[ 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 v5.17.0
+perldelta - what is new for perl v5.17.2
=head1 DESCRIPTION
-This document describes differences between the 5.16.0 release and
-the 5.17.0 release.
+This document describes differences between the 5.17.1 release and
+the 5.17.2 release.
-If you are upgrading from an earlier release such as 5.16.0, first read
-L<perl5160delta>, which describes differences between 5.15.0 and
-5.16.0.
+If you are upgrading from an earlier release such as 5.17.0, first read
+L<perl5171delta>, which describes differences between 5.17.0 and
+5.17.1.
=head1 Notice
[ List each incompatible change as a =head2 entry ]
-=head2 C<\s> in regular expressions now matches a Vertical Tab (experimental)
-
-This is an experiment early in the development cycle to see what
-repercussions arise from this change. It may well be that we decide
-to require a C<"use feature"> to activate this behavior. Because
-of the experimental nature of this, which may be reversed, the
-documentation has not been changed to reflect it.
-
=head1 Deprecations
XXX Any deprecated features, syntax, modules etc. should be listed here.
=item *
-L<File::stat> has been upgraded from version 1.05 to 1.06.
-
-C<File::stat> ignores the L<filetest> pragma, and warns when used in
-combination therewith. But it was not warning for C<-r>. This has been
-fixed [perl #111640].
-
-C<-p> now works, and does not return false for pipes [perl #111638].
-
-=item *
-
-L<Hash::Util> has been upgraded from version 0.11 to 0.12.
-
-C<hash_unlocked> and C<hashref_unlocked> now returns true if the hash is
-unlocked, instead of always returning false [perl #112126].
+L<File::stat> has been upgraded from version 1.06 to 1.07.
-C<hash_unlocked>, C<hashref_unlocked>, C<lock_hash_recurse> and
-C<unlock_hash_recurse> are now exportable [perl #112126].
-
-Two new functions, C<hash_locked> and C<hashref_locked>, have been added.
-Oddly enough, these two functions were already exported, even though they
-did not exist [perl #112126].
+Previously C<File::stat>'s overloaded C<-x> and C<-X> operators did not give
+the correct results for directories or executable files when running as
+root. They had been treating executable permissions for root just like for
+any other user, performing group membership tests I<etc> for files not owned
+by root. They now follow the correct Unix behaviour - for a directory they
+are always true, and for a file if any of the three execute permission bits
+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<overload> has been upgraded from version 1.18 to 1.19.
+L<Tie::StdHandle> has been upgraded from version 4.2 to 4.3.
-C<no overload> now warns for invalid arguments, just like C<use overload>.
-
-=item *
-
-L<Storable> has been upgraded from version 2.34 to 2.35.
-
-Modifying C<$_[0]> within C<STORABLE_freeze> no longer results in crashes
-[perl #112358].
+C<READ> now respects the offset argument to C<read> [perl #112826].
=back
=item *
-XXX L<message|perldiag/"message">
+L<Group name must start with a non-digit word character in regex; marked by <-- HERE in m/%s/|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].
=back
=item *
-XXX L<message|perldiag/"message">
+C<chr()> now warns when passed a negative value [perl #83048].
+
+=item *
+
+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].
=back
=item *
-The C<SVf_AMAGIC> flag to indicate overloading is now on the stash, not the
-object. It is now set automatically whenever a method or @ISA changes, so
-its meaning has changed, too. It now means "potentially overloaded". When
-the overload table is calculated, the flag is automatically turned off if
-there is no overloading, so there should be no noticeable slowdown.
-
-The staleness of the overload tables is now checked when overload methods
-are invoked, rather than during C<bless>.
-
-"A" magic is gone. The changes to the handling of the C<SVf_AMAGIC> flag
-eliminate the need for it.
-
-The core no longer increments C<PL_amagic_generation> (it doesn't need to).
-But an XS module can still increment it to mark all overload tables as
-stale. (It is still not part of the API, though.) Do not rely on this.
-It may be deleted in the next release.
-
-The fallback overload setting is now stored in its own stash entry, called
-"(fallback".
+XXX
=back
=item *
-C<goto ''> now looks for an empty label, producing the "goto must have
-label" error message, instead of exiting the program [perl #111794].
