=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
+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<$matched_string> either. This variable has no
-single character equivalent. Note, like the other regex magic variables
-the contents of this variable is dynamic, if you wish to store it beyond
+have to keep track of the C<$matched_string> either. This variable has no
+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 create a safer 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.
-
-=head1 Security
-
-=head2 '.' and @INC
-
-Since time immemorial Perl has, as a last resort, loaded libraries
-from the current directory. For security reasons this is no longer the
-case. This is controlled by the C<@INC> variable, and it no longer
-defaults to containing C<.> as its last element.
+=head2 New Hash Function For 64-bit Builds
-If you want to disable this behavior at compile-time, build perl with
-C<-Udefault_inc_excludes_dot> (C<-Ddefault_inc_excludes_dot> being the
-default now).
+We have switched to a hybrid hash function to better balance
+performance for short and long keys.
-If you'd like to add C<.> back to C<@INC> at runtime set
-C<PERL_USE_UNSAFE_INC=1> in the environment before starting
-perl. Setting it to 1 restores C<.> in the C<@INC> when perl otherwise
-lacks it.
+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.
-Various toolchain modules will set C<PERL_USE_UNSAFE_INC=1>
-themselves. For example, L<Test::Harness> sets it, since loading modules from a
-relative path is a common idiom in test code. If you find that you
-have C<.> in C<@INC> on a perl built with default settings it's likely
-that your code is being invoked by a toolchain module of some sort.
+=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,
-unless run with taint mode enabled (C<perl -T>). While convenient, this has
+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,
+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 v5.26.0, C<.> is always removed by default, not just under
-tainting. This has major implications for installing modules and executing
+Starting with v5.26, C<"."> is always removed by default, not just under
+tainting. This has major implications for installing modules and executing
scripts.
The following new features have been added to help ameliorate these
=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
-option using C<-U> reverts perl to the old behaviour. This may fix your
+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
such issues are not a concern in your environment.
=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,
+case-by-case basis. But note that this is intended to be a temporary crutch,
and this feature will likely be removed in some future perl version.
It is currently set by the C<cpan> utility and C<Test::Harness> to
ease installation of CPAN modules which have not been updated to handle the
-lack of dot. Once again, don't use this unless you are sure that this
+lack of dot. Once again, don't use this unless you are sure that this
will not reintroduce any security concerns.
-=item * A new mandatory warning issued by C<do>.
+=item * A new deprecation warning issued by C<do>.
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
+the current directory. Since this is commonly expected behaviour, a new
+deprecation warning is now issued whenever C<do> fails to load a file which
it otherwise would have found if dot had been in C<@INC>.
=back
=item * Script authors
If the issue is within your own code (rather than within included
-modules), then you have two main options. Firstly, if you are confident
+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 {
On the other hand, if your script is intended to be run from within
untrusted directories (such as F</tmp>), then your script suddenly failing
-to load files may be indicative of a security issue. You most likely want
+to load files may be indicative of a security issue. You most likely want
to replace any relative paths with full paths; for example,
- do ".foo_config.pl"
+ do "foo_config.pl"
might become
- do "$ENV{HOME}/.foo_config.pl"
+ do "$ENV{HOME}/foo_config.pl"
If you are absolutely certain that you want your script to load and
execute a file from the current directory, then use a C<./> prefix; for
example:
- do "./.foo_config.pl"
+ do "./foo_config.pl"
=item * Installing and using CPAN modules
(export PERL_USE_UNSAFE_INC=1; \
perl Makefile.PL && make && make test && make install)
-Note that this only helps build and install an unfixed module. It's
+Note that this only helps build and install an unfixed module. It's
possible for the tests to pass (since they were run under
C<PERL_USE_UNSAFE_INC=1>), but for the module itself to fail to perform
-correctly in production. In this case you may have to temporarily modify
-your script until such time as fixed version of the module is released.
+correctly in production. In this case you may have to temporarily modify
+your script until such time as a fixed version of the module is released.
For example:
use Foo::Bar;
$config = Foo::Bar->read_config();
}
-This is only rarely expected to be necessary. Again, if doing this,
+This is only rarely expected to be necessary. Again, if doing this,
assess the resultant risks first.
=item * Module Authors
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
-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
+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
+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.
During build, test and install, it will normally be the case that any perl
processes will be executing directly within the root directory of the
-untarred distribution, or a known subdirectory of that, such as F<t/>. It
+untarred distribution, or a known subdirectory of that, such as F<t/>. It
may well be that F<Makefile.PL> or F<t/foo.t> will attempt to include
local modules and configuration files using their direct relative
filenames, which will now fail.
This makes it likely that your existing build and test code will work, but
this may mask issues with your code which only manifest when used after
-install. It is prudent to try and run your build process with that
+install. It is prudent to try and run your build process with that
variable explicitly disabled:
+
(export PERL_USE_UNSAFE_INC=0; \
perl Makefile.PL && make && make test && make install)
This is more likely to show up any potential problems with your module's
-build process, or even with the module itself. Fixing such issues will
+build process, or even with the module itself. Fixing such issues will
ensure both that your module can again be installed manually, and that
it will still build once the C<PERL_USE_UNSAFE_INC> crutch goes away.
When fixing issues in tests due to the removal of dot from C<@INC>,
reinsertion of dot into C<@INC> should be performed with caution, for this
-too may suppress real errors in your runtime code. You are encouraged
+too may suppress real errors in your runtime code. You are encouraged
wherever possible to apply the aforementioned approaches with explicit
-absolute/relative paths, or relocate your needed files into a subdirectory
-and insert that subdirectory into C<@INC> instead.
+absolute/relative paths, or to relocate your needed files into a
+subdirectory and insert that subdirectory into C<@INC> instead.
If your runtime code has problems under the dotless C<@INC>, then the comments
-above on how to fix for script authors will mostly apply here too. Bear in
+above on how to fix for script authors will mostly apply here too. Bear in
mind though that it is considered bad form for a module to globally add dot to
C<@INC>, since it introduces both a security risk and hides issues of
accidentally requiring dot in C<@INC>, as explained above.
=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
+=head2 New C<-Di> switch is now required for PerlIO debugging output
-Previously PerlIO debugging output would be sent to the file specified
+This is used for debugging of code within PerlIO to avoid recursive
+calls. Previously this output would be sent to the file specified
by the C<PERLIO_DEBUG> environment variable if perl wasn't running
setuid and the C<-T> or C<-t> switches hadn't been parsed yet.
switches this could result in perl creating or overwriting the file
named by C<PERLIO_DEBUG> even when the C<-T> switch had been supplied.
-Perl now requires the C<-Di> switch to produce PerlIO debugging
+Perl now requires the C<-Di> switch to be present before it will produce
+PerlIO debugging
output. By default this is written to C<stderr>, but can optionally
be redirected to a file by setting the C<PERLIO_DEBUG> environment
variable.
-If perl is running setuid or the C<-T> switch has supplied
+If perl is running setuid or the C<-T> switch was supplied,
C<PERLIO_DEBUG> is ignored and the debugging output is sent to
C<stderr> as for any other C<-D> switch.
These have been deprecated since v5.16, with a deprecation message
raised for some uses starting in v5.22. Unfortunately, the code added
-to raise the message had bugs, and did not catch all the relevant uses
-of literal C<"{">. So, some uses failed to be warned about. Therefore,
-enforcement of this ban for these uses is deferred until Perl 5.30, and
-a deprecation message is now raised for them.
+to raise the message was buggy, and failed to warn in some cases where
+it should have. Therefore, enforcement of this ban for these cases is
+deferred until Perl 5.30, but the code has been fixed to raise a
+default-on deprecation message for them in the meantime.
Some uses of literal C<"{"> occur in contexts where we do not foresee
-the meaning be anything but the literal, such as the very first
-character in the pattern. To avoid forcing needless code changes, this
-restriction is not enforced, nor are there current plans to enforce it,
-in those areas. But is always correct to escape C<"{">, and the simple
-rule to remember is to do so.
+the meaning ever being anything but the literal, such as the very first
+character in the pattern, or after a C<"|"> meaning alternation. Thus
+
+ qr/{fee|{fie/
+
+matches either of the strings C<{fee> or C<{fie>. To avoid forcing
+unnecessary code changes, these uses do not need to be escaped, and no
+warning is raised about them, and there are no current plans to change this.
+
+But it is always correct to escape C<"{">, and the simple rule to
+remember is to always do so.
+
+See 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>>.
