=encoding utf8
=for comment
-This has been completed up to 11e0f19.
+This has been completed up to 1a50d74bac4, except for:
+8629c11317 smueller Escape double-quotes in generated #line directives
+8dc67a69b shlomif perl -d: display lines inside subroutines.
+3dfd1b5cd2 leont Export PerlIOBase_open
=head1 NAME
the C<:full> and C<:short> options had been specified. See
L<charnames>.
+=head2 Improved performance for Unicode properties in regular expressions
+
+Matching a code point against a Unicode property is now done via a
+binary search instead of linear. This means for example that the worst
+case for a 1000 item property is 10 probes instead of 1000. This
+inefficiency has been compensated for in the past by permanently storing
+in a hash the results of a given probe plus the results for the adjacent
+64 code points, under the theory that near-by code points are likely to
+be searched for. A separate hash was used for each mention of a Unicode
+property in each regular expression. Thus, C<qr/\p{foo}abc\p{foo}/>
+would generate two hashes. Any probes in one instance would be unknown
+to the other, and the hashes could expand separately to be quite large
+if the regular expression were used on many different widely-separated
+code points. This can lead to running out of memory in extreme cases.
+Now, however, there is just one hash shared by all instances of a given
+property. This means that if C<\p{foo}> is matched against "A" in one
+regular expression in a thread, the result will be known immediately to
+all regular expressions, and the relentless march of using up memory is
+slowed considerably.
+
=head1 Security
XXX Any security-related notices go here. In particular, any security
Version declarations with the C<use> keyword (e.g., C<use 5.012>) are now
faster, as they enable features without loading F<feature.pm>.
+=item *
+
+C<local $_> is faster now, as it no longer iterates through magic that it
+is not going to copy anyway.
+
=back
=head1 Modules and Pragmata
Feature hints are now deparsed with C<use feature> rather than C<%^H>
assignments.
-A regression in 1.10 that caused C<ambient_pragmas> to disabled strict mode
+A regression in 1.10 that caused C<ambient_pragmas> to disable strict mode
in obscure cases has been fixed.
Strict mode is now fully deparsed, including subs and vars [perl #24027].
The global variables C<$(>, C<$|> and C<$)> are now deparsed with braces
(i.e., C<${(}>) in regular expressions [perl #86060].
+C<continue> blocks after C<for> loops are now deparsed correctly, as they
+were back in 0.67 (included with Perl 5.8.5) [perl #108224]
+
=item *
L<CGI> has been upgraded from version 3.58 to version 3.59.
=item *
-L<CPANPLUS> has been upgraded from version 0.9113 to version 0.9115.
+L<CPANPLUS> has been upgraded from version 0.9113 to version 0.9116.
+
+=item *
+
+L<Data::Dumper> has been upgraded from version 2.135_01 to version
+2.135_03.
+
+It can now dump vstrings [perl #101162].
+
+The nameless typeglob (C<*{""}>) is now dumped properly.
+
+=item *
+
+L<diagnostics> has been upgraded from version 1.26 to version 1.27.
+
+See the entry for splain in the L</Utility Changes> section, for the
+changes. The diagnostics module and the splain utility are actually one
+and the same.
+
+=item *
+
+L<ExtUtils::Packlist> has been upgraded from version 1.45 to version 1.46.
+
+It no longer produces "used once" warnings when the C<read> and C<write>
+methods are called while the main program is still compiling (e.g., from
+within a BEGIN block) [perl #107410] [rt.cpan.org #50315].
+
+=item *
+
+L<Locale::Maketext> has been upgraded from version 1.21 to version 1.22.
+
+=item *
+
+L<Module::Pluggable> has been upgraded from version 3.9 to version 4.0.
+
+=item *
+
+L<overload> has been upgraded from version 1.16 to version 1.17.
