints on the corresponding C<@{'_<...'}>
476 rather than whichever array C<@DB::dbline> is aliased to. [perl #119799]
480 Setting C<$!> to EACCESS before calling C<require> could affect
481 C<require>'s behaviour. This has been fixed.
485 The "Can't use \1 to mean $1 in expression" warning message now only occurs
486 on the right-hand (replacement) part of a substitution. Formerly it could
487 happen in code embedded in the left-hand side, or in any other quote-like
492 The C<\N> regular expression escape, when used without the curly braces (to
493 mean C<[^\n]>), was ignoring a following C<*> if followed by whitespace
494 under /x. It had been this way since C<\N> to mean C<[^\n]> was introduced
499 Blessing into a reference (C<bless $thisref, $thatref>) has long been
500 disallowed, but magical scalars for the second like C<$/> and those tied
501 were exempt. They no longer are. [perl #119809]
505 Blessing into a reference was accidentally allowed in 5.18 if the class
506 argument were a blessed reference with stale method caches (i.e., whose
507 class had had subs defined since the last method call). They are
508 disallowed once more, as in 5.16.
512 An undefined lexical sub used as an inherited method no longer crashes.
516 C<< $x->{key} >> where $x was declared as C<my Class $x> no longer crashes
517 if a Class::FIELDS subroutine stub has been declared.
521 C<@$obj{'key'}> and C<${$obj}{key}> used to be exempt from compile-time
522 field checking ("No such class field"; see L<fields>) but no longer are.
526 That compile-time field checking also applies now to the C<%$obj{'key'}>
527 syntax, added recently in Perl 5.19.4.
531 A nonexistent array element with a large index passed to a subroutine that
532 ties the array and then tries to access the element no longer results in a
537 Declaring a subroutine stub named NEGATIVE_INDICES no longer makes negative
538 array indices crash when the current package is a tied array class.
542 Declaring a C<require>, C<glob>, or C<do> subroutine stub in the
543 CORE::GLOBAL:: package no longer makes compilation of calls to the
544 corresponding functions crash.
548 Aliasing CORE::GLOBAL:: functions to constants stopped working in Perl 5.10
549 but has now been fixed.
553 When C<`...`> or C<qx/.../> calls a C<readpipe> override, double-quotish
554 interpolation now happens, as is the case when there is no override.
555 Previously, the presence of an override would make these quote-like
556 operators act like C<q{}>, suppressing interpolation. [perl #115330]
560 C<<<`...`> here-docs (with backticks as the delimiters) now call
561 C<readpipe> overrides. [perl #119827]
565 The presence of a lexical sub named "CORE" no longer stops the CORE::
570 C<&CORE::exit()> and C<&CORE::die()> now respect L<vmsish> hints.
574 Undefining a glob that triggers a DESTROY method that undefines the same
575 glob is now safe. It used to produce "Attempt to free unreferenced glob
576 pointer" warnings and leak memory.
580 If subroutine redefinition (C<eval 'sub foo{}'> or C<newXS> for XS code)
581 triggers a DESTROY method on the sub that is being redefined, and that
582 method assigns a subroutine to the same slot (C<*foo = sub {}>), C<$_[0]>
583 is no longer left pointing to a freed scalar. Now DESTROY is delayed until
584 the new subroutine has been installed.
588 C<s///>, C<tr///> and C<y///> now work when a wide character is used as the
589 delimiter. [perl #120463]
593 On Windows, perl no longer calls CloseHandle() on a socket handle. This makes
594 debugging easier on Windows by removing certain irrelevant bad handle
595 exceptions. It also fixes a race condition and possible test failure in
596 F<dist/IO/t/cachepropagate-tcp.t>. [perl #120091/118059]
600 =head1 Known Problems
602 XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
603 tests that had to be C<TODO>ed for the release would be noted here. Unfixed
604 platform specific bugs also go here.
606 [ List each fix as a =item entry ]
612 C<do CORE()> used to call a sub named "CORE" and treat its return value as
613 a file name to execute. A bug fix inadvertently caused it to be
614 interpreted as the deprecated "do-SUB" construct. (Yes, C<do
615 I<bareword>()> is inconsistent.) This will likely be changed back.
621 XXX If any significant core contributor has died, we've added a short obituary
624 =head1 Acknowledgements
626 XXX Generate this with:
628 perl Porting/acknowledgements.pl v5.19.5..HEAD
630 =head1 Reporting Bugs
632 If you find what you think is a bug, you might check the articles recently
633 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
634 http://rt.perl.org/perlbug/ . There may also be information at
635 http://www.perl.org/ , the Perl Home Page.
637 If you believe you have an unreported bug, please run the L<perlbug> program
638 included with your release. Be sure to trim your bug down to a tiny but
639 sufficient test case. Your bug report, along with the output of C<perl -V>,
640 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
642 If the bug you are reporting has security implications, which make it
643 inappropriate to send to a publicly archived mailing list, then please send it
644 to perl5-security-report@perl.org. This points to a closed subscription
645 unarchived mailing list, which includes all the core committers, who will be
646 able to help assess the impact of issues, figure out a resolution, and help
647 co-ordinate the release of patches to mitigate or fix the problem across all
648 platforms on which Perl is supported. Please only use this address for
649 security issues in the Perl core, not for modules independently distributed on
654 The F<Changes> file for an explanation of how to view exhaustive details on
657 The F<INSTALL> file for how to build Perl.
659 The F<README> file for general stuff.
661 The F<Artistic> and F<Copying> files for copyright information.