=over 4
-=item * C<.> no longer in C<@INC>
+=item * C<"."> no longer in C<@INC>
-The current modules, and for the execution of scripts. See the section
-L<< Removal of the current directory (C<.>) from C<@INC> >> for the full details.
+For security reasons, the current directory (C<".">) is no longer included
+by default at the end of the module search path (C<@INC>). This may have
+widespread implications for the building, testing and installing of
+modules, and for the execution of scripts. See the section
+L<< Removal of the current directory (C<".">) from C<@INC> >>
+for the full details.
=item * C<do> may now warn
-C<do> now gives a mandatory warning when it fails to load a file which it
-would have loaded had C<.> been in C<@INC>.
+C<do> now gives a deprecation warning when it fails to load a file which
+it would have loaded had C<"."> been in C<@INC>.
=item * In regular expression patterns, a literal left brace C<"{">
should be escaped
=head1 Core Enhancements
-=head2 New regular expression modifier C</xx>
-
-Specifying two C<x> characters to modify a regular expression pattern
-does everything that a single one does, but additionally TAB and SPACE
-characters within a bracketed character class are generally ignored and
-can be added to improve readability, like
-S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
-L<perlre/E<sol>x and E<sol>xx>.
-
-=head2 New Hash Function For 64-bit Builds
-
-We have switched to a hybrid hash function to better balance
-performance for short and long keys.
+=head2 Lexical subroutines are no longer experimental
-For short keys, 16 bytes and under, we use an optimised variant of
-One At A Time Hard, and for longer keys we use Siphash 1-3. For very
-long keys this is a big improvement in performance. For shorter keys
-there is a modest improvement.
+Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
+code that disables the C<experimental::lexical_subs> warning category
+that the feature previously used will continue to work. The
+C<lexical_subs> feature has no effect; all Perl code can use lexical
+subroutines, regardless of what feature declarations are in scope.
=head2 Indented Here-documents
-This adds a new modifier '~' to here-docs that tells the parser
-that it should look for /^\s*$DELIM\n/ as the closing delimiter.
+This adds a new modifier C<"~"> to here-docs that tells the parser
+that it should look for C</^\s*$DELIM\n/> as the closing delimiter.
These syntaxes are all supported:
<<~ "EOF";
<<~ `EOF`;
-The '~' modifier will strip, from each line in the here-doc, the
+The C<"~"> modifier will strip, from each line in the here-doc, the
same whitespace that appears before the delimiter.
Newlines will be copied as-is, and lines that don't include the
prints "Hello there\n" with no leading whitespace.
-=head2 @{^CAPTURE}, %{^CAPTURE}, and %{^CAPTURE_ALL}
+=head2 New regular expression modifier C</xx>
+
+Specifying two C<"x"> characters to modify a regular expression pattern
+does everything that a single one does, but additionally TAB and SPACE
+characters within a bracketed character class are generally ignored and
+can be added to improve readability, like
+S<C</[ ^ A-Z d-f p-x ]/xx>>. Details are at
+L<perlre/E<sol>x and E<sol>xx>.
+
+=head2 C<@{^CAPTURE}>, C<%{^CAPTURE}>, and C<%{^CAPTURE_ALL}>
C<@{^CAPTURE}> exposes the capture buffers of the last match as an
array. So C<$1> is C<${^CAPTURE}[0]>. This is a more efficient equivalent
to code like C<substr($matched_string,$-[0],$+[0]-$-[0])>, and you don't
have to keep track of the C<$matched_string> either. This variable has no
-single character equivalent. Note, like the other regex magic variables
-the contents of this variable is dynamic, if you wish to store it beyond
+single character equivalent. Note that, like the other regex magic variables,
+the contents of this variable is dynamic; if you wish to store it beyond
the lifetime of the match you must copy it to another array.
-C<%{^CAPTURE}> is the equivalent to C<%+> (I<i.e.>, named captures). Other than
+C<%{^CAPTURE}> is equivalent to C<%+> (I<i.e.>, named captures). Other than
being more self documenting there is no difference between the two forms.
-C<%{^CAPTURE_ALL}> is the equivalent to C<%-> (I<i.e.>, all named captures).
+C<%{^CAPTURE_ALL}> is equivalent to C<%-> (I<i.e.>, all named captures).
Other than being more self documenting there is no difference between the
two forms.
+=head2 Declaring a reference to a variable
+
+As an experimental feature, Perl now allows the referencing operator to come
+after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
+L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
+be enabled with C<use feature 'declared_refs'>. It is experimental, and will
+warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
+It is intended mainly for use in assignments to references. For example:
+
+ use experimental 'refaliasing', 'declared_refs';
+ my \$a = \$b;
+
+See L<perlref/Assigning to References> for more details.
+
=head2 Unicode 9.0 is now supported
A list of changes is at L<http://www.unicode.org/versions/Unicode9.0.0/>.
compound forms, like C<\p{sc=I<script>}> are unchanged. See
L<perlunicode/Scripts>.
-=head2 Declaring a reference to a variable
-
-As an experimental feature, Perl now allows the referencing operator to come
-after L<C<my()>|perlfunc/my>, L<C<state()>|perlfunc/state>,
-L<C<our()>|perlfunc/our>, or L<C<local()>|perlfunc/local>. This syntax must
-be enabled with C<use feature 'declared_refs'>. It is experimental, and will
-warn by default unless C<no warnings 'experimental::refaliasing'> is in effect.
-It is intended mainly for use in assignments to references. For example:
-
- use experimental 'refaliasing', 'declared_refs';
- my \$a = \$b;
-
-See L<perlref/Assigning to References> for more details.
-
=head2 Perl can now do default collation in UTF-8 locales on platforms
that support it
some strings, though. See
L<perllocale/Collation of strings containing embedded C<NUL> characters>.
-=head2 Lexical subroutines are no longer experimental
-
-Using the C<lexical_subs> feature introduced in v5.18 no longer emits a warning. Existing
-code that disables the C<experimental::lexical_subs> warning category
-that the feature previously used will continue to work. The
-C<lexical_subs> feature has no effect; all Perl code can use lexical
-subroutines, regardless of what feature declarations are in scope.
-
=head2 C<CORE> subroutines for hash and array functions callable via
reference
-The hash and array functions in the C<CORE> namespace--C<keys>, C<each>,
-C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>--, can now
+The hash and array functions in the C<CORE> namespace (C<keys>, C<each>,
+C<values>, C<push>, C<pop>, C<shift>, C<unshift> and C<splice>) can now
be called with ampersand syntax (C<&CORE::keys(\%hash>) and via reference
(C<< my $k = \&CORE::keys; $k-E<gt>(\%hash) >>). Previously they could only be
used when inlined.