=head2 C<scalar(%hash)> return signature changed
the buckets allocated in the hash. It will simply return the count of used
keys. It is thus equivalent to C<0+keys(%hash)>.
-A form of backwards compatibility is provided via C<Hash::Util::bucket_ratio()>
-which provides the same behavior as C<scalar(%hash)> provided prior to Perl
-5.25.
+A form of backwards compatibility is provided via
+L<C<Hash::Util::bucket_ratio()>|Hash::Util/bucket_ratio> which provides
+the same behavior as
+C<scalar(%hash)> provided in Perl 5.24 and earlier.
=head2 C<keys> returned from an lvalue subroutine
(bar) = 3; # also an error
This makes the lvalue sub case consistent with C<(keys %hash) = ...> and
-C<(keys @_) = ...>, which are also errors. [perl #128187]
+C<(keys @_) = ...>, which are also errors.
+L<[perl #128187]|https://rt.perl.org/Public/Bug/Display.html?id=128187>
-=head2 C<${^ENCODING}> has been removed
+=head2 The C<${^ENCODING}> facility has been removed
-Consequently, the L<encoding> pragma's default mode is no longer supported. If
+The special behaviour associated with assigning a value to this variable
+has been removed. As a consequence, the L<encoding> pragma's default mode
+is no longer supported. If
you still need to write your source code in encodings other than UTF-8, use a
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 5.22.0 and has now been removed. In its place you can use,
+Perl 5.22 and has now been removed. In its place you can use,
for example, the L<File::Temp> interfaces.
=head2 require ::Foo::Bar is now illegal.
-Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
+Formerly, C<require ::Foo::Bar> would try to read F</Foo/Bar.pm>. Now any
bareword require which starts with a double colon dies instead.
=head2 Literal control character variable names are no longer permissible
=head2 C<NBSP> is no longer permissible in C<\N{...}>
The name of a character may no longer contain non-breaking spaces. It
-has been deprecated to do so since Perl v5.22.
+has been deprecated to do so since Perl 5.22.
=head1 Deprecations
In order for Perl to eventually allow string delimiters to be Unicode
grapheme clusters (which look like a single character, but may be
-a sequence of several ones), we have to stop allowing a single char
+a sequence of several ones), we have to stop allowing a single character
delimiter that isn't a grapheme by itself. These are unlikely to exist
in actual code, as they would typically display as attached to the
character in front of them.
+=head2 C<\cI<X>> that maps to a printable is no longer deprecated
+
+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
=over 4
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
-We use a different hash function for short and long keys. This should
+We use a different hash function for short and long keys. This should
improve performance and security, especially for long keys.
=item * readline is faster
=item *
-Reduce cost of SvVALID().
+Assigning one reference to another, I<e.g.> C<$ref1 = $ref2> has been
+optimized in some cases.
=item *
-C<$ref1 = $ref2> has been optimized.
+Remove some exceptions to creating Copy-on-Write strings. The string
+buffer growth algorithm has been altered slightly so that you're less
+likely to encounter a string which which can't be COWed.
=item *
-Array and hash assignment are now faster, I<e.g.>
-
- (..., @a) = (...);
- (..., %h) = (...);
-
-especially when the RHS is empty.
-
-=item *
-
-Reduce the number of odd special cases for the C<SvSCREAM> flag.
-
-=item *
-
-Avoid sv_catpvn() in do_vop() when unneeded.
-
-=item *
-
-Enhancements in Regex concat COW implementation.
-
-=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 a third 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 $i (1..3_000_000) {
- %h = qw(a 1 b 2);
- %h = ();
- }
-
-=item *
-
-Better optimise array and hash assignment
-
=item *
Converting a single-digit string to a number is now substantially faster.
=item *
-The internal op implementing the C<split> builtin has been simplified and
-sped up. Firstly, it no longer requires a subsidiary internal C<pushre> op
-to do its work. Secondly, code of the form C<my @x = split(...)> is now
-optimised in the same way as C<@x = split(...)>, and is therefore a few
-percent faster.
+The C<split> builtin is now slightly faster in many cases: in particular
+for the two specially-handled forms
+
+ my @a = split ...;
+ local @a = split ...;
=item *
The rather slow implementation for the experimental subroutine signatures
feature has been made much faster; it is now comparable in speed with the
-old-style C<my ($a, $b, @c) = @_>.
+traditional C<my ($a, $b, @c) = @_>.
=item *
Bareword constant strings are now permitted to take part in constant
-folding. They were originally exempted from constant folding in August 1999,
+folding. They were originally exempted from constant folding in August 1999,
during the development of Perl 5.6, to ensure that C<use strict "subs">
-would still apply to bareword constants. That has now been accomplished a
+would still apply to bareword constants. That has now been accomplished a
different way, so barewords, like other constants, now gain the performance
benefits of constant folding.
L<attributes> has been upgraded from version 0.27 to 0.29.
The deprecation message for the C<:unique> and C<:locked> attributes
-now mention they will disappear in Perl 5.28.
+now mention that they will disappear in Perl 5.28.
=item *
L<B::Xref> has been upgraded from version 1.05 to 1.06.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
The XS implementation now supports Deparse.
-This fixes a stack management bug. [perl #130487].
-
=item *
L<DB_File> has been upgraded from version 1.835 to 1.840.
L<Devel::SelfStubber> has been upgraded from version 1.05 to 1.06.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<diagnostics> has been upgraded from version 1.34 to 1.36.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<Errno> has been upgraded from version 1.25 to 1.28.
-Document that using C<%!> loads Errno for you.
+It now documents that using C<%!> automatically loads Errno for you.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<ExtUtils::Embed> has been upgraded from version 1.33 to 1.34.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<feature> has been upgraded from version 1.42 to 1.47.
-Fixes the Unicode Bug in the range operator.
-
=item *
L<File::Copy> has been upgraded from version 2.31 to 2.32.
L<File::Glob> has been upgraded from version 1.26 to 1.28.
-Issue a deprecation message for C<File::Glob::glob()>.
+It now Issues a deprecation message for C<File::Glob::glob()>.
=item *
L<Filter::Simple> has been upgraded from version 0.92 to 0.93.
It no longer treats C<no MyFilter> immediately following C<use MyFilter> as
-end-of-file. [perl #107726]
+end-of-file.
+L<[perl #107726]|https://rt.perl.org/Public/Bug/Display.html?id=107726>
=item *
L<I18N::LangTags> has been upgraded from version 0.40 to 0.42.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
=item *
-IO-Compress has been upgraded from version 2.069 to 2.074.
+IO::Compress has been upgraded from version 2.069 to 2.074.
=item *
L<lib> has been upgraded from version 0.63 to 0.64.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<Math::BigInt> has been upgraded from version 1.999715 to 1.999806.
-There have also been some core customizations.
-
=item *
L<Math::BigInt::FastCalc> has been upgraded from version 0.40 to 0.5005.
IPv6 addresses and C<AF_INET6> sockets are now supported, along with several
other enhancements.
-Remove sudo from 500_ping_icmp.t.
-
-Avoid stderr noise in tests
-
-Check for echo in new Net::Ping tests.
-
=item *
L<NEXT> has been upgraded from version 0.65 to 0.67.
L<OS2::Process> has been upgraded from version 1.11 to 1.12.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<perl5db.pl> has been upgraded from version 1.50 to 1.51.
-Ignore F</dev/tty> on non-Unix systems. [perl #113960]
+It now ignores F</dev/tty> on non-Unix systems.
+L<[perl #113960]|https://rt.perl.org/Public/Bug/Display.html?id=113960>
=item *
=item *
-L<POSIX> has been upgraded from version 1.65 to 1.76. This remedies several
-defects in making its symbols exportable. [perl #127821]
+L<POSIX> has been upgraded from version 1.65 to 1.76.
+
+This remedies several defects in making its symbols exportable.
+L<[perl #127821]|https://rt.perl.org/Public/Bug/Display.html?id=127821>
+
The C<POSIX::tmpnam()> interface has been removed,
see L</"POSIX::tmpnam() has been removed">.
+
Trying to import POSIX subs that have no real implementations
(like C<POSIX::atend()>) now fails at import time, instead of
waiting until runtime.
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,
L<Storable> has been upgraded from version 2.56 to 2.62.
-Fixes [perl #130098].
+Fixes
+L<[perl #130098]|https://rt.perl.org/Public/Bug/Display.html?id=130098>.
=item *
L<Term::ReadLine> has been upgraded from version 1.15 to 1.16.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<Test> has been upgraded from version 1.28 to 1.30.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<threads> has been upgraded from version 2.07 to 2.15.