+
+C<overload::Overloaded> no longer calls C<can> on the class, but uses
+another means to determine whether the object has overloading. It was
+never correct for it to call C<can>, as overloading does not respect
+AUTOLOAD. So classes that autoload methods and implement C<can> no longer
+have to account for overloading [perl #40333].
+
+A warning is now produced for invalid arguments. See L</New Diagnostics>.
=item *
-L<POSIX> has been upgraded from version 1.28 to version 1.29.
+L<perlfaq> has been upgraded from version 5.0150036 to version 5.0150037.
+
+=item *
+
+L<PerlIO::scalar> has been upgraded from version 0.12 to version 0.13.
+
+(This is the module that implements C<< open $fh, '>', \$scalar >>.)
+
+It no longer assumes during C<seek> that $scalar is a string internally.
+If it didn't crash, it was close to doing so [perl #92706].
+
+Printing to an in-memory handle now works if the $scalar holds a reference,
+stringifying the reference before modifying it. References used to be
+treated as empty strings.
+
+Printing to an in-memory handle no longer crashes if the $scalar happens to
+hold a number internally, but no string buffer.
+
+=item *
+
+L<Pod::Html> has been upgraded from version 1.12 to 1.13
+
+=item *
+
+L<POSIX> has been upgraded from version 1.27 to version 1.29.
+
+C<sigsuspend> and C<pause> now run signals handle before returning, as the
+whole point of these two functions is to wait until a signal has
+arrived, and then return I<after> it has been triggered. Delayed, or
+"safe", signals were preventing that from happening, possibly resulting in
+race conditions [perl #107216].
C<POSIX::sleep> is now a direct call into the underlying OS C<sleep>
function, instead of being a Perl wrapper on C<CORE::sleep>. C<POSIX::dup2>
now returns the correct value on Win32 (I<i.e.> the file descriptor).
=item *
-L<Data::Dumper> has been upgraded from version 2.135_01 to version
-2.135_03.
-
-It can now dump vstrings [perl #101162].
+L<Pod::Perldoc> has been upgraded from version 3.15_01 to version 3.15_15.
=item *
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
+C<dbmopen> treats a 0 mode as a special case, that prevents a nonexistent
+file from being created. This has been the case since Perl 5.000, but was
+never documented anywhere. Now the perlfunc entry mentions it
+[perl #90064].
+
+=item *
+
+The entry for C<split> has been rewritten. It is now far clearer than
+before.
+
+=back
+
+=head3 L<perlop> and L<perlsyn>
+
+=over 4
+
+=item *
+
+Documentation of the smartmatch operator has been reworked and moved from
+perlsyn to perlop where it belongs.
+
+=item *
+
+Documentation of the ellipsis statement (C<...>) has been reworked and
+moved from perlop to perlsyn.
=back
=head2 New Diagnostics
-XXX Newly added diagnostic messages go here
-
=head3 New Errors
=over 4
=item *
-XXX L<message|perldiag/"message">
+L<Cannot set tied @DB::args|perldiag/"Cannot set tied @DB::args">
+
+This error occurs when C<caller> tries to set C<@DB::args> but finds it
+tied. Before this error was added, it used to crash instead.
+
+=item *
+
+L<Cannot tie unreifiable array|perldiag/"Cannot tie unreifiable array">
+
+This error is part of a safety check that the C<tie> operator does before
+tying a special array like C<@_>. You should never see this message.
=back
=item *
-XXX L<message|perldiag/"message">
+L<defined(@array) is deprecated|perldiag/"defined(@array) is deprecated">
+
+The long-deprecated C<defined(@array)> now also warns for package variables.
+Previously it only issued a warning for lexical variables.
+
+=item *
+
+L<Useless use of \E|perldiag/"Useless use of \E">
+
+C<\E> does nothing unless preceded by C<\Q>, C<\L> or C<\U>.
+
+=item *
+
+L<overload arg '%s' is invalid|perldiag/"overload arg '%s' is invalid">
+
+This warning, in the "overload" category, is produced when the overload
+pragma is given an argument it doesn't recognize, presumably a mistyped
+operator.
