=encoding utf8
-=for todo
-83b195e49dd1 ensure correctness if sv_2mortal modifies errno
-
=head1 NAME
[ 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 v5.17.1
+perldelta - what is new for perl v5.17.2
=head1 DESCRIPTION
-This document describes differences between the 5.17.0 release and
-the 5.17.1 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<perl5170delta>, which describes differences between 5.16.0 and
-5.17.0.
+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 enhancement as a =head2 entry ]
-=head2 More CORE:: subs
-
-Several more built-in functions have been added as subroutines to the
-CORE:: namespace, namely, those non-overridable keywords that can be
-implemented without custom parsers: C<defined>, C<delete>, C<exists>,
-C<glob>, C<pos>, C<protoytpe>, C<scalar>, C<split>, C<study>, and C<undef>.
+=head2 C<kill> with negative signal names
-As some of these have prototypes, C<prototype('CORE::...')> has been
-changed to not make a distinction between overridable and non-overridable
-keywords. This is to make C<prototype('CORE::pos')> consistent with
-C<prototype(&CORE::pos)>.
+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
If any exist, they are bugs, and we request that you submit a
report. See L</Reporting Bugs> below.
-=head2 C</(?{})/> and C</(??{}> have been heavily reworked.
-
-The implementation of this feature has been almost completely rewritten.
-Although its main intent is to fix bugs, some behaviours, especially
-related to the scope of lexical variables, will have changed. This is
-described more fully in the L</Selected Bug Fixes> section.
-
-=head2 C<\N{BELL}> now refers to U+1F514 instead of U+0007
-
-Unicode 6.0 reused the name "BELL" for a different code point than it
-traditionally had meant. Since Perl v5.14, use of this name still
-referred to U+0007, but would raise a deprecated warning. Now, "BELL"
-refers to U+1F514, and the name for U+0007 is "ALERT". All the
-functions in L<charnames> have been correspondingly updated.
-
-=head2 Alphanumeric operators must now be separated from the closing
-delimiter of regular expressions
-
-You may no longer write something like:
-
- m/a/and 1
-
-Instead you must write
-
- m/a/ and 1
-
-with whitespace separating the operator from the closing delimiter of
-the regular expression. Not having whitespace has resulted in a
-deprecated warning since Perl v5.14.0.
-
-=head2 C<require> dies for unreadable files
-
-When C<require> encounters an unreadable file, it now dies. It used to
-ignore the file and continue searching the directories in @INC
-[perl #113422].
+[ List each incompatible change as a =head2 entry ]
=head1 Deprecations
=item *
-The C<x> repetition operator is now folded to a single constant at compile
-time if called in scalar context with constant operands and no parentheses
-around the left operand.
+XXX
=back
=item *
-L<ExtUtils::CBuilder> has been upgraded from version 0.280206 to 0.280208.
+L<File::stat> has been upgraded from version 1.06 to 1.07.
-Manifest files are now correctly embedded for those versions of VC++ which
-make use of them.
+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<B> has been upgraded from version 1.35 to 1.36.
-
-C<B::COP::stashlen> has been replaced with C<B::COP::stashoff>.
+L<Tie::StdHandle> has been upgraded from version 4.2 to 4.3.
-C<B::COP::stashpv> now supports UTF8 package names and embedded nulls.
+C<READ> now respects the offset argument to C<read> [perl #112826].
=item *
-L<Class::Struct> has been upgraded from version 0.63 to 0.64.
+L<IO> has been upgraded from version 1.25_07 to 1.25_08.
-The constructor now respects overridden accessor methods [perl #29230].
+L<IO::Socket> tries harder to cache or otherwise fetch socket
+information.
=item *
-L<DynaLoader> has been upgraded from version 1.14 to 1.15.
+L<Storable> has been upgraded from version 2.36 to 2.37.
-This is due to a minor code change in the XS for the VMS implementation.
+Restricted hashes were not always thawed correctly [perl #73972].
-=item *
-
-L<ExtUtils::CBuilder> has been upgraded from version 0.280206 to 0.280208.
-
-It no longer fails when trying to embed manifests on Windows
-[perl #111782, #111798].
+Storable would croak when freezing a blessed REF object with a
+C<STORABLE_freeze()> method [perl #113880].
=item *
-L<File::DosGlob> has been upgraded from version 1.07 to 1.08.
-
-There are no visible changes, only minor internal refactorings.
-
-=item *
-
-L<File::Spec::Unix> has been upgraded from version 3.39_02 to 3.39_03.
-
-C<abs2rel> could produce incorrect results when given two relative paths or
-the root directory twice [perl #111510].
-
-=item *
-
-L<IO> has been upgraded from version 1.25_06 to 1.25_07.
