5 perl5173delta - what is new for perl v5.17.3
9 This document describes differences between the 5.17.2 release and the 5.17.3
12 If you are upgrading from an earlier release such as 5.17.1, first read
13 L<perl5172delta>, which describes differences between 5.17.1 and 5.17.2.
15 =head1 Core Enhancements
17 =head2 Computed Labels
19 The loop controls C<next>, C<last> and C<redo>, and the special C<dump>
20 operator, now allow arbitrary expressions to be used to compute labels at run
21 time. Previously, any argument that was not a constant was treated as the
24 =head1 Incompatible Changes
26 =head2 C<$ENV{foo}=undef> deletes value from environ, like C<delete $ENV{foo}>
28 This facilitates use of C<local()> with C<%ENV> entries. In previous versions
29 of Perl, C<undef> was converted to the empty string.
31 =head2 Defined values stored in environment are forced to byte strings
33 A value stored in an environment variable has always been stringified. In this
34 release, it is converted to be only a byte string. First, it is forced to be a
35 only a string. Then if the string is utf8 and the equivalent of
36 C<utf8::downgrade()> works, that result is used; otherwise, the equivalent of
37 C<utf8::encode()> is used, and a warning is issued about wide characters
40 =head2 C<given> now aliases the global C<$_>
42 Instead of assigning to an implicit lexical C<$_>, C<given> now makes the
43 global C<$_> an alias for its argument, just like C<foreach>. However, it
44 still uses lexical C<$_> if there is lexical C<$_> in scope (again, just like
45 C<foreach>) [perl #114020].
47 =head1 Modules and Pragmata
49 =head2 Updated Modules and Pragmata
55 L<B> has been upgraded from version 1.36 to 1.37. All C<CVf_*> and C<GVf_*>
56 and more SV-related flag values are now provided as constants in the C<B::>
57 namespace and available for export. The default export list has not changed.
61 L<B::Concise> has been upgraded from version 0.91 to 0.92. The C<-nobanner>
62 option has been fixed, and C<format>s can now be dumped. When passed a sub
63 name to dump, it will check also to see whether it is the name of a format. If
64 a sub and a format share the same name, it will dump both.
68 L<B::Debug> has been upgraded from version 1.17 to 1.18. This adds support
69 (experimentally) for C<B::PADLIST>, which will be added in Perl 5.17.4.
73 L<B::Deparse> has been upgraded from version 1.15 to 1.16. It now deparses
74 loop controls with the correct precedence, and multiple statements in a
75 C<format> line are also now deparsed correctly.
79 L<CGI> has been upgraded from version 3.59 to 3.60. Unrecognized HTML escape
80 sequences are now handled better, problematic trailing newlines are no longer
81 inserted after E<lt>formE<gt> tags by C<startform()> or C<start_form()>, and
82 bogus "Insecure Dependency" warnings appearing with some versions of perl are
87 L<Compress::Raw::Bzip2> has been upgraded from version 2.05201 to 2.055. The
88 misuse of Perl's "magic" API has been fixed.
92 L<Compress::Raw::Zlib> has been upgraded from version 2.05401 to 2.056. The
93 misuse of Perl's "magic" API has been fixed.
97 L<Compress::Zlib> has been upgraded from version 2.052 to 2.055. C<compress()>,
98 C<uncompress()>, C<memGzip()> and C<memGunzip()> have been speeded up by making
99 parameter validation more efficient.
103 L<Data::Dumper> has been upgraded from version 2.135_06 to 2.135_07. It has
104 been optimized to only build a seen-scalar hash as necessary, thereby speeding
105 up serialization drastically.
109 L<Devel::Peek> has been upgraded from version 1.08 to 1.09. The only change
110 has been to the test script, to account for changes to some flags in perl's
115 L<Encode> has been upgraded from version 2.44 to 2.47. The Mac alias x-mac-ce
116 has been added, and various bugs have been fixed in Encode::Unicode,
117 Encode::UTF7 and Encode::GSM0338.
121 L<Module::Build> has been upgraded from version 0.40 to 0.4003. A minor bug
122 fix allows markup to be used around the leading "Name" in a POD "abstract"
123 line, and some documentation improvements have been made.
