=head1 NAME
-perldelta - what is new for perl v5.22.0
+[ this is a template for a new perldelta file. Any text flagged as XXX needs
+to be processed before release. ]
-=head1 DESCRIPTION
-
-This document describes differences between the 5.20.0 release and the 5.22.0
-release.
-
-If you are upgrading from an earlier release such as 5.18.0, first read
-L<perl5200delta>, which describes differences between 5.18.0 and 5.20.0.
-
-=head1 Core Enhancements
-
-=head2 New bitwise operators
-
-A new experimental facility has been added that makes the four standard
-bitwise operators (C<& | ^ ~>) treat their operands consistently as
-numbers, and introduces four new dotted operators (C<&. |. ^. ~.>) that
-treat their operands consistently as strings. The same applies to the
-assignment variants (C<&= |= ^= &.= |.= ^.=>).
-
-To use this, enable the "bitwise" feature and disable the
-"experimental::bitwise" warnings category. See L<perlop/Bitwise String
-Operators> for details.
-L<[perl #123466]|https://rt.perl.org/Ticket/Display.html?id=123466>.
-
-=head2 New double-diamond operator
-
-C<<< <<>> >>> is like C<< <> >> but uses three-argument C<open> to open
-each file in C<@ARGV>. This means that each element of C<@ARGV> will be treated
-as an actual file name, and C<"|foo"> won't be treated as a pipe open.
-
-=head2 New C<\b> boundaries in regular expressions
-
-=head3 C<qr/\b{gcb}/>
-
-C<gcb> stands for Grapheme Cluster Boundary. It is a Unicode property
-that finds the boundary between sequences of characters that look like a
-single character to a native speaker of a language. Perl has long had
-the ability to deal with these through the C<\X> regular escape
-sequence. Now, there is an alternative way of handling these. See
-L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
-
-=head3 C<qr/\b{wb}/>
-
-C<wb> stands for Word Boundary. It is a Unicode property
-that finds the boundary between words. This is similar to the plain
-C<\b> (without braces) but is more suitable for natural language
-processing. It knows, for example, that apostrophes can occur in the
-middle of words. See L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
-
-=head3 C<qr/\b{sb}/>
-
-C<sb> stands for Sentence Boundary. It is a Unicode property
-to aid in parsing natural language sentences.
-See L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
-
-=head2 Non-Capturing Regular Expression Flag
-
-Regular expressions now support a C</n> flag that disables capturing
-and filling in C<$1>, C<$2>, etc inside of groups:
-
- "hello" =~ /(hi|hello)/n; # $1 is not set
-
-This is equivalent to putting C<?:> at the beginning of every capturing group.
-
-See L<perlre/"n"> for more information.
-
-=head2 C<use re 'strict'>
-
-This applies stricter syntax rules to regular expression patterns
-compiled within its scope. This will hopefully alert you to typos and
-other unintentional behavior that backwards-compatibility issues prevent
-us from reporting in normal regular expression compilations. Because the
-behavior of this is subject to change in future Perl releases as we gain
-experience, using this pragma will raise a warning of category
-C<experimental::re_strict>.
-See L<'strict' in re|re/'strict' mode>.
-
-=head2 Unicode 7.0 (with correction) is now supported
-
-For details on what is in this release, see
-L<http://www.unicode.org/versions/Unicode7.0.0/>.
-The version of Unicode 7.0 that comes with Perl includes
-a correction dealing with glyph shaping in Arabic
-(see L<http://www.unicode.org/errata/#current_errata>).
-
-
-=head2 S<C<use locale>> can restrict which locale categories are affected
-
-It is now possible to pass a parameter to S<C<use locale>> to specify
-a subset of locale categories to be locale-aware, with the remaining
-ones unaffected. See L<perllocale/The "use locale" pragma> for details.
-
-=head2 Perl now supports POSIX 2008 locale currency additions
-
-On platforms that are able to handle POSIX.1-2008, the
-hash returned by
-L<C<POSIX::localeconv()>|perllocale/The localeconv function>
-includes the international currency fields added by that version of the
-POSIX standard. These are
-C<int_n_cs_precedes>,
-C<int_n_sep_by_space>,
-C<int_n_sign_posn>,
-C<int_p_cs_precedes>,
-C<int_p_sep_by_space>,
-and
-C<int_p_sign_posn>.
-
-=head2 Better heuristics on older platforms for determining locale UTF-8ness
-
-On platforms that implement neither the C99 standard nor the POSIX 2001
-standard, determining if the current locale is UTF-8 or not depends on
-heuristics. These are improved in this release.
-
-=head2 Aliasing via reference
-
-Variables and subroutines can now be aliased by assigning to a reference:
-
- \$c = \$d;
- \&x = \&y;
-
-Aliasing can also be accomplished
-by using a backslash before a C<foreach> iterator variable; this is
-perhaps the most useful idiom this feature provides:
-
- foreach \%hash (@array_of_hash_refs) { ... }
-
-This feature is experimental and must be enabled via S<C<use feature
-'refaliasing'>>. It will warn unless the C<experimental::refaliasing>
-warnings category is disabled.
-
-See L<perlref/Assigning to References>
-
-=head2 C<prototype> with no arguments
-
-C<prototype()> with no arguments now infers C<$_>.
-L<[perl #123514]|https://rt.perl.org/Ticket/Display.html?id=123514>.
-
-=head2 New C<:const> subroutine attribute
-
-The C<const> attribute can be applied to an anonymous subroutine. It
-causes the new sub to be executed immediately whenever one is created
-(I<i.e.> when the C<sub> expression is evaluated). Its value is captured
-and used to create a new constant subroutine that is returned. This
-feature is experimental. See L<perlsub/Constant Functions>.
-
-=head2 C<fileno> now works on directory handles
-
-When the relevant support is available in the operating system, the
-C<fileno> builtin now works on directory handles, yielding the
-underlying file descriptor in the same way as for filehandles. On
-operating systems without such support, C<fileno> on a directory handle
-continues to return the undefined value, as before, but also sets C<$!> to
-indicate that the operation is not supported.
-
-Currently, this uses either a C<dd_fd> member in the OS C<DIR>
-structure, or a C<dirfd(3)> function as specified by POSIX.1-2008.
-
-=head2 List form of pipe open implemented for Win32
-
-The list form of pipe:
-
- open my $fh, "-|", "program", @arguments;
-
-is now implemented on Win32. It has the same limitations as C<system
-LIST> on Win32, since the Win32 API doesn't accept program arguments
-as a list.
