=encoding utf8
-=for comment complete up to commit 80b8b050d2c6976822563e9f8edb2baa83539b12
-
=head1 NAME
-[ this is a template for a new perldelta file. Any text flagged as
-XXX needs to be processed before release. ]
-
-perldelta - what is new for perl v5.17.0
+perldelta - what is new for perl v5.17.1
=head1 DESCRIPTION
-This document describes differences between the 5.16.0 release and
-the 5.17.0 release.
+This document describes differences between the 5.17.0 release and
+the 5.17.1 release.
If you are upgrading from an earlier release such as 5.16.0, first read
-L<perl5160delta>, which describes differences between 5.14.0 and
-5.16.0.
+L<perl5170delta>, which describes differences between 5.16.0 and
+5.17.0.
-=head1 Notice
+=head1 Core Enhancements
-XXX Any important notices here
+=head2 More CORE:: subs
-=head1 Core Enhancements
+Several more built-in functions have been added as subroutines to the
+CORE:: namespace, namely, those non-overridable keywords that can be
+implemented without custom parsers: C<defined>, C<delete>, C<exists>,
+C<glob>, C<pos>, C<protoytpe>, C<scalar>, C<split>, C<study>, and C<undef>.
-XXX New core language features go here. Summarise user-visible core language
-enhancements. Particularly prominent performance optimisations could go
-here, but most should go in the L</Performance Enhancements> section.
+As some of these have prototypes, C<prototype('CORE::...')> has been
+changed to not make a distinction between overridable and non-overridable
+keywords. This is to make C<prototype('CORE::pos')> consistent with
+C<prototype(&CORE::pos)>.
-[ List each enhancement as a =head2 entry ]
+=head1 Incompatible Changes
-=head1 Security
+=head2 C</(?{})/> and C</(??{})/> have been heavily reworked
-XXX Any security-related notices go here. In particular, any security
-vulnerabilities closed should be noted here rather than in the
-L</Selected Bug Fixes> section.
+The implementation of this feature has been almost completely rewritten.
+Although its main intent is to fix bugs, some behaviors, especially
+related to the scope of lexical variables, will have changed. This is
+described more fully in the L</Selected Bug Fixes> section.
-[ List each security issue as a =head2 entry ]
+=head2 C<\N{BELL}> now refers to U+1F514 instead of U+0007
-=head1 Incompatible Changes
+Unicode 6.0 reused the name "BELL" for a different code point than it
+traditionally had meant. Since Perl v5.14, use of this name still
+referred to U+0007, but would raise a deprecation warning. Now, "BELL"
+refers to U+1F514, and the name for U+0007 is "ALERT". All the
+functions in L<charnames> have been correspondingly updated.
-XXX For a release on a stable branch, this section aspires to be:
+=head2 Alphanumeric operators must now be separated from the closing
+delimiter of regular expressions
- There are no changes intentionally incompatible with 5.XXX.XXX
- If any exist, they are bugs, and we request that you submit a
- report. See L</Reporting Bugs> below.
+You may no longer write something like:
-[ List each incompatible change as a =head2 entry ]
+ m/a/and 1
-=head2 C<\s> in regular expressions now matches a Vertical Tab (experimental)
+Instead you must write
-This is an experiment early in the development cycle to see what
-repercussions arise from this change. It may well be that we decide
-to require a C<"use feature"> to activate this behavior. Because
-of the experimental nature of this, which may be reversed, the
-documentation has not been changed to reflect it.
+ m/a/ and 1
-=head1 Deprecations
+with whitespace separating the operator from the closing delimiter of
+the regular expression. Not having whitespace has resulted in a
+deprecation warning since Perl v5.14.0.
-XXX Any deprecated features, syntax, modules etc. should be listed here.
-In particular, deprecated modules should be listed here even if they are
-listed as an updated module in the L</Modules and Pragmata> section.
+=head2 C<require> dies for unreadable files
-[ List each deprecation as a =head2 entry ]
+When C<require> encounters an unreadable file, it now dies. It used to
+ignore the file and continue searching the directories in @INC
+[perl #113422].
-=head2 Unescaped braces in regexps
+=head2 Upgrade to the Unicode 6.2 beta
-Literal unescaped C<{> in regular expressions is now deprecated. Every
-brace character should be either escaped (by a preceding backslash) or
-part of a construct where it's a metacharacter. This catches likely typos
-such as C</f{,3}/>. It will also allow braces to be used in the future
-to delimit parameters to metacharacters that currently take no parameters.