127 L<Module::CoreList> has been upgraded from version 2.69 to 2.71. Version
128 information is now stored as a delta, which greatly reduces the size of the
133 L<Module::Load::Conditional> has been upgraded from version 0.50 to 0.54.
134 Various enhancements include the new use of Module::Metadata.
138 L<Module::Metadata> has been upgraded from version 1.000009 to 1.000011. The
139 creation of a Module::Metadata object for a typical module file has been sped
140 up by about 40%, and some spurious warnings about C<$VERSION>s have been
145 L<Module::Pluggable> has been upgraded from version 4.0 to 4.3. Amongst other
146 changes, triggers are now allowed on events, which gives a powerful way to
151 L<perlfaq> has been upgraded from version 5.0150040 to 5.0150041. This
152 contains a couple of minor corrections and lists one new editor.
156 L<Pod::Simple> has been upgraded from version 3.20 to 3.23. Numerous
157 improvements have been made, mostly to Pod::Simple::XHTML, which also has a
158 compatibility change: the C<codes_in_verbatim> option is now disabled by
159 default. See F<cpan/Pod-Simple/ChangeLog> for the full details.
163 L<re> has been upgraded from version 0.21 to 0.22. Single character [class]es
164 like C</[s]/> or C</[s]/i> are now optimized as if they did not have the
165 brackets, i.e. C</s/> or C</s/i>.
169 L<Socket> has been upgraded from version 2.002 to 2.004. Constants and
170 functions required for IP multicast source group membership have been added.
174 L<Storable> has been upgraded from version 2.37 to 2.38. It can now freeze and
175 thaw vstrings correctly. This causes a slight incompatible change in the
176 storage format, so the format version has increased to 2.9.
180 L<Sys::Syslog> has been upgraded from version 0.29 to 0.31. This contains
181 several bug fixes relating to C<getservbyname()>, C<setlogsock()>and log levels
182 in C<syslog()>, together with fixes for Windows, Haiku-OS and GNU/kFreeBSD.
183 See F<cpan/Sys-Syslog/Changes> for the full details.
187 L<Term::ReadLine> has been upgraded from version 1.09 to 1.10. This fixes the
188 use of the B<cpan> and B<cpanp> shells on Windows in the event that the current
189 drive happens to contain a F<\dev\tty> file.
193 L<Text::Tabs> and L<Text::Wrap> have been upgraded from version 2009.0305 to
194 2012.0818. Support for Unicode combining characters has been added to them
199 L<Time::Local> has been upgraded from version 1.2000 to 1.2300. Seconds values
200 greater than 59 but less than 60 no longer cause C<timegm()> and C<timelocal()>
205 L<Unicode::UCD> has been upgraded from version 0.44 to 0.45. This has been
206 modified slightly for reasons of perl internal use only.
210 L<Win32> has been upgraded from version 0.44 to 0.45. New APIs have been added
211 for getting and setting the current code page.
215 L<Win32CORE> has been upgraded from version 0.02 to 0.03. The use of
216 PERL_NO_GET_CONTEXT here has resulted in smaller machine code.
222 =head2 Changes to Existing Documentation
224 =head3 L<perlfunc>, L<perlop>
230 Loop control verbs (C<dump>, C<goto>, C<next>, C<last> and C<redo>) have always
231 had the same precedence as assignment operators, but this was not documented
242 A caveat has been added to the documentation for C<$_> warning against the use
243 of lexical C<$_> [perl #114020].
249 The following additions or changes have been made to diagnostic output,
250 including warnings and fatal error messages. For the complete list of
251 diagnostic messages, see L<perldiag>.
253 =head2 New Diagnostics
261 L<Unterminated delimiter for here document|perldiag/"Unterminated delimiter for here document">
263 This message now occurs when a here document label has an initial quotation
264 mark but the final quotation mark is missing.
266 This replaces a bogus and misleading error message about not finding the label
267 itself [perl #114104].
271 L<panic: child pseudo-process was never scheduled|perldiag/"panic: child pseudo-process was never scheduled">
273 This error is thrown when a child pseudo-process in the ithreads implementation
274 on Windows was not scheduled within the time period allowed and therefore was
275 not able to initialize properly [perl #88840].