-Compatibility with 5.8 has been restored.
-
-Fixes [perl #130469].
-
=item *
L<threads::shared> has been upgraded from version 1.51 to 1.56.
-This fixes [cpan #119529], [perl #130457]
-
=item *
L<Tie::Hash::NamedCapture> has been upgraded from version 0.09 to 0.10.
L<Unicode::UCD> has been upgraded from version 0.64 to 0.68.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
L<VMS::DCLsym> has been upgraded from version 1.06 to 1.08.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=item *
Fixed a security hole in which binary files could be loaded from a path
outside of L<C<@INC>|perlvar/@INC>.
-It now uses 3-arg C<open()> instead of 2-arg C<open()>. [perl #130122]
+It now uses 3-arg C<open()> instead of 2-arg C<open()>.
+L<[perl #130122]|https://rt.perl.org/Public/Bug/Display.html?id=130122>
=back
=head3 L<perldeprecation>
This file documents all upcoming deprecations, and some of the deprecations
-which already have been removed. The purpose of this documentation is
+which already have been removed. The purpose of this documentation is
two-fold: document what will disappear, and by which version, and serve
as a guide for people dealing with code which has features that no longer
work after an upgrade of their perl.
=head2 Changes to Existing Documentation
-=head3 L<perlcall>
-
-=over 4
+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>.
-=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> noted that certain pattern modifiers are
+legal, and added a caution about its use in Perls before v5.11,
=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>.
+Clarify what editor tab stop rules to use, and note that we are
+migrating away from using tabs, 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
-=head3 L<perlmodinstall>
+=head3 L<perlmod>
=over 4
=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
=item *
-Clarify behavior single quote regexps.
+Note that white space must be used for quoting operators if the
+delimiter is a word character (I<i.e.>, matches C<\w>).
+
+=item *
+
+Clarify that in regular expression patterns delimited by single quotes,
+no variable interpolation is done.
=back
=item *
-Several minor enhancements to the documentation.
-
-=back
-
-=head3 L<perlsec>
-
-=over 4
+The first part was extensively rewritten to incorporate various basic
+points, that in earlier versions were mentioned in sort of an appendix
+on Version 8 regular expressions.
=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</${^ENCODING} has
-been removed> above.
-
-=item *
-
-Document C<@ISA>. Was documented other places, not not in L<perlvar>.
+Document C<@ISA>. Was documented other places, not not in L<perlvar>.
=back
=item *
-Since C<.> is now removed from C<@INC> by default, C<do> will now trigger
-a warning recommending to fix the C<do> statement:
-
-L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
+L<A signature parameter must start with C<'$'>, C<'@'> or C<'%'>
+|perldiag/A signature parameter must start with C<'$'>, C<'@'> or C<'%'>>
=item *
-Using the empty pattern (which re-executes the last successfully-matched
-pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
-always previously yielded a segfault. It now produces an error:
-L<Infinite recursion in regex|perldiag/"Infinite recursion in regex">.
+L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
=item *
-L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
+L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
-(F) To declare references to variables, as in C<my \%x>, you must first enable
-the feature:
+=item *
- no warnings "experimental::declared_refs";
- use feature "declared_refs";
+L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
=item *
-L<Version control conflict marker|perldiag/"Version control conflict marker">
-
-(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
-C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
-version control system to mark conflicts after a failed merge operation.
+L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
=item *
L<%s: command not found|perldiag/"%s: command not found">
(A) You've accidentally run your script through B<bash> or another shell
-instead of Perl. Check the #! line, or manually feed your script into
-Perl yourself. The #! line at the top of your file could look like:
+instead of Perl. Check the C<#!> line, or manually feed your script into
+Perl yourself. The C<#!> line at the top of your file could look like:
#!/usr/bin/perl
L<%s: command not found: %s|perldiag/"%s: command not found: %s">
(A) You've accidentally run your script through B<zsh> or another shell
-instead of Perl. Check the #! line, or manually feed your script into
-Perl yourself. The #! line at the top of your file could look like:
+instead of Perl. Check the C<#!> line, or manually feed your script into
+Perl yourself. The C<#!> line at the top of your file could look like:
#!/usr/bin/perl
=item *
-L<Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<E<lt>-- HERE> in mE<sol>%sE<sol>|perldiag/"Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<<-- HERE> in m/%s/">
+L<The experimental declared_refs feature is not enabled|perldiag/"The experimental declared_refs feature is not enabled">
+
+(F) To declare references to variables, as in C<my \%x>, you must first enable
+the feature:
+
+ no warnings "experimental::declared_refs";
+ use feature "declared_refs";
-Unescaped left braces are already illegal in some contexts in regular
-expression patterns, but, due to an oversight, no deprecation warning
-was raised in other contexts where they are intended to become illegal.
-This warning is now raised in these contexts.
+See L</Declaring a reference to a variable>.
=item *
-L<Bareword in require contains "%s"|perldiag/"Bareword in require contains "%s"">
+L<Illegal character following sigil in a subroutine signature
+|perldiag/Illegal character following sigil in a subroutine signature>
=item *
-L<Bareword in require maps to empty filename|perldiag/"Bareword in require maps to empty filename">
+L<Indentation on line %d of here-doc doesn't match delimiter
+|perldiag/Indentation on line %d of here-doc doesn't match delimiter>
=item *
-L<Bareword in require maps to disallowed filename "%s"|perldiag/"Bareword in require maps to disallowed filename "%s"">
+L<Infinite recursion via empty pattern|perldiag/"Infinite recursion via empty pattern">.
+
+Using the empty pattern (which re-executes the last successfully-matched
+pattern) inside a code block in another regex, as in C</(?{ s!!new! })/>, has
+always previously yielded a segfault. It now produces this error.
=item *
-L<Bareword in require must not start with a double-colon: "%s"|perldiag/"Bareword in require must not start with a double-colon: "%s"">
+L<Malformed UTF-8 string in "%s"
+|perldiag/Malformed UTF-8 string in "%s">
+
+=item *
+
+L<Multiple slurpy parameters not allowed
+|perldiag/Multiple slurpy parameters not allowed>
+
+=item *
+
+L<C<'#'> not allowed immediately following a sigil in a subroutine signature
+|perldiag/C<'#'> not allowed immediately following a sigil in a subroutine signature>
+
+=item *
+
+L<panic: unknown OA_*: %x
+|perldiag/panic: unknown OA_*: %x>
+
+=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 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
+be illegal in Perl 5.30.
+
+=item *
+
+L<Version control conflict marker|perldiag/"Version control conflict marker">
+
+(F) The parser found a line starting with C<E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>E<lt>>,
+C<E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>E<gt>>, or C<=======>. These may be left by a
+version control system to mark conflicts after a failed merge operation.
=back
=item *
-L<Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30|perldiag/"Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30">
-
-See L</Deprecations>
+L<Can't determine class of operator %s, assuming C<BASEOP>
+|perldiag/Can't determine class of operator %s, assuming C<BASEOP>>
=item *
use feature "declared_refs";
$fooref = my \$foo;
+See L</Declaring a reference to a variable>.
+
=item *
-L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
+L<do "%s" failed, '.' is no longer in @INC|perldiag/do "%s" failed, '.' is no longer in @INC; did you mean do ".E<sol>%s"?>
-(D deprecated) The special variable C<${^ENCODING}>, formerly used to implement
-the C<encoding> pragma, is no longer supported as of Perl 5.26.0.
+Since C<"."> is now removed from C<@INC> by default, C<do> will now trigger a warning recommending to fix the C<do> statement.
=item *
-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<C<File::Glob::glob()> will disappear in perl 5.30. Use C<File::Glob::bsd_glob()> instead.
+|perldiag/C<File::Glob::glob()> will disappear in perl 5.30. Use C<File::Glob::bsd_glob()> instead.>
-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 literal '%c' in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>
+|perldiag/Unescaped literal '%c' in regex; marked by <-- HERE in mE<sol>%sE<sol>>
+
+=item *
+
+L<Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30|perldiag/"Use of unassigned code point or non-standalone grapheme for a delimiter will be a fatal error starting in Perl 5.30">
+
+See L</Deprecations>
=back
=item *
-Attribute "locked" is deprecated, and will disappear in Perl 5.28
+L<Attribute "locked" is deprecated, and will disappear in Perl 5.28
+|perldiag/Attribute "locked" is deprecated, and will disappear in Perl 5.28>
+
+This existing warning has had the I<and will disappear> text added in this
+release.