+Unicode 6.2 is proposing some changes that may very well break some CPAN
+modules. The timing of this nicely coincides with Perl's being early in the
+release cycle. This commit takes the current beta 6.2, adds the proposed
+changes that aren't yet in it, and subtracts the changes that would affect \X
+processing, as those turn out to have errors, and may have to be rethought.
+Unicode has been notified of these problems.
-=head1 Performance Enhancements
+This will allow us to gather data as to whether or not the proposed changes
+cause us problems. These will be presented to Unicode to aid in their final
+decision as to whether or not to go forward with the changes.
-XXX Changes which enhance performance without changing behaviour go here. There
-may well be none in a stable release.
+These changes will be replaced by the final version of Unicode 6.2 before
+5.18.0 is released.
-[ List each enhancement as a =item entry ]
+=head1 Performance Enhancements
=over 4
=item *
-Filetest ops manage the stack in a fractionally more efficient manner.
+The C<x> repetition operator is now folded to a single constant at compile
+time if called in scalar context with constant operands and no parentheses
+around the left operand.
+
+=back
+
+=head1 Modules and Pragmata
+
+=head2 Updated Modules and Pragmata
+
+=over 4
=item *
-Globs used in a numeric context are now numerified directly in most cases,
-rather than being numerified via stringification.
+L<Archive::Extract> has been upgraded from version 0.58 to 0.60.
+
+Work around an edge case on Linux with Busybox's unzip.
=item *
-XXX
+L<Archive::Tar> has been upgraded from version 1.82 to 1.88.
-=back
+ptar now supports the -T option as well as dashless options
+[rt.cpan.org #75473], [rt.cpan.org #75475].
-=head1 Modules and Pragmata
+Auto-encode filenames marked as UTF-8 [rt.cpan.org #75474].
-XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
-go here. If Module::CoreList is updated, generate an initial draft of the
-following sections using F<Porting/corelist-perldelta.pl>, which prints stub
-entries to STDOUT. Results can be pasted in place of the '=head2' entries
-below. A paragraph summary for important changes should then be added by hand.
-In an ideal world, dual-life modules would have a F<Changes> file that could be
-cribbed.
+Don't use C<tell> on L<IO::Zlib> handles [rt.cpan.org #64339].
-[ Within each section, list entries as a =item entry ]
+Don't try to C<chown> on symlinks.
-=head2 New Modules and Pragmata
+=item *
-=over 4
+L<attributes> has been upgraded from version 0.19 to 0.20.
=item *
-XXX
+L<autodie> has been upgraded from version 2.10 to 2.11.
-=back
+=item *
-=head2 Updated Modules and Pragmata
+L<B> has been upgraded from version 1.35 to 1.36.
-=over 4
+C<B::COP::stashlen> has been replaced with C<B::COP::stashoff>.
+
+C<B::COP::stashpv> now supports UTF-8 package names and embedded NULs.
=item *
-L<B> has been upgraded from version 1.34 to 1.35.
+L<B::Deparse> has been upgraded from version 1.14 to 1.15.
-The C<stashlen> method of COPs has been added. This provides access to an
-internal field added in perl 5.16 under threaded builds [perl #113034].
+Avoid warning when run under C<perl -w>.
=item *
-L<ExtUtils::ParseXS> has been upgraded from version 3.16 to 3.17.
+L<Class::Struct> has been upgraded from version 0.63 to 0.64.
-The generated C code now avoids unnecessarily incrementing
-C<PL_amagic_generation> on Perl versions where it's done automatically
-(or on current Perl where the variable no longer exists).
+The constructor now respects overridden accessor methods [perl #29230].
=item *
-L<File::DosGlob> has been upgraded from version 1.06 to 1.07.
-
-Small documentation and comment fixes.
+L<Compress::Raw::Bzip2> has been upgraded from version 2.048 to 2.052.
=item *
-L<File::Find> has been upgraded from version 1.20 to 1.21.
+L<Compress::Raw::Zlib> has been upgraded from version 2.048 to 2.054.
+
+Upgrade bundled zlib to version 1.2.7.
-Individual files may now appear in list of directories to be searched
-[perl #59750].
+Fix build failures on Irix, Solaris, and Win32, and also when building as C++
+[rt.cpan.org #69985], [rt.cpan.org #77030], [rt.cpan.org #75222].
=item *
-L<File::stat> has been upgraded from version 1.05 to 1.06.
+L<CPAN::Meta> has been upgraded from version 2.120630 to 2.120921.
-C<File::stat> ignores the L<filetest> pragma, and warns when used in
-combination therewith. But it was not warning for C<-r>. This has been
-fixed [perl #111640].