-
-=head2 Assignment to list repetition
-
-C<(...) x ...> can now be used within a list that is assigned to, as long
-as the left-hand side is a valid lvalue. This allows S<C<(undef,undef,$foo)
-= that_function()>> to be written as S<C<((undef)x2, $foo) = that_function()>>.
-
-=head2 Infinity and NaN (not-a-number) handling improved
-
-Floating point values are able to hold the special values infinity, negative
-infinity, and NaN (not-a-number). Now we more robustly recognize and
-propagate the value in computations, and on output normalize them to the strings
-C<Inf>, C<-Inf>, and C<NaN>.
-
-See also the L<POSIX> enhancements.
-
-=head2 Floating point parsing has been improved
-
-Parsing and printing of floating point values has been improved.
-
-As a completely new feature, hexadecimal floating point literals
-(like C<0x1.23p-4>) are now supported, and they can be output with
-S<C<printf "%a">>. See L<perldata/Scalar value constructors> for more
-details.
-
-=head2 Packing infinity or not-a-number into a character is now fatal
-
-Before, when trying to pack infinity or not-a-number into a
-(signed) character, Perl would warn, and assumed you tried to
-pack C<< 0xFF >>; if you gave it as an argument to C<< chr >>,
-C<< U+FFFD >> was returned.
-
-But now, all such actions (C<< pack >>, C<< chr >>, and C<< print '%c' >>)
-result in a fatal error.
-
-=head2 Experimental C Backtrace API
-
-Perl now supports (via a C level API) retrieving
-the C level backtrace (similar to what symbolic debuggers like gdb do).
-
-The backtrace returns the stack trace of the C call frames,
-with the symbol names (function names), the object names (like "perl"),
-and if it can, also the source code locations (file:line).
-
-The supported platforms are Linux and OS X (some *BSD might work at
-least partly, but they have not yet been tested).
-
-The feature needs to be enabled with C<Configure -Dusecbacktrace>.
-
-See L<perlhacktips/"C backtrace"> for more information.
-
-=head1 Security
-
-=head2 Perl is now compiled with C<-fstack-protector-strong> if available
-
-Perl has been compiled with the anti-stack-smashing option
-C<-fstack-protector> since 5.10.1. Now Perl uses the newer variant
-called C<-fstack-protector-strong>, if available.
-
-=head2 The L<Safe> module could allow outside packages to be replaced
-
-Critical bugfix: outside packages could be replaced. L<Safe> has
-been patched to 2.38 to address this.
-
-=head2 Perl is now always compiled with C<-D_FORTIFY_SOURCE=2> if available
-
-The 'code hardening' option called C<_FORTIFY_SOURCE>, available in
-gcc 4.*, is now always used for compiling Perl, if available.
-
-Note that this isn't necessarily a huge step since in many platforms
-the step had already been taken several years ago: many Linux
-distributions (like Fedora) have been using this option for Perl,
-and OS X has enforced the same for many years.
-
-=head1 Incompatible Changes
-
-=head2 Subroutine signatures moved before attributes
-
-The experimental sub signatures feature, as introduced in 5.20, parsed
-signatures after attributes. In this release, following feedback from users
-of the experimental feature, the positioning has been moved such that
-signatures occur after the subroutine name (if any) and before the attribute
-list (if any).
-
-=head2 C<&> and C<\&> prototypes accepts only subs
-
-The C<&> prototype character now accepts only anonymous subs (C<sub
-{...}>), things beginning with C<\&>, or an explicit C<undef>. Formerly
-it erroneously also allowed references to arrays, hashes, and lists.
-L<[perl #4539]|https://rt.perl.org/Ticket/Display.html?id=4539>.
-L<[perl #123062]|https://rt.perl.org/Ticket/Display.html?id=123062>.
-L<[perl #123062]|https://rt.perl.org/Ticket/Display.html?id=123475>.
-
-In addition, the C<\&> prototype was allowing subroutine calls, whereas
-now it only allows subroutines: C<&foo> is still permitted as an argument,
-while C<&foo()> and C<foo()> no longer are.
-L<[perl #77860]|https://rt.perl.org/Ticket/Display.html?id=77860>.
-
-=head2 C<use encoding> is now lexical
-
-The L<encoding> pragma's effect is now limited to lexical scope. This
-pragma is deprecated, but in the meantime, it could adversely affect
-unrelated modules that are included in the same program; this change
-fixes that.
-
-=head2 List slices returning empty lists
-
-List slices now return an empty list only if the original list was empty
-(or if there are no indices). Formerly, a list slice would return an empty
-list if all indices fell outside the original list; now it returns a list
-of C<undef> values in that case.
-L<[perl #114498]|https://rt.perl.org/Ticket/Display.html?id=114498>.
-
-=head2 C<\N{}> with a sequence of multiple spaces is now a fatal error
-
-E.g. S<C<\N{TOOE<nbsp>E<nbsp>MANY SPACES}>> or S<C<\N{TRAILING SPACE }>>.
-This has been deprecated since v5.18.
-
-=head2 S<C<use UNIVERSAL '...'>> is now a fatal error
-
-Importing functions from C<UNIVERSAL> has been deprecated since v5.12, and
-is now a fatal error. S<C<use UNIVERSAL>> without any arguments is still
-allowed.
-
-=head2 In double-quotish C<\cI<X>>, I<X> must now be a printable ASCII character
-
-In prior releases, failure to do this raised a deprecation warning.
-
-=head2 Splitting the tokens C<(?> and C<(*> in regular expressions is now a fatal compilation error.
-
-These had been deprecated since v5.18.
-
-=head2 C<qr/foo/x> now ignores all Unicode pattern white space
-
-The C</x> regular expression modifier allows the pattern to contain
-white space and comments (both of which are ignored) for improved
-readability. Until now, not all the white space characters that Unicode
-designates for this purpose were handled. The additional ones now
-recognized are:
-
- U+0085 NEXT LINE
- U+200E LEFT-TO-RIGHT MARK
- U+200F RIGHT-TO-LEFT MARK
- U+2028 LINE SEPARATOR
- U+2029 PARAGRAPH SEPARATOR
-
-The use of these characters with C</x> outside bracketed character
-classes and when not preceded by a backslash has raised a deprecation
-warning since v5.18. Now they will be ignored.