-=head2 for XS code, create a safer utf8_hop() called utf8_hop_safe()
+=head2 New Hash Function For 64-bit Builds
+
+We have switched to a hybrid hash function to better balance
+performance for short and long keys.
-Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or after
-the end of the supplied buffer.
+For short keys, 16 bytes and under, we use an optimised variant of
+One At A Time Hard, and for longer keys we use Siphash 1-3. For very
+long keys this is a big improvement in performance. For shorter keys
+there is a modest improvement.
=head1 Security
-=head2 Removal of the current directory (C<.>) from C<@INC>
+=head2 Removal of the current directory (C<".">) from C<@INC>
The perl binary includes a default set of paths in C<@INC>. Historically
-it has also included the current directory (C<.>) as the final entry,
+it has also included the current directory (C<".">) as the final entry,
unless run with taint mode enabled (C<perl -T>). While convenient, this has
security implications: for example, where a script attempts to load an
optional module when its current directory is untrusted (such as F</tmp>),
it could load and execute code from under that directory.
-Starting with v5.26, C<.> is always removed by default, not just under
+Starting with v5.26, C<"."> is always removed by default, not just under
tainting. This has major implications for installing modules and executing
scripts.
=item * C<Configure -Udefault_inc_excludes_dot>
There is a new C<Configure> option, C<default_inc_excludes_dot> (enabled
-by default) which builds a perl executable without C<.>; unsetting this
+by default) which builds a perl executable without C<".">; unsetting this
option using C<-U> reverts perl to the old behaviour. This may fix your
path issues but will reintroduce all the security concerns, so don't
build a perl executable like this unless you're I<really> confident that
=item * C<PERL_USE_UNSAFE_INC>
There is a new environment variable recognised by the perl interpreter.
-If this variable has the value C<1> when the perl interpreter starts up,
-then C<.> will be automatically appended to C<@INC> (except under tainting).
+If this variable has the value 1 when the perl interpreter starts up,
+then C<"."> will be automatically appended to C<@INC> (except under tainting).
This allows you restore the old perl interpreter behaviour on a
case-by-case basis. But note that this is intended to be a temporary crutch,
While it is well-known that C<use> and C<require> use C<@INC> to search
for the file to load, many people don't realise that C<do "file"> also
-searches C<@INC> if the file is a relative path. With the removal of C<.>,
+searches C<@INC> if the file is a relative path. With the removal of C<".">,
a simple C<do "file.pl"> will fail to read in and execute C<file.pl> from
the current directory. Since this is commonly expected behaviour, a new
mandatory warning is now issued whenever C<do> fails to load a file which
If the issue is within your own code (rather than within included
modules), then you have two main options. Firstly, if you are confident
that your script will only be run within a trusted directory (under which
-you expect to find trusted files and modules), then add C<.> back into the
+you expect to find trusted files and modules), then add C<"."> back into the
path; I<e.g.>:
BEGIN {
If you maintain a CPAN distribution, it may need updating to run in
a dotless environment. Although C<cpan> and other such tools will
currently set the C<PERL_USE_UNSAFE_INC> during module build, this is a
-temporary workaround for the set of modules which rely on C<.> being in
+temporary workaround for the set of modules which rely on C<"."> being in
C<@INC> for installation and testing, and this may mask deeper issues. It
could result in a module which passes tests and installs, but which
fails at run time.
=back
-=head2 "Escaped" colons and relative paths in PATH
+=head2 Escaped colons and relative paths in PATH
On Unix systems, Perl treats any relative paths in the PATH environment
variable as tainted when starting a new process. Previously, it was
allowing a backslash to escape a colon (unlike the OS), consequently
allowing relative paths to be considered safe if the PATH was set to
-something like C</\:.>. The check has been fixed to treat C<.> as tainted
+something like C</\:.>. The check has been fixed to treat C<"."> as tainted
in that example.
=head2 C<-Di> switch is now required for PerlIO debugging output
source filter such as L<Filter::Encoding> on CPAN or L<encoding>'s C<Filter>
option.
-=head2 POSIX::tmpnam() has been removed
+=head2 C<POSIX::tmpnam()> has been removed
The fundamentally unsafe C<tmpnam()> interface was deprecated in
Perl 5.22 and has now been removed. In its place you can use,
in actual code, as they would typically display as attached to the
character in front of them.
-=head1 Removed Deprecations
+=head2 C<\cI<X>> that maps to a printable is no longer deprecated
-The C<\cI<X>> construct is intended to be a way to specify non-printable
-characters. Previously it was deprecated to use it for a printable one,
-which is better written as simply itself, perhaps preceded by a
-backslash for non-word characters. Now this raises a warning, but not a
-deprecation. See
+This means we have no plans to remove this feature. It still raises a
+warning, but only if syntax warnings are enabled. The feature was
+originally intended to be a way to express non-printable characters that
+don't have a mnemonic (C<\t> and C<\n> are mnemonics for two
+non-printable characters, but most non-printables don't have a
+mnemonic.) But the feature can be used to specify a few printable
+characters, though those are more clearly expressed as the printable
+itself. See
L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>.
=head1 Performance Enhancements
if (!%h) { ... }
-This was already special-cased, but some cases were missed, and even the
-ones which weren't have been improved.
-
-=item *
-
-Several other ops may now also be faster in boolean context.
+This was already special-cased, but some cases were missed (such as
+C<grep %$_, @AoH>, and even the ones which weren't have been improved.
=item * New Faster Hash Function on 64 bit builds
=item *
-Reduce cost of SvVALID().
+Reduce cost of C<SvVALID()>.
=item *
=item *
-Avoid sv_catpvn() in do_vop() when unneeded.
+Avoid C<sv_catpvn()> in C<do_vop()> when unneeded.