+=item *
+
+L<CPAN::Meta::Requirements> has been upgraded from version 2.120630 to 2.122.
+
+Treat undef requirements to C<from_string_hash> as 0 (with a warning).
-C<-p> now works, and does not return false for pipes [perl #111638].
+Added C<requirements_for_module> method.
=item *
-L<Hash::Util> has been upgraded from version 0.11 to 0.12.
+L<CPAN::Meta::YAML> has been upgraded from version 0.007 to 0.008.
-C<hash_unlocked> and C<hashref_unlocked> now returns true if the hash is
-unlocked, instead of always returning false [perl #112126].
+=item *
-C<hash_unlocked>, C<hashref_unlocked>, C<lock_hash_recurse> and
-C<unlock_hash_recurse> are now exportable [perl #112126].
+L<CPANPLUS> has been upgraded from version 0.9121 to 0.9130.
-Two new functions, C<hash_locked> and C<hashref_locked>, have been added.
-Oddly enough, these two functions were already exported, even though they
-did not exist [perl #112126].
+Allow adding F<blib/script> to PATH.
-=item *
+Save the history between invocations of the shell.
-L<overload> has been upgraded from version 1.18 to 1.19.
+Handle multiple C<makemakerargs> and C<makeflags> arguments better.
-C<no overload> now warns for invalid arguments, just like C<use overload>.
+Use C<File::HomeDir> when available, and provide C<PERL5_CPANPLUS_HOME> to
+override the autodetection.
+
+Always re-fetch F<CHECKSUMS> if C<fetchdir> is set.
=item *
-L<Pod::Functions> has been upgraded from version 1.05 to 1.06.
+L<Digest::MD5> has been upgraded from version 2.51 to 2.52.
-Typo fix in generated documentation.
+Fix C<Digest::Perl::MD5> OO fallback [rt.cpan.org #66634].
=item *
-L<Storable> has been upgraded from version 2.34 to 2.35.
-
-Modifying C<$_[0]> within C<STORABLE_freeze> no longer results in crashes
-[perl #112358].
+L<DynaLoader> has been upgraded from version 1.14 to 1.15.
-An object whose class implements C<STORABLE_attach> is now thawed only once
-when there are multiple references to it in the structure being thawed
-[perl #111918].
+This is due to a minor code change in the XS for the VMS implementation.
=item *
-L<utf8> has been upgraded from version 1.09 to 1.10.
+L<ExtUtils::CBuilder> has been upgraded from version 0.280206 to 0.280208.
-Some documentation has been clarified.
+Manifest files are now correctly embedded for those versions of VC++ which
+make use of them. [perl #111782, #111798].
-=back
+=item *
-=head2 Removed Modules and Pragmata
+L<File::DosGlob> has been upgraded from version 1.07 to 1.08.
-=over 4
+=item *
+
+L<File::Fetch> has been upgraded from version 0.32 to 0.34.
=item *
-L<Version::Requirements> has been removed from the core distribution. It is
-available under a different name: L<CPAN::Meta::Requirements>.
+L<File::Spec::Unix> has been upgraded from version 3.39_02 to 3.39_03.
-=back
+C<abs2rel> could produce incorrect results when given two relative paths or
+the root directory twice [perl #111510].
-=head1 Documentation
+=item *
-XXX Changes to files in F<pod/> go here. Consider grouping entries by
-file and be sure to link to the appropriate page, e.g. L<perlfunc>.
+L<Filter::Util::Call> has been upgraded from version 1.40 to 1.45.
-=head2 New Documentation
+=item *
-XXX Changes which create B<new> files in F<pod/> go here.
+L<HTTP::Tiny> has been upgraded from version 0.017 to 0.022.
-=head3 L<XXX>
+Add SSL verification features [github #6], [github #9].
-XXX Description of the purpose of the new file here
+Include the final URL in the response hashref.
-=head2 Changes to Existing Documentation
+Add C<local_address> option.
-XXX Changes which significantly change existing files in F<pod/> go here.
-However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
-section.
+=item *
-=head3 L<perldata>
+L<IO> has been upgraded from version 1.25_06 to 1.25_07.
-=over 4
+C<sync()> can now be called on read-only file handles [perl #64772].
=item *
-Now explicitly documents the behaviour of hash initializer lists that
-contain duplicate keys.
+L<IPC::Cmd> has been upgraded from version 0.76 to 0.78.
+
+Use C<POSIX::_exit> instead of C<exit> in C<run_forked> [rt.cpan.org #76901].
=item *
-XXX Description of the change here
+L<Memoize> has been upgraded from version 1.02 to 1.03.
-=back
+Fix the C<MERGE> cache option.