-
-=head2 Comment lines within S<C<(?[ ])>> are now ended only by a C<\n>
-
-S<C<(?[ ])>> is an experimental feature, introduced in v5.18. It operates
-as if C</x> is always enabled. But there was a difference: comment
-lines (following a C<#> character) were terminated by anything matching
-C<\R> which includes all vertical whitespace, such as form feeds. For
-consistency, this is now changed to match what terminates comment lines
-outside S<C<(?[ ])>>, namely a C<\n> (even if escaped), which is the
-same as what terminates a heredoc string and formats.
-
-=head2 C<(?[...])> operators now follow standard Perl precedence
-
-This experimental feature allows set operations in regular expression patterns.
-Prior to this, the intersection operator had the same precedence as the other
-binary operators. Now it has higher precedence. This could lead to different
-outcomes than existing code expects (though the documentation has always noted
-that this change might happen, recommending fully parenthesizing the
-expressions). See L<perlrecharclass/Extended Bracketed Character Classes>.
-
-=head2 Omitting C<%> and C<@> on hash and array names is no longer permitted
-
-Really old Perl let you omit the C<@> on array names and the C<%> on hash
-names in some spots. This has issued a deprecation warning since Perl
-5.000, and is no longer permitted.
-
-=head2 C<"$!"> text is now in English outside the scope of C<use locale>
-
-Previously, the text, unlike almost everything else, always came out
-based on the current underlying locale of the program. (Also affected
-on some systems is C<"$^E">.) For programs that are unprepared to
-handle locale differences, this can cause garbage text to be displayed.
-It's better to display text that is translatable via some tool than
-garbage text which is much harder to figure out.
-
-=head2 C<"$!"> text will be returned in UTF-8 when appropriate
-
-The stringification of C<$!> and C<$^E> will have the UTF-8 flag set
-when the text is actually non-ASCII UTF-8. This will enable programs
-that are set up to be locale-aware to properly output messages in the
-user's native language. Code that needs to continue the 5.20 and
-earlier behavior can do the stringification within the scopes of both
-S<C<use bytes>> and S<C<use locale ":messages">>. Within these two
-scopes, no other Perl operations will
-be affected by locale; only C<$!> and C<$^E> stringification. The
-C<bytes> pragma causes the UTF-8 flag to not be set, just as in previous
-Perl releases. This resolves
-L<[perl #112208]|https://rt.perl.org/Ticket/Display.html?id=112208>.
-
-=head2 Support for C<?PATTERN?> without explicit operator has been removed
-
-The C<m?PATTERN?> construct, which allows matching a regex only once,
-previously had an alternative form that was written directly with a question
-mark delimiter, omitting the explicit C<m> operator. This usage has produced
-a deprecation warning since 5.14.0. It is now a syntax error, so that the
-question mark can be available for use in new operators.
-
-=head2 C<defined(@array)> and C<defined(%hash)> are now fatal errors
-
-These have been deprecated since v5.6.1 and have raised deprecation
-warnings since v5.16.
-
-=head2 Using a hash or an array as a reference are now fatal errors
-
-For example, C<< %foo->{"bar"} >> now causes a fatal compilation
-error. These have been deprecated since before v5.8, and have raised
-deprecation warnings since then.
-
-=head2 Changes to the C<*> prototype
-
-The C<*> character in a subroutine's prototype used to allow barewords to take
-precedence over most, but not all, subroutine names. It was never
-consistent and exhibited buggy behavior.
-
-Now it has been changed, so subroutines always take precedence over barewords,
-which brings it into conformity with similarly prototyped built-in functions:
-
- sub splat(*) { ... }
- sub foo { ... }
- splat(foo); # now always splat(foo())
- splat(bar); # still splat('bar') as before
- close(foo); # close(foo())
- close(bar); # close('bar')
-
-=head1 Deprecations
-
-=head2 Setting C<${^ENCODING}> to anything but C<undef>
-
-This variable allows Perl scripts to be written in an encoding other than
-ASCII or UTF-8. However, it affects all modules globally, leading
-to wrong answers and segmentation faults. New scripts should be written
-in UTF-8; old scripts should be converted to UTF-8, which is easily done
-with the L<piconv> utility.
-
-=head2 Use of non-graphic characters in single-character variable names
-
-The syntax for single-character variable names is more lenient than
-for longer variable names, allowing the one-character name to be a
-punctuation character or even invisible (a non-graphic). Perl v5.20
-deprecated the ASCII-range controls as such a name. Now, all
-non-graphic characters that formerly were allowed are deprecated.
-The practical effect of this occurs only when not under C<S<use
-utf8>>, and affects just the C1 controls (code points 0x80 through
-0xFF), NO-BREAK SPACE, and SOFT HYPHEN.
-
-=head2 Inlining of C<sub () { $var }> with observable side-effects
-
-In many cases Perl makes S<C<sub () { $var }>> into an inlinable constant
-subroutine, capturing the value of C<$var> at the time the C<sub> expression
-is evaluated. This can break the closure behavior in those cases where
-C<$var> is subsequently modified, since the subroutine won't return the
-changed value. (Note that this all only applies to anonymous subroutines
-with an empty prototype (S<C<sub ()>>).)
-
-This usage is now deprecated in those cases where the variable could be
-modified elsewhere. Perl detects those cases and emits a deprecation
-warning. Such code will likely change in the future and stop producing a
-constant.
-
-If your variable is only modified in the place where it is declared, then
-Perl will continue to make the sub inlinable with no warnings.
-
- sub make_constant {
- my $var = shift;
- return sub () { $var }; # fine
- }
-
- sub make_constant_deprecated {
- my $var;
- $var = shift;
- return sub () { $var }; # deprecated
- }
-
- sub make_constant_deprecated2 {
- my $var = shift;
- log_that_value($var); # could modify $var
- return sub () { $var }; # deprecated
- }
-
-In the second example above, detecting that C<$var> is assigned to only once
-is too hard to detect. That it happens in a spot other than the C<my>
-declaration is enough for Perl to find it suspicious.
-
-This deprecation warning happens only for a simple variable for the body of
-the sub. (A C<BEGIN> block or C<use> statement inside the sub is ignored,
-because it does not become part of the sub's body.) For more complex
-cases, such as S<C<sub () { do_something() if 0; $var }>> the behavior has
-changed such that inlining does not happen if the variable is modifiable
-elsewhere. Such cases should be rare.
-
-=head2 Use of multiple C</x> regexp modifiers
-
-It is now deprecated to say something like any of the following:
-
- qr/foo/xx;
- /(?xax:foo)/;
- use re qw(/amxx);
-
-That is, now C<x> should only occur once in any string of contiguous
-regular expression pattern modifiers. We do not believe there are any
-occurrences of this in all of CPAN. This is in preparation for a future
-Perl release having C</xx> permit white-space for readability in
-bracketed character classes (those enclosed in square brackets:
-C<[...]>).