=item *
=item *
-Clearing hashes and arrays has been made slightly faster. Now code
-like this is around 5% faster:
+Better optimise array and hash assignment: where an array or hash appears
+in the LHS of a list assignment, such as C<(..., @a) = (...);>, it's
+likely to be considerably faster, especially if it involves emptying the
+array/hash. For example this code runs about 1/3 faster compared to
+Perl 5.24.0:
my @a;
- for my $i (1..3_000_000) {
+ for my $i (1..10_000_000) {
@a = (1,2,3);
@a = ();
}
-and this code around 3% faster:
-
- my %h;
- for my $i (1..3_000_000) {
- %h = qw(a 1 b 2);
- %h = ();
- }
-
-=item *
-
-Better optimise array and hash assignment
=item *
regular expression pattern modifier, and a change to the L<S<C<use re
'strict'>>|re/'strict' mode> experimental feature. When S<C<re
'strict'>> is enabled, a warning now will be generated for all
-unescaped uses of the two characters C<}> and C<]> in regular
+unescaped uses of the two characters C<"}"> and C<"]"> in regular
expression patterns (outside bracketed character classes) that are taken
-literally. This brings them more in line with the C<)> character which
+literally. This brings them more in line with the C<")"> character which
is always a metacharacter unless escaped. Being a metacharacter only
sometimes, depending on action at a distance, can lead to silently
having the pattern mean something quite different than was intended,
=head2 Changes to Existing Documentation
-=head3 L<perlcall>
+We have attempted to update the documentation to reflect the changes
+listed in this document. If you find any we have missed, send email to
+L<perlbug@perl.org|mailto:perlbug@perl.org>.
-=over 4
-
-=item *
+Additionally all references to Usenet have been removed, and the
+following selected changes have been made:
-Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30
+=head3 L<perlfunc>
-This was changed to drop a leading C<v> in C<v5.30>, so it uses the same
-style as other deprecation messages.
+=over 4
=item *
-"\c%c" is more clearly written simply as "%s".
-
-It was decided to undeprecate the use of C<\c%c>, see L<http://www.nntp.perl.org/group/perl.perl5.porters/2017/02/msg242944.html>
+Removed obsolete text about L<C<defined()>|perlfunc/defined>
+on aggregates that should have been deleted earlier, when the feature
+was removed.
=item *
-Removed redundant C<dSP> from an example.
-
-=back
-
-=head3 L<perlcommunity>
-
-=over 4
+Corrected documentation of L<C<eval()>|perlfunc/eval>,
+and L<C<evalbytes()>|perlfunc/evalbytes>.
=item *
-All references to Usenet have been removed.
-
-=back
-
-=head3 L<perldata>
-
-=over 4
+Clarified documentation of L<C<seek()>|perlfunc/seek>,
+L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>
+emphasizing that positions are in bytes and not characters.
+L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
=item *
-Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
-signature changed> above.
+Clarified documentation of L<C<sort()>|perlfunc/sort LIST> concerning
+the variables C<$a> and C<$b>.
=item *
-Use of single character variables, with the variable name a non printable
-character in the range C<\x80>-C<\xFF> is no longer allowed. Update the docs to
-reflect this.
-
-=back
-
-=head3 L<perldelta>
-
-=over 4
+In L<C<split()>|perlfunc/split> added a caution about its use in Perls
+before v5.11, and noted that certain pattern modifiers are legal in it.
=item *
-All references to Usenet have been removed.
-
-=back
-
-=head3 L<perldiag>
-
-=over 4
+Removed obsolete documentation of L<C<study()>|perlfunc/study>, noting
+that it is now a no-op.
=item *
-Deprecations are to be marked with a D.
-C<"%s() is deprecated on :utf8 handles"> use a deprecation message, and as
-such, such be marked C<"(D deprecated)"> and not C<"(W deprecated)">.
+Noted that L<C<vec()>|perlfunc/vec> doesn't work well when the string
+contains characters whose code points are above 255.
=back
-=head3 L<perlexperiment>
+=head3 L<perlguts>
=over 4
=item *
-Documented new feature: See L</Declaring a reference to a variable> above.
+Added advice on
+L<formatted printing of operands of C<Size_t> and C<SSize_t>|perlguts/Formatted Printing of Size_t and SSize_t>
=back
-=head3 L<perlfunc>
+=head3 L<perlhack>
=over 4
=item *
-Defined on aggregates is no longer allowed. Perlfunc was still reporting it as
-deprecated, and that it will be deleted in the future.
-
-=item *
-
-Clarified documentation of L<C<seek()>|perlfunc/seek>,
-L<C<tell()>|perlfunc/tell> and L<C<sysseek()>|perlfunc/sysseek>.
-L<[perl #128607]|https://rt.perl.org/Public/Bug/Display.html?id=128607>
-
-=item *
-
-Removed obsolete documentation of L<C<study()>|perlfunc/study>.
+Clariy indentation rules, and note that we are migrating away from using
+tabs to indent, replacing them with sequences of SPACE characters.
=back
-=head3 L<perlguts>
+=head3 L<perlhacktips>
=over 4
=item *
-Add C<pTHX_> to magic method examples.
-
-=back
-
-=head3 L<perlhack>
-
-=over 4
+Give another reason to use C<cBOOL> to cast an expression to boolean.
=item *
-Document Tab VS Space.
+Note that there are macros C<TRUE> and C<FALSE> available to express
+boolean values.
=back
=item *
-Document C<NUL> collation handling.
-
-=item *
-
-Some locales aren't compatible with Perl. Note the potential bad
-consequences of using them.
+Some locales aren't compatible with Perl. Note that these can cause
+core dumps.
=back
=item *
-All references to Usenet have been removed.
+Various clarifications have been added.
=back
=item *
-Updated the mirror list.
-
-=item *
-
-All references to Usenet have been removed.
-
-=back
-
-=head3 L<perlnewmod>
-
-=over 4
-
-=item *
-
-All references to Usenet have been removed.
+Updated the site mirror list.
=back
=item *
-Do not discourage manual @ISA.
+Do not discourage manual C<@ISA>.
=back
=item *
-Tidy the document.
-
-=item *
-
Mention C<Moo> more.
=back
points, that in earlier versions were mentioned in sort of an appendix
on Version 8 regular expressions.
-Several minor enhancements to the documentation.
-
-=back
-
-=head3 L<perlsec>
-
-=over 4
-
=item *
-Fixed link to Crosby paper on hash complexity attack.
+Note that it is common to have the C</x> modifier and forget that this
+means that C<"#"> has to be escaped.
=back
-=head3 L<perlref>
+=head3 L<perlretut>
=over 4
=item *
-Documented new feature: See L</Declaring a reference to a variable> above.
-
-=back
-
-=head3 L<perltie>
-
-=over 4
+Add introductory material
=item *
-Updated documentation of C<scalar(%hash)>. See L</scalar(%hash) return
-signature changed> above.
+Note that a metacharacter occurring in a context where it can't mean
+that, silently loses its meta-ness and matches literally.