-=head3 L<perldiag>
+=item *
-=over 4
+L<Module::Build> has been upgraded from version 0.39_01 to 0.40.
-=item *
+Fixed bug where modules without C<$VERSION> might have a version of '0' listed
+in 'provides' metadata, which will be rejected by PAUSE.
-The explanation of symbolic references being prevented by "strict refs"
-now doesn't assume that the reader knows what symbolic references are.
+Fixed bug in PodParser to allow numerals in module names.
+
+Fixed bug where giving arguments twice led to them becoming arrays, resulting
+in install paths like F<ARRAY(0xdeadbeef)/lib/Foo.pm>.
=item *
-XXX Description of the change here
+L<Module::Load::Conditional> has been upgraded from version 0.46 to 0.50.
-=back
+Fix use of C<requires> on perls installed to a path with spaces.
-=head3 L<perlfunc>
+=item *
-=over 4
+L<Object::Accessor> has been upgraded from version 0.42 to 0.44.
=item *
-The return value of C<pipe> is now documented.
+L<Params::Check> has been upgraded from version 0.32 to 0.36.
=item *
-XXX Description of the change here
+L<Parse::CPAN::Meta> has been upgraded from version 1.4402 to 1.4404.
-=back
+=item *
-=head3 L<XXX>
+L<PerlIO::mmap> has been upgraded from version 0.010 to 0.011.
-=over 4
+=item *
+
+L<PerlIO::via::QuotedPrint> has been upgraded from version 0.06 to 0.07.
=item *
-XXX Description of the change here
+L<Pod::Html> has been upgraded from version 1.15_02 to 1.16.
-=back
+The option C<--libpods> has been reinstated. It is deprecated, and its use
+does nothing other than issue a warning that it is no longer supported.
-=head1 Diagnostics
+Since the HTML files generated by pod2html claim to have a UTF-8 charset,
+actually write the files out using UTF-8 [perl #111446].
-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 L<perldiag>.
+=item *
-XXX New or changed warnings emitted by the core's C<C> code go here. Also
-include any changes in L<perldiag> that reconcile it to the C<C> code.
+L<POSIX> has been upgraded from version 1.30 to 1.31.
-[ Within each section, list entries as a =item entry that links to perldiag,
- e.g.
+=item *
- =item *
+L<re> has been upgraded from version 0.19 to 0.20.
- L<Invalid version object|perldiag/"Invalid version object">
-]
+See note about C<op_comp> in the L</Internal Changes> section below.
-=head2 New Diagnostics
+=item *
-XXX Newly added diagnostic messages go here
+L<Safe> has been upgraded from version 2.31_01 to 2.33_01.
-=head3 New Errors
+Fix interactions with C<Devel::Cover>.
-=over 4
+Don't eval code under C<no strict>.
=item *
-XXX L<message|perldiag/"message">
+L<Scalar::Util> has been upgraded from version 1.23 to version 1.25.
-=back
+Fix an overloading issue with C<sum>.
-=head3 New Warnings
+C<first> and C<reduce> now check the callback first (so C<&first(1)> is
+disallowed).
-=over 4
+Fix C<tainted> on magical values [rt.cpan.org #55763].
+
+Fix C<sum> on previously magical values [rt.cpan.org #61118].
+
+Fix reading past the end of a fixed buffer [rt.cpan.org #72700].
=item *
-"L<Unescaped left brace in regex is deprecated, passed
-through|perldiag/"Unescaped left brace in regex is deprecated, passed
-through">" is a new deprecation warning. See L</Unescaped braces in
-regexps>.
+L<Search::Dict> has been upgraded from version 1.04 to 1.07.
+
+No longer require C<stat> on filehandles.
+
+Use C<fc> for casefolding.
=item *
-XXX L<message|perldiag/"message">
+L<Storable> has been upgraded from version 2.35 to 2.36.
-=back
+=item *
-=head2 Changes to Existing Diagnostics
+L<Term::ANSIColor> has been upgraded from version 3.01 to 3.02.
-XXX Changes (i.e. rewording) of diagnostic messages go here
+Add support for italics.
-=over 4
+Improve error handling.
=item *
-XXX Describe change here
+L<Test::Harness> has been upgraded from version 3.23 to 3.25.
-=back
+Fix glob semantics on Win32 [rt.cpan.org #49732].
-=head1 Utility Changes
+Don't use C<Win32::GetShortPathName> when calling perl [rt.cpan.org #47890].
-XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
-here. Most of these are built within the directories F<utils> and F<x2p>.
+Ignore -T when reading shebang [rt.cpan.org #64404].