-
-=head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now deprecated
-
-This non-graphic character is essentially indistinguishable from a
-regular space, and so should not be allowed. See
-L<charnames/CUSTOM ALIASES>.
-
-=head2 A literal C<"{"> should now be escaped in a pattern
-
-If you want a literal left curly bracket (also called a left brace) in a
-regular expression pattern, you should now escape it by either
-preceding it with a backslash (C<"\{">) or enclosing it within square
-brackets C<"[{]">, or by using C<\Q>; otherwise a deprecation warning
-will be raised. This was first announced as forthcoming in the v5.16
-release; it will allow future extensions to the language to happen.
-
-=head2 Making all warnings fatal is discouraged
-
-The documentation for L<fatal warnings|warnings/Fatal Warnings> notes that
-C<< use warnings FATAL => 'all' >> is discouraged, and provides stronger
-language about the risks of fatal warnings in general.
-
-=head1 Performance Enhancements
-
-=over 4
-
-=item *
-
-If a method or class name is known at compile time, a hash is precomputed
-to speed up run-time method lookup. Also, compound method names like
-C<SUPER::new> are parsed at compile time, to save having to parse them at
-run time.
-
-=item *
-
-Array and hash lookups (especially nested ones) that use only constants
-or simple variables as keys, are now considerably faster. See
-L</Internal Changes> for more details.
-
-=item *
-
-C<(...)x1>, C<("constant")x0> and C<($scalar)x0> are now optimised in list
-context. If the right-hand argument is a constant 1, the repetition
-operator disappears. If the right-hand argument is a constant 0, the whole
-expression is optimised to the empty list, so long as the left-hand
-argument is a simple scalar or constant. (That is, C<(foo())x0> is not
-subject to this optimisation.)
-
-=item *
-
-C<substr> assignment is now optimised into 4-argument C<substr> at the end
-of a subroutine (or as the argument to C<return>). Previously, this
-optimisation only happened in void context.
-
-=item *
-
-In C<"\L...">, C<"\Q...">, etc., the extra "stringify" op is now optimised
-away, making these just as fast as C<lcfirst>, C<quotemeta>, etc.
-
-=item *
-
-Assignment to an empty list is now sometimes faster. In particular, it
-never calls C<FETCH> on tied arguments on the right-hand side, whereas it
-used to sometimes.
-
-=item *
-
-There is a performance improvement of up to 20% when C<length> is applied to
-a non-magical, non-tied string, and either C<use bytes> is in scope or the
-string doesn't use UTF-8 internally.
-
-=item *
-
-On most perl builds with 64-bit integers, memory usage for non-magical,
-non-tied scalars containing only a floating point value has been reduced
-by between 8 and 32 bytes, depending on OS.
-
-=item *
-
-In C<@array = split>, the assignment can be optimized away, so that C<split>
-writes directly to the array. This optimisation was happening only for
-package arrays other than C<@_>, and only sometimes. Now this
-optimisation happens almost all the time.
-
-=item *
-
-C<join> is now subject to constant folding. So for example
-S<C<join "-", "a", "b">> is converted at compile-time to C<"a-b">.
-Moreover, C<join> with a scalar or constant for the separator and a
-single-item list to join is simplified to a stringification, and the
-separator doesn't even get evaluated.
-
-=item *
-
-C<qq(@array)> is implemented using two ops: a stringify op and a join op.
-If the C<qq> contains nothing but a single array, the stringification is
-optimized away.
-
-=item *
-
-S<C<our $var>> and S<C<our($s,@a,%h)>> in void context are no longer evaluated at
-run time. Even a whole sequence of S<C<our $foo;>> statements will simply be
-skipped over. The same applies to C<state> variables.
-
-=item *
-
-Many internal functions have been refactored to improve performance and reduce
-their memory footprints.
-L<[perl #121436]|https://rt.perl.org/Ticket/Display.html?id=121436>
-L<[perl #121906]|https://rt.perl.org/Ticket/Display.html?id=121906>
-L<[perl #121969]|https://rt.perl.org/Ticket/Display.html?id=121969>
-
-=item *
-
-C<-T> and C<-B> filetests will return sooner when an empty file is detected.
-L<[perl #121489]|https://rt.perl.org/Ticket/Display.html?id=121489>
-
-=item *
-
-Hash lookups where the key is a constant are faster.
-
-=item *
-
-Subroutines with an empty prototype and a body containing just C<undef> are now
-eligible for inlining.
-L<[perl #122728]|https://rt.perl.org/Ticket/Display.html?id=122728>
-
-=item *
-
-Subroutines in packages no longer need to be stored in typeglobs:
-declaring a subroutine will now put a simple sub reference directly in the
-stash if possible, saving memory. The typeglob still notionally exists,
-so accessing it will cause the stash entry to be upgraded to a typeglob
-(I<i.e.> this is just an internal implementation detail).
-This optimization does not currently apply to XSUBs or exported
-subroutines, and method calls will undo it, since they cache things in
-typeglobs.
-L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
-
-=item *
-
-The functions C<utf8::native_to_unicode()> and C<utf8::unicode_to_native()>
-(see L<utf8>) are now optimized out on ASCII platforms. There is now not even
-a minimal performance hit in writing code portable between ASCII and EBCDIC
-platforms.
-
-=item *
-
-Win32 Perl uses 8 KB less of per-process memory than before for every perl
-process, because some data is now memory mapped from disk and shared
-between processes from the same perl binary.
-
-=back
-
-=head1 Modules and Pragmata
-
-=head2 Updated Modules and Pragmata
-
-Many of the libraries distributed with perl have been upgraded since v5.20.0.
-For a complete list of changes, run:
-
- corelist --diff 5.20.0 5.22.0
-
-You can substitute your favorite version in place of 5.20.0, too.
-
-Some notable changes include:
-
-=over 4
-
-=item *
-
-L<Archive::Tar> has been upgraded to version 2.04.
-
-Tests can now be run in parallel.
-
-=item *
-
-L<attributes> has been upgraded to version 0.27.
-
-The usage of C<memEQs> in the XS has been corrected.
-L<[perl #122701]|https://rt.perl.org/Ticket/Display.html?id=122701>
-
-Avoid reading beyond the end of a buffer. [perl #122629]
-
-=item *
-
-L<B> has been upgraded to version 1.58.
