[ List each enhancement as a =head2 entry ]
+=head2 faster array and hash lookups
+
+Array and hash lookups (especially nested ones) that use only constants
+or simple variables as keys, are now considerably faster. See
+L</Internal Changes> for more details.
+
=head2 C<fileno> now works on directory handles
When the relevant support is available in the operating system, the
process of this version. This data is now memory mapped from disk and shared
between perl processes from the same perl binary.
+=item *
+
+If method and class names are known at compile time, hashes are precomputed
+to speed up run-time method lookup. Also, compound method names like
+C<SUPER::new> are parsed at compile time, to save having to parse them at
+run time.
+
=back
=head1 Modules and Pragmata
Whitespace is no longer escaped in regular expressions, because it was
getting erroneously escaped within C<(?x:...)> sections.
+C<sub foo { foo() }> is now deparsed with those mandatory parentheses.
+
+C</@array/> is now deparsed as a regular expression, and not just
+C<@array>.
+
+C</@{-}/>, C</@{+}/> and C<$#{1}> are now deparsed with the braces, which
+are mandatory in these cases.
+
+In deparsing feature bundles, B::Deparse was emitting C<no feature;> first
+instead of C<no feature ':all';>. This has been fixed.
+
+C<chdir FH> is now deparsed without quotation marks.
+
+C<\my @a> is now deparsed without parentheses. (Parenthese would flatten
+the array.)
+
=item *
L<ExtUtils::ParseXS> has been upgraded from version 3.26 to 3.27.
Improve generated C<RETVAL> code generation to avoid repeated
references to C<ST(0)>. [perl #123278]
+Broaden and document the C</OBJ$/> to C</REF$/> typemap optimization
+for the C<DESTROY> method. [perl #123418]
+
=item *
The PathTools module collection has been upgraded from 3.52 to 3.53.
release have been renamed C<OpSIBLING> and C<OpHAS_SIBLING>, following the
existing convention.
+=item *
+
+A new op class, C<UNOP_AUX>, has been added. This is a subclass of
+C<UNOP> with an C<op_aux> field added, which points to an array of unions
+of C<UV>, C<SV*> etc. It is intended for where an op needs to store more data
+than a simple C<op_sv> or whatever. Currently the only op of this type is
+C<OP_MULTIDEREF> (see below).
+
+=item *
+
+A new op has been added, C<OP_MULTIDEREF>, which performs one or more
+nested array and hash lookups where the key is a constant or simple
+variable. For example the expression C<$a[0]{$k}[$i]>, which previously
+involved ten C<rv2Xv>, C<Xelem>, C<gvsv> and C<const> ops is now performed
+by a single C<multideref> op. It can also handle C<local>, C<exists> and
+C<delete>. A non-simple index expression, such as C<[$i+1]> is still done
+using C<aelem/helem>, and single-level array lookup with a small constant
+index is still done using C<aelemfast>.
+
=back
=head1 Selected Bug Fixes
C<eval '$variable'> in nested named subroutines would sometimes look up a
global variable even with a lexical variable in scope.
+In perl 5.20.0, C<sort CORE::fake> where 'fake' is anything other than a
+keyword started chopping of the last 6 characters and treating the result
+as a sort sub name. The previous behaviour of treating "CORE::fake" as a
+sort sub name has been restored. [perl #123410]
+
+=item *
+
+Outside of C<use utf8>, a single-character Latin-1 lexical variable is
+disallowed. The error message for it, "Can't use global $foo...", was
+giving garbage instead of the variable name.
+
=back
=head1 Known Problems
https://perl5.git.perl.org / perl5.git / blobdiff