-
-=item *
-
-C<goto "\0"> now dies with "Can't find label" instead of "goto must have
-label".
+A regression introduced in v5.14.0 has been fixed, in which some calls
+to the C<re> module would clobber C<$_>.
=item *
-The C function C<hv_store> used to result in crashes when used on C<%^H>
-[perl #111000].
+C<do FILE> now always either sets or clears C<$@>, even when the file can't be
+read. This ensures that testing C<$@> first (as recommended by the
+documentation) always returns the correct result.
=item *
-A call checker attached to a closure prototype via C<cv_set_call_checker>
-is now copied to closures cloned from it. So C<cv_set_call_checker> now
-works inside an attribute handler for a closure.
-
-=item *
+The array iterator used for the C<each @array> construct is now correctly
+reset when C<@array> is cleared (RT #75596). This happens for example when the
+array is globally assigned to, as in C<@array = (...)>, but not when its
+B<values> are assigned to. In terms of the XS API, it means that C<av_clear()>
+will now reset the iterator.
-Writing to C<$^N> used to have no effect. Now it croaks with "Modification
-of a read-only value" by default, but that can be overridden by a custom
-regular expression engine, as with C<$1> [perl #112184].
+This mirrors the behaviour of the hash iterator when the hash is cleared.
=item *
-C<undef> on a control character glob (C<undef *^H>) no longer emits an
-erroneous warning about ambiguity [perl #112456].
+C<< $class->can >>, C<< $class->isa >>, and C<< $class->DOES >> now return
+correct results, regardless of whether that package referred to by C<$class>
+exists [perl #47113].
=item *
-For efficiency's sake, many operators and built-in functions return the
-same scalar each time. Lvalue subroutines and subroutines in the CORE::
-namespace were allowing this implementation detail to leak through.
-C<print &CORE::uc("a"), &CORE::uc("b")> used to print "BB". The same thing
-would happen with an lvalue subroutine returning the return value of C<uc>.
-Now the value is copied in such cases.
+Arriving signals no longer clear C<$@> [perl #45173].
=item *
-C<method {}> syntax with an empty block or a block returning an empty list
-used to crash or use some random value left on the stack as its invocant.
-Now it produces an error.
+Allow C<my ()> declarations with an empty variable list [perl #113554].
=item *
-C<vec> now works with extremely large offsets (>2 GB) [perl #111730].
+During parsing, subs declared after errors no longer leave stubs
+[perl #113712].
=item *
-Changes to overload settings now take effect immediately, as do changes to
-inheritance that affect overloading. They used to take effect only after
-C<bless>.
-
-Objects that were created before a class had any overloading used to remain
-non-overloaded even if the class gained overloading through C<use overload>
-or @ISA changes, and even after C<bless>. This has been fixed
-[perl #112708].
+Closures containing no string evals no longer hang on to their containing
+subroutines, allowing variables closed over by outer subroutines to be
+freed when the outer sub is freed, even if the inner sub still exists
+[perl #89544].
=item *
-Classes with overloading can now inherit fallback values.
-
-=item *
-
-C<pos> now croaks with hash and array arguments, instead of producing
-erroneous warnings.
-
-=item *
-
-C<while(each %h)> now implies C<while(defined($_ = each %h))>, like
-C<readline> and C<readdir>.
-
-=item *
-
-Subs in the CORE:: namespace no longer crash after C<undef *_> when called
-with no argument list (C<&CORE::time> with no parentheses).
+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].
=back
=head1 Known Problems
XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
-tests that had to be C<TODO>ed for the release would be noted here, unless
-they were specific to a particular platform (see below).
-
-This is a list of some significant unfixed bugs, which are regressions
-from either 5.XXX.XXX or 5.XXX.XXX.
+tests that had to be C<TODO>ed for the release would be noted here. Unfixed
+platform specific bugs also go here.
[ List each fix as a =item entry ]
XXX Generate this with:
- perl Porting/acknowledgements.pl v5.16.0..HEAD
+ perl Porting/acknowledgements.pl v5.17.1..HEAD
=head1 Reporting Bugs