+L<C<use re 'strict'>|re/'strict' mode> can catch some of these.
=back
=item *
-Documented change to C<\p{I<script>}> to now use the improved Script_Extensions
-property. See L</Use of \p{script} uses the improved Script_Extensions
-property> above.
+Corrected the text about Unicode BYTE ORDER MARK handling.
=item *
=item *
-Removed obsolete documentation of C<${^ENCODING}>. See L</${^ENCODING} has
-been removed> above.
-
-=item *
-
Document C<@ISA>. Was documented other places, not not in L<perlvar>.
=back
=item *
-Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
+Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
a warning recommending to fix the C<do> statement:
L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
=item *
-L<Unescaped left brace in regex is illegal here|perldiag/Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in m/%s/>
+L<Unescaped left brace in regex is illegal here|perldiag/Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in mE<sol>%sE<sol>>
Unescaped left braces are now illegal in some contexts in regular expression
patterns. In other contexts, they are still just deprecated; they will
=item *
-Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
+Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger
a warning recommending to fix the C<do> statement:
L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
=item *
-Deprecated use of my() in false conditional. This will be a fatal error
+Deprecated use of C<my()> in false conditional. This will be a fatal error
in Perl 5.30
=item *
-dump() better written as CORE::dump(). dump() will no longer be available
+C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available
in Perl 5.30
=item *
=item *
-Setting $/ to a reference to %s as a form of slurp is deprecated,
+Setting C<$/> to a reference to %s as a form of slurp is deprecated,
treating as undef. This will be fatal in Perl 5.28
=item *
=item *
-Improve error for missing tie() package/method. This brings the error messages
+Improve error for missing C<tie()> package/method. This brings the error messages
in line with the ones used for normal method calls, despite not using
call_method().
=item *
-Make the sysread()/syswrite/() etc :utf8 handle warnings default. These
-warnings were under 'deprecated' previously.
+Make the C<sysread()>/C<syswrite()> I<etc.>, C<:utf8> handle warnings
+XXX default. These warnings were under 'deprecated' previously.
=item *
-'do' errors now refer to 'do' (not 'require').
+C<do> errors now refer to C<do> (not C<require>).
=item *
=item *
-Account for possibility of DOS file endings.
+Account for the possibility of DOS file endings.
=back
=item *
-The C<dtrace> build process has further changes:
+The C<dtrace> build process has further changes [perl #130108]:
=over
=back
-[perl #130108]
-
=item *
-You can now disable perl's use of the PERL_HASH_SEED and
-PERL_PERTURB_KEYS environment variables by configuring perl with
+You can now disable perl's use of the C<PERL_HASH_SEED> and
+C<PERL_PERTURB_KEYS> environment variables by configuring perl with
C<-Accflags=NO_PERL_HASH_ENV>.
=item *
-You can now disable perl's use of the PERL_HASH_SEED_DEBUG environment
+You can now disable perl's use of the C<PERL_HASH_SEED_DEBUG> environment
variable by configuring perl with
C<-Accflags=-DNO_PERL_HASH_SEED_DEBUG>.
=item *
-Since 5.18 for testing purposes we have included support for
+Since v5.18 for testing purposes, we have included support for
building perl with a variety of non-standard, and non-recommended
hash functions. Since we do not recommend the use of these functions
we have removed them and their corresponding build options. Specifically
Remove "Warning: perl appears in your path"
This install warning is more or less obsolete, since most platforms already
-*will* have a /usr/bin/perl or similar provided by the OS.
+B<will> have a F</usr/bin/perl> or similar provided by the OS.
=item *
-Reduce verbosity of "make install.man"
+Reduce verbosity of C<make install.man>
Previously, two progress messages were emitted for each manpage: one by
installman itself, and one by the function in install_lib.pl that it calls to
=item *
-Cleanup for clang -Weverything support. [perl 129961]
+Cleanup for C<clang -Weverything> support. [perl 129961]
=item *
=item *
A probe for C<gai_strerror> was added to F<Configure> that checks if the
-the gai_strerror() routine is available and can be used to
-translate error codes returned by getaddrinfo() into human
+the C<gai_strerror()> routine is available and can be used to
+translate error codes returned by C<getaddrinfo()> into human
readable strings.
=item *
-F<Configure> now aborts if both "-Duselongdouble" and "-Dusequadmath" are
+F<Configure> now aborts if both C<-Duselongdouble> and C<-Dusequadmath> are
requested.
L<[perl #126203]|https://rt.perl.org/Public/Bug/Display.html?id=126203>
=item *
-Fixed a bug in which F<Configure> could append "-quadmath" to the archname even
+Fixed a bug in which F<Configure> could append C<-quadmath> to the archname even
if it was already present.
L<[perl #128538]|https://rt.perl.org/Public/Bug/Display.html?id=128538>
=item *
-Clang builds with "-DPERL_GLOBAL_STRUCT" or "-DPERL_GLOBAL_STRUCT_PRIVATE" have
+Clang builds with C<-DPERL_GLOBAL_STRUCT> or
+C<-DPERL_GLOBAL_STRUCT_PRIVATE> have
been fixed (by disabling Thread Safety Analysis for these configurations).
=item *
=head1 Testing
+Tests were added and changed to reflect the other additions and changes
+in this release. In addition, these substantive changes were made:
+
=over 4
=item *
-F<XS-APItest/t/utf8.t>: Several small fixes and enhancements.
+A new test script, F<comp/parser_run.t>, has been added to test
+reads through invalid pointers.
=item *
=item *
+A new test script, F<t/re/keep_tabs.t> has been added to contain tests
+where C<\t> characters should not be expanded into spaces.
+
+=item *
+
A new test script, F<t/re/anyof.t>, has been added to test that the ANYOF nodes
generated by bracketed character classes are as expected.
=item *
+There is now more extensive testing of the Unicode-related API macros
+and functions.
+
+=item *
+
+Several of the longer running API test files have been split into
+multiple test files so that they can be run in parallel.
+
+=item *
+
F<t/harness> now tries really hard not to run tests outside of the Perl
source tree. [perl #124050]
=item Darwin
-don't treat -Dprefix=/usr as special, instead require an extra option
--Ddarwin_distribution to produce the same results.
+don't treat C<-Dprefix=/usr> as special, instead require an extra option
+C<-Ddarwin_distribution> to produce the same results.
=item POSIX
=item OS X
-OS X El Capitan doesn't implement the clock_gettime() or clock_getres() APIs;
-emulate them as necessary.