=back
=back
+=head2 Removals
+
+=over 4
+
+=item *
+
+"sort is now a reserved word"
+
+This error used to occur when C<sort> was called without arguments, followed by C<;> or C<)>. (E.g., C<sort;> would die, but C<{sort}> was
+OK.) This error message was added in Perl 3 to catch code like
+C<close(sort)> which would no longer work. More than two decades later,
+this message is no longer appropriate. Now C<sort> without arguments is
+always allowed, and returns an empty list, as it did in those cases where
+it was already allowed [perl #90030].
+
+=back
+
=head1 Utility Changes
XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go
entries for each change
Use L<XXX> with program names to get proper documentation linking. ]
-=head3 L<XXX>
+=head3 L<splain>
=over 4
=item *
-XXX
+splain no longer emits backtraces with the first line number repeated.
+This:
+
+ Uncaught exception from user code:
+ Cannot fwiddle the fwuddle at -e line 1.
+ at -e line 1
+ main::baz() called at -e line 1
+ main::bar() called at -e line 1
+ main::foo() called at -e line 1
+
+has become this:
+
+ Uncaught exception from user code:
+ Cannot fwiddle the fwuddle at -e line 1.
+ main::baz() called at -e line 1
+ main::bar() called at -e line 1
+ main::foo() called at -e line 1
+
+=item *
+
+Some error messages consist of multiple lines that are listed as separate
+entries in L<perldiag>. splain has been taught to find the separate
+entries in these cases, instead of simply failing to find the message.
=back
F<lib/feature.pm> is now a generated file, created by the new
F<regen/feature.pl> script, which also generates F<feature.h>.
+=item *
+
+Tied arrays are now always C<AvREAL>. If C<@_> or C<DB::args> is tied, it
+is reified first, to make sure this is always the case.
+
=back
=head1 Selected Bug Fixes
When one writes C<open foo || die>, which used to work in Perl 4, a
"Precedence problem" warning is produced. This warning used erroneously to
-apply to fully-qualified bareword handle names as well. This has been
-corrected.
+apply to fully-qualified bareword handle names not followed by C<||>. This
+has been corrected.
=item * C<select> and package aliasing
numeric, while treating others as filehandle names. It is now consistent
for flat scalars (i.e., not references).
+=item * Lvalue subs and strict mode
+
+Lvalue sub calls that are not determined to be such at compile time
+(C<&$name> or &{"name"}) are no longer exempt from strict refs if they
+occur in the last statement of an lvalue subroutine [perl #102486].
+
+=item * Non-lvalue sub calls in potentially lvalue context
+
+Sub calls whose subs are not visible at compile time, if
+they occurred in the last statement of an lvalue subroutine,
+would reject non-lvalue subroutines and die with "Can't modify non-lvalue
+subroutine call" [perl #102486].
+
+Non-lvalue sub calls whose subs I<are> visible at compile time exhibited
+the opposite bug. If the call occurred in the last statement of an lvalue
+subroutine, there would be no error when the lvalue sub was called in
+lvalue context. Perl would blindly assign to the temporary value returned
+by the non-lvalue subroutine.
+
+=item * AUTOLOADing lvalue subs
+
+C<AUTOLOAD> routines used to take precedence over the actual sub being
+called (i.e., when autoloading wasn't needed), for sub calls in lvalue or
+potential lvalue context, if the subroutine was not visible at compile
+time.
+
+=item * C<caller> and tied C<@DB::args>
+
+C<caller> sets C<@DB::args> to the subroutine arguments when called from
+the DB package. It used to crash when doing so if C<@DB::args> happened to
+be tied. Now it croaks instead.
+
+=item * Tying C<@_>
+
+Under debugging builds, this code:
+
+ sub TIEARRAY{bless[]}
+ sub {
+ tie @_, "";
+ \@_;
+ }->(1);
+
+use to produce an "av_reify called on tied array" warning. It doesn't any
+more.