-
-It provides a new C<B::safename> function, based on the existing
-C<< B::GV->SAFENAME >>, that converts C<\cOPEN> to C<^OPEN>.
-
-Nulled COPs are now of class C<B::COP>, rather than C<B::OP>.
-
-C<B::REGEXP> objects now provide a C<qr_anoncv> method for accessing the
-implicit CV associated with C<qr//> things containing code blocks, and a
-C<compflags> method that returns the pertinent flags originating from the
-C<qr//blahblah> op.
-
-C<B::PMOP> now provides a C<pmregexp> method returning a C<B::REGEXP> object.
-Two new classes, C<B::PADNAME> and C<B::PADNAMELIST>, have been introduced.
-
-A bug where, after an ithread creation or psuedofork, special/immortal SVs in
-the child ithread/psuedoprocess did not have the correct class of
-C<B::SPECIAL>, has been fixed.
-The C<id> and C<outid> PADLIST methods have been added.
-
-=item *
-
-L<B::Concise> has been upgraded to version 0.996.
-
-Null ops that are part of the execution chain are now given sequence
-numbers.
-
-Private flags for nulled ops are now dumped with mnemonics as they would be
-for the non-nulled counterparts.
-
-=item *
-
-L<B::Deparse> has been upgraded to version 1.35.
-
-It now deparses C<+sub : attr { ... }> correctly at the start of a
-statement. Without the initial C<+>, C<sub> would be a statement label.
-
-C<BEGIN> blocks are now emitted in the right place most of the time, but
-the change unfortunately introduced a regression, in that C<BEGIN> blocks
-occurring just before the end of the enclosing block may appear below it
-instead.
-
-C<B::Deparse> no longer puts erroneous C<local> here and there, such as for
-C<LIST = tr/a//d>. [perl #119815]
-
-Adjacent C<use> statements are no longer accidentally nested if one
-contains a C<do> block. [perl #115066]
-
-Parenthesised arrays in lists passed to C<\> are now correctly deparsed
-with parentheses (I<e.g.>, C<\(@a, (@b), @c)> now retains the parentheses
-around @b), thus preserving the flattening behavior of referenced
-parenthesised arrays. Formerly, it only worked for one array: C<\(@a)>.
-
-C<local our> is now deparsed correctly, with the C<our> included.
-
-C<for($foo; !$bar; $baz) {...}> was deparsed without the C<!> (or C<not>).
-This has been fixed.
-
-Core keywords that conflict with lexical subroutines are now deparsed with
-the C<CORE::> prefix.
-
-C<foreach state $x (...) {...}> now deparses correctly with C<state> and
-not C<my>.
-
-C<our @array = split(...)> now deparses correctly with C<our> in those
-cases where the assignment is optimized away.
-
-It now deparses C<our(I<LIST>)> and typed lexical (C<my Dog $spot>) correctly.
-
-Deparse C<$#_> as that instead of as C<$#{_}>.
-L<[perl #123947]|https://rt.perl.org/Ticket/Display.html?id=123947>
-
-BEGIN blocks at the end of the enclosing scope are now deparsed in the
-right place. [perl #77452]
-
-BEGIN blocks were sometimes deparsed as __ANON__, but are now always called
-BEGIN.
-
-Lexical subroutines are now fully deparsed. [perl #116553]
-
-C<Anything =~ y///r> with C</r> no longer omits the left-hand operand.
-
-The op trees that make up regexp code blocks are now deparsed for real.
-Formerly, the original string that made up the regular expression was used.
-That caused problems with C<qr/(?{E<lt>E<lt>heredoc})/> and multiline code blocks,
-which were deparsed incorrectly. [perl #123217] [perl #115256]
-
-C<$;> at the end of a statement no longer loses its semicolon.
-[perl #123357]
-
-Some cases of subroutine declarations stored in the stash in shorthand form
-were being omitted.
-
-Non-ASCII characters are now consistently escaped in strings, instead of
-some of the time. (There are still outstanding problems with regular
-expressions and identifiers that have not been fixed.)
-
-When prototype sub calls are deparsed with C<&> (I<e.g.>, under the B<-P>
-option), C<scalar> is now added where appropriate, to force the scalar
-context implied by the prototype.
-
-C<require(foo())>, C<do(foo())>, C<goto(foo())> and similar constructs with
-loop controls are now deparsed correctly. The outer parentheses are not
-optional.
-
-Whitespace is no longer escaped in regular expressions, because it was
-getting erroneously escaped within C<(?x:...)> sections.
-
-C<sub foo { foo() }> is now deparsed with those mandatory parentheses.
-
-C</@array/> is now deparsed as a regular expression, and not just
-C<@array>.
-
-C</@{-}/>, C</@{+}/> and C<$#{1}> are now deparsed with the braces, which
-are mandatory in these cases.
-
-In deparsing feature bundles, C<B::Deparse> was emitting C<no feature;> first
-instead of C<no feature ':all';>. This has been fixed.
-
-C<chdir FH> is now deparsed without quotation marks.
-
-C<\my @a> is now deparsed without parentheses. (Parenthese would flatten
-the array.)
-
-C<system> and C<exec> followed by a block are now deparsed correctly.
-Formerly there was an erroneous C<do> before the block.
-
-C<< use constant QR =E<gt> qr/.../flags >> followed by C<"" =~ QR> is no longer
-without the flags.
-
-Deparsing C<BEGIN { undef &foo }> with the B<-w> switch enabled started to
-emit 'uninitialized' warnings in Perl 5.14. This has been fixed.
-
-Deparsing calls to subs with a C<(;+)> prototype resulted in an infinite
-loop. The C<(;$>) C<(_)> and C<(;_)> prototypes were given the wrong
-precedence, causing C<foo($aE<lt>$b)> to be deparsed without the parentheses.
-
-Deparse now provides a defined state sub in inner subs.
-
-=item *
-
-L<B::Op_private> has been added.
-
-L<B::Op_private> provides detailed information about the flags used in the
-C<op_private> field of perl opcodes.
-
-=item *
-
-L<bigint>, L<bignum>, L<bigrat> have been upgraded to version 0.39.
-
-Document in CAVEATS that using strings as numbers won't always invoke
-the big number overloading, and how to invoke it. [rt.perl.org #123064]
-
-=item *
-
-L<Carp> has been upgraded to version 1.36.
-
-C<Carp::Heavy> now ignores version mismatches with Carp if Carp is newer
-than 1.12, since C<Carp::Heavy>'s guts were merged into Carp at that
-point.