+OS X El Capitan doesn't implement the C<clock_gettime()> or
+C<clock_getres()> APIs; emulate them as necessary.
=item macOS
-Deprecated syscall(2) on macOS 10.12.
+Deprecated C<syscall(2)> on macOS 10.12.
=item EBCDIC
=item *
The path separator for the C<PERL5LIB> and C<PERLLIB> environment entries is
-now a colon (C<:>) when running under a Unix shell. There is no change when
-running under DCL (it's still C<|>).
+now a colon (C<":">) when running under a Unix shell. There is no change when
+running under DCL (it's still C<"|">).
=item *
(containing Visual C++ 14.0) has been added.
This version of VC++ includes a completely rewritten C run-time library, some
-of the changes in which mean that work done to resolve a socket close() bug in
+of the changes in which mean that work done to resolve a socket
+C<close()> bug in
perl #120091 and perl #118059 is not workable in its current state with this
version of VC++. Therefore, we have effectively reverted that bug fix for
VS2015 onwards on the basis that being able to build with VS2015 onwards is
=item FreeBSD
-t/uni/overload.t: Skip hanging test on FreeBSD.
+F<t/uni/overload.t>: Skip hanging test on FreeBSD.
=back
=item *
-The C<op_class()> API function has been added. This is like the existing
-C<OP_CLASS()> macro, but can more accurately determine what struct an op
-has been allocated as. For example C<OP_CLASS()> might return
-C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
-allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
-C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
+A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
+length and allocated size of the buffer in an C<SV>, growing the buffer if
+necessary.
=item *
-The output format of the C<op_dump()> function (as used by C<perl -Dx>)
-has changed: it now displays an "ASCII-art" tree structure, and shows more
-low-level details about each op, such as its address and class.
+A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
+like Perl-space C<$x = ''>, but with several optimisations.
+
+=item *
+
+Several new macros and functions for dealing with Unicode and
+UTF-8-encoded strings have been added to the API, as well as some
+changes in
+functionality of existing functions (see L<perlapi/Unicode Support> for
+more details):
+
+=over
=item *
=item *
-Calling the functions C<utf8n_to_uvchr> and its derivatives, while
-passing a string length of 0 is now asserted against in DEBUGGING
-builds, and otherwise returns the Unicode REPLACEMENT CHARACTER. If
-you have nothing to decode, you shouldn't call the decode function.
+Several new macros for analysing the validity of utf8 sequences. These
+are:
+
+L<C<UTF8_GOT_ABOVE_31_BIT>|perlapi/UTF8_GOT_ABOVE_31_BIT>
+L<C<UTF8_GOT_CONTINUATION>|perlapi/UTF8_GOT_CONTINUATION>
+L<C<UTF8_GOT_EMPTY>|perlapi/UTF8_GOT_EMPTY>
+L<C<UTF8_GOT_LONG>|perlapi/UTF8_GOT_LONG>
+L<C<UTF8_GOT_NONCHAR>|perlapi/UTF8_GOT_NONCHAR>
+L<C<UTF8_GOT_NON_CONTINUATION>|perlapi/UTF8_GOT_NON_CONTINUATION>
+L<C<UTF8_GOT_OVERFLOW>|perlapi/UTF8_GOT_OVERFLOW>
+L<C<UTF8_GOT_SHORT>|perlapi/UTF8_GOT_SHORT>
+L<C<UTF8_GOT_SUPER>|perlapi/UTF8_GOT_SUPER>
+L<C<UTF8_GOT_SURROGATE>|perlapi/UTF8_GOT_SURROGATE>
+L<C<UTF8_IS_INVARIANT>|perlapi/UTF8_IS_INVARIANT>
+L<C<UTF8_IS_NONCHAR>|perlapi/UTF8_IS_NONCHAR>
+L<C<UTF8_IS_SUPER>|perlapi/UTF8_IS_SUPER>
+L<C<UTF8_IS_SURROGATE>|perlapi/UTF8_IS_SURROGATE>
+L<C<UVCHR_IS_INVARIANT>|perlapi/UVCHR_IS_INVARIANT>
+L<C<isUTF8_CHAR_flags>|perlapi/isUTF8_CHAR_flags>
+L<C<isSTRICT_UTF8_CHAR>|perlapi/isSTRICT_UTF8_CHAR>
+L<C<isC9_STRICT_UTF8_CHAR>|perlapi/isC9_STRICT_UTF8_CHAR>
=item *
-The functions C<utf8n_to_uvchr> and its derivatives now return the
-Unicode REPLACEMENT CHARACTER if called with UTF-8 that has the overlong
-malformation, and that malformation is allowed by the input parameters.
-This malformation is where the UTF-8 looks valid syntactically, but
-there is a shorter sequence that yields the same code point. This has
-been forbidden since Unicode version 3.1.
+Functions that are all extensions of the C<is_utf8_string_I<*>()> functions,
+that apply various restrictions to the UTF-8 recognized as valid:
+
+L<C<is_strict_utf8_string>|perlapi/is_strict_utf8_string>,
+L<C<is_strict_utf8_string_loc>|perlapi/is_strict_utf8_string_loc>,
+L<C<is_strict_utf8_string_loclen>|perlapi/is_strict_utf8_string_loclen>,
+
+L<C<is_c9strict_utf8_string>|perlapi/is_c9strict_utf8_string>,
+L<C<is_c9strict_utf8_string_loc>|perlapi/is_c9strict_utf8_string_loc>,
+L<C<is_c9strict_utf8_string_loclen>|perlapi/is_c9strict_utf8_string_loclen>,
+
+L<C<is_utf8_string_flags>|perlapi/is_utf8_string_flags>,
+L<C<is_utf8_string_loc_flags>|perlapi/is_utf8_string_loc_flags>,
+L<C<is_utf8_string_loclen_flags>|perlapi/is_utf8_string_loclen_flags>,
+
+L<C<is_utf8_fixed_width_buf_flags>|perlapi/is_utf8_fixed_width_buf_flags>,
+L<C<is_utf8_fixed_width_buf_loc_flags>|perlapi/is_utf8_fixed_width_buf_loc_flags>,
+L<C<is_utf8_fixed_width_buf_loclen_flags>|perlapi/is_utf8_fixed_width_buf_loclen_flags>.
+
+L<C<is_utf8_invariant_string>|perlapi/is_utf8_invariant_string>.
+L<C<is_utf8_valid_partial_char>|perlapi/is_utf8_valid_partial_char>.
+L<C<is_utf8_valid_partial_char_flags>|perlapi/is_utf8_valid_partial_char_flags>.
