[ 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 v5.21.4
+perldelta - what is new for perl v5.21.5
=head1 DESCRIPTION
-This document describes differences between the 5.21.3 release and the 5.21.4
+This document describes differences between the 5.21.4 release and the 5.21.5
release.
-If you are upgrading from an earlier release such as 5.21.2, first read
-L<perl5213delta>, which describes differences between 5.21.2 and 5.21.3.
+If you are upgrading from an earlier release such as 5.21.3, first read
+L<perl5214delta>, which describes differences between 5.21.3 and 5.21.4.
=head1 Notice
[ List each enhancement as a =head2 entry ]
+=head2 New double-diamond operator
+
+C<<< <<>>> >>> is like C<< <> >> but uses three-argument C<open> to open
+each file in @ARGV. So each element of @ARGV is an actual file name, and
+"|foo" won't be treated as a pipe open.
+
+=head2 Perl now supports POSIX 2008 locale currency additions.
+
+On platforms that are able to handle POSIX.1-2008, the
+hash returned by
+L<C<POSIX::localeconv()>|perllocale/The localeconv function>
+includes the international currency fields added by that version of the
+POSIX standard. These are
+C<int_n_cs_precedes>,
+C<int_n_sep_by_space>,
+C<int_n_sign_posn>,
+C<int_p_cs_precedes>,
+C<int_p_sep_by_space>,
+and
+C<int_p_sign_posn>.
+
=head1 Security
-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.
+=head2 Perl is now compiled with -fstack-protector-strong if available
+
+Perl has been compiled with the anti-stack-smashing option
+C<-fstack-protector> since 5.10.1. Now Perl uses the newer variant
+called C<-fstack-protector-strong>, if available. (This was added
+already in 5.21.4.)
[ List each security issue as a =head2 entry ]
=back
-[ List each other deprecation as a =head2 entry ]
+=head2 Use of multiple /x regexp modifiers
+
+It is now deprecated to say something like any of the following:
+
+ qr/foo/xx;
+ /(?xax:foo)/;
+ use re qw(/amxx);
+
+That is, now C<x> should only occur once in any string of contiguous
+regular expression pattern modifiers. We do not believe there are any
+occurrences of this in all of CPAN. This is in preparation for a future
+Perl release having C</xx> mean to allow white-space for readability in
+bracketed character classes (those enclosed in square brackets:
+C<[...]>).
=head1 Performance Enhancements
=item *
-XXX
+C<length> is up to 20% faster for non-magical/non-tied scalars containing a
+string if it is a non-utf8 string or if C<use bytes;> is in scope.
+
+=item *
+
+Non-magical/non-tied scalars that contain only a floating point value and are
+on most Perl builds with 64 bit integers now use 8-32 less bytes of memory
+depending on OS.
+
+=item *
+
+In C<@array = split>, the assigment can be optimised away with C<split>
+writing directly to the array. This optimisation was happening only for
+package arrays other than @_ and only if the argument to split was an
+explicit constant or scalar other than $_. Now this optimisation happens
+almost all the time.
=back
=item *
-L<XXX> has been upgraded from version A.xx to B.yy.
+L<attributes> has been upgraded from version 0.23 to 0.24.
+
+Avoid reading beyond the end of a buffer. [perl #122629]
=item *
-L<File::Find> has been upgraded from version 1.27 to 1.28.
-C<find()> and C<finddepth()> will now warn if passed inappropriate or
-misspelled options.
+L<B::Deparse> has been upgraded from version 1.28 to 1.29.
-=item *
+Parenthesised arrays in lists passed to C<\> are now correctly deparsed
+with parentheses (e.g., C<\(@a, (@b), @c)> now retains the parentheses
+around @b), this preserving the flattening behaviour of referenced
+parenthesised arrays. Formerly, it only worked for one array: C<\(@a)>.
-L<B::Concise> has been upgraded from version 0.992 to 0.993.
+C<local our> is now deparsed correctly, with the C<our> included.
-=item *
+C<for($foo; !$bar; $baz) {...}> was deparsed without the C<!> (or C<not>).
+This has been fixed.
-L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
+Core keywords that conflict with lexical subroutines are now deparsed with
+the C<CORE::> prefix.
-=item *
+C<foreach state $x (...) {...}> now deparses correctly with C<state> and
+not C<my>.
-L<Module::CoreList> has been upgraded from version 5.021003 to 5.021004.
+C<our @array = split(...)> now deparses correctly with C<our> in those
+cases where the assignment is optimised away.
=item *
-L<POSIX> has been upgraded from version 1.42 to 1.43.
+L<DynaLoader> has been upgraded from version 1.26 to 1.27.
+
+Remove dl_nonlazy global if unused in Dynaloader. [perl #122926]
=item *
-L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
+L<Fcntl> has been upgraded from version 1.12 to 1.13.