=item *
-Attribute "unique" is deprecated, and will disappear in Perl 5.28
+L<Attribute "unique" is deprecated, and will disappear in Perl 5.28
+|perldiag/Attribute "unique" is deprecated, and will disappear in Perl 5.28>
+
+This existing warning has had the I<and will disappear> text added in this
+release.
=item *
-Constants from lexical variables potentially modified elsewhere are
-deprecated. This will not be allowed in Perl 5.32
+Calling POSIX::%s() is deprecated
+
+This warning has been removed, as the deprecated functions have been
+removed from POSIX.
=item *
-Deprecated use of my() in false conditional. This will be a fatal error
-in Perl 5.30
+L<Constants from lexical variables potentially modified elsewhere are deprecated. This will not be allowed in Perl 5.32
+|perldiag/Constants from lexical variables potentially modified elsewhere are deprecated. This will not be allowed in Perl 5.32>
+
+This existing warning has had the I<this will not be allowed> text added
+in this release.
=item *
-dump() better written as CORE::dump(). dump() will no longer be available
-in Perl 5.30
+L<Deprecated use of C<my()> in false conditional. This will be a fatal error in Perl 5.30
+|perldiag/Deprecated use of C<my()> in false conditional. This will be a fatal error in Perl 5.30>
+
+This existing warning has had the I<this will be a fatal error> text added
+in this release.
=item *
-${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28
+L<C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available in Perl 5.30
+|perldiag/C<dump()> better written as C<CORE::dump()>. C<dump()> will no longer be available in Perl 5.30>
+
+This existing warning has had the I<no longer be available> text added in
+this release.
=item *
-File::Glob::glob() will disappear in perl 5.30. Use File::Glob::bsd_glob()
-instead.
+L<Experimental %s on scalar is now forbidden
+|perldiag/Experimental %s on scalar is now forbidden>
+
+This message is now followed by more helpful text.
+L<[perl #127976]|https://rt.perl.org/Public/Bug/Display.html?id=127976>
=item *
-%s() is deprecated on :utf8 handles. This will be a fatal error in Perl 5.30
+Experimental "%s" subs not enabled
+
+This warning was been removed, as lexical subs are no longer experimental.
=item *
-$* is no longer supported. Its use will be fatal in Perl 5.30
+Having more than one /%c regexp modifier is deprecated
+
+This deprecation warning has been removed, since C</xx> now has a new
+meaning.
=item *
-$* is no longer supported. Its use will be fatal in Perl 5.30
+L<%s() is deprecated on C<:utf8> handles. This will be a fatal error in Perl 5.30
+|perldiag/%s() is deprecated on C<:utf8> handles. This will be a fatal error in Perl 5.30>.
-=item *
+where "%s" is one of C<sysread>, C<recv>, C<syswrite>, or C<send>.
+
+This existing warning has had the I<this will be a fatal error> text added
+in this release.
-Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
+This warning is now enabled by default, as all C<deprecated> category
+warnings should be.
=item *
-Opening filehandle %s also as a directory. This will be a fatal
-error in Perl 5.28
+L<C<$*> is no longer supported. Its use will be fatal in Perl 5.30
+|perldiag/C<$*> is no longer supported. Its use will be fatal in Perl 5.30>
+
+This existing warning has had the I<its use will be fatal> text added in
+this release.
=item *
-Setting $/ to a reference to %s as a form of slurp is deprecated,
-treating as undef. This will be fatal in Perl 5.28
+L<C<$#> is no longer supported. Its use will be fatal in Perl 5.30
+|perldiag/C<$#> is no longer supported. Its use will be fatal in Perl 5.30>
+
+This existing warning has had the I<its use will be fatal> text added in
+this release.
=item *
-Unescaped left brace in regex is deprecated here (and will be fatal
-in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in m/%s/
+L<Malformed UTF-8 character%s
+|perldiag/Malformed UTF-8 character%s>
+
+Details as to the exact problem have been added at the end of this
+message
=item *
-Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
+L<Missing or undefined argument to %s
+|perldiag/Missing or undefined argument to %s>
+
+This warning used to warn about C<require>, even if it was actually C<do>
+which being executed. It now gets the operation name right.
=item *
-Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
+NO-BREAK SPACE in a charnames alias definition is deprecated
+
+This warning has been removed as the behavior is now an error.
=item *
-Use of code point 0x%s is deprecated; the permissible max is 0x%s.
-This will be fatal in Perl 5.28
+L<Odd nameE<sol>value argument for subroutine '%s'
+|perldiag/"Odd nameE<sol>value argument for subroutine '%s'">
+
+This warning now includes the name of the offending subroutine.
=item *
-Use of comma-less variable list is deprecated. Its use will be fatal
-in Perl 5.28
+L<Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28
+|perldiag/Opening dirhandle %s also as a file. This will be a fatal error in Perl 5.28>
+
+This existing warning has had the I<this will be a fatal error> text added
+in this release.
=item *
-Use of inherited AUTOLOAD for non-method %s() is deprecated. This
-will be fatal in Perl 5.28
+L<Opening filehandle %s also as a directory. This will be a fatal error in Perl 5.28
+|perldiag/Opening filehandle %s also as a directory. This will be a fatal error in Perl 5.28>
+
+This existing warning has had the I<this will be a fatal error> text added
+in this release.
=item *
-Use of strings with code points over 0xFF as arguments to %s operator
-is deprecated. This will be a fatal error in Perl 5.28
+panic: ck_split, type=%u
+
+panic: pp_split, pm=%p, s=%p
+
+These panic errors have been removed.
=item *
-Improve error for missing tie() package/method. This brings the error messages
-in line with the ones used for normal method calls, despite not using
-call_method().
+Passing malformed UTF-8 to "%s" is deprecated
+
+This warning has been changed to the fatal
+L<Malformed UTF-8 string in "%s"
+|perldiag/Malformed UTF-8 string in "%s">
=item *
-Make the sysread()/syswrite/() etc :utf8 handle warnings default. These
-warnings were under 'deprecated' previously.
+L<Setting C<< $E<sol> >> to a reference to %s as a form of slurp is deprecated, treating as undef. This will be fatal in Perl 5.28
+|perldiag/Setting C<< $E<sol> >> to a reference to %s as a form of slurp is deprecated, treating as undef. This will be fatal in Perl 5.28>
+
+This existing warning has had the I<this will be fatal> text added in
+this release.
=item *
-'do' errors now refer to 'do' (not 'require').
+L<C<${^ENCODING}> is no longer supported. Its use will be fatal in Perl 5.28|perldiag/"${^ENCODING} is no longer supported. Its use will be fatal in Perl 5.28">
+
+This warning used to be: "Setting C<${^ENCODING}> is deprecated".
+
+The special action of the variable C<${^ENCODING}> was formerly used to
+implement the C<encoding> pragma. As of Perl 5.26, rather than being
+deprecated, assigning to this variable now has no effect except to issue
+the warning.
=item *
-Details as to the exact problem have been added to the diagnostics that
-occur when malformed UTF-8 is encountered when trying to convert to a
-code point.
+L<Too few arguments for subroutine '%s'
+|perldiag/Too few arguments for subroutine '%s'>
+
+This warning now includes the name of the offending subroutine.
=item *
-Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
-blames the variable for an uninitialized-value warning encountered by the
-tied/magical code.
+L<Too many arguments for subroutine '%s'
+|perldiag/Too many arguments for subroutine '%s'>
+
+This warning now includes the name of the offending subroutine.
=item *
-L<Unescaped left brace in regex is illegal here in regex; marked by S<E<lt>-- HERE> in mE<sol>%sE<sol>|perldiag/"Unescaped left brace in regex is illegal here in regex; marked by S<<-- HERE> in m/%s/">
+L<Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in mE<sol>%sE<sol>
+|perldiag/Unescaped left brace in regex is deprecated here (and will be fatal in Perl 5.30), passed through in regex; marked by S<< E<lt>-- HERE >> in mE<sol>%sE<sol>>
-The word "here" has been added to the message that was raised in
-v5.25.1. This is to indicate that there are contexts in which unescaped
-left braces are not (yet) illegal.
+This existing warning has had the I<here (and will be fatal...)> text
+added in this release.
=item *
-Code like C<$x = $x . "a"> was incorrectly failing to yield a
-L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
-warning when C<$x> was a lexical variable with an undefined value. That has
-now been fixed. [perl #127877]
+L<Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28
+|perldiag/Unknown charname '' is deprecated. Its use will be fatal in Perl 5.28>
+
+This existing warning has had the I<its use will be fatal> text added in
+this release.