=item *
-The functions C<utf8n_to_uvchr> and its derivatives now accept an input
+The functions L<C<utf8n_to_uvchr>|perlapi/utf8n_to_uvchr> and its
+derivatives have had several changes of behaviour.
+
+Calling them, while passing a string length of 0 is now asserted against
+in DEBUGGING builds, and otherwise returns the Unicode REPLACEMENT
+CHARACTER. If you have nothing to decode, you shouldn't call the decode
+function.
+
+They now return the Unicode REPLACEMENT CHARACTER if called with UTF-8
+that has the overlong malformation, and that malformation is allowed by
+the input parameters. This malformation is where the UTF-8 looks valid
+syntactically, but there is a shorter sequence that yields the same code
+point. This has been forbidden since Unicode version 3.1.
+
+They now accept an input
flag to allow the overflow malformation. This malformation is when the
UTF-8 may be syntactically valid, but the code point it represents is
not capable of being represented in the word length on the platform.
What "allowed" means in this case is that the function doesn't return an
-error, and advances the parse pointer to beyond the UTF-8 in question,
-but it returns the Unicode REPLACEMENT CHARACTER as the value of the
-code point (since the real value is not representable).
+error, and it advances the parse pointer to beyond the UTF-8 in
+question, but it returns the Unicode REPLACEMENT CHARACTER as the value
+of the code point (since the real value is not representable).
-=item *
-
-The C<PADOFFSET> type has changed from being unsigned to signed, and
-several pad-related variables such as C<PL_padix> have changed from being
-of type C<I32> to type C<PADOFFSET>.
-
-=item *
-
-The function C<L<perlapi/utf8n_to_uvchr>> has been changed to not
+C<utf8n_to_uvchr> has been changed to not
abandon searching for other malformations when the first one is
encountered. A call to it thus can generate multiple diagnostics,
instead of just one.
=item *
-A new function, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
+C<valid_utf8_to_uvchr()> has been added to the API (although it was
+present in core earlier). Like C<utf8_to_uvchr_buf()>, but assumes that
+the next character is well-formed. Use with caution.
+
+=item *
+
+A new function, L<C<utf8n_to_uvchr_error>|perlapi/utf8n_to_uvchr_error>,
+has been added for
use by modules that need to know the details of UTF-8 malformations
beyond pass/fail. Previously, the only ways to know why a sequence was
ill-formed was to capture and parse the generated diagnostics, or to do
=item *
-Several new functions for handling Unicode have been added to the API:
-C<L<perlapi/is_strict_utf8_string>>,
-C<L<perlapi/is_c9strict_utf8_string>>,
-C<L<perlapi/is_utf8_string_flags>>,
-C<L<perlapi/is_strict_utf8_string_loc>>,
-C<L<perlapi/is_strict_utf8_string_loclen>>,
-C<L<perlapi/is_c9strict_utf8_string_loc>>,
-C<L<perlapi/is_c9strict_utf8_string_loclen>>,
-C<L<perlapi/is_utf8_string_loc_flags>>,
-C<L<perlapi/is_utf8_string_loclen_flags>>,
-C<L<perlapi/is_utf8_fixed_width_buf_flags>>,
-C<L<perlapi/is_utf8_fixed_width_buf_loc_flags>>,
-C<L<perlapi/is_utf8_fixed_width_buf_loclen_flags>>.
-
-These functions are all extensions of the C<is_utf8_string_*()> functions,
-that apply various restrictions to the UTF-8 recognized as valid.
+There is now a safer version of utf8_hop(), called utf8_hop_safe().
+Unlike utf8_hop(), utf8_hop_safe() won't navigate before the beginning or
+after the end of the supplied buffer.
=item *
-A new API function C<sv_setvpv_bufsize()> allows simultaneously setting the
-length and allocated size of the buffer in an C<SV>, growing the buffer if
-necessary.
+Two new functions, C<utf8_hop_forward()> and C<utf8_hop_back()> are
+similar to C<utf8_hop_safe()> but are for when you know which direction
+you wish to travel.
=item *
-A new API macro C<SvPVCLEAR()> sets its C<SV> argument to an empty string,
-like Perl-space C<$x = ''>, but with several optimisations.
+Two new macros which return useful utf8 byte sequences:
-=item *
+L<C<BOM_UTF8>|perlapi/BOM_UTF8>
+L<C<REPLACEMENT_CHARACTER_UTF8>|perlapi/REPLACEMENT_CHARACTER_UTF8>
-All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
-previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
-that several parts of the internals had to be special-cased to accommodate
-it. This oddity's original motivation was to handle code like C<$x ||= 1>;
-that is now handled in a simpler way.
+=back
=item *
-Several new internal C macros have been added that take a string literal as
-arguments, alongside existing routines that take the equivalent value as two
-arguments, a character pointer and a length. The advantage of this is that
-the length of the string is calculated automatically, rather than having to
-be done manually. These routines are now used where appropriate across the
-entire codebase.
-
-=item *
+Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
+default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
+This flag alters how the C<op_sibling> field is used in C<OP> structures,
+and has been available optionally since perl 5.22.
-The code in F<gv.c> that determines whether a variable has a special meaning
-to Perl has been simplified.
+See L<perl5220delta/"Internal Changes"> for more details of what this
+build option does.
=item *
-The C<DEBUGGING>-mode output for regex compilation and execution has been
-enhanced.
+Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
+been added. These are intended principally to implement the individual
+elements of a subroutine signature, plus any overall checking required.
=item *
-Several macros and functions have been added to the public API for
-dealing with Unicode and UTF-8-encoded strings. See
-L<perlapi/Unicode Support>.
+The C<op_class()> API function has been added. This is like the existing
+C<OP_CLASS()> macro, but can more accurately determine what struct an op
+has been allocated as. For example C<OP_CLASS()> might return
+C<OA_BASEOP_OR_UNOP> indicating that ops of this type are usually
+allocated as an C<OP> or C<UNOP>; while C<op_class()> will return
+C<OPclass_BASEOP> or C<OPclass_UNOP> as appropriate.
=item *
-Use C<my_strlcat()> in C<locale.c>. While C<strcat()> is safe in this context,
-some compilers were optimizing this to C<strcpy()> causing a porting test to
-fail that looks for unsafe code. Rather than fighting this, we just use
-C<my_strlcat()> instead.