285 L<Wide character in setenv|perldiag/"Wide character in %s">
287 Attempts to put wide characters into environment variables via C<%ENV> now
288 provoke this warning.
292 =head1 Configuration and Compilation
298 The pager detection in F<Configure> has been improved to allow responses which
299 specify options after the program name, e.g. B</usr/bin/less -R>, if the user
300 accepts the default value. This helps B<perldoc> when handling ANSI escapes
305 =head1 Platform Support
307 =head2 Discontinued Platforms
313 Support code relating to UTS global has been removed. UTS was a mainframe
314 version of System V created by Amdahl, subsequently sold to UTS Global. The
315 port has not been touched since before Perl 5.8.0, and UTS Global is now
320 =head2 Platform-Specific Notes
326 A new makefile option, USE_64_BIT_INT, has been added to the Windows makefiles.
327 Set this to "define" when building a 32-bit perl if you want it to use 64-bit
330 Machine code size reductions, already made to the DLLs of XS modules in Perl
331 5.17.2, have now been extended to the perl DLL itself.
333 Building with VC++ 6.0 was inadvertently broken in Perl 5.17.2 but has now been
338 The B<a2p> build has been fixed for the HP C++ compiler on OpenVMS.
342 =head1 Selected Bug Fixes
348 C<\w> now matches the code points U+200C (ZERO WIDTH NON-JOINER) and U+200D
349 (ZERO WIDTH JOINER). C<\W> no longer matches these. This change is because
350 Unicode corrected their definition of what C<\w> should match.
354 C<dump LABEL> no longer leaks its label.
358 Constant folding no longer changes the behaviour of functions like C<stat()>
359 and C<truncate()> that can take either filenames or handles.
360 C<stat 1 ? foo : bar> nows treats its argument as a file name (since it is an
361 arbitrary expression), rather than the handle "foo".
365 C<truncate FOO, $len> no longer falls back to treating "FOO" as a file name if
366 the filehandle has been deleted. This was broken in Perl 5.16.0.
370 Subroutine redefinitions after sub-to-glob and glob-to-glob assignments no
371 longer cause double frees or panic messages.
375 C<s///> now turns vstrings into plain strings when performing a substitution,
376 even if the resulting string is the same (C<s/a/a/>).
380 Prototype mismatch warnings no longer erroneously treat constant subs as having
381 no prototype when they actually have "".
385 Constant subroutines and forward declarations no longer prevent prototype
386 mismatch warnings from omitting the sub name.
390 C<undef> on a subroutine now clears call checkers.
394 The C<ref> operator started leaking memory on blessed objects in Perl 5.16.0.
395 This has been fixed [perl #114340].
399 C<use> no longer tries to parse its arguments as a statement, making
400 C<use constant { () };> a syntax error [perl #114222].
404 On debugging builds, "uninitialized" warnings inside formats no longer cause
409 On debugging builds, subroutines nested inside formats no longer cause
410 assertion failures [perl #78550].
414 Formats and C<use> statements are now permitted inside formats.
418 C<print $x> and C<sub { print $x }-E<gt>()> now always produce the same output.
419 It was possible for the latter to refuse to close over $x if the variable was
420 not active; e.g., if it was defined outside a currently-running named
425 Similarly, C<print $x> and C<print eval '$x'> now produce the same output.
426 This also allows "my $x if 0" variables to be seen in the debugger [perl
431 Formats called recursively no longer stomp on their own lexical variables, but
432 each recursive call has its own set of lexicals.
436 Attempting to free an active format or the handle associated with it no longer
441 Format parsing no longer gets confused by braces, semicolons and low-precedence
442 operators. It used to be possible to use braces as format delimiters (instead
443 of C<=> and C<.>), but only sometimes. Semicolons and low-precedence operators
444 in format argument lines no longer confuse the parser into ignoring the line's
445 return value. In format argument lines, braces can now be used for anonymous
446 hashes, instead of being treated always as C<do> blocks.
450 Formats can now be nested inside code blocks in regular expressions and other
451 quoted constructs (C</(?{...})/> and C<qq/${...}/>) [perl #114040].