=item *
-When the error "Experimental push on scalar is now forbidden" is raised for
-the hash functions C<keys>, C<each>, and C<values>, it is now followed by
-the more helpful message, "Type of arg 1 to whatever must be hash or
-array". [perl #127976]
+L<Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28
+|perldiag/Use of bare E<lt>E<lt> to mean E<lt>E<lt>"" is deprecated. Its use will be fatal in Perl 5.28>
+
+This existing warning has had the I<its use will be fatal> text added in
+this release.
=item *
-C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
-argument to C<shift> or C<pop>, began crashing in Perl 5.14.0, but has now
-been fixed.
+L<Use of code point 0x%s is deprecated; the permissible max is 0x%s. This will be fatal in Perl 5.28
+|perldiag/Use of code point 0x%s is deprecated; the permissible max is 0x%s. This will be fatal in Perl 5.28>
+
+This existing warning has had the I<this will be fatal> text added in
+this release.
=item *
-C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
-string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
-bringing it into consistency with C<$$scalar>.
+L<Use of comma-less variable list is deprecated. Its use will be fatal in Perl 5.28
+|perldiag/Use of comma-less variable list is deprecated. Its use will be fatal in Perl 5.28>
+
+This existing warning has had the I<its use will be fatal> text added in
+this release.
=item *
-C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
-do, but merely produce a syntax error. [perl #128171]
+L<Use of inherited C<AUTOLOAD> for non-method %s() is deprecated. This will be fatal in Perl 5.28
+|perldiag/Use of inherited C<AUTOLOAD> for non-method %s() is deprecated. This will be fatal in Perl 5.28>
+
+This existing warning has had the I<this will be fatal> text added in
+this release.
=item *
-C<do> or C<require> with a reference or typeglob which, when stringified,
-contains a null character started crashing in Perl 5.20.0, but has now been
-fixed. [perl #128182]
+L<Use of strings with code points over 0xFF as arguments to %s operator is deprecated. This will be a fatal error in Perl 5.28
+|perldiag/Use of strings with code points over 0xFF as arguments to %s operator is deprecated. This will be a fatal error in Perl 5.28>
+
+This existing warning has had the I<this will be a fatal error> text added in
+this release.
=back
=item *
-Account for possibility of DOS file endings.
+Account for the possibility of DOS file endings.
=back
=item *
-Replace obscure character range with \w.
+Replace obscure character range with C<\w>.
=back
well within the 1000-character limit imposed by SMTP mail transfer agents.
This is particularly likely to be important for the list of arguments to
C<Configure>, which can readily exceed the limit if, for example, it names
-several non-default installation paths. This change also adds the first unit
-tests for perlbug. [perl #128020]
+several non-default installation paths. This change also adds the first unit
+tests for perlbug.
+L<[perl #128020]|https://rt.perl.org/Public/Bug/Display.html?id=128020>
=back
=item *
-The C<dtrace> build process has further changes:
+The C<dtrace> build process has further changes
+L<[perl #130108]|https://rt.perl.org/Public/Bug/Display.html?id=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 *
Zero out the alignment bytes when calculating the bytes for 80-bit C<NaN>
-and C<Inf> to make builds more reproducible. [perl #130133]
+and C<Inf> to make builds more reproducible.
+L<[perl #130133]|https://rt.perl.org/Public/Bug/Display.html?id=130133>
=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
+hash functions. Since we do not recommend the use of these functions
+we have removed them and their corresponding build options. Specifically
this includes the following build options:
PERL_HASH_FUNC_SDBM
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
-actually install the file. Disabling the second of those in each case saves
+actually install the file. Disabling the second of those in each case saves
over 750 lines of unhelpful output.
=item *
-Cleanup for clang -Weverything support. [perl 129961]
+Cleanup for C<clang -Weverything> support.
+L<[perl #129961]|https://rt.perl.org/Public/Bug/Display.html?id=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 *
F<make_ext.pl> no longer updates a module's F<pm_to_blib> file when no
files require updates. This could cause dependencies, F<perlmain.c>
-in particular, to be rebuilt unnecessarily. [perl #126710]
+in particular, to be rebuilt unnecessarily.
+L<[perl #126710]|https://rt.perl.org/Public/Bug/Display.html?id=126710>
=item *
C<Configure> now builds C<miniperl> and C<generate_uudmap> if you
invoke it with C<-Dusecrosscompiler> but not C<-Dtargethost=somehost>.
This means you can supply your target platform C<config.sh>, generate
-the headers and proceed to build your cross-target perl. [perl #127234]
+the headers and proceed to build your cross-target perl.
+L<[perl #127234]|https://rt.perl.org/Public/Bug/Display.html?id=127234>
=item *
When building with GCC 6 and link-time optimization (the C<-flto> option to
C<gcc>), C<Configure> was treating all probed symbols as present on the
-system, regardless of whether they actually exist. This has been fixed.
-[perl #128131]
+system, regardless of whether they actually exist. This has been fixed.
+L<[perl #128131]|https://rt.perl.org/Public/Bug/Display.html?id=128131>
=item *
The F<t/test.pl> library is used for internal testing of Perl itself, and
-also copied by several CPAN modules. Some of those modules must work on
+also copied by several CPAN modules. Some of those modules must work on
older versions of Perl, so F<t/test.pl> must in turn avoid newer Perl
-features. Compatibility with Perl 5.8 was inadvertently removed some time
-ago; it has now been restored. [perl #128052]
+features. Compatibility with Perl 5.8 was inadvertently removed some time
+ago; it has now been restored.
+L<[perl #128052]|https://rt.perl.org/Public/Bug/Display.html?id=128052>
=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 *
Some parts of the test suite that try to exhaustively test edge cases in the
regex implementation have been restricted to running for a maximum of five
-minutes. On slow systems they could otherwise take several hours, without
+minutes. On slow systems they could otherwise take several hours, without
significantly improving our understanding of the correctness of the code
under test.
=item *
-A new test script, F<t/op/decl-refs.t>, has been added to test the new feature,
-"Declaring a reference to a variable".
+A new test script, F<t/op/decl-refs.t>, has been added to test the new feature
+L</Declaring a reference to a variable>.
+
+=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 *
=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]
+source tree.
+L<[perl #124050]|https://rt.perl.org/Public/Bug/Display.html?id=124050>
=back
=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 VAX
-VAX floating point formats are now supported.
+VAX floating point formats are now supported on NetBSD.
=item VMS
=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<|>).
-
-=item *
-
-Remove some VMS-specific hacks from C<showlex.t>. These were added 15 years
-ago, and are no longer necessary for any VMS version now supported.
-
-=item *
-
-Move C<_pDEPTH> and C<_aDEPTH> after F<config.h> otherwise DEBUGGING
-may not be defined yet.
+now a colon (C<":">) when running under a Unix shell. There is no change when
+running under DCL (it's still C<"|">).
=item *
-VAXC has not been a possibility for a good long while, and the versions of the
-DEC/Compaq/HP/VSI C compiler that report themselves as "DEC" in a listing file
-are 15 years or more out-of-date and can be safely desupported.
+C<configure.com> now recognizes the VSI-branded C compiler and no longer
+recognizes the "DEC"-branded C compiler (as there hasn't been such a thing for
+15 or more years).
=back
(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
Some incompatibility may arise because of the bug fix that has been reverted
for VS2015 builds of perl, but there may well be incompatibility anyway because
of the rewritten CRT in VS2015 (I<e.g.>, see discussion at
-http://stackoverflow.com/questions/30412951).
+L<http://stackoverflow.com/questions/30412951>).
=back
=item *
-Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
+Tweaks for Win32 VC vs GCC detection makefile code. This fixes issue that CCHOME
depends on CCTYPE, which in auto detect mode is set after CCHOME, so CCHOME uses
-the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
+the uninit CCTYPE var. Also fix else vs .ELSE in makefile.mk
=item *
=back
-=item VMS And Win32
-
-Fix some breakage, add 'undef' value for default_inc_excludes_dot in build
-scripts.
-
=item Linux
Drop support for Linux a.out Linux has used ELF for over twenty years.
=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 L<C<sv_setpv_bufsize()>|perlapi/sv_setpv_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 L<C<SvPVCLEAR()>|perlapi/SvPVCLEAR> sets its C<SV>
+argument to an empty string,
+like Perl-space C<$x = ''>, but with several optimisations.