-[ List utility changes as a =head3 entry for each utility and =item
-entries for each change
-Use L<XXX> with program names to get proper documentation linking. ]
+Handle the case where we don't know the wait status of the test more
+gracefully.
-=head3 L<XXX>
+Make the test summary 'ok' line overridable so that it can be changed to a
+plugin to make the output of prove idempotent.
-=over 4
+Don't run world-writable files.
=item *
-XXX
+L<Unicode::UCD> has been upgraded from version 0.43 to 0.44.
+
+This adds a function L<all_casefolds()|Unicode::UCD/all_casefolds()>
+that returns all the casefolds.
=back
-=head1 Configuration and Compilation
+=head1 Documentation
-XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
-go here. Any other changes to the Perl build process should be listed here.
-However, any platform-specific changes should be listed in the
-L</Platform Support> section, instead.
+=head2 Changes to Existing Documentation
-[ List changes as a =item entry ].
+=head3 L<perlfaq>
=over 4
=item *
-The test suite now has a section for tests that require very large amounts
-of memory. These tests won't run by default; they can be enabled by
-setting the C<PERL_TEST_MEMORY> environment variable to the number of
-gibibytes of memory that may be safely used.
+L<perlfaq> has been synchronized with version 5.0150040 from CPAN.
+
+=back
+
+=head3 L<perlcheat>
+
+=over 4
=item *
-XXX
+L<perlcheat> has been reorganized, and a few new sections were added.
=back
-=head1 Testing
-
-XXX Any significant changes to the testing of a freshly built perl should be
-listed here. Changes which create B<new> files in F<t/> go here as do any
-large changes to the testing harness (e.g. when parallel testing was added).
-Changes to existing files in F<t/> aren't worth summarising, although the bugs
-that they represent may be covered elsewhere.
+=head1 Diagnostics
-[ List each test improvement as a =item entry ]
+=head2 Removals of Diagnostics
=over 4
=item *
-XXX
+The "Runaway prototype" warning that occurs in bizarre cases has been
+removed as being unhelpful and inconsistent.
+
+=item *
+
+The "Not a format reference" error has been removed, as the only case in
+which it could be triggered was a bug.
+
+=item *
+
+The "Unable to create sub named %s" error has been removed for the same
+reason.
=back
=head1 Platform Support
-XXX Any changes to platform support should be listed in the sections below.
+=head2 Platform-Specific Notes
+
+=over 4
+
+=item Win32
+
+C<link> on Win32 now attempts to set C<$!> to more appropriate values
+based on the Win32 API error code. [perl #112272]
+
+Perl no longer mangles the environment block, e.g. when launching a new
+sub-process, when the environment contains non-ASCII characters. Known
+problems still remain, however, when the environment contains characters
+outside of the current ANSI codepage (e.g. see the item about Unicode in
+C<%ENV> in L<http://perl5.git.perl.org/perl.git/blob/HEAD:/Porting/todo.pod>).
+[perl #113536]
+
+=item VMS
-[ Within the sections, list each platform as a =item entry with specific
-changes as paragraphs below it. ]
+All C header files from the top-level directory of the distribution are now
+installed on VMS, providing consistency with a long-standing practice on other
+platforms. Previously only a subset were installed, which broke non-core extension
+builds for extensions that depended on the missing include files.
-=head2 New Platforms
+=back
-XXX List any platforms that this version of perl compiles on, that previous
-versions did not. These will either be enabled by new files in the F<hints/>
-directories, or new subdirectories and F<README> files at the top level of the
-source tree.
+=head1 Internal Changes
=over 4
-=item clang++
+=item *
-There is now a workaround for a compiler bug that prevented compiling
-with clang++ since Perl 5.15.7 [perl #112786].
+The C<study> function was made a no-op in 5.16. It was simply disabled via
+a C<return> statement; the code was left in place. Now the code supporting
+what C<study> used to do has been removed.
-=item C++
+=item *
-When compiling the Perl core as C++ (which is only semi-supported), the
-mathom functions are now compiled as C<extern "C">, to ensure proper
-binary compatibility. (However, binary compatibility isn't generally
-guaranteed anyway in the situations where this would matter.)
+Under threaded perls, there is no longer a separate PV allocated for every
+COP to store its package name (C<< cop->stashpv >>). Instead, there is an
+offset (C<< cop->stashoff >>) into the new C<PL_stashpad> array, which
+holds stash pointers.
-=item VMS
+=item *
-It should now be possible to compile Perl as C++ on VMS.