-
-C<sync()> can now be called on read-only file handles [perl #64772].
-
-=item *
-
-L<Pod::Html> has been upgraded from version 1.15_02 to 1.16.
-
-The option C<--libpods> has been reinstated. It is deprecated, and its use
-does nothing other than issue a warning that it is no longer supported.
-
-=item *
-
-L<Unicode::UCD> has been upgraded from version 0.43 to 0.44.
-
-This adds a function L<all_casefolds()|Unicode::UCD/all_casefolds()>
-that returns all the casefolds.
-
-=item *
-
-L<Scalar::Util> has been upgraded from version 1.23 to version 1.25.
+L<Socket> has been upgraded from version 2.001 to 2.002.
=back
However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
section.
-=head3 L<perlfaq>
+=head3 L<perlfunc>
=over 4
=item *
-L<perlfaq> has been synchronised with version 5.0150040 from C<CPAN>.
+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].
=back
=item *
-XXX L<message|perldiag/"message">
+C<chr()> now warns when passed a negative value [perl #83048].
-=back
-
-=head2 Changes to Existing Diagnostics
-
-XXX Changes (i.e. rewording) of diagnostic messages go here
+=item *
-=over 4
+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 *
-XXX Describe change here
+Running perl with the C<-i> flag now warns if no input files are provided on
+the command line [perl #113410].
=back
-=head2 Removals of Diagnostics
-
-=over 4
+=head2 Changes to Existing Diagnostics
-=item *
+XXX Changes (i.e. rewording) of diagnostic messages go here
-The "Runaway prototype" warning that occurs in bizarre cases has been
-removed as being unhelpful and inconsistent.
+=over 4
=item *
-The "Not a format reference" error has been removed, as the only case in
-which it could be triggered was a bug.
+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 $b to be ignored [perl #86136].
=back
=item *
-XXX
+Building perl with some Windows compilers used to fail due to a problem
+with miniperl's C<glob> operator (which uses the C<perlglob> program)
+deleting the PATH environment variable [perl #113798].
=back
=over 4
-=item XXX-some-platform
+=item XXX
-XXX
=back
=over 4
-=item Win32
+=item VMS
+
+Quotes are now removed from the command verb (but not the parameters) for commands
+spawned via C<system>, backticks, or a piped C<open>. Previously, quotes on the verb
+were passed through to DCL, which would fail to recognize the command. Also, if the
+verb is actually a path to an image or command procedure on an ODS-5 volume, quoting it
+now allows the path to contain spaces.
-C<link> on Win32 now attempts to set C<$!> to more appropriate values
-based on the Win32 API error code. [perl #112272]
+=item AIX
-Perl no longer mangles the environment block, e.g. when launching a new
-sub-process, when the environment contains non-ASCII characters. Known
-problems still remain, however, when the environment contains characters
-outside of the current ANSI codepage (e.g. see the item about Unicode in
-C<%ENV> in L<http://perl5.git.perl.org/perl.git/blob/HEAD:/Porting/todo.pod>).
-[perl #113536]
+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 *
-The C<study> function was made a no-op in 5.16. It was simply disabled via
-a C<return> statement; the code was left in place. Now the code supporting
-what C<study> used to do has been removed.
-
-=item *
-
-Under threaded perls, there is no longer a separate PV allocated for every
-COP to store its package name (C<< cop->stashpv >>). Instead, there is an
-offset (C<< cop->stashoff >>) into the new C<PL_stashpad> array, which
-holds stash pointers.
+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 *
-In the pluggable regex API, the C<regexp_engine> struct has acquired a new
-field C<op_comp>, which is currently just for perl's internal use, and
-should be initialised to NULL by other regex plugin modules.
+PERL_DEBUG_READONLY_OPS has been rewritten to work with the new slab
+allocator, allowing it to catch more violations that befor.
=item *
-A new function C<alloccoptash> has been added to the API, but is considered
-experimental. See L<perlapi>.
+The old slab allocator for ops, which was only enabled for PERL_IMPLICIT_SYS and PERL_DEBUG_READONLY_OPS, has been retired.
=back
=item *
-The implementation of code blocks in regular expressions, such as C<(?{})>
-and C<(??{})> has been heavily reworked to eliminate a whole slew of bugs.
-The main user-visible changes are:
-
-=over 4
+A regression introduced in v5.14.0 has been fixed, in which some calls
+to the C<re> module would clobber C<$_> [perl #113750].