455 Formats are no longer created after compilation errors.
459 Some format syntax errors started causing crashes in Perl 5.17.2, but have now
464 Under debugging builds, the B<-DA> command line option started crashing in Perl
465 5.16.0. It has been fixed [perl #114368].
469 Scope::Escape compatibility, which was broken in Perl 5.17.2, has been restored
474 A potential deadlock scenario involving the premature termination of a pseudo-
475 forked child in a Windows build with ithreads enabled has been fixed. This
476 resolves the common problem of the F<t/op/fork.t> test hanging on Windows [perl
481 The microperl build, broken since Perl 5.15.7, has now been restored.
485 The code which generates errors from C<require()> could potentially read one or
486 two bytes before the start of the filename for filenames less than three bytes
487 long and ending C</\.p?\z/>. This has now been fixed. Note that it could
488 never have happened with module names given to C<use()> or C<require()> anyway.
492 The handling of pathnames of modules given to C<require()> has been made
497 The C<re_compile()> API function, the entry point for perl's regex compiler,
498 was accidentally changed in Perl 5.17.1 to operate on the current engine. This
499 has now been restored to its former core-engine-specific state [perl #114302].
503 Perl 5.17.1 introduced a memory leak into the re-use of run-time regexes where
504 the pattern hasn't changed (i.e. C</$unchanging/>). This has now been fixed.
508 A bug in the compilation of a C</(?{})/> expression which affected the TryCatch
509 test suite has been fixed [perl #114242].
513 Formats no longer leak. They started leaking in Perl 5.17.2.
517 Pod can now be nested in code inside a quoted construct outside of a string
518 eval. This used to work only within string evals [perl #114040].
522 =head1 Acknowledgements
524 Perl 5.17.3 represents approximately 4 weeks of development since Perl 5.17.2
525 and contains approximately 85,000 lines of changes across 470 files from 24
528 Perl continues to flourish into its third decade thanks to a vibrant community
529 of users and developers. The following people are known to have contributed
530 the improvements that became Perl 5.17.3:
532 Andy Dougherty, Chip Salzenberg, Chris 'BinGOs' Williams, Craig A. Berry,
533 Daniel Dragan, Dave Rolsky, David Leadbeater, David Mitchell, Eric Brine,
534 Father Chrysostomos, Goro Fuji, James E Keenan, Jan Dubois, Joaquin Ferrero,
535 Karl Williamson, Nicholas Clark, Paul Marquess, Reini Urban, Ricardo Signes,
536 Robin Barker, Shirakata Kentaro, Steffen Müller, Steve Hay, Tony Cook.
538 The list above is almost certainly incomplete as it is automatically generated
539 from version control history. In particular, it does not include the names of
540 the (very much appreciated) contributors who reported issues to the Perl bug
543 Many of the changes included in this version originated in the CPAN modules
544 included in Perl's core. We're grateful to the entire CPAN community for
545 helping Perl to flourish.
547 For a more complete list of all of Perl's historical contributors, please see
548 the F<AUTHORS> file in the Perl source distribution.
550 =head1 Reporting Bugs
552 If you find what you think is a bug, you might check the articles recently
553 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
554 http://rt.perl.org/perlbug/ . There may also be information at
555 http://www.perl.org/ , the Perl Home Page.
557 If you believe you have an unreported bug, please run the L<perlbug> program
558 included with your release. Be sure to trim your bug down to a tiny but
559 sufficient test case. Your bug report, along with the output of C<perl -V>,
560 will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
562 If the bug you are reporting has security implications, which make it
563 inappropriate to send to a publicly archived mailing list, then please send it
564 to perl5-security-report@perl.org. This points to a closed subscription
565 unarchived mailing list, which includes all the core committers, who will be
566 able to help assess the impact of issues, figure out a resolution, and help
567 co-ordinate the release of patches to mitigate or fix the problem across all
568 platforms on which Perl is supported. Please only use this address for
569 security issues in the Perl core, not for modules independently distributed on
574 The F<Changes> file for an explanation of how to view exhaustive details on
577 The F<INSTALL> file for how to build Perl.
579 The F<README> file for general stuff.
581 The F<Artistic> and F<Copying> files for copyright information.