+All parts of the internals now agree that the C<sassign> op is a C<BINOP>;
+previously it was listed as a C<BASEOP> in F<regen/opcodes>, which meant
+that several parts of the internals had to be special-cased to accommodate
+it. This oddity's original motivation was to handle code like C<$x ||= 1>;
+that is now handled in a simpler way.
=item *
-Three new ops, C<OP_ARGELEM>, C<OP_ARGDEFELEM> and C<OP_ARGCHECK> have
-been added. These are intended principally to implement the individual
-elements of a subroutine signature, plus any overall checking required.
+The output format of the C<op_dump()> function (as used by C<perl -Dx>)
+has changed: it now displays an "ASCII-art" tree structure, and shows more
+low-level details about each op, such as its address and class.
=item *
-Perl no longer panics when switching into some locales on machines with
-buggy C<strxfrm()> implementations in their libc. [perl #121734]
+The C<PADOFFSET> type has changed from being unsigned to signed, and
+several pad-related variables such as C<PL_padix> have changed from being
+of type C<I32> to type C<PADOFFSET>.
=item *
-Perl is now built with the C<PERL_OP_PARENT> compiler define enabled by
-default. To disable it, use the C<PERL_NO_OP_PARENT> compiler define.
-This flag alters how the C<op_sibling> field is used in C<OP> structures,
-and has been available optionally since perl 5.22.
-
-See L<perl5220delta/"Internal Changes"> for more details of what this
-build option does.
+The C<DEBUGGING>-mode output for regex compilation and execution has been
+enhanced.
=item *
-The meanings of some internal SV flags have been changed
-
-OPpRUNTIME, SVpbm_VALID, SVpbm_TAIL, SvTAIL_on, SvTAIL_off, SVrepl_EVAL,
-SvEVALED
+Several obscure SV flags have been eliminated, sometimes along with the
+macros which manipulate them: C<SVpbm_VALID>, C<SVpbm_TAIL>, C<SvTAIL_on>,
+C<SvTAIL_off>, C<SVrepl_EVAL>, C<SvEVALED>
=item *
-Change C<hv_fetch(…, "…", …, …)> to C<hv_fetchs(…, "…", …)>
-
-The dual-life dists all use Devel::PPPort, so they can use this function even
-though it was only added in 5.10.
+An OP op_private flag has been eliminated: C<OPpRUNTIME>. This used to
+often get set on C<PMOP>s, but had become meaningless over time.
=back
=item *
+Perl no longer panics when switching into some locales on machines with
+buggy C<strxfrm()> implementations in their libc. [perl #121734]
+
+=item *
+
C< $-{$name} > would leak an C<AV> on each access if the regular
expression had no named captures. The same applies to access to any
hash tied with L<Tie::Hash::NamedCapture> and C<< all =E<gt> 1 >>. [perl
=item *
-Supplying a glob as the format argument to L<perlfunc/formline> would
+Supplying a glob as the format argument to
+L<C<formline>|perlfunc/formline> would
cause an assertion failure. [perl #130722]
=item *
Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
-converted into a qr// operator, leaving extra elements on the stack to
+converted into a C<qr//> operator, leaving extra elements on the stack to
confuse any surrounding expression. [perl #130705]
=item *
-Since 5.24 in some obscure cases, a regex which included code blocks
-from multiple sources (I<e.g.>, via embedded via qr// objects) could end up
+Since v5.24 in some obscure cases, a regex which included code blocks
+from multiple sources (I<e.g.>, via embedded via C<qr//> objects) could end up
with the wrong current pad and crash or give weird results. [perl #129881]
=item *
=item *
Under C<use utf8>, the entire Perl program is now checked that the UTF-8
-is wellformed. This resolves [perl #126310].
+is wellformed. [perl #126310].
=item *
-The range operator C<..> on strings now handles its arguments correctly when in
+The range operator C<".."> on strings now handles its arguments correctly when in
the scope of the L<< C<unicode_strings>|feature/"The 'unicode_strings' feature" >>
feature. The previous behaviour was sufficiently unexpected that we believe no
correct program could have made use of it.
=item *
-The S<split> operator did not ensure enough space was allocated for
+The C<split> operator did not ensure enough space was allocated for
its return value in scalar context. It could then write a single
pointer immediately beyond the end of the memory block allocated for
the stack. [perl #130262]
=item *
-Using a large code point with the C<W> pack template character with
+Using a large code point with the C<"W"> pack template character with
the current output position aligned at just the right point could
cause a write a single zero byte immediately beyond the end of an
allocated buffer. [perl #129149]
=item *
-Fix issues with /(?{ ... E<lt>E<lt>EOF })/ that broke Method-Signatures. [perl #130398]
+Fix issues with C</(?{ ... E<lt>E<lt>EOF })/> that broke Method-Signatures. [perl #130398]
=item *
=item *
-Fixed a comment skipping error under C</x>; it could stop skipping a
-byte early, which could be in the middle of a UTF-8 character.
-[perl #130495].
+Fixed a comment skipping error in patterns under C</x>; it could stop
+skipping a byte early, which could be in the middle of a UTF-8
+character. [perl #130495].
=item *
=item *
-DragonFly BSD now has support for setproctitle(). [perl #130068].
+DragonFly BSD now has support for C<setproctitle()>. [perl #130068].
=item *
-Fix an assertion error which could be triggered when lookahead string
+Fix an assertion error which could be triggered when a lookahead string
in patterns exceeded a minimum length. [perl #130522].
=item *
-Only warn once per literal about a misplaced C<_>. [perl #70878].
+Only warn once per literal about a misplaced C<"_">. [perl #70878].
=item *
=item *
-Properly recognize mathematical digit ranges starting at U+1D7E.
C<use re 'strict'> is supposed to warn if you use a range whose start
and end digit aren't from the same group of 10. It didn't do that
for five groups of mathematical digits starting at U+1D7E.
=item *
-A crash in executing a regex with a floating UTF-8 substring against a
+A crash in executing a regex with a non-anchored UTF-8 substring against a
target string that also used UTF-8 has been fixed. [perl #129350]
=item *
The regex engine was previously producing incorrect results in some rare
situations when backtracking past a trie that matches only one thing; this
-showed up as capture buffers (C<$1>, C<$2>, etc) erroneously containing data
+showed up as capture buffers (C<$1>, C<$2>, I<etc.>) erroneously containing data
from regex execution paths that weren't actually executed for the final
match. [perl #129897]
=item *
-A sub containing with a "forward" declaration with the same name
-(I<e.g.>,
-C<sub c { sub c; }>) could sometimes crash or loop infinitely. [perl
-#129090]
-
-=item *
-
The use of C<splice> on arrays with nonexistent elements could cause other
operators to crash. [perl #129164]
=item *
-The C<&.> operator (and the C<&> operator, when it treats its arguments as
+The C<&.> operator (and the C<"&"> operator, when it treats its arguments as
strings) were failing to append a trailing null byte if at least one string
was marked as utf8 internally. Many code paths (system calls, regexp
compilation) still expect there to be a null byte in the string buffer
=item *
Fixed the parser error handling for an 'C<:attr(foo>' that does not have
-an ending 'C<)>'.
