[ List each enhancement as a =head2 entry ]
+=head2 Infinity and NaN (not-a-number) handling improved
+
+Floating point values are able to hold the special values infinity
+(also -infinity), and NaN (not-a-number). Now we more robustly recognize
+and propagate the value in computations, and on output normalize them
+to C<Inf> and C<NaN>.
+
+See also the L<POSIX> enhancements.
+
=head1 Security
XXX Any security-related notices go here. In particular, any security
[ List each incompatible change as a =head2 entry ]
+=head2 Changes to the C<*> prototype
+
+The C<*> character in a subroutine's prototype used to allow barewords
+to take precedence over most, but not all subroutines. It was never
+consistent and exhibited buggy behaviour.
+
+Now it has been changed, so subroutines always take precedence over
+barewords, which brings it into conformity with similarly prototyped
+built-in functions:
+
+ sub splat($) { ... }
+ sub foo { ... }
+ splat(foo); # now always splat(foo())
+ splat(bar); # still splat('bar') as before
+ close(foo); # close(foo())
+ close(bar); # close('bar')
+
=head1 Deprecations
XXX Any deprecated features, syntax, modules etc. should be listed here.
=item *
-XXX
+Subroutines with an empty prototype and bodies containing just C<undef> are
+now eligible for inlining. [perl #122728]
+
+=item *
+
+Subroutines in packages no longer need to carry typeglobs around with them.
+Declaring a subroutine will now put a simple sub reference in the stash if
+possible, saving memory. The typeglobs still notionally exist, so
+accessing them will cause the subroutine reference to be upgraded to a
+typeglob. This optimisation does not currently apply to XSUBs or exported
+subroutines, and method calls will undo it, since they cache things in
+typeglobs. [perl #120441]
=back
=item *
-L<XXX> has been upgraded from version A.xx to B.yy.
+L<B> has been upgraded from version 1.50 to 1.51.
+
+It provides a new C<B::safename> function, based on the existing
+C<< B::GV->SAFENAME >>, that converts "\cOPEN" to "^OPEN".
=item *
-L<File::Find> has been upgraded from version 1.27 to 1.28.
+L<B::Concise> has been upgraded from version 0.992 to 0.993.
-C<find()> and C<finddepth()> will now warn if passed inappropriate or
-misspelled options.
+=item *
+
+L<B::Deparse> has been upgraded from version 1.27 to 1.28.
+
+It now deparses C<our(I<LIST>)> and typed lexical (C<my Dog $spot>)
+correctly.
=item *
-L<B::Concise> has been upgraded from version 0.992 to 0.993.
+L<CPAN::Meta::Requirements> has been upgraded from version 2.126 to 2.128.
+
+=item *
+
+L<ExtUtils::CBuilder> has been upgraded from version 0.280216 to 0.280219.
+[perl #122675].
=item *
=item *
+L<ExtUtils::ParseXS>: Documentation has been added to
+F<ExtUtils-ParseXS/lib/perlxs.pod> concerning handling of locales when writing
+XS code.
+
+=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.
+
+=item *
+
+L<Getopt::Std> has been upgraded from version 1.10 to 1.11.
+
+=item *
+
L<HTTP::Tiny> has been upgraded from version 0.047 to 0.048.
=item *
L<POSIX> has been upgraded from version 1.42 to 1.43.
+The C99 math functions and constants (for example acosh, round,
+M_E, M_PI) have been added.
+
=item *
L<Pod::Perldoc> has been upgraded from version 3.23 to 3.24.
=item *
+Scalar-List-Utils has been upgraded from version 1.40 to 1.41.
+
+=item *
+
L<constant> has been upgraded from version 1.31 to 1.32.
It now accepts fully-qualified constant names, allowing constants to be
XXX Description of the change here
+=item *
+
+L<perlsyn>: An ambiguity in the documentation of the Ellipsis statement has
+been corrected. [perl #122661]
+
=back
=head1 Diagnostics
=back
+=head2 Diagnostic Removals
+
+=over 4
+
+=item *
+
+"Constant is not a FOO reference"
+
+Compile-time checking of constant dereferencing (e.g.,
+C<< my_constant->() >>) has been removed, since it was not taking
+overloading into account. [perl #69456] [perl #122607]
+
+=item *
+
+The warning "Ambiguous use of -foo resolved as -&foo()" has been removed.
+There is actually no ambiguity here, and this impedes the use of negated
+constants; e.g., C<-Inf>.