+
+=item * Unrecognised switches on C<#!> line
+
+If a switch, such as B<-x>, that cannot occur on the C<#!> line is used
+there, perl dies with "Can't emulate...".
+
+It used to produce the same message for switches that perl did not
+recognise at all, whether on the command line or the C<#!> line.
+
+Now it produces the "Unrecognized switch" error message [perl #104288].
+
+=item * C<system> and SIGCHLD
+
+C<system> now temporarily blocks the SIGCHLD signal handler, to prevent the
+signal handler from stealing the exit status [perl #105700].
+
+=item * Deleting methods via C<delete>
+
+Deletion of methods via C<delete $Class::{method}> syntax used to update
+method caches if called in void context, but not scalar or list context.
+Now it always updates those caches.
+
+=item * Hash element deletion and destructors
+
+When hash elements are deleted in void context, the internal hash entry is
+now freed before the value is freed, to prevent destructors called by that
+latter freeing from seeing the hash in an inconsistent state. It was
+possible to cause double-frees if the destructor freed the hash itself
+[perl #100340].
+
+=item * C<(s)printf>'s %n formatting code
+
+The %n formatting code, which causes the number of characters to be
+assigned to the next argument to C<printf> or C<sprintf> now actually
+assigns the number of characters, instead of the number of bytes.
+
+It also works now with special lvalue functions like C<substr> and with
+nonexistent hash and array elements [perl #103492].
+
+=item * Typeglobs and threads
+
+Typeglobs returned from threads are no longer cloned if the parent thread
+already has a glob with the same name. This means that returned
+subroutines will now assign to the right package variables [perl #107366].
+
+=item * C<local $_>
+
+In Perl 5.14, C<local $_> was changed to create a new variable not tied to
+anything, even if $_ was tied before that. But, due to an oversight, it
+would still call FETCH once on a tied $_ before replacing it with the new
+variable. This has been fixed [perl #105912].
+
+=item * Returning tied variables
+
+When returning a value from a non-lvalue subroutine, Perl copies the value.
+Sometimes it cheats for the sake of speed, and does not copy the value if
+it makes no observable difference. This optimisation was erroneously
+allowing the copy to be skipped on tied variables, causing a difference in
+behaviour depending on the tied variable's reference count. This has been
+fixed [perl #95548].
+
+=item * C<{@a = sort}> no longer crashes
+
+This particular piece of code (C<sort> with no arguments assigned to an
+array, inside a block with no C<;>) started crashing in an earlier 5.15.x
+release. It has been fixed.
+
+=item * C<utf8::decode> and read-only scalars
+
+C<utf8::decode> now refuses to modify read-only scalars [perl #91850].
+
+=item * C<dbmopen> with undefined mode
+
+C<dbmopen> now only warns once, rather than three times, if the mode
+argument is C<undef> [perl #90064].
+
+=item * Freeing an aggregate during list assignment
+
+If list assignment to a hash or array triggered destructors that freed the
+hash or array itself, a crash would ensue. This is no longer the case
+[perl #107440].
+
+=item * Confused internal bookkeeping with @ISA arrays
+
+Creating a weak reference to an @ISA array or accessing the array index
+(C<$#ISA>) could result in confused internal bookkeeping for elements
+subsequently added to the @ISA array. For instance, creating a weak
+reference to the element itself could push that weak reference on to @ISA;
+and elements added after use of C<$#ISA> would be ignored by method lookup
+[perl #85670].
+
+=item * DELETE on scalar ties
+
+Tying an element of %ENV or C<%^H> and then deleting that element would
+result in a call to the tie object's DELETE method, even though tying the
+element itself is supposed to be equivalent to tying a scalar (the element
+is, of course, a scalar) [perl #67490].
+
+=item * Freeing $_ inside C<grep> or C<map>
+
+Freeing $_ inside a C<grep> or C<map> block or a code block embedded in a
+regular expression used to result in double frees [perl #92254, #92256].