+an ending 'C<")">'.
=item *
=item *
-[perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to
-prevent possible string overrun with invalid len in gv.c
+[perl #129267] rework C<gv_fetchmethod_pvn_flags> separator parsing to
+prevent possible string overrun with invalid len in F<gv.c>
=item *
=item *
C<gethostent> and similar functions now perform a null check internally, to
-avoid crashing with torsocks. This was a regression from 5.22. [perl
+avoid crashing with torsocks. This was a regression from v5.22. [perl
#128740]
=item *
Mentioning the same constant twice in a row (which is a syntax error) no
longer fails an assertion under debugging builds. This was a regression
-from 5.20. [perl #126482]
+from v5.20. [perl #126482]
=item *
Many issues relating to C<printf "%a"> of hexadecimal floating point
were fixed. In addition, the "subnormals" (formerly known as "denormals")
-floating point anumbers are now supported both with the plain IEEE 754
+floating point numbers are now supported both with the plain IEEE 754
floating point numbers (64-bit or 128-bit) and the x86 80-bit
"extended precision". Note that subnormal hexadecimal floating
point literals will give a warning about "exponent underflow".
=item *
-A regression in 5.24 with C<tr/\N{U+...}/foo/> when the code point was between
+A regression in v5.24 with C<tr/\N{U+...}/foo/> when the code point was between
128 and 255 has been fixed. [perl #128734].
=item *
-A regression from the previous development release, 5.23.3, where
-compiling a regular expression could crash the interpreter has been
-fixed. [perl #128686].
-
-=item *
-
Use of a string delimiter whose code point is above 2**31 now works
correctly on platforms that allow this. Previously, certain characters,
due to truncation, would be confused with other delimiter characters
-with special meaning (such as C<?> in C<m?...?>), resulting
+with special meaning (such as C<"?"> in C<m?...?>), resulting
in inconsistent behaviour. Note that this is non-portable,
and is based on Perl's extension to UTF-8, and is probably not
displayable nor enterable by any editor. [perl #128738]
=item *
-C<@{x> followed by a newline where C<x> represents a control or non-ASCII
+C<@{x> followed by a newline where C<"x"> represents a control or non-ASCII
character no longer produces a garbled syntax error message or a crash.
[perl #128951]
=item *
Code that looks for a variable name associated with an uninitialized value
-could cause an assertion in cases where magic is involved, such as
+could cause an assertion failure in cases where magic is involved, such as
C<$ISA[0][0]>. This has now been fixed.
L<[perl #128253]|https://rt.perl.org/Public/Bug/Display.html?id=128253>
=item *
C<require> followed by a single colon (as in C<foo() ? require : ...> is
-now parsed correctly as C<require> with implicit $_, rather than
+now parsed correctly as C<require> with implicit C<$_>, rather than
C<require "">. [perl #128307]
=item *
=item *
-Handle SvIMMORTALs in LHS of list assign. [perl #129991]
+Handle C<SvIMMORTALs> in LHS of list assign. [perl #129991]
=item *
-[perl #130010] a5540cf breaks texinfo
-
-This involved user-defined Unicode properties.
+Assertion failure with user-defined Unicode-like properties. [perl #130010]
=item *
=item *
-[perl 129903]
-
-The basic problem is that code like this: /(?{ s!!! })/ can trigger infinite
-recursion on the C stack (not the normal perl stack) when the last successful
-pattern in scope is itself. Since the C stack overflows this manifests as an
-untrappable error/segfault, which then kills perl.
-
-We avoid the segfault by simply forbidding the use of the empty pattern when it
-would resolve to the currently executing pattern.
+Code like this: C</(?{ s!!! })/> can trigger infinite recursion on the C
+stack (not the normal perl stack) when the last successful pattern in
+scope is itself. We avoid the segfault by simply forbidding the use of
+the empty pattern when it would resolve to the currently executing
+pattern. [perl 129903]
=item *
-[perl 128997] Avoid reading beyond the end of the line buffer when there's a
-short UTF-8 character at the end.
+Avoid reading beyond the end of the line buffer when there's a
+short UTF-8 character at the end. [perl 128997]
=item *
-[perl 129950] fix firstchar bitmap under utf8 with prefix optimisation.
+Fix firstchar bitmap under utf8 with prefix optimisation. [perl 129950]
=item *
-[perl 129954] Carp/t/arg_string.t: be liberal in f/p formats.
+Make F<Carp/t/arg_string.t>: be liberal in C<f>/C<p> formats. [perl 129954]
=item *
-[perl 129928] make do "a\0b" fail silently instead of throwing.
+Make C<do "a\0b"> fail silently instead of throwing an error. [perl 129928]
=item *
-[perl 129130] make chdir allocate the stack it needs.
+Make C<chdir> allocate the stack it needs. [perl 129130]
=back
=item *
Some modules have been broken by the L<context stack rework|/Internal Changes>.
-These modules were relying on non-guaranteed implementation details in perl.
+These modules were relying on non-guaranteed implementation details in
+the perl interpreter.
Their maintainers have been informed, and should contact perl5-porters for
advice if needed. Below is a subset of these modules:
=item * L<Coro>
-L<Coro> and perl 5.22 were already incompatible due to a change in the perl,
+L<Coro> and Perl 5.22 were already incompatible due to a change in the perl
+interpreter,
and the reworking on the perl context stack creates a further incompatibility.
perl5-porters has L<discussed the issue on the mailing
list|http://www.nntp.perl.org/group/perl.perl5.porters/2016/05/msg236174.html>.
If you believe you have an unreported bug, please run the L<perlbug> program
included with your release. Be sure to trim your bug down to a tiny but
sufficient test case. Your bug report, along with the output of C<perl -V>,
-will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
+will be sent off to C<perlbug@perl.org> to be analysed by the Perl porting team.
If the bug you are reporting has security implications which make it
inappropriate to send to a publicly archived mailing list, then see
https://perl5.git.perl.org / perl5.git / blobdiff