=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 v5.23.8
+perldelta - what is new for perl v5.25.1
=head1 DESCRIPTION
-This document describes differences between the 5.23.7 release and the 5.23.8
+This document describes differences between the 5.25.0 release and the 5.25.1
release.
-If you are upgrading from an earlier release such as 5.23.6, first read
-L<perl5237delta>, which describes differences between 5.23.6 and 5.23.7.
+If you are upgrading from an earlier release such as 5.24.0, first read
+L<perl5250delta>, which describes differences between 5.24.0 and 5.25.0.
=head1 Notice
[ List each enhancement as a =head2 entry ]
-=head2 More fields provided to C<sigaction> callback with C<SA_SIGINFO>
-
-When passing the C<SA_SIGINFO> flag to L<sigaction|POSIX/sigaction>, the
-C<errno>, C<status>, C<uid>, C<pid>, C<addr> and C<band> fields are now
-included in the hash passed to the handler, if supported by the
-platform.
-
=head1 Security
XXX Any security-related notices go here. In particular, any security
[ List each security issue as a =head2 entry ]
-=head1 Incompatible Changes
+=head2 POSIX::tmpnam() has been removed
+
+The fundamentally unsafe C<tmpnam()> interface was deprecated in
+Perl 5.22.0 and has now been removed. In its place you can use
+for example the L<File::Temp> interfaces.
+
+=head2 require ::Foo::Bar is now illegal.
+
+Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
+bareword require which starts with a double colon dies instead.
+
+=head2 Unescaped literal C<"{"> characters in regular expression
+patterns are no longer permissible
+
+You have to now say something like C<"\{"> or C<"[{]"> to specify to
+match a LEFT CURLY BRACKET. This will allow future extensions to the
+language. This restriction is not enforced, nor are there current plans
+to enforce it, if the C<"{"> is the first character in the pattern.
+
+These have been deprecated since v5.16, with a deprecation message
+displayed starting in v5.22.
+
+=head2 Literal control character variable names are no longer permissible
-XXX For a release on a stable branch, this section aspires to be:
+A variable name may no longer contain a literal control character under
+any circumstances. These previously were allowed in single-character
+names on ASCII platforms, but have been deprecated there since Perl
+v5.20. This affects things like C<$I<\cT>>, where I<\cT> is a literal
+control (such as a C<NAK> or C<NEGATIVE ACKNOWLEDGE> character) in the
+source code.
- 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.
+=head2 C<qr//xx> is no longer permissible
-[ List each incompatible change as a =head2 entry ]
+Using more than one C</x> regular expression pattern modifier on a
+single pattern is now forbidden. This is to allow a future enhancement
+to the language. This usage has been deprecated since v5.22.
+
+=head2 C<NBSP> is no longer permissible in C<\N{...}>
+
+The name of a character may no longer contain non-breaking spaces. It
+has been deprecated to do so since Perl v5.22.
=head1 Deprecations
=item *
-The overhead of scope entry and exit has been considerably reduced, so
-for example subroutine calls, loops and basic blocks are all faster now.
-This empty function call now takes about a third less time to execute:
+Bareword constant strings are now permitted to take part in constant
+folding. They were originally exempted from constant folding in August 1999,
+during the development of Perl 5.6, to ensure that C<use strict "subs">
+would still apply to bareword constants. That has now been accomplished a
+different way, so barewords, like other constants, now gain the performance
+benefits of constant folding.
- sub f{} f();
+This also means that void-context warnings on constant expressions of
+barewords now report the folded constant operand, rather than the operation;
+this matches the behaviour for non-bareword constants.
=back
=item *
-F<cpan/podlators/> has been upgraded from version 4.04 to 4.06.
-
-=item *
-
-L<POSIX> has been upgraded from version 1.59 to 1.60.
-
-It can now export constants for the C<code> value in the hash passed to the
-L<sigaction|POSIX/sigaction> handler when using the C<SA_SIGINFO> flag.
+L<POSIX> has been upgraded from version 1.66 to 1.69. This remedies several
+defects in making its symbols exportable. [perl #127821] Furthermore,
+the C<POSIX::tmpnam()> interface has been removed,
+see L</"POSIX::tmpnam() has been removed">.
=back
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.
-=head3 L<perlguts>
+=head3 L<XXX>
=over 4
=item *
-A new section has been added, L<perlguts/"Dynamic Scope and the Context
-Stack">, which explains how the perl context stack works.