-L<[perl #121574]|https://rt.perl.org/Ticket/Display.html?id=121574>
-
-Carp now handles non-ASCII platforms better.
-
-Off-by-one error fix for Perl E<lt> 5.14.
-
-=item *
-
-L<constant> has been upgraded to version 1.33.
-
-It now accepts fully-qualified constant names, allowing constants to be defined
-in packages other than the caller.
-
-=item *
-
-L<CPAN> has been upgraded to version 2.11.
-
-Add support for C<Cwd::getdcwd()> and introduce workaround for a misbehavior
-seen on Strawberry Perl 5.20.1.
-
-Fix C<chdir()> after building dependencies bug.
-
-Introduce experimental support for plugins/hooks.
-
-Integrate the C<App::Cpan> sources.
-
-Do not check recursion on optional dependencies.
-
-Sanity check F<META.yml> to contain a hash.
-L<[cpan #95271]|https://rt.cpan.org/Ticket/Display.html?id=95271>
-
-=item *
-
-L<CPAN::Meta::Requirements> has been upgraded to version 2.132.
-
-Works around limitations in C<version::vpp> detecting v-string magic and adds
-support for forthcoming L<ExtUtils::MakeMaker> bootstrap F<version.pm> for
-Perls older than 5.10.0.
-
-=item *
-
-L<Data::Dumper> has been upgraded to version 2.158.
-
-Fixes CVE-2014-4330 by adding a configuration variable/option to limit
-recursion when dumping deep data structures.
-
-Changes to resolve Coverity issues.
-XS dumps incorrectly stored the name of code references stored in a
-GLOB.
-L<[perl #122070]|https://rt.perl.org/Ticket/Display.html?id=122070>
-
-=item *
-
-L<DynaLoader> has been upgraded to version 1.32.
-
-Remove C<dl_nonlazy> global if unused in Dynaloader. [perl #122926]
-
-=item *
-
-L<Encode> has been upgraded to version 2.72.
-
-C<piconv> now has better error handling when the encoding name is nonexistent,
-and a build breakage when upgrading L<Encode> in perl-5.8.2 and earlier has
-been fixed.
-
-Building in C++ mode on Windows now works.
-
-=item *
-
-L<Errno> has been upgraded to version 1.23.
-
-Add C<-P> to the preprocessor command-line on GCC 5. GCC added extra
-line directives, breaking parsing of error code definitions. [rt.perl.org
-#123784]
-
-=item *
-
-L<experimental> has been upgraded to version 0.013.
-
-Hardcodes features for Perls older than 5.15.7.
-
-=item *
-
-L<ExtUtils::CBuilder> has been upgraded to version 0.280221.
-
-Fixes a regression on Android.
-L<[perl #122675]|https://rt.perl.org/Ticket/Display.html?id=122675>
-
-=item *
-
-L<ExtUtils::Manifest> has been upgraded to version 1.70.
-
-Fixes a bug with C<maniread()>'s handling of quoted filenames and improves
-C<manifind()> to follow symlinks.
-L<[perl #122415]|https://rt.perl.org/Ticket/Display.html?id=122415>
-
-=item *
-
-L<ExtUtils::ParseXS> has been upgraded to version 3.28.
-
-Only declare C<file> unused if we actually define it.
-Improve generated C<RETVAL> code generation to avoid repeated
-references to C<ST(0)>. [perl #123278]
-Broaden and document the C</OBJ$/> to C</REF$/> typemap optimization
-for the C<DESTROY> method. [perl #123418]
-
-=item *
-
-L<Fcntl> has been upgraded to version 1.13.
-
-Add support for the Linux pipe buffer size C<fcntl()> commands.
-
-=item *
-
-L<File::Find> has been upgraded to version 1.29.
-
-C<find()> and C<finddepth()> will now warn if passed inappropriate or
-misspelled options.
-
-=item *
-
-L<File::Glob> has been upgraded to version 1.24.
-
-Avoid C<SvIV()> expanding to call C<get_sv()> three times in a few
-places. [perl #123606]
-
-=item *
-
-L<HTTP::Tiny> has been upgraded to version 0.054.
-
-C<keep_alive> is now fork-safe and thread-safe.
-
-=item *
-
-L<IO> has been upgraded to version 1.35.
-
-The XS implementation has been fixed for the sake of older Perls.
-
-=item *
-
-L<IO::Socket> has been upgraded to version 1.38.
-
-Document the limitations of the C<connected()> method. [perl #123096]
-
-=item *
-
-L<IO::Socket::IP> has been upgraded to version 0.37.
-
-A better fix for subclassing C<connect()>.
-L<[cpan #95983]|https://rt.cpan.org/Ticket/Display.html?id=95983>
-L<[cpan #97050]|https://rt.cpan.org/Ticket/Display.html?id=97050>
-
-Implements Timeout for C<connect()>.
-L<[cpan #92075]|https://rt.cpan.org/Ticket/Display.html?id=92075>
-
-=item *
-
-The libnet collection of modules has been upgraded to version 3.05.
-
-Support for IPv6 and SSL to C<Net::FTP>, C<Net::NNTP>, C<Net::POP3> and C<Net::SMTP>.
-Improvements in C<Net::SMTP> authentication.
-
-=item *
-
-L<Locale::Codes> has been upgraded to version 3.34.
-
-Fixed a bug in the scripts used to extract data from spreadsheets that
-prevented the SHP currency code from being found.
-L<[cpan #94229]|https://rt.cpan.org/Ticket/Display.html?id=94229>
-
-New codes have been added.
-
-=item *
-
-L<Math::BigInt> has been upgraded to version 1.9997.
-
-Synchronize POD changes from the CPAN release.
-C<< Math::BigFloat->blog(x) >> would sometimes return C<blog(2*x)> when
-the accuracy was greater than 70 digits.
-The result of C<< Math::BigFloat->bdiv() >> in list context now
-satisfies C<< x = quotient * divisor + remainder >>.
-
-Correct handling of subclasses.
-L<[cpan #96254]|https://rt.cpan.org/Ticket/Display.html?id=96254>
-L<[cpan #96329]|https://rt.cpan.org/Ticket/Display.html?id=96329>
-
-=item *
-
-L<Module::Metadata> has been upgraded to version 1.000026.
-
-Support installations on older perls with an L<ExtUtils::MakeMaker> earlier
-than 6.63_03
-
-=item *
-
-L<overload> has been upgraded to version 1.26.