=item *
-New versions of macros like C<isALPHA_utf8> and C<toLOWER_utf8> have
-been added, each with the
-suffix C<_safe>, like C<isSPACE_utf8_safe>. These take an extra
-parameter, giving an upper limit of how far into the string it is safe
-to read. Using the old versions could cause attempts to read beyond the
-end of the input buffer if the UTF-8 is not well-formed, and their use
-now raises a deprecation warning. Details are at
-L<perlapi/Character classification>.
+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 *
-Calling macros like C<isALPHA_utf8> on malformed UTF-8 have issued a
-deprecation warning since Perl v5.18. They now die.
-Similarly, macros like C<toLOWER_utf8> on malformed UTF-8 now die.
+New versions of the API macros like C<isALPHA_utf8> and C<toLOWER_utf8>
+have been added, each with the suffix C<_safe>, like
+L<C<isSPACE_utf8_safe>|perlapi/isSPACE>. These take an extra
+parameter, giving an upper
+limit of how far into the string it is safe to read. Using the old
+versions could cause attempts to read beyond the end of the input buffer
+if the UTF-8 is not well-formed, and their use now raises a deprecation
+warning. Details are at L<perlapi/Character classification>.
=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.
+Macros like L<C<isALPHA_utf8>|perlapi/isALPHA> and
+L<C<toLOWER_utf8>|perlapi/toLOWER_utf8> now die if they detect
+that their input UTF-8 is malformed. A deprecation warning had been
+issued since Perl 5.18.
=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.
+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 *
+
+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>.
+They no longer abandon searching for other malformations when the first
+one is encountered. A call to one of these functions thus can generate
+multiple diagnostics, instead of just one.
=item *
-The function C<L<perlapi/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.
+L<C<valid_utf8_to_uvchr()>|perlapi/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, C<L<perlapi/utf8n_to_uvchr_error>>, has been added for
+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
+L<C<utf8_hop_safe()>|perlapi/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, L<C<utf8_hop_forward()>|perlapi/utf8_hop_forward> and
+L<C<utf8_hop_back()>|perlapi/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.
+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.
=item *
-The code in F<gv.c> that determines whether a variable has a special meaning
-to Perl has been simplified.
+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 *
-The C<DEBUGGING>-mode output for regex compilation and execution has been
-enhanced.
+The C<OP_PUSHRE> op has been eliminated and the C<OP_SPLIT> op has been
+changed from class C<LISTOP> to C<PMOP>.
+
+Formerly the first child of a split would be a pushre, which would have the
+split's regex attached to it. Now the regex is attached directly to the
+split op, and the pushre has been eliminated.
=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 L<C<op_class()>|perlapi/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 L<C<op_dump()>|perlapi/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 5.22.0.
-
-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.
+L<[perl #121734]|https://rt.perl.org/Public/Bug/Display.html?id=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
Attempting to use the deprecated variable C<$#> as the object in an
indirect object method call could cause a heap use after free or
-buffer overflow. [perl #129274]
+buffer overflow.
+L<[perl #129274]|https://rt.perl.org/Public/Bug/Display.html?id=129274>
=item *
When checking for an indirect object method call in some rare cases
the parser could reallocate the line buffer but then continue to use
-pointers to the old buffer. [perl #129190]
+pointers to the old buffer.
+L<[perl #129190]|https://rt.perl.org/Public/Bug/Display.html?id=129190>
=item *
-Supplying a glob as the format argument to L<perlfunc/formline> would
-cause an assertion failure. [perl #130722]
+Supplying a glob as the format argument to
+L<C<formline>|perlfunc/formline> would
+cause an assertion failure.
+L<[perl #130722]|https://rt.perl.org/Public/Bug/Display.html?id=130722>
=item *
Code like C< $value1 =~ qr/.../ ~~ $value2 > would have the match
-converted into a qr// operator, leaving extra elements on the stack to
-confuse any surrounding expression. [perl #130705]
+converted into a C<qr//> operator, leaving extra elements on the stack to
+confuse any surrounding expression.
+L<[perl #130705]|https://rt.perl.org/Public/Bug/Display.html?id=130705>
=item *
-Since 5.24.0 in some obscure cases, a regex which included code blocks
-from multiple sources (I<e.g.>, via embedded via qr// objects) could end up
-with the wrong current pad and crash or give weird results. [perl #129881]
+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.
+L<[perl #129881]|https://rt.perl.org/Public/Bug/Display.html?id=129881>
=item *
Occasionally C<local()>s in a code block within a patterns weren't being
undone when the pattern matching backtracked over the code block.
-[perl #126697]
+L<[perl #126697]|https://rt.perl.org/Public/Bug/Display.html?id=126697>
=item *
Using C<substr()> to modify a magic variable could access freed memory
-in some cases. [perl #129340]
+in some cases.
+L<[perl #129340]|https://rt.perl.org/Public/Bug/Display.html?id=129340>
=item *
Under C<use utf8>, the entire Perl program is now checked that the UTF-8
-is wellformed. This resolves [perl #126310].
+is wellformed.
+L<[perl #126310]|https://rt.perl.org/Public/Bug/Display.html?id=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
+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]
+the stack.
+L<[perl #130262]|https://rt.perl.org/Public/Bug/Display.html?id=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]
+allocated buffer.
+L<[perl #129149]|https://rt.perl.org/Public/Bug/Display.html?id=129149>
=item *
Supplying the form picture argument as part of the form argument list
where the picture specifies modifying the argument could cause an
-access to the new freed compiled form. [perl #129125]
-
-=item *
-
-Fix a problem with sort's build-in compare, where it would not sort
-correctly with 64-bit integers, and non-long doubles. [perl #130335]
+access to the new freed compiled form.
+L<[perl #129125]|https://rt.perl.org/Public/Bug/Display.html?id=129125>
=item *
-Fix issues with /(?{ ... E<lt>E<lt>EOF })/ that broke Method-Signatures. [perl #130398]
+The L<sort()|perlfunc/sort> operator's built-in numeric comparison
+function didn't handle large integers that weren't exactly
+representable by a double. This now uses the same code used to
+implement the C<< E<lt>=E<gt> >> operator.
+L<[perl #130335]|https://rt.perl.org/Public/Bug/Display.html?id=130335>
=item *
-Fix a macro which caused syntax error on an EBCDIC build.
+Fix issues with C</(?{ ... E<lt>E<lt>EOF })/> that broke
+L<Method::Signatures>.
+L<[perl #130398]|https://rt.perl.org/Public/Bug/Display.html?id=130398>
=item *
-Prevent tests from getting hung up on 'NonStop' option. [perl #130445]
+Prevent tests from getting hung up on 'NonStop' option.
+L<[perl #130445]|https://rt.perl.org/Public/Bug/Display.html?id=130445>
=item *
Fixed an assertion failure with C<chop> and C<chomp>, which
-could be triggered by C<chop(@x =~ tr/1/1/)>. [perl #130198].
+could be triggered by C<chop(@x =~ tr/1/1/)>.
+L<[perl #130198]|https://rt.perl.org/Public/Bug/Display.html?id=130198>.
=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.
+L<[perl #130495]|https://rt.perl.org/Public/Bug/Display.html?id=130495>.
=item *
-F<perldb> now ignores F</dev/tty> on non-Unix systems. [perl #113960];
+F<perldb> now ignores F</dev/tty> on non-Unix systems.
+L<[perl #113960]|https://rt.perl.org/Public/Bug/Display.html?id=113960>;
=item *
-Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined. [perl #130496].
+Fix assertion failure for C<{}-E<gt>$x> when C<$x> isn't defined.
+L<[perl #130496]|https://rt.perl.org/Public/Bug/Display.html?id=130496>.
=item *
-DragonFly BSD now has support for setproctitle(). [perl #130068].
+DragonFly BSD now has support for C<setproctitle()>.
+L<[perl #130068]|https://rt.perl.org/Public/Bug/Display.html?id=130068>.
=item *
-Fix an assertion error which could be triggered when lookahead string
-in patterns exceeded a minimum length. [perl #130522].
+Fix an assertion error which could be triggered when a lookahead string
+in patterns exceeded a minimum length.
+L<[perl #130522]|https://rt.perl.org/Public/Bug/Display.html?id=130522>.
=item *
-Only warn once per literal about a misplaced C<_>. [perl #70878].
+Only warn once per literal about a misplaced C<"_">.
+L<[perl #70878]|https://rt.perl.org/Public/Bug/Display.html?id=70878>.