+XXX Description of the change here
=back
=item *
-XXX L<message|perldiag/"message">
+L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
+
+=item *
+
+L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
+
+=item *
+
+L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
+
+=item *
+
+L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
=back
=item *
-L<Assuming NOT a POSIX class since %s in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|
-perldiag/Assuming NOT a POSIX class since %s in regex; marked by <-- HERE in mE<sol>%sE<sol>>
+XXX L<message|perldiag/"message">
=back
=item *
-XXX Describe change here
+Code like C<$x = $x . "a"> was incorrectly failing to yield a
+L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
+warning when C<$x> was a lexical variable with an undefined value. That has
+now been fixed. [perl #127877]
+
+=item *
+
+When the error "Experimental push on scalar is now forbidden" is raised for
+the hash functions C<keys>, C<each>, and C<values>, it is now followed by
+the more helpful message, "Type of arg 1 to whatever must be hash or
+array". [perl #127976]
+
+=item *
+
+C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
+argument to C<shift> or C<pop>, began crashing in Perl 5.14.0, but has now
+been fixed.
+
+=item *
+
+C<< "string$scalar->$*" >> now correctly prefers concat overloading to
+string overlading if C<< $scalar->$* >> returns an overloaded object,
+bringing it into consistency with C<$$scalar>.
+
+=item *
+
+C<< /@0{0*->@*/*0 >> and similar contortions used to crash, but no longer
+do, but merely produce a syntax error. [perl #128171]
+
+=item *
+
+C<do> or C<require> with a reference or typeglob which, when stringified,
+contains a null character started crashing in Perl 5.20.0, but has now been
+fixed. [perl #128182]
=back
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]
-=head2 L<XXX>
+=head2 L<perlbug>
=over 4
=item *
-XXX
+Long lines in the message body are now wrapped at 900 characters, to stay
+well within the 1000-character limit imposed by SMTP mail transfer agents.
+This is particularly likely to be important for the list of arguments to
+C<Configure>, which can readily exceed the limit if, for example, it names
+several non-default installation paths. This change also adds the first unit
+tests for perlbug. [perl #128020]
=back
=item *
-XXX
-
-=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 summarizing, although the bugs
-that they represent may be covered elsewhere.
+C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
+invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
+This means you can supply your target platform C<config.sh>, generate
+the headers and proceed to build your cross-target perl. [perl #127234]
-[ List each test improvement as a =item entry ]
+=item *
-=over 4
+Builds with C<-Accflags=-DPERL_TRACE_OPS> now only dump the operator
+counts when the environment variable C<PERL_TRACE_OPS> to be set to a
+non-zero integer. This allows C<make test> to pass on such a build.
=item *
-XXX
+When building with GCC 6 and link-time optimization (the C<-flto> option to
+C<gcc>), C<Configure> was treating all probed symbols as present on the
+system, regardless of whether they actually exist. This has been fixed.
+[perl #128131]
=item *
-The GNU Make makefile for Win32 now supports parallel builds. [perl #126632]
+The F<t/test.pl> library is used for internal testing of Perl itself, and
+also copied by several CPAN modules. Some of those modules must work on
+older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
+features. Compatibility with Perl 5.8 was inadvertently removed some time
+ago; it has now been restored. [perl #128052]
=item *
-You can now build perl with MSVC++ on Win32 using GNU Make. [perl #126632]
+The build process no longer emits an extra blank line before building each
+"simple" extension (those with only F<*.pm> and F<*.pod> files).
=back
-=head1 Platform Support
-
-=head2 Platform-Specific Notes
+=head1 Testing
-=over 4
+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 summarizing, although the bugs
+that they represent may be covered elsewhere.
-=item VMS
+[ List each test improvement as a =item entry ]
-=over
+=over 4
=item *
-For those C<%ENV> elements based on the CRTL environ array, we've always
-preserved case when setting them but did look-ups only after upcasing the
-key first, which made lower- or mixed-case entries go missing. This problem
-has been corrected by making C<%ENV> elements derived from the environ array
-case-sensitive on look-up as well as case-preserving on store.
+XXX
-=item *
+=back
-Environment look-ups for C<PERL5LIB> and C<PERLLIB> previously only
-considered logical names, but now consider all sources of C<%ENV> as
-determined by C<PERL_ENV_TABLES> and as documented in L<perlvms/%ENV>.