=item *
-Code blocks within patterns are now parsed in the same pass as the
-surrounding code; in particular it is no longer necessary to have balanced
-braces: this now works:
-
- /(?{ $x='{' })/
-
-This means that this error message is longer generated:
-
- Sequence (?{...}) not terminated or not {}-balanced in regex
-
-but a new error may be seen:
-
- Sequence (?{...}) not terminated with ')'
-
-In addition, literal code blocks within run-time patterns are only
-compiled once, at perl compile-time:
-
- for my $p (...) {
- # this 'FOO' block of code is compiled once,
- # at the same time as the surrounding 'for' loop
- /$p{(?{FOO;})/;
- }
+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 *
-Lexical variables are now sane as regards scope, recursion and closure
-behaviour. In particular, C</A(?{B})C/> behaves (from a closure viewpoint)
-exactly like C</A/ && do { B } && /C/>, while C<qr/A(?{B})C/> is like
-C<sub {/A/ && do { B } && /C/}>. So this code now works how you might
-expect, creating three regexes that match 0, 1, and 2:
+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.
- for my $i (0..2) {
- push @r, qr/^(??{$i})$/;
- }
- "1" =~ $r[1]; # matches
+This mirrors the behaviour of the hash iterator when the hash is cleared.
=item *
-The C<use re 'eval'> pragma is now only required for code blocks defined
-at runtime; in particular in the following, the text of the C<$r> pattern is
-still interpolated into the new pattern and recompiled, but the individual
-compiled code-blocks within C<$r> are reused rather than being recompiled,
-and C<use re 'eval'> isn't needed any more:
-
- my $r = qr/abc(?{....})def/;
- /xyz$r/;
+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 *
-Flow control operators no longer crash. Each code block runs in a new
-dynamic scope, so C<next> etc. will not see any enclosing loops and
-C<caller> will not see any calling subroutines. C<return> returns a value
-from the code block, not from any enclosing subroutine.
+Arriving signals no longer clear C<$@> [perl #45173].
=item *
-Perl normally caches the compilation of run-time patterns, and doesn't
-recompile if the pattern hasn't changed; but this is now disabled if
-required for the correct behaviour of closures; for example:
-
- my $code = '(??{$x})';
- for my $x (1..3) {
- # recompile to see fresh value of $x each time
- $x =~ /$code/;
- }
-
+Allow C<my ()> declarations with an empty variable list [perl #113554].
=item *
-The C</msix> and C<(?msix)> etc. flags are now propagated into the return
-value from C<(??{})>; this now works:
-
- "AB" =~ /a(??{'b'})/i;
+During parsing, subs declared after errors no longer leave stubs
+[perl #113712].
=item *
-Warnings and errors will appear to come from the surrounding code (or for
-run-time code blocks, from an eval) rather than from an C<re_eval>:
+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].
- use re 'eval'; $c = '(?{ warn "foo" })'; /$c/;
- /(?{ warn "foo" })/;
+=item *
-formerly gave:
+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].
- foo at (re_eval 1) line 1.
- foo at (re_eval 2) line 1.
+=item *
-and now gives:
+C<qr//> expressions no longer crash with custom regular expression engines
+that do not set C<offs> at regular expression compilation time
+[perl #112962].
- foo at (eval 1) line 1.
- foo at /some/prog line 2.
+=item *
-=back
+C<delete local> no longer crashes with certain magical arrays and hashes
+[perl #112966].
=item *
-Perl now works as well as can be expected on all releases of Unicode so
-far. In v5.16, it worked on Unicodes 6.0 and 6.1, but there were
-various bugs for earlier releases; the older the release the more
-problems.
+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<vec> no longer produces "uninitialized" warnings in lvalue context
-[perl #9423].
+C<scalar(write)> no longer returns multiple items [perl #73690].
=item *
-An optimisation involving fixed strings in regular expressions could cause
-a severe performance penalty in edge cases. This has been fixed
-[perl #76546].
+String to floating point conversions no longer misparse certain strings under
+C<use locale> [perl #109318].
=item *
-The "Can't find an opnumber" message that C<prototype> produces when passed
-a string like "CORE::nonexistent_keyword" now passes UTF8 and embedded
-nuls through unchanged [perl #97478].
+C<@INC> filters that die no longer leak memory [perl #92252].
=item *
-C<prototype> now treats magical variables like C<$1> the same way as
-non-magical variables when checking for the CORE:: prefix, instead of
-treating them as subroutine names.
+The implementations of overloaded operations are now called in the correct
+context. This allows, among other things, being able to properly override
+C<< <> >> [perl #47119].
=item *
-Under threaded perls, a runtime code block in a regular expression could
-corrupt the package name stored in the op tree, resulting in bad reads
-in C<caller>, and possibly crashes [perl #113060].
+Specifying only the C<fallback> key when calling C<use overload> now behaves
+properly [perl #113010].
