[ 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]
=back
=item *
+L<B::Concise> has been upgraded from version 0.992 to 0.993.
+
+=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<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 *
+
+L<ExtUtils::Manifest> has been upgraded from version 1.65 to 1.66.
+[perl #122415].
+
+=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<B::Concise> has been upgraded from version 0.992 to 0.993.
+L<Getopt::Std> has been upgraded from version 1.10 to 1.11.
=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
+defined in packages other than the caller.
+
=item *
L<threads> has been upgraded from version 1.95 to 1.96.
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 $var> syntax (see L<fields> and L<attributes>)
+could get confused in the scope of C<use utf8> if C<Class> were a constant
+whose value contained Latin-1 characters.
+
+=back
+
=head1 Utility Changes
XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
=over 4
-=item *
-
-The parser no longer gets confused by C<\U=> within a double-quoted string.
-It used to roduce a syntax error, but now compile it correctly.
-[perl #80368]
+C<save_re_context> no longer does anything and has been moved to
+F<mathoms.c>.
=back
XXX
+=item *
+
+Constant dereferencing now works correctly for typeglob constants.
+Previously the glob was stringified and its name looked up. Now the glob
+itself is used. [perl #69456]
+
+=item *
+
+When parsing a funny character ($ @ % &) followed by braces, the parser no
+longer tries to guess whether it is a block or a hash constructor (causing
+a syntax error when it guesses the latter), since it can only be a block.
+
+=item *
+
+C<undef $reference> now frees the referent immediately, instead of hanging
+on to it until the next statement. [perl #122556]
+
+=item *
+
+Various cases where the name of a sub is used (autoload, overloading, error
+messages) used to crash for lexical subs, but have been fixed.
+
+=item *
+
+Bareword lookup now tries to avoid vivifying packages if it turns out the
+bareword is not going to be a subroutine name.
+
+=item *
+
+Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer
+deletes any subroutine named C<__ANON__> in the current package. Not only
+was C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug
+goes back to perl 5.8.0.
+
+=item *
+
+Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out
+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