+
+=item * Warnings with C<+=>
+
+The C<+=> operator does not usually warn when the left-hand side is
+C<undef>, but it was doing so for tied variables. This has been fixed
+[perl #44895].
+
+=item * Tying and autovivification
+
+When Perl autovivifies an element of a tied array or hash (which entails
+calling STORE with a new reference), it now calls FETCH immediately after
+the STORE, instead of assuming that FETCH would have returned the same
+reference. This can make it easier to implement tied objects [perl #35865, #43011].
+
+=item * C<@&> and C<$&>
+
+Mentioning a variable named "&" other than C<$&> (i.e., C<@&> or C<%&>) no
+longer stops C<$&> from working. The same applies to variables named "'"
+and "`" [perl #24237].
+
+=item * Stacked filetests
+
+C<-T> and C<-B> now work when stacked up with other filetest operators
+[perl #77388].
+
+=item * Filetests and stat buffers
+
+Perl keeps several internal variables to keep track of the last stat
+buffer, from which file(handle) it originated, what type it was, and
+whether the last stat succeeded.
+
+There were various cases where these could get out of synch, resulting in
+inconsistent or erratic behaviour in edge cases (every mention of C<-T>
+applies to C<-B> as well):
+
+=over
+
+=item *
+
+C<-T I<HANDLE>>, even though it does a C<stat>, was not resetting the last
+stat type, so an C<lstat _> following it would merrily return the wrong
+results. Also, it was not setting the success status.
+
+=item *
+
+Freeing the handle last used by C<stat> or a filetest could result in
+S<C<-T _>> using an unrelated handle.
+
+=item *
+
+C<stat> with an IO reference (as returned by C<*STDIO{IO}>, for instance)
+would not reset the stat type.
+
+=item *
+
+C<stat> with an IO reference was not recording the filehandle for
+S<C<-T _>> to use.
+
+=item *
+
+The presence of fatal warnings could cause the stat buffer not to be reset
+for a filetest operator on an unopened filehandle or C<-l> on any handle.
+
+=item *
+
+Fatal warnings would stop C<-T> from setting C<$!>.
+
+=item *
+
+When the last stat was on an unreadable file, C<-T _> is supposed to
+return C<undef>, leaving the last stat buffer unchanged. But it was
+setting the stat type, causing C<lstat _> to stop working.
+
+=item *
+
+C<-T I<FILENAME>> was not resetting the internal stat buffers for
+unreadable files.
+
+=back
+
+These have all been fixed.
+
+=item * C<defined *{"!"}>
+
+An earlier 5.15.x release caused this construct to stop the C<%!> hash
+from working. Likewise C<defined *{"+"}> and C<defined *{"-"}> caused
+C<%+> and C<%->, respectively, to stop working. This has been fixed.
+
+=item * C<-T _> with no preceding C<stat>
+
+This used to produce a confusing "uninitialized" warning, even though there
+is no visible uninitialized value to speak of.
+
+=item * C<stat I<HANDLE>> and fstat failures
+
+If the operating system's C<fstat> function failed, C<stat> would warn
+about an unopened handle, even though that was not the case. This has been
+fixed.
+
+=item * C<lstat I<IOREF>>
+
+C<lstat> is documented to fall back to C<stat> (with a warning) when given
+a filehandle. When passed an IO reference, it was actually doing the
+equivalent of S<C<stat _>> and ignoring the handle.
+
+=item * Crashes with warnings
+
+Two warning messages that mention variable names started crashing in
+5.15.5, but have been fixed [perl #106726].
+
+=item * Bitwise assignment operators and copy-on-write
+
+In 5.14.0, the bitwise assignment operators C<|=>, C<^=> and C<&=> starting
+leaving the left-hand side undefined if it happened to be a copy-on-write
+string. This has been fixed [perl #108480].
+
=back
=head1 Known Problems
https://perl5.git.perl.org / perl5.git / blobdiff