=item *
-Ensure range-start is set after error in C<tr///>. [perl #129342].
+Ensure range-start is set after error in C<tr///>.
+L<[perl #129342]|https://rt.perl.org/Public/Bug/Display.html?id=129342>.
=item *
Don't read past start of string for unmatched backref; otherwise,
-we may have heap buffer overflow. [perl #129377].
+we may have heap buffer overflow.
+L<[perl #129377]|https://rt.perl.org/Public/Bug/Display.html?id=129377>.
=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
+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 *
=item *
-A crash in executing a regex with a floating UTF-8 substring against a
-target string that also used UTF-8 has been fixed. [perl #129350]
+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.
+L<[perl #129350]|https://rt.perl.org/Public/Bug/Display.html?id=129350>
=item *
Previously, a shebang line like C<#!perl -i u> could be erroneously
-interpreted as requesting the C<-u> option. This has been fixed. [perl
+interpreted as requesting the C<-u> option. This has been fixed. [perl
#129336]
=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]
+match.
+L<[perl #129897]|https://rt.perl.org/Public/Bug/Display.html?id=129897>
=item *
Certain regexes making use of the experimental C<regex_sets> feature could
-trigger an assertion failure. This has been fixed. [perl #129322]
+trigger an assertion failure. This has been fixed.
+L<[perl #129322]|https://rt.perl.org/Public/Bug/Display.html?id=129322>
=item *
Invalid assignments to a reference constructor (I<e.g.>, C<\eval=time>) could
-sometimes crash in addition to giving a syntax error. [perl #125679]
+sometimes crash in addition to giving a syntax error.
+L<[perl #125679]|https://rt.perl.org/Public/Bug/Display.html?id=125679>
=item *
The parser could sometimes crash if a bareword came after C<evalbytes>.
-[perl #129196]
+L<[perl #129196]|https://rt.perl.org/Public/Bug/Display.html?id=129196>
=item *
Autoloading via a method call would warn erroneously ("Use of inherited
AUTOLOAD for non-method") if there was a stub present in the package into
which the invocant had been blessed. The warning is no longer emitted in
-such circumstances. [perl #47047]
-
-=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]
+such circumstances.
+L<[perl #47047]|https://rt.perl.org/Public/Bug/Display.html?id=47047>
=item *
The use of C<splice> on arrays with nonexistent elements could cause other
-operators to crash. [perl #129164]
+operators to crash.
+L<[perl #129164]|https://rt.perl.org/Public/Bug/Display.html?id=129164>
=item *
Fixed case where C<re_untuit_start> will overshoot the length of a utf8
-string. [perl #129012]
+string.
+L<[perl #129012]|https://rt.perl.org/Public/Bug/Display.html?id=129012>
=item *
Handle C<CXt_SUBST> better in C<Perl_deb_stack_all>, previously it wasn't
checking that the I<current> C<cx> is the right type, and instead was always
-checking the base C<cx> (effectively a noop). [perl #129029]
+checking the base C<cx> (effectively a noop).
+L<[perl #129029]|https://rt.perl.org/Public/Bug/Display.html?id=129029>
=item *
-Fixed two possible use-after-free bugs in C<Perl_yylex>. C<Perl_yylex>
+Fixed two possible use-after-free bugs in C<Perl_yylex>.
C<Perl_yylex>
maintains up to two pointers into the parser buffer, one of which can
-become stale under the right conditions. [perl #129069]
+become stale under the right conditions.
+L<[perl #129069]|https://rt.perl.org/Public/Bug/Display.html?id=129069>
=item *
Fixed a crash with C<s///l> where it thought it was dealing with UTF-8
-when it wasn't. [perl #129038]
+when it wasn't.
+L<[perl #129038]|https://rt.perl.org/Public/Bug/Display.html?id=129038>
=item *
Fixed place where regex was not setting the syntax error correctly.
-[perl #129122]
+L<[perl #129122]|https://rt.perl.org/Public/Bug/Display.html?id=129122>
=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
just past the end of the logical string. An assertion failure was the
-result. [perl #129287]
+result.
+L<[perl #129287]|https://rt.perl.org/Public/Bug/Display.html?id=129287>
=item *
-Check C<pack_sockaddr_un()>'s return value because C<pack_sockaddr_un()>
-silently truncates the supplied path if it won't fit into the C<sun_path>
-member of C<sockaddr_un>. This may change in the future, but for now
-check the path in theC<sockaddr> matches the desired path, and skip if
-it doesn't. [perl #128095]
+Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
+cases this is used in building error messages.
+L<[perl #128988]|https://rt.perl.org/Public/Bug/Display.html?id=128988>
=item *
-Make sure C<PL_oldoldbufptr> is preserved in C<scan_heredoc()>. In some
-cases this is used in building error messages. [perl #128988]
-
-=item *
-
-Check for null PL_curcop in IN_LC() [perl #129106]
+Fix segfault when run with C<-DC> options on DEBUGGING builds.
+L<[perl #129106]|https://rt.perl.org/Public/Bug/Display.html?id=129106>
=item *
Fixed the parser error handling for an 'C<:attr(foo>' that does not have
-an ending 'C<)>'.
+an ending 'C<")">'.
=item *
Fix C<Perl_delimcpy()> to handle a backslash as last char, this
-actually fixed two bugs, [perl #129064] and [perl #129176].
+actually fixed two bugs,
+L<[perl #129064]|https://rt.perl.org/Public/Bug/Display.html?id=129064> and
+L<[perl #129176]|https://rt.perl.org/Public/Bug/Display.html?id=129176>.
=item *
-[perl #129267] rework gv_fetchmethod_pvn_flags separator parsing to
-prevent possible string overrun with invalid len in gv.c
+L<[perl #129267]|https://rt.perl.org/Public/Bug/Display.html?id=129267> rework C<gv_fetchmethod_pvn_flags> separator parsing to
+prevent possible string overrun with invalid len in F<gv.c>
=item *
Problems with in-place array sorts: code like C<@a = sort { ... } @a>,
where the source and destination of the sort are the same plain array, are
-optimised to do less copying around. Two side-effects of this optimisation
+optimised to do less copying around. Two side-effects of this optimisation
were that the contents of C<@a> as visible to to sort routine were
partially sorted, and under some circumstances accessing C<@a> during the
-sort could crash the interpreter. Both these issues have been fixed, and
+sort could crash the interpreter. Both these issues have been fixed, and
Sort functions see the original value of C<@a>.
=item *
Non-ASCII string delimiters are now reported correctly in error messages
-for unterminated strings. [perl #128701]
+for unterminated strings.
+L<[perl #128701]|https://rt.perl.org/Public/Bug/Display.html?id=128701>
=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.
+L<[perl #126482]|https://rt.perl.org/Public/Bug/Display.html?id=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
-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].
+A regression in v5.24 with C<tr/\N{U+...}/foo/> when the code point was between
+128 and 255 has been fixed.
+L<[perl #128734]|https://rt.perl.org/Public/Bug/Display.html?id=128734>.
=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]
+displayable nor enterable by any editor.
+L<[perl #128738]|https://rt.perl.org/Public/Bug/Display.html?id=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]
+L<[perl #128951]|https://rt.perl.org/Public/Bug/Display.html?id=128951>
=item *
=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< until ($x = 1) { ... } > and C< ... until $x = 1 > now properly
-warn when syntax warnings are enabled. [perl #127333]
+warn when syntax warnings are enabled.
+L<[perl #127333]|https://rt.perl.org/Public/Bug/Display.html?id=127333>
=item *
socket() now leaves the error code returned by the system in C<$!> on
-failure. [perl #128316]
+failure.
+L<[perl #128316]|https://rt.perl.org/Public/Bug/Display.html?id=128316>
=item *
Assignment variants of any bitwise ops under the C<bitwise> feature would
-crash if the left-hand side was an array or hash. [perl #128204]
+crash if the left-hand side was an array or hash.
+L<[perl #128204]|https://rt.perl.org/Public/Bug/Display.html?id=128204>
=item *
C<require> followed by a single colon (as in C<foo() ? require : ...> is
-now parsed correctly as C<require> with implicit $_, rather than
-C<require "">. [perl #128307]
+now parsed correctly as C<require> with implicit C<$_>, rather than
+C<require "">.
+L<[perl #128307]|https://rt.perl.org/Public/Bug/Display.html?id=128307>
=item *
List assignment to C<vec> or C<substr> with an array or hash for its first
argument used to result in crashes or "Can't coerce" error messages at run
time, unlike scalar assignment, which would give an error at compile time.