-
-A redundant C<ref $sub> check has been removed.
-
-=item *
-
-The PathTools module collection has been upgraded to version 3.56.
-
-A warning from the B<gcc> compiler is now avoided when building the XS.
-
-Don't turn leading C<//> into C</> on Cygwin. [perl #122635]
-
-=item *
-
-L<perl5db.pl> has been upgraded to version 1.49.
-
-The debugger would cause an assertion failure.
-L<[perl #124127]|https://rt.perl.org/Ticket/Display.html?id=124127>
-
-C<fork()> in the debugger under C<tmux> will now create a new window for
-the forked process. L<[perl
-#121333]|https://rt.perl.org/Ticket/Display.html?id=121333>
-
-The debugger now saves the current working directory on startup and
-restores it when you restart your program with C<R> or C<rerun>. L<[perl
-#121509]|https://rt.perl.org/Ticket/Display.html?id=121509>
-
-=item *
-
-L<PerlIO::scalar> has been upgraded to version 0.22.
-
-Reading from a position well past the end of the scalar now correctly
-returns end of file. [perl #123443]
-
-Seeking to a negative position still fails, but no longer leaves the
-file position set to a negation location.
-
-C<eof()> on a C<PerlIO::scalar> handle now properly returns true when
-the file position is past the 2GB mark on 32-bit systems.
-
-Attempting to write at file positions impossible for the platform now
-fail early rather than wrapping at 4GB.
-
-=item *
-
-L<Pod::Perldoc> has been upgraded to version 3.25.
-
-Filehandles opened for reading or writing now have C<:encoding(UTF-8)> set.
-L<[cpan #98019]|https://rt.cpan.org/Ticket/Display.html?id=98019>
-
-=item *
-
-L<POSIX> has been upgraded to version 1.53.
-
-The C99 math functions and constants (for example C<acosh>, C<isinf>, C<isnan>, C<round>,
-C<trunc>; C<M_E>, C<M_SQRT2>, C<M_PI>) have been added.
-
-C<POSIX::tmpnam()> now produces a deprecation warning. [perl #122005]
-
-=item *
-
-L<Safe> has been upgraded to version 2.39.
-
-C<reval> was not propagating void context properly.
-
-=item *
-
-Scalar-List-Utils has been upgraded to version 1.41.
-
-A new module, L<Sub::Util>, has been added, containing functions related to
-CODE refs, including C<subname> (inspired by C<Sub::Identity>) and C<set_subname>
-(copied and renamed from C<Sub::Name>).
-The use of C<GetMagic> in C<List::Util::reduce()> has also been fixed.
-L<[cpan #63211]|https://rt.cpan.org/Ticket/Display.html?id=63211>
-
-=item *
-
-L<SDBM_File> has been upgraded to version 1.13.
-
-Simplified the build process. [perl #123413]
-
-=item *
-
-L<Time::Piece> has been upgraded to version 1.29.
-
-When pretty printing negative C<Time::Seconds>, the "minus" is no longer lost.
-
-=item *
-
-L<Unicode::Collate> has been upgraded to version 1.12.
-
-Version 0.67's improved discontiguous contractions is invalidated by default
-and is supported as a parameter C<long_contraction>.
-
-=item *
-
-L<Unicode::Normalize> has been upgraded to version 1.18.
-
-The XSUB implementation has been removed in favor of pure Perl.
-
-=item *
-
-L<Unicode::UCD> has been upgraded to version 0.61.
-
-A new function L<property_values()|Unicode::UCD/prop_values()>
-has been added to return a given property's possible values.
-
-A new function L<charprop()|Unicode::UCD/charprop()>
-has been added to return the value of a given property for a given code
-point.
-
-A new function L<charprops_all()|Unicode::UCD/charprops_all()>
-has been added to return the values of all Unicode properties for a
-given code point.
-
-A bug has been fixed so that L<propaliases()|Unicode::UCD/prop_aliases()>
-returns the correct short and long names for the Perl extensions where
-it was incorrect.
-
-A bug has been fixed so that
-L<prop_value_aliases()|Unicode::UCD/prop_value_aliases()>
-returns C<undef> instead of a wrong result for properties that are Perl
-extensions.
-
-This module now works on EBCDIC platforms.
-
-=item *
-
-L<utf8> has been upgraded to version 1.17
-
-A mismatch between the documentation and the code in C<utf8::downgrade()>
-was fixed in favor of the documentation. The optional second argument
-is now correctly treated as a perl boolean (true/false semantics) and
-not as an integer.
-
-=item *
-
-L<version> has been upgraded to version 0.9909.
-
-Numerous changes. See the F<Changes> file in the CPAN distribution for
-details.
-
-=item *
-
-L<Win32> has been upgraded to version 0.51.
-
-C<GetOSName()> now supports Windows 8.1, and building in C++ mode now works.
-
-=item *
-
-L<Win32API::File> has been upgraded to version 0.1202
-
-Building in C++ mode now works.
-
-=item *
-
-L<XSLoader> has been upgraded to version 0.20.
-
-Allow XSLoader to load modules from a different namespace.
-[perl #122455]
-
-=back
-
-=head2 Removed Modules and Pragmata
-
-The following modules (and associated modules) have been removed from the core
-perl distribution:
-
-=over 4
-
-=item *
-
-L<CGI>
-
-=item *
-
-L<Module::Build>
-
-=back
-
-=head1 Documentation
-
-=head2 New Documentation
-
-=head3 L<perlunicook>
-
-This document, by Tom Christiansen, provides examples of handling Unicode in
-Perl.
-
-=head2 Changes to Existing Documentation
-
-=head3 L<perlaix>
-
-=over 4
-
-=item *
-
-A note on long doubles has been added.
-
-=back
-
-
-=head3 L<perlapi>
-
-=over 4
-
-=item *
-
-Note that C<SvSetSV> doesn't do set magic.
-
-=item *
-
-C<sv_usepvn_flags> - fix documentation to mention the use of C<Newx> instead of
-C<malloc>.
-
-L<[perl #121869]|https://rt.perl.org/Ticket/Display.html?id=121869>
-
-=item *
-
-Clarify where C<NUL> may be embedded or is required to terminate a string.
-
-=item *
-
-Some documentation that was previously missing due to formatting errors is
-now included.
-
-=item *
-
-Entries are now organized into groups rather than by the file where they
-are found.
-
-=item *
-
-Alphabetical sorting of entries is now done consistently (automatically
-by the POD generator) to make entries easier to find when scanning.