+In the pluggable regex API, the C<regexp_engine> struct has acquired a new
+field C<op_comp>, which is currently just for perl's internal use, and
+should be initialised to NULL by other regex plugin modules.
-=item XXX-some-platform
+=item *
-XXX
+A new function C<alloccoptash> has been added to the API, but is considered
+experimental. See L<perlapi>.
=back
-=head2 Discontinued Platforms
+=head1 Selected Bug Fixes
-XXX List any platforms that this version of perl no longer compiles on.
+=over 4
+
+=item *
+
+The implementation of code blocks in regular expressions, such as C<(?{})>
+and C<(??{})>, has been heavily reworked to eliminate a whole slew of bugs.
+The main user-visible changes are:
=over 4
-=item XXX-some-platform
+=item *
-XXX
+Code blocks within patterns are now parsed in the same pass as the
+surrounding code; in particular it is no longer necessary to have balanced
+braces: this now works:
-=back
+ /(?{ $x='{' })/
-=head2 Platform-Specific Notes
+This means that this error message is longer generated:
-XXX List any changes for specific platforms. This could include configuration
-and compilation changes or changes in portability/compatibility. However,
-changes within modules for platforms should generally be listed in the
-L</Modules and Pragmata> section.
+ Sequence (?{...}) not terminated or not {}-balanced in regex
-=over 4
+but a new error may be seen:
-=item XXX-some-platform
+ Sequence (?{...}) not terminated with ')'
-XXX
+In addition, literal code blocks within run-time patterns are only
+compiled once, at perl compile-time:
-=back
+ for my $p (...) {
+ # this 'FOO' block of code is compiled once,
+ # at the same time as the surrounding 'for' loop
+ /$p{(?{FOO;})/;
+ }
-=head1 Internal Changes
+=item *
-XXX Changes which affect the interface available to C<XS> code go here.
-Other significant internal changes for future core maintainers should
-be noted as well.
+Lexical variables are now sane as regards scope, recursion and closure
+behavior. In particular, C</A(?{B})C/> behaves (from a closure viewpoint)
+exactly like C</A/ && do { B } && /C/>, while C<qr/A(?{B})C/> is like
+C<sub {/A/ && do { B } && /C/}>. So this code now works how you might
+expect, creating three regexes that match 0, 1, and 2:
-[ List each change as a =item entry ]
+ for my $i (0..2) {
+ push @r, qr/^(??{$i})$/;
+ }
+ "1" =~ $r[1]; # matches
-=over 4
+=item *
+
+The C<use re 'eval'> pragma is now only required for code blocks defined
+at runtime; in particular in the following, the text of the C<$r> pattern is
+still interpolated into the new pattern and recompiled, but the individual
+compiled code-blocks within C<$r> are reused rather than being recompiled,
+and C<use re 'eval'> isn't needed any more:
+
+ my $r = qr/abc(?{....})def/;
+ /xyz$r/;
=item *
-The C<CV *> typemap entry now supports C<&{}> overloading and typeglobs,
-just like C<&{...}> [perl #96872].
+Flow control operators no longer crash. Each code block runs in a new
+dynamic scope, so C<next> etc. will not see any enclosing loops and
+C<caller> will not see any calling subroutines. C<return> returns a value
+from the code block, not from any enclosing subroutine.
=item *
-The C<SVf_AMAGIC> flag to indicate overloading is now on the stash, not the
-object. It is now set automatically whenever a method or @ISA changes, so
-its meaning has changed, too. It now means "potentially overloaded". When
-the overload table is calculated, the flag is automatically turned off if
-there is no overloading, so there should be no noticeable slowdown.
+Perl normally caches the compilation of run-time patterns, and doesn't
+recompile if the pattern hasn't changed, but this is now disabled if
+required for the correct behavior of closures. For example:
-The staleness of the overload tables is now checked when overload methods
-are invoked, rather than during C<bless>.
+ my $code = '(??{$x})';
+ for my $x (1..3) {
+ # recompile to see fresh value of $x each time
+ $x =~ /$code/;
+ }
-"A" magic is gone. The changes to the handling of the C<SVf_AMAGIC> flag
-eliminate the need for it.
-C<PL_amagic_generation> has been removed as no longer necessary. For XS
-modules, it is now a macro alias to C<PL_na>.
+=item *
+
+The C</msix> and C<(?msix)> etc. flags are now propagated into the return
+value from C<(??{})>; this now works:
-The fallback overload setting is now stored in a stash entry separate from
-overloadedness itself.
+ "AB" =~ /a(??{'b'})/i;
=item *
-The character-processing code has been cleaned up in places. The changes
-should be operationally invisible.