-List assignment now gives a compile-time error, too. [perl #128260]
+List assignment now gives a compile-time error, too.
+L<[perl #128260]|https://rt.perl.org/Public/Bug/Display.html?id=128260>
=item *
Expressions containing an C<&&> or C<||> operator (or their synonyms C<and>
-and C<or>) were being compiled incorrectly in some cases. If the left-hand
+and C<or>) were being compiled incorrectly in some cases. If the left-hand
side consisted of either a negated bareword constant or a negated C<do {}>
block containing a constant expression, and the right-hand side consisted of
a negated non-foldable expression, one of the negations was effectively
-ignored. The same was true of C<if> and C<unless> statement modifiers,
-though with the left-hand and right-hand sides swapped. This long-standing
-bug has now been fixed. [perl #127952]
+ignored. The same was true of C<if> and C<unless> statement modifiers,
+though with the left-hand and right-hand sides swapped. This long-standing
+bug has now been fixed.
+L<[perl #127952]|https://rt.perl.org/Public/Bug/Display.html?id=127952>
=item *
C<reset> with an argument no longer crashes when encountering stash entries
-other than globs. [perl #128106]
+other than globs.
+L<[perl #128106]|https://rt.perl.org/Public/Bug/Display.html?id=128106>
=item *
Assignment of hashes to, and deletion of, typeglobs named C<*::::::> no
-longer causes crashes. [perl #128086]
+longer causes crashes.
+L<[perl #128086]|https://rt.perl.org/Public/Bug/Display.html?id=128086>
=item *
-Handle SvIMMORTALs in LHS of list assign. [perl #129991]
+Handle C<SvIMMORTALs> in LHS of list assign.
+L<[perl #129991]|https://rt.perl.org/Public/Bug/Display.html?id=129991>
=item *
-[perl #130010] a5540cf breaks texinfo
-
-This involved user-defined Unicode properties.
+Assertion failure with user-defined Unicode-like properties.
+L<[perl #130010]|https://rt.perl.org/Public/Bug/Display.html?id=130010>
=item *
List assignment in list context where the LHS contained aggregates and
where there were not enough RHS elements, used to skip scalar lvalues.
Previously, C<(($a,$b,@c,$d) = (1))> in list context returned C<($a)>; now
-it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
-returns C<($a,$b,$c)>. This can be seen in the following:
+it returns C<($a,$b,$d)>. C<(($a,$b,$c) = (1))> is unchanged: it still
+returns C<($a,$b,$c)>. This can be seen in the following:
sub inc { $_++ for @_ }
inc(($a,$b,@c,$d) = (10))
=item *
-[perl 129903]
+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.
+L<[perl #129903]|https://rt.perl.org/Public/Bug/Display.html?id=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.
+=item *
-We avoid the segfault by simply forbidding the use of the empty pattern when it
-would resolve to the currently executing pattern.
+Avoid reading beyond the end of the line buffer when there's a
+short UTF-8 character at the end.
+L<[perl #128997]|https://rt.perl.org/Public/Bug/Display.html?id=128997>
=item *
-[perl 128997] Avoid reading beyond the end of the line buffer when there's a
-short UTF-8 character at the end.
+Fix firstchar bitmap under utf8 with prefix optimisation.
+L<[perl #129950]|https://rt.perl.org/Public/Bug/Display.html?id=129950>
+
+=item *
+
+Make F<Carp/t/arg_string.t>: be liberal in C<f>/C<p> formats.
+L<[perl #129954]|https://rt.perl.org/Public/Bug/Display.html?id=129954>
=item *
-[perl 129950] fix firstchar bitmap under utf8 with prefix optimisation.
+Make C<do "a\0b"> fail silently instead of throwing an error.
+L<[perl #129928]|https://rt.perl.org/Public/Bug/Display.html?id=129928>
=item *
-[perl 129954] Carp/t/arg_string.t: be liberal in f/p formats.
+Make C<chdir> allocate the stack it needs.
+L<[perl #129130]|https://rt.perl.org/Public/Bug/Display.html?id=129130>
=item *
-[perl 129928] make do "a\0b" fail silently instead of throwing.
+C<do> errors now refer to C<do> (not C<require>).
=item *
-[perl 129130] make chdir allocate the stack it needs.
+Executing C<undef $x> where C<$x> is tied or magical no longer incorrectly
+blames the variable for an uninitialized-value warning encountered by the
+tied/magical code.
+
+=item *
+
+Code like C<$x = $x . "a"> was incorrectly failing to yield a
+L<use of uninitialized value|perldiag/"Use of uninitialized value%s">
+warning when C<$x> was a lexical variable with an undefined value. That has
+now been fixed.
+L<[perl #127877]|https://rt.perl.org/Public/Bug/Display.html?id=127877>
+
+=item *
+
+C<undef *_; shift> or C<undef *_; pop> inside a subroutine, with no
+argument to C<shift> or C<pop>, began crashing in Perl 5.14, but has now
+been fixed.
+
+=item *
+
+C<< "string$scalar-E<gt>$*" >> now correctly prefers concat overloading to
+string overloading if C<< $scalar-E<gt>$* >> returns an overloaded object,
+bringing it into consistency with C<$$scalar>.
+
+=item *
+
+C<< /@0{0*-E<gt>@*/*0 >> and similar contortions used to crash, but no longer
+do, but merely produce a syntax error.
+L<[perl #128171]|https://rt.perl.org/Public/Bug/Display.html?id=128171>
+
+=item *
+
+C<do> or C<require> with a reference or typeglob which, when stringified,
+contains a null character started crashing in Perl 5.20, but has now been
+fixed.
+L<[perl #128182]|https://rt.perl.org/Public/Bug/Display.html?id=128182>
+
+=item *
+
+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().
=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 v5.22.0 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>.
=item *
-The module L<lexical::underscore> no longer works on perl v5.24.0, because perl
+The module L<lexical::underscore> no longer works on Perl 5.24, because perl
no longer has a lexical C<$_>!
=item *
-C<mod_perl> has been patched for compatibility for v5.22.0 and later but no
+C<mod_perl> has been patched for compatibility for v5.22 and later but no
release has been made. The relevant patch (and other changes) can be found in
their source code repository, L<mirrored at
GitHub|https://github.com/apache/mod_perl/commit/82827132efd3c2e25cc413c85af61bb63375da6e>.
=item *
-Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.0.
+Fixed issues with recursive regexes. The behavior was fixed in Perl 5.24.
L<[perl #126182]|https://rt.perl.org/Public/Bug/Display.html?id=126182>
=back
=head1 Obituary
Jon Portnoy (AVENJ), a prolific Perl author and admired Gentoo community
-member, has passed away on August 10, 2016. He will be remembered and
-missed by all those with which he came in contact and enriched with his
+member, has passed away on August 10, 2016. He will be remembered and
+missed by all those who he came in contact with, and enriched with his
intellect, wit, and spirit.
-It is with great sadness we also note Kip Hampton's passing.. Probably
+It is with great sadness that we also note Kip Hampton's passing. Probably
best known as the author of the Perl & XML column on XML.com, he was a
core contributor to AxKit, an XML server platform that became an Apache
-Foundation project. He was a frequent speaker in the early days at
-OSCON, and most recently at YAPC::NA in Madison. He was frequently on
+Foundation project. He was a frequent speaker in the early days at
+OSCON, and most recently at YAPC::NA in Madison. He was frequently on
irc.perl.org as `ubu`, generally in the #axkit-dahut community, the
group responsible for YAPC::NA Asheville in 2011.
approximately 230,000 lines of changes to 1,800 .pm, .t, .c and .h files.
Perl continues to flourish into its third decade thanks to a vibrant community
-of users and developers. The following people are known to have contributed the
+of users and developers. The following people are known to have contributed the
improvements that became Perl 5.26.0:
Aaron Crane, Abigail, Ævar Arnfjörð Bjarmason, Alex Vandiver, Andreas
Yves Orton, Zefram.
The list above is almost certainly incomplete as it is automatically generated
-from version control history. In particular, it does not include the names of
+from version control history. In particular, it does not include the names of
the (very much appreciated) contributors who reported issues to the Perl bug
tracker.
Many of the changes included in this version originated in the CPAN modules
-included in Perl's core. We're grateful to the entire CPAN community for
+included in Perl's core. We're grateful to the entire CPAN community for
helping Perl to flourish.
For a more complete list of all of Perl's historical contributors, please see
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