=item *
-Referencing a closure prototype (C<\&{$_[1]}> in an attribute handler for a
-closure) no longer results in a copy of the subroutine (or assertion
-failures on debugging builds).
+C<< sub foo { my $a = 0; while ($a) { ... } } >> and
+C<< sub foo { while (0) { ... } } >> now return the same thing [perl #73618].
=item *
-C<eval '__PACKAGE__'> now returns the right answer on threaded builds if
-the current package has been assigned over (as in
-C<*ThisPackage:: = *ThatPackage::>) [perl #78742].
+Fixed the debugger C<l> and C<M> commands, and other debugger
+functionality which was broken in 5.17.0 [perl #113918].
=item *
-If a package is deleted by code that it calls, it is possible for C<caller>
-to see a stack frame belonging to that deleted package. C<caller> could
-crash if the stash's memory address was reused for a scalar and a
-substitution was performed on the same scalar [perl #113486].
+String negation now behaves the same under C<use integer;> as it does
+without [perl #113012].
=item *
-C<UNIVERSAL::can> no longer treats its first argument differently
-depending on whether it is a string or number internally.
+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 *
-C<open> with "<&" for the mode checks to see whether the third argument is
-a number, in determining whether to treat it as a file descriptor or a
-handle name. Magical variables like C<$1> were always failing the numeric
-check and being treated as handle names.
+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 *
-C<warn>'s handling of magical variables (C<$1>, ties) has undergone several
-fixes. FETCH is only called once now on a tied argument or a tied C<$@>
-[perl #97480]. Tied variables returning objects that stringify as "" are
-no longer ignored. A tied C<$@> that happened to return a reference the
-I<previous> time is was used is no longer ignored.
+Using a C<format> after its enclosing sub was undefined could crash as of
+perl 5.10.0, if the format referenced lexical variables from the outer sub.
=item *
-C<warn ""> now treats C<$@> with a number in it the same way, regardless of
-whether it happened via C<$@=3> or C<$@="3">. It used to ignore the
-former. Now it appends "\t...caught", as it has always done with
-C<$@="3">.
+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 *
-Numeric operators on magical variables (e.g., S<C<$1 + 1>>) used to use
-floating point operations even where integer operations were more appropriate,
-resulting in loss of accuracy on 64-bit platforms [perl #109542].
+Formats that close over variables in special blocks no longer crash if a
+stub exists with the same name as the special block before the special
+block is compiled.
=item *
-Unary negation no longer treats a string as a number if the string happened
-to be used as a number at some point. So, if C<$x> contains the string "dogs",
-C<-$x> returns "-dogs" even if C<$y=0+$x> has happened at some point.
+The parser no longer gets confused, treating C<eval foo ()> as a syntax
+error if preceded by C<print;> [perl #16249].
=item *
-In Perl 5.14, C<-'-10'> was fixed to return "10", not "+10". But magical
-variables (C<$1>, ties) were not fixed till now [perl #57706].
+The return value of C<syscall> is no longer truncated on 64-bit platforms
+[perl #113980].
=item *
-Unary negation now treats strings consistently, regardless of the internal
-UTF8 flag.
+Constant folding no longer causes C<print 1 ? FOO : BAR> to print to the
+FOO handle [perl #78064].
=item *
-A regression introduced in Perl v5.16.0 involving
-C<tr/I<SEARCHLIST>/I<REPLACEMENTLIST>/> has been fixed. Only the first
-instance is supposed to be meaningful if a character appears more than
-once in C<I<SEARCHLIST>>. Under some circumstances, the final instance
-was overriding all earlier ones. [perl #113584]
+C<do subname> now calls the named subroutine and uses the file name it
+returns, instead of opening a file named "subname".
=item *
-Regular expressions like C<qr/\87/> previously silently inserted a NUL
-character, thus matching as if it had been written C<qr/\00087/>. Now it
-matches as if it had been written as C<qr/87/>, with a message that the
-sequence C<"\8"> is unrecognized.
+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<__SUB__> now works in special blocks (BEGIN, END, etc.).
+C<CORE::foo::bar> is no longer treated specially, allowing global overrides
+to be called directly via C<CORE::GLOBAL::uc(...)> [perl #113016].
=item *
-Thread creation on Windows could theoretically result in a crash if done
-inside a BEGIN block. It still does not work properly, but it no longer
-crashes [perl #111610].
+Calling an undefined sub whose typeglob has been undefined now produces the
+customary "Undefined subroutine called" error, instead of "Not a CODE
+reference".
=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 v5.17.0..HEAD
+ perl Porting/acknowledgements.pl v5.17.1..HEAD
=head1 Reporting Bugs
https://perl5.git.perl.org / perl5.git / blobdiff