+=head1 Platform Support
-=back
+XXX Any changes to platform support should be listed in the sections below.
-=back
+[ Within the sections, list each platform as a =item entry with specific
+changes as paragraphs below it. ]
=head2 New Platforms
=over 4
-=item Win32
+=item XXX-some-platform
-Builds using Microsoft Visual C++ 2003 and earlier no longer produce
-an "INTERNAL COMPILER ERROR" message. [perl #126045]
+XXX
=back
=item *
-The implementation of perl's context stack system, and its internal API,
-have been heavily reworked. Note that no significant changes have been
-made to any external APIs, but XS code which relies on such internal
-details may need to be fixed. The main changes are:
-
-=over 4
-
-=item *
-
-The C<PUSHBLOCK()>, C<POPSUB()> etc. macros have been replaced with static
-inline functions such as C<cx_pushblock()>, C<cx_popsub()> etc. These use
-function args rather than implicitly relying on local vars such as
-C<gimme> and C<newsp> being available. Also their functionality has
-changed: in particular, C<cx_popblock()> no longer decrements
-C<cxstack_ix>. The ordering of the steps in the C<pp_leave*> functions
-involving C<cx_popblock()>, C<cx_popsub()> etc. has changed. See the new
-documentation, L<perlguts/"Dynamic Scope and the Context Stack">, for
-details on how to use them.
-
-=item *
-
-Various macros, which now consistently have a CX_ prefix, have been added:
-
- CX_CUR(), CX_LEAVE_SCOPE(), CX_POP()
-
-or renamed:
-
- CX_POP_SAVEARRAY(), CX_DEBUG(), CX_PUSHSUBST() ,CX_POPSUBST()
-
-=item *
-
-C<cx_pushblock()> now saves C<PL_savestack_ix> and C<PL_tmps_floor>, so
-CMpp_enter*> and C<pp_leave*> no longer do
-
- ENTER; SAVETMPS; ....; LEAVE
-
-=item *
-
-C<cx_popblock()> now also restores C<PL_curpm>.
-
-=item *
-
-In C<dounwind()> for every context type, the current savestack frame is
-now processed before each context is popped; formerly this was only done
-for sub-like context frames. This action has been removed from
-C<cx_popsub()> and placed into its own macro, C<CX_LEAVE_SCOPE(cx)>, which
-must be called before C<cx_popsub()> etc.
-
-C<dounwind()> now also does a C<cx_popblock()> on the last popped frame
-(formerly it only did the C<cx_popsub()> etc. actions on each frame).
-
-=item *
-
-The temps stack is now freed on scope exit; previously, temps created
-during the last statement of a block wouldn't be freed until the next
-C<nextstate> following the block (apart from an existing hack that did
-this for recursive subs in scalar context); and in something like
-C<f(g())>, the temps created by the last statement in C<g()> would
-formerly not be freed until the statement following the return from
-C<f()>.
-
-=item *
-
-Most values that were saved on the savestack on scope entry are now
-saved in suitable new fields in the context struct, and saved and
-restored directly by C<cx_pushfoo()> and C<cx_popfoo()>, which is much
-faster.
-
-=item *
-
-Various context struct fields have been added, removed or modified.
-
-=item *
-
-The handling of C<@_> in C<cx_pushsub()> and C<cx_popsub()> has been
-considerably tidied up, including removing the C<argarray> field from the
-context struct, and extracting out some common (but rarely used) code into
-a separate function, C<clear_defarray()>. Also, useful subsets of
-C<cx_popsub()> which had been unrolled in places like C<pp_goto> have been
-gathered into the new functions C<cx_popsub_args()> and
-C<cx_popsub_common()>.
-
-=item *
-
-C<pp_leavesub> and C<pp_leavesublv> now use the same function as the rest
-of the C<pp_leave*>'s to process return args.
-
-=item *
-
-C<CXp_FOR_PAD> and C<CXp_FOR_GV> flags have been added, and
-C<CXt_LOOP_FOR> has been split into C<CXt_LOOP_LIST>, C<CXt_LOOP_ARY>.
-
-=item *
-
-Some variables formerly declared by C<dMULTICALL> (but not documented) have
-been removed.