+
+=item *
+
+The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
+could get confused in the scope of C<use utf8> if C<Class> were a constant
+whose value contained Latin-1 characters.
+
+=back
+
=head1 Utility Changes
XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
=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]
+C<save_re_context> no longer does anything and has been moved to
+F<mathoms.c>.
+
+=item *
+
+C<cv_name> is a new API function that can be passed a CV or GV. It returns
+an SV containing the name of the subroutine for use in diagnostics.
+[perl #116735] [perl #120441]
+
+=item *
+
+C<cv_set_call_checker_flags> is a new API function that works like
+C<cv_set_call_checker>, except that it allows the caller to specify whether
+the call checker requires a full GV for reporting the subroutine's name, or
+whether it could be passed a CV instead. Whatever value is passed will be
+acceptable to C<cv_name>. C<cv_set_call_checker> guarantees there will be
+a GV, but it may have to create one on the fly, which is inefficient.
+[perl #116735]
+
+=item *
+
+C<CvGV> (which is not part of the API) is now a more complex macro, which
+may call a function and reify a GV. For those cases where is has been used
+as a boolean, C<CvHASGV> has been added, which will return true for CVs
+that notionally have GVs, but without reifying the GV. C<CvGV> also
+returns a GV now for lexical subs. [perl #120441]
=back
=item *
-Compile-time checking of constant dereferencing (e.g.,
-C<< my_constant->() >>) has been removed, since it was not taking
-overloading into account. [perl #69456] [perl #122607]
-
-=item *
-
Constant dereferencing now works correctly for typeglob constants.
Previously the glob was stringified and its name looked up. Now the glob
itself is used. [perl #69456]
constants of the same name declared by C<use constant>. This bug was
introduced in perl 5.10.0.
+=item *
+
+Under some conditions a warning raised in compilation of regular
+expression patterns could be displayed multiple times. This is now
+fixed.
+
+=item *
+
+C<qr/[\N{named sequence}]/> now works properly in many instances. Some
+names known to C<\N{...}> refer to a sequence of multiple characters,
+instead of the usual single character. Bracketed character classes
+generally only match single characters, but now special handling has
+been added so that they can match named sequences, but not if the class
+is inverted or the sequence is specified as the beginning or end of a
+range. In these cases, the only behavior change from before is a slight
+rewording of the fatal error message given when this class is part of a
+C<?[...])> construct. When the C<[...]> stands alone, the same
+non-fatal warning as before is raised, and only the first character in
+the sequence is used, again just as before.
+
+=item *
+
+Tainted constants evaluated at compile time no longer cause unrelated
+statements to become tainted. [perl #122669]
+
+=item *
+
+C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0",
+was not giving the handle the right reference count, so a double free could
+happen.
+
+=item *
+
+When deciding that a bareword was a method name, the parser would get
+confused if an "our" sub with the same name existed, and look up the method
+in the package of the "our" sub, instead of the package of the invocant.
+
+=item *
+
+The parser no longer gets confused by C<\U=> within a double-quoted string.
+It used to roduce a syntax error, but now compiles it correctly.
+[perl #80368]
+
+=item *
+
+It has always been the intention for the C<-B> and C<-T> file test
+operators to treat UTF-8 encoded files as text.
+(L<perlfunc|perlfunc/-X FILEHANDLE> has been updated to say this.)
+Previously, it was possible for some files to be considered UTF-8 that
+actually weren't valid UTF-8. This is now fixed. The operators now
+work on EBCDIC platforms as well.
+
+=item *
+
+Under some conditions warning messages raised during regular expression
+pattern compilation were being output more than once. This has now been
+fixed.
+
+=item *
+
+A regression has been fixed that was introduced in v5.20.0 (fixed in
+v5.20.1 as well as here) in which a UTF-8 encoded regular expression
+pattern that contains a single ASCII lowercase letter does not match its
+uppercase counterpart. [perl #122655]
+
+=item *
+
+Constant folding could incorrectly suppress warnings if lexical warnings
+(C<use warnings> or C<no warnings>) were not in effect and C<$^W> were
+false at compile time and true at run time.
+
+=item *
+
+Loading UTF8 tables during a regular expression match could cause assertion
+failures under debugging builds if the previous match used the very same
+regular expression. [perl #122747]
+
+=item *
+
+Thread cloning used to work incorrectly for lexical subs, possibly causing
+crashes or double frees on exit.
+
=back
=head1 Known Problems
https://perl5.git.perl.org / perl5.git / blobdiff