[ List each enhancement as a =head2 entry ]
+=head2 C<kill> with negative signal names
+
+C<kill> has always allowed a negative signal number, which kills the
+process group instead of a single process. It has also allowed signal
+names. But it did not behave consistently, because negative signal names
+were treated as 0. Now negative signals names like C<-INT> are supported
+and treated the same way as -2 [perl #112990].
+
=head1 Security
XXX Any security-related notices go here. In particular, any security
are set then they report that root can execute the file. Perl's builtin
C<-x> and C<-X> operators have always been correct.
+=item *
+
+L<Tie::StdHandle> has been upgraded from version 4.2 to 4.3.
+
+C<READ> now respects the offset argument to C<read> [perl #112826].
+
+=item *
+
+L<IO> has been upgraded from version 1.25_07 to 1.25_08.
+
+L<IO::Socket> tries harder to cache or otherwise fetch socket
+information.
+
+=item *
+
+L<Storable> has been upgraded from version 2.36 to 2.37.
+
+Restricted hashes were not always thawed correctly [perl #73972].
+
+Storable would croak when freezing a blessed REF object with a
+C<STORABLE_freeze()> method [perl #113880].
+
+=item *
+
+L<Socket> has been upgraded from version 2.001 to 2.002.
+
=back
=head2 Removed Modules and Pragmata
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.
-=head3 L<XXX>
+=head3 L<perlfunc>
=over 4
=item *
-XXX Description of the change here
+Clarified documentation of C<our>.
=back
=item *
-XXX L<message|perldiag/"message">
+L<Group name must start with a non-digit word character in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Group name must start with a non-digit word character in regex; marked by <-- HERE in m/%s/">
+
+This error has been added for C<(?&0)>, which is invalid. It used to
+produce an incomprehensible error message [perl #101666].
+
+=item *
+
+L<Can't use an undefined value as a subroutine reference|perldiag/"Can't use an undefined value as %s reference">
+
+Calling an undefined value as a subroutine now produces this error message.
+It used to, but was accidentally disabled, first in Perl 5.004 for
+non-magical variables, and then in Perl 5.14 for magical (e.g., tied)
+variables. It has now been restored. In the mean time, undef was treated
+as an empty string [perl #113576].
=back
C<srand()> now warns when passed a value that doesn't fit in a C<UV> (since the
value will be truncated rather than overflowing) [perl #40605].
+=item *
+
+Running perl with the C<-i> flag now warns if no input files are provided on
+the command line [perl #113410].
+
=back
=head2 Changes to Existing Diagnostics
=item *
-XXX Describe change here
+The 'Can't use "my %s" in sort comparison' error has been downgraded to a
+warning, '"my %s" used in sort comparison' (with 'state' instead of 'my'
+for state variables). In addition, the heuristics for guessing whether
+lexical $a or $b has been misused have been improved to generate fewer
+false positives. Lexical $a and $b are no longer disallowed if they are
+outside the sort block. Also, a named unary or list operator inside the
+sort block no longer causes the $a or $b to be ignored [perl #86136].
=back
=item *
-XXX
+Building perl with some Windows compilers used to fail due to a problem
+with miniperl's C<glob> operator (which uses the C<perlglob> program)
+deleting the PATH environment variable [perl #113798].
=back
=over 4
-=item XXX-some-platform
+=item XXX
-XXX
=back
=over 4
-=item XXX-some-platform
+=item VMS
-XXX
+Quotes are now removed from the command verb (but not the parameters) for commands
+spawned via C<system>, backticks, or a piped C<open>. Previously, quotes on the verb
+were passed through to DCL, which would fail to recognize the command. Also, if the
+verb is actually a path to an image or command procedure on an ODS-5 volume, quoting it
+now allows the path to contain spaces.
+
+=item AIX
+
+Configure now always adds -qlanglvl=extc99 to the CC flags on AIX when
+using xlC. This will make it easier to compile a number of XS-based modules
+that assume C99 [perl #113778].
=back
=item *
-XXX
+OP allocation for CVs now uses a slab allocator. This simplifies
+memory management for OPs allocated to a CV, so cleaning up after a
+compilation error is simpler and safer [perl #111462][perl #112312].
+
+=item *
+
+PERL_DEBUG_READONLY_OPS has been rewritten to work with the new slab
+allocator, allowing it to catch more violations that befor.
+
+=item *
+
+The old slab allocator for ops, which was only enabled for PERL_IMPLICIT_SYS and PERL_DEBUG_READONLY_OPS, has been retired.
=back
=item *
A regression introduced in v5.14.0 has been fixed, in which some calls
-to the C<re> module would clobber C<$_>.
+to the C<re> module would clobber C<$_> [perl #113750].