+Warnings and errors will appear to come from the surrounding code (or for
+run-time code blocks, from an eval) rather than from an C<re_eval>:
-=back
+ use re 'eval'; $c = '(?{ warn "foo" })'; /$c/;
+ /(?{ warn "foo" })/;
-=head1 Selected Bug Fixes
+formerly gave:
-XXX Important bug fixes in the core language are summarised here.
-Bug fixes in files in F<ext/> and F<lib/> are best summarised in
-L</Modules and Pragmata>.
+ foo at (re_eval 1) line 1.
+ foo at (re_eval 2) line 1.
-[ List each fix as a =item entry ]
+and now gives:
-=over 4
+ foo at (eval 1) line 1.
+ foo at /some/prog line 2.
+
+=back
=item *
-C<goto ''> now looks for an empty label, producing the "goto must have
-label" error message, instead of exiting the program [perl #111794].
+Perl now works as well as can be expected on all releases of Unicode so
+far. In v5.16, it worked on Unicodes 6.0 and 6.1, but there were
+various bugs for earlier releases; the older the release the more
+problems.
=item *
-C<goto "\0"> now dies with "Can't find label" instead of "goto must have
-label".
+C<vec> no longer produces "uninitialized" warnings in lvalue context
+[perl #9423].
=item *
-The C function C<hv_store> used to result in crashes when used on C<%^H>
-[perl #111000].
+An optimization involving fixed strings in regular expressions could cause
+a severe performance penalty in edge cases. This has been fixed
+[perl #76546].
=item *
-A call checker attached to a closure prototype via C<cv_set_call_checker>
-is now copied to closures cloned from it. So C<cv_set_call_checker> now
-works inside an attribute handler for a closure.
+In certain cases, including empty subpatterns within a regular expression (such
+as C<(?:)> or C<(?:|)>) could disable some optimizations. This has been fixed.
=item *
-Writing to C<$^N> used to have no effect. Now it croaks with "Modification
-of a read-only value" by default, but that can be overridden by a custom
-regular expression engine, as with C<$1> [perl #112184].
+The "Can't find an opnumber" message that C<prototype> produces when passed
+a string like "CORE::nonexistent_keyword" now passes UTF-8 and embedded
+NULs through unchanged [perl #97478].
=item *
-C<undef> on a control character glob (C<undef *^H>) no longer emits an
-erroneous warning about ambiguity [perl #112456].
+C<prototype> now treats magical variables like C<$1> the same way as
+non-magical variables when checking for the CORE:: prefix, instead of
+treating them as subroutine names.
=item *
-For efficiency's sake, many operators and built-in functions return the
-same scalar each time. Lvalue subroutines and subroutines in the CORE::
-namespace were allowing this implementation detail to leak through.
-C<print &CORE::uc("a"), &CORE::uc("b")> used to print "BB". The same thing
-would happen with an lvalue subroutine returning the return value of C<uc>.
-Now the value is copied in such cases.
+Under threaded perls, a runtime code block in a regular expression could
+corrupt the package name stored in the op tree, resulting in bad reads
+in C<caller>, and possibly crashes [perl #113060].
=item *
-C<method {}> syntax with an empty block or a block returning an empty list
-used to crash or use some random value left on the stack as its invocant.
-Now it produces an error.
+Referencing a closure prototype (C<\&{$_[1]}> in an attribute handler for a
+closure) no longer results in a copy of the subroutine (or assertion
+failures on debugging builds).
=item *
-C<vec> now works with extremely large offsets (>2 GB) [perl #111730].
+C<eval '__PACKAGE__'> now returns the right answer on threaded builds if
+the current package has been assigned over (as in
+C<*ThisPackage:: = *ThatPackage::>) [perl #78742].
=item *
-Changes to overload settings now take effect immediately, as do changes to
-inheritance that affect overloading. They used to take effect only after
-C<bless>.
+If a package is deleted by code that it calls, it is possible for C<caller>
+to see a stack frame belonging to that deleted package. C<caller> could
+crash if the stash's memory address was reused for a scalar and a
+substitution was performed on the same scalar [perl #113486].
+
+=item *
-Objects that were created before a class had any overloading used to remain
-non-overloaded even if the class gained overloading through C<use overload>
-or @ISA changes, and even after C<bless>. This has been fixed
-[perl #112708].
+C<UNIVERSAL::can> no longer treats its first argument differently
+depending on whether it is a string or number internally.
=item *
-Classes with overloading can now inherit fallback values.
+C<open> with C<< <& >> for the mode checks to see whether the third argument is
+a number, in determining whether to treat it as a file descriptor or a handle
+name. Magical variables like C<$1> were always failing the numeric check and
+being treated as handle names.