-
-=back
+Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
+default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
+This flag alters how the C<op_sibling> field is used in C<OP> structures,
+and has been available optionally since perl 5.22.0.
+See L<perl5220delta/"Internal Changes"> for more details of what this
+build option does.
=back
=item *
-Line numbers larger than 2**31-1 but less than 2**32 are no longer
-returned by caller() as negative numbers. [perl #126991]
-
-=item *
-
-C<< unless ( I<assignment> ) >> now properly warns when syntax
-warnings are enabled. [perl #127122]
-
-=item *
-
-Setting an C<ISA> glob to an array reference now properly adds
-C<isaelem> magic to any existing elements. Previously modifying such
-an element would not update the ISA cache, so method calls would call
-the wrong function. Perl would also crash if the C<ISA> glob was
-destroyed, since new code added in 5.23.7 would try to release the
-C<isaelem> magic from the elements. [perl #127351]
-
-=item *
-
-If a here-doc was found while parsing another operator, the parser had
-already read end of file, and the here-doc was not terminated, perl
-could produce an assertion or a segmentation fault. This now reliably
-complains about the unterminated here-doc. [perl #125540]
-
-=item *
-
-untie() would sometimes return the last value returned by the UNTIE()
-handler as well as it's normal value, messing up the stack. [perl
-#126621]
-
-=item *
-
-Fixed an operator precedence problem when C< castflags & 2> is true.
-[perl #127474]
-
-=item *
-
-Caching of DESTROY methods could result in a non-pointer or a
-non-STASH stored in the SvSTASH() slot of a stash, breaking the B
-STASH() method. The DESTROY method is now cached in the MRO metadata
-for the stash. [perl #126410]
-
-=item *
-
-The AUTOLOAD method is now called when searching for a DESTROY method,
-and correctly sets C<$AUTOLOAD> too. [perl #124387] [perl #127494]
+Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
+and C<or>) were being compiled incorrectly in some cases. If the left-hand
+side consisted of either a negated bareword constant or a negated C<do {}>
+block containing a constant expression, and the right-hand side consisted of
+a negated non-foldable expression, one of the negations was effectively
+ignored. The same was true of C<if> and C<unless> statement modifiers,
+though with the left-hand and right-hand sides swapped. This long-standing
+bug has now been fixed. [perl #127952]
=item *
-Avoid parsing beyond the end of the buffer when processing a C<#line>
-directive with no filename. [perl #127334]
+C<reset> with an argument no longer crashes when encountering stash entries
+other than globs. [perl #128106]
=item *
-Perl now raises a warning when a regular expression pattern looks like
-it was supposed to contain a POSIX class, like C<qr/[[:alpha:]]/>, but
-there was some slight defect in its specification which causes it to
-instead be treated as a regular bracketed character class. An example
-would be missing the second colon in the above like this:
-C<qr/[[:alpha]]/>. This compiles to match a sequence of two characters.
-The second is C<"]">, and the first is any of: C<"[">, C<":">, C<"a">,
-C<"h">, C<"l">, or C<"p">. This is unlikely to be the intended
-meaning, and now a warning is raised. No warning is raised unless the
-specification is very close to one of the 14 legal POSIX classes. (See
-L<perlrecharclass/POSIX Character Classes>.)
-[perl #8904]
+Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
+longer causes crashes. [perl #128086]
=back
=head1 Acknowledgements
-XXX Generate this with:
+Generate this with:
- perl Porting/acknowledgements.pl v5.23.7..HEAD
+ perl Porting/acknowledgements.pl v5.25.1..HEAD
=head1 Reporting Bugs
sufficient test case. Your bug report, along with the output of C<perl -V>,
will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
-If the bug you are reporting has security implications, which make it
-inappropriate to send to a publicly archived mailing list, then please send it
-to perl5-security-report@perl.org. This points to a closed subscription
-unarchived mailing list, which includes all the core committers, who will be
-able to help assess the impact of issues, figure out a resolution, and help
-co-ordinate the release of patches to mitigate or fix the problem across all
-platforms on which Perl is supported. Please only use this address for
-security issues in the Perl core, not for modules independently distributed on
-CPAN.
+If the bug you are reporting has security implications which make it
+inappropriate to send to a publicly archived mailing list, then see
+L<perlsec/SECURITY VULNERABILITY CONTACT INFORMATION>
+for details of how to report the issue.
=head1 SEE ALSO