+
+Add support for the Linux pipe buffer size fcntl() commands.
=item *
-L<constant> has been upgraded from version 1.31 to 1.32.
+L<Module::CoreList> has been upgraded from version 5.20140920 to 5.20141020.
+
+Updated to cover the latest releases of Perl.
=item *
-L<threads> has been upgraded from version 1.95 to 1.96.
+L<XSLoader> has been upgraded from version 0.17 to 0.18.
+
+Allow XSLoader to load modules from a different namespace.
+[perl #122455]
=back
=item *
-XXX Description of the change here
+Clarifications have been added to L<perlrecharclass/Character Ranges>
+to the effect that Perl guarantees that C<[A-Z]>, C<[a-z]>, C<[0-9]> and
+any subranges thereof in regular expression bracketed character classes
+are guaranteed to match exactly what a naive English speaker would
+expect them to match, even on platforms (such as EBCDIC) where special
+handling is required to accomplish this.
=back
=item *
-XXX Describe change here
+'"my" variable &foo::bar can't be in a package' has been reworded to say
+'subroutine' instead of 'variable'.
=back
=over 4
-=item XXX-some-platform
+=item EBCDIC
-XXX
+Special handling is required on EBCDIC platforms to get C<qr/[i-j]/> to
+match only C<"i"> and C<"j">, since there are 7 characters between the
+code points for C<"i"> and C<"j">. This special handling had only been
+invoked when both ends of the range are literals. Now it is also
+invoked if any of the C<\N{...}> forms for specifying a character by
+name or Unicode code point is used instead of a literal. See
+L<perlrecharclass/Character Ranges>.
=back
=item *
-The parser no longer gets confused by C<\U=> within a double-quoted string.
-It used to roduce a syntax error, but now compile it correctly.
-[perl #80368]
+SVs of type SVt_NV are now bodyless when a build configure and platform allow
+it, specifically C<sizeof(NV) <= sizeof(IV)>. The bodyless trick is the same one
+as for IVs since 5.9.2, but for NVs, unlike IVs, is not guarenteed on all
+platforms and build configurations.
+
+=item *
+
+The C<$DB::single>, C<$DB::signal> and C<$DB::trace> now have set and
+get magic that stores their values as IVs and those IVs are used when
+testing their values in C<pp_dbstate>. This prevents perl from
+recursing infinity if an overloaded object is assigned to any of those
+variables. [perl #122445]
+
+=item *
+
+C<Perl_tmps_grow> which is marked as public API but undocumented has been
+removed from public API. If you use C<EXTEND_MORTAL> macro in your XS code to
+preextend the mortal stack, you are unaffected by this change.
+
+=item *
+
+C<cv_name>, which was introduced in 5.21.4, has been changed incompatibly.
+It now has a flags field that allows the caller to specify whether the name
+should be fully qualified. See L<perlapi/cv_name>.
+
+=item *
+
+Internally Perl no longer uses the C<SVs_PADMY> flag. C<SvPADMY()> now
+returns a true value for anything not marked PADTMP. C<SVs_PADMY> is now
+defined as 0.
=back
=item *
-XXX
+Locking and unlocking values via L<Hash::Util> or C<Internals::SvREADONLY>
+no longer has any affect on values that are read-only to begin. Unlocking
+such values could result in crashes, hangs or other erratic behaviour.
+
+=item *
+
+The internal C<looks_like_number> function (which L<Scalar::Util> provides
+access to) began erroneously to return true for "-e1" in 5.21.4, affecting
+also C<-'-e1'>. This has been fixed.
+
+=item *
+
+The flip-flop operator (C<..> in scalar context) would return the same
+scalar each time, unles the containing subroutine was called recursively.
+Now it always returns a new scalar. [perl #122829]
+
+=item *
+
+Some unterminated C<(?(...)...)> constructs in regular expressions would
+either crash or give erroneous error messages. C</(?(1)/> is one such
+example.
+
+=item *
+
+C<pack "w", $tied> no longer calls FETCH twice.
+
+=item *
+
+List assignments like C<($x, $z) = (1, $y)> now work correctly if $x and $y
+have been aliased by C<foreach>.
+
+=item *
+
+Some patterns including code blocks with syntax errors, such as
+C</ (?{(^{})/>, would hang or fail assertions on debugging builds. Now
+they produce errors.
+
+=item *
+
+An assertion failure when parsing C<sort> with debugging enabled has been
+fixed. [perl #122771]
+
+=item *
+
+C<*a = *b; @a = split //, $b[1]> could do a bad read and produce junk
+results.
=back
XXX Generate this with:
- perl Porting/acknowledgements.pl v5.21.3..HEAD
+ perl Porting/acknowledgements.pl v5.21.4..HEAD
=head1 Reporting Bugs