=item *
-Overloading was not respecting a fallback value of 0 if there were
-overloaded objects on both sides of an assignment operator like C<+=>
-[perl #111856].
+C<warn>'s handling of magical variables (C<$1>, ties) has undergone several
+fixes. C<FETCH> is only called once now on a tied argument or a tied C<$@>
+[perl #97480]. Tied variables returning objects that stringify as "" are
+no longer ignored. A tied C<$@> that happened to return a reference the
+I<previous> time is was used is no longer ignored.
=item *
-C<pos> now croaks with hash and array arguments, instead of producing
-erroneous warnings.
+C<warn ""> now treats C<$@> with a number in it the same way, regardless of
+whether it happened via C<$@=3> or C<$@="3">. It used to ignore the
+former. Now it appends "\t...caught", as it has always done with
+C<$@="3">.
=item *
-C<while(each %h)> now implies C<while(defined($_ = each %h))>, like
-C<readline> and C<readdir>.
+Numeric operators on magical variables (e.g., S<C<$1 + 1>>) used to use
+floating point operations even where integer operations were more appropriate,
+resulting in loss of accuracy on 64-bit platforms [perl #109542].
=item *
-Subs in the CORE:: namespace no longer crash after C<undef *_> when called
-with no argument list (C<&CORE::time> with no parentheses).
+Unary negation no longer treats a string as a number if the string happened
+to be used as a number at some point. So, if C<$x> contains the string "dogs",
+C<-$x> returns "-dogs" even if C<$y=0+$x> has happened at some point.
=item *
-Unicode 6.1 published an incorrect alias for one of the
-Canonical_Combining_Class property's values (which range between 0 and
-254). The alias C<CCC133> should have been C<CCC132>. Perl now
-overrides the data file furnished by Unicode to give the correct value.
+In Perl 5.14, C<-'-10'> was fixed to return "10", not "+10". But magical
+variables (C<$1>, ties) were not fixed till now [perl #57706].
=item *
-C<unpack> no longer produces the "'/' must follow a numeric type in unpack"
-error when it is the data that are at fault [perl #60204].
+Unary negation now treats strings consistently, regardless of the internal
+C<UTF8> flag.
=item *
-C<join> and C<"@array"> now call FETCH only once on a tied C<$">
-[perl #8931].
+A regression introduced in Perl v5.16.0 involving
+C<tr/I<SEARCHLIST>/I<REPLACEMENTLIST>/> has been fixed. Only the first
+instance is supposed to be meaningful if a character appears more than
+once in C<I<SEARCHLIST>>. Under some circumstances, the final instance
+was overriding all earlier ones. [perl #113584]
=item *
-Some subroutine calls generated by compiling core ops affected by a
-C<CORE::GLOBAL> override had op checking performed twice. The checking
-is always idempotent for pure Perl code, but the double checking can
-matter when custom call checkers are involved.
+Regular expressions like C<qr/\87/> previously silently inserted a NUL
+character, thus matching as if it had been written C<qr/\00087/>. Now it
+matches as if it had been written as C<qr/87/>, with a message that the
+sequence C<"\8"> is unrecognized.
-=back
+=item *
-=head1 Known Problems
+C<__SUB__> now works in special blocks (C<BEGIN>, C<END>, etc.).
+
+=item *
-XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
-tests that had to be C<TODO>ed for the release would be noted here, unless
-they were specific to a particular platform (see below).
+Thread creation on Windows could theoretically result in a crash if done
+inside a C<BEGIN> block. It still does not work properly, but it no longer
+crashes [perl #111610].
-This is a list of some significant unfixed bugs, which are regressions
-from either 5.XXX.XXX or 5.XXX.XXX.
+=item *
-[ List each fix as a =item entry ]
+C<\&{''}> (with the empty string) now autovivifies a stub like any other
+sub name, and no longer produces the "Unable to create sub" error
+[perl #94476].
+
+=back
+
+=head1 Known Problems
=over 4
=item *
-XXX
+On VMS, L<Module::Build> still fails its test suite.
-=back
+=item *
-=head1 Obituary
+On Win32, several tests fail intermittently, and may hang unless STDERR is
+redirected.
-XXX If any significant core contributor has died, we've added a short obituary
-here.
+=back
=head1 Acknowledgements
XXX Generate this with:
- perl Porting/acknowledgements.pl v5.16.0..HEAD
+ perl Porting/acknowledgements.pl v5.17.0..HEAD
=head1 Reporting Bugs
https://perl5.git.perl.org / perl5.git / blobdiff