=item *
During parsing, subs declared after errors no longer leave stubs
[perl #113712].
+=item *
+
+Closures containing no string evals no longer hang on to their containing
+subroutines, allowing variables closed over by outer subroutines to be
+freed when the outer sub is freed, even if the inner sub still exists
+[perl #89544].
+
+=item *
+
+Duplication of in-memory filehandles by opening with a "<&=" or ">&=" mode
+stopped working properly in 5.16.0. It was causing the new handle to
+reference a different scalar variable. This has been fixed [perl #113764].
+
+=item *
+
+C<qr//> expressions no longer crash with custom regular expression engines
+that do not set C<offs> at regular expression compilation time
+[perl #112962].
+
+=item *
+
+C<delete local> no longer crashes with certain magical arrays and hashes
+[perl #112966].
+
+=item *
+
+C<local> on elements of certain magical arrays and hashes used not to
+arrange to have the element deleted on scope exit, even if the element did
+not exist before C<local>.
+
+=item *
+
+C<scalar(write)> no longer returns multiple items [perl #73690].
+
+=item *
+
+String to floating point conversions no longer misparse certain strings under
+C<use locale> [perl #109318].
+
+=item *
+
+C<@INC> filters that die no longer leak memory [perl #92252].
+
+=item *
+
+The implementations of overloaded operations are now called in the correct
+context. This allows, among other things, being able to properly override
+C<< <> >> [perl #47119].
+
+=item *
+
+Specifying only the C<fallback> key when calling C<use overload> now behaves
+properly [perl #113010].
+
+=item *
+
+C<< sub foo { my $a = 0; while ($a) { ... } } >> and
+C<< sub foo { while (0) { ... } } >> now return the same thing [perl #73618].
+
+=item *
+
+Fixed the debugger C<l> and C<M> commands, and other debugger
+functionality which was broken in 5.17.0 [perl #113918].
+
+=item *
+
+String negation now behaves the same under C<use integer;> as it does
+without [perl #113012].
+
+=item *
+
+C<chr> now returns the Unicode replacement character (U+FFFD) for -1,
+regardless of the internal representation. -1 used to wrap if the argument
+was tied or a string internally.
+
+=item *
+
+Using a C<format> after its enclosing sub was freed could crash as of
+perl 5.12.0, if the format referenced lexical variables from the outer sub.
+
+=item *
+
+Using a C<format> after its enclosing sub was undefined could crash as of
+perl 5.10.0, if the format referenced lexical variables from the outer sub.
+
+=item *
+
+Using a C<format> defined inside a closures, which format references
+lexical variables from outside, never really worked unless the C<write>
+call was directly inside the closure. In 5.10.0 it even started crashing.
+Now the copy of that closure nearest the top of the call stack is used to
+find those variables.
+
+=item *
+
+Formats that close over variables in special blocks no longer crash if a
+stub exists with the same name as the special block before the special
+block is compiled.
+
+=item *
+
+The parser no longer gets confused, treating C<eval foo ()> as a syntax
+error if preceded by C<print;> [perl #16249].
+
+=item *
+
+The return value of C<syscall> is no longer truncated on 64-bit platforms
+[perl #113980].
+
+=item *
+
+Constant folding no longer causes C<print 1 ? FOO : BAR> to print to the
+FOO handle [perl #78064].
+
+=item *
+
+C<do subname> now calls the named subroutine and uses the file name it
+returns, instead of opening a file named "subname".
+
+=item *
+
+Subroutines looked up by rv2cv check hooks (registered by XS modules) are
+now taken into consideration when determining whether C<foo bar> should be
+the sub call C<foo(bar)> or the method call C<< "bar"->foo >>.
+
+=item *
+
+C<CORE::foo::bar> is no longer treated specially, allowing global overrides
+to be called directly via C<CORE::GLOBAL::uc(...)> [perl #113016].
+
+=item *
+
+Calling an undefined sub whose typeglob has been undefined now produces the
+customary "Undefined subroutine called" error, instead of "Not a CODE
+reference".
+
+=item *
+
+Two bugs involving @ISA have been fixed. C<*ISA = *glob_without_array> and
+C<undef *ISA; @{*ISA}> would prevent future modifications to @ISA from
+updating the internal caches used to look up methods. The
+*glob_without_array case was a regression from Perl 5.12.
+
+=item *
+
+Regular expression optimisations sometimes caused C<$> with C</m> to
+produce failed or incorrect matches [perl #114068].
+
+=item *
+
+C<__SUB__> now works in a C<sort> block when the enclosing subroutine is
+predeclared with C<sub foo;> syntax [perl #113710].
+
=back
=head1 Known Problems
https://perl5.git.perl.org / perl5.git / blobdiff