-
-=back
-
-=head3 L<perldata>
-
-=over 4
-
-=item *
-
-The syntax of single-character variable names has been brought
-up-to-date and more fully explained.
-
-=item *
-
-Hexadecimal floating point numbers are described, as are infinity and
-NaN.
-
-=back
-
-=head3 L<perlebcdic>
-
-=over 4
-
-=item *
-
-This document has been significantly updated in the light of recent
-improvements to EBCDIC support.
-
-=back
-
-=head3 L<perlfilter>
-
-=over 4
-
-=item *
-
-Added a L<LIMITATIONS|perlfilter/LIMITATIONS> section.
-
-=back
-
-
-=head3 L<perlfunc>
-
-=over 4
-
-=item *
-
-Mention that C<study()> is currently a no-op.
-
-=item *
-
-Calling C<delete> or C<exists> on array values is now described as "strongly
-discouraged" rather than "deprecated".
-
-=item *
-
-Improve documentation of C<< our >>.
-
-=item *
-
-C<-l> now notes that it will return false if symlinks aren't supported by the
-file system.
-L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523>
-
-=item *
-
-Note that C<exec LIST> and C<system LIST> may fall back to the shell on
-Win32. Only the indirect-object syntax C<exec PROGRAM LIST> and
-C<system PROGRAM LIST> will reliably avoid using the shell.
-
-This has also been noted in L<perlport>.
-
-L<[perl #122046]|https://rt.perl.org/Ticket/Display.html?id=122046>
-
-=back
-
-=head3 L<perlguts>
-
-=over 4
-
-=item *
-
-The OOK example has been updated to account for COW changes and a change in the
-storage of the offset.
-
-=item *
-
-Details on C level symbols and libperl.t added.
-
-=item *
-
-Information on Unicode handling has been added
-
-=item *
-
-Information on EBCDIC handling has been added
-
-=back
-
-=head3 L<perlhack>
-
-=over 4
-
-=item *
-
-A note has been added about running on platforms with non-ASCII
-character sets
-
-=item *
-
-A note has been added about performance testing
-
-=back
-
-=head3 L<perlhacktips>
-
-=over 4
-
-=item *
-
-Documentation has been added illustrating the perils of assuming that
-there is no change to the contents of static memory pointed to by the
-return values of Perl's wrappers for C library functions.
-
-=item *
-
-Replacements for C<tmpfile>, C<atoi>, C<strtol>, and C<strtoul> are now
-recommended.
-
-=item *
-
-Updated documentation for the C<test.valgrind> C<make> target.
-L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
-
-=item *
-
-Information is given about writing test files portably to non-ASCII
-platforms.
-
-=item *
-
-A note has been added about how to get a C language stack backtrace.
-
-=back
-
-=head3 L<perlhpux>
-
-=over 4
-
-=item *
-
-Note that the message "Redeclaration of "sendpath" with a different
-storage class specifier" is harmless.
-
-=back
-
-=head3 L<perllocale>
-
-=over 4
-
-=item *
-
-Updated for the enhancements in v5.22, along with some clarifications.
-
-=back
-
-=head3 L<perlmodstyle>
-
-=over 4
-
-=item *
-
-Instead of pointing to the module list, we are now pointing to
-L<PrePAN|http://prepan.org/>.
-
-=back
-
-=head3 L<perlop>
-
-=over 4
-
-=item *
-
-Updated for the enhancements in v5.22, along with some clarifications.
-
-=back
-
-=head3 L<perlpodspec>
-
-=over 4
-
-=item *
-
-The specification of the pod language is changing so that the default
-encoding of pods that aren't in UTF-8 (unless otherwise indicated) is
-CP1252 instead of ISO 8859-1 (Latin1).
-
-=back
-
-=head3 L<perlpolicy>
-
-=over 4
-
-=item *
-
-We now have a code of conduct for the I<< p5p >> mailing list, as documented
-in L<< perlpolicy/STANDARDS OF CONDUCT >>.
-
-=item *
-
-The conditions for marking an experimental feature as non-experimental are now
-set out.
-
-=item *
-
-Clarification has been made as to what sorts of changes are permissible in
-maintenance releases.
-
-=back
-
-=head3 L<perlport>
-
-=over 4
-
-=item *
-
-Out-of-date VMS-specific information has been fixed and/or simplified.
-
-=item *
-
-Notes about EBCDIC have been added.
-
-=back
-
-=head3 L<perlre>
-
-=over 4
-
-=item *
-
-The description of the C</x> modifier has been clarified to note that
-comments cannot be continued onto the next line by escaping them; and
-there is now a list of all the characters that are considered whitespace
-by this modifier.
-
-=item *
-
-The new C</n> modifier is described.
-
-=item *
-
-A note has been added on how to make bracketed character class ranges
-portable to non-ASCII machines.
-
-=back
-
-=head3 L<perlrebackslash>
-
-=over 4
-
-=item *
-
-Added documentation of C<\b{sb}>, C<\b{wb}>, C<\b{gcb}>, and C<\b{g}>.
-
-=back
-
-=head3 L<perlrecharclass>
-
-=over 4
-
-=item *
-
-Clarifications have been added to L<perlrecharclass/Character Ranges>
-to the effect C<[A-Z]>, C<[a-z]>, C<[0-9]> and
-any subranges thereof in regular expression bracketed character classes
-are guaranteed to match exactly what a naive English speaker would
-expect them to match, even on platforms (such as EBCDIC) where perl
-has to do extra work to accomplish this.
-
-=item *
-
-The documentation of Bracketed Character Classes has been expanded to cover the
-improvements in C<qr/[\N{named sequence}]/> (see under L</Selected Bug Fixes>).
-
-=back
-
-=head3 L<perlref>
-
-=over 4
-
-=item *
-
-A new section has been added
-L<Assigning to References|perlref/Assigning to References>
-
-=back
-
-=head3 L<perlsec>
-
-=over 4
-
-=item *
-
-Comments added on algorithmic complexity and tied hashes.
-
-=back
-
-=head3 L<perlsyn>
-
-=over 4
-
-=item *
-
-An ambiguity in the documentation of the C<...> statement has been corrected.
-L<[perl #122661]|https://rt.perl.org/Ticket/Display.html?id=122661>
-
-=item *
-
-The empty conditional in C<< for >> and C<< while >> is now documented
-in L<< perlsyn >>.
-
-=back
-
-=head3 L<perlunicode>
-
-=over 4
-
-=item *
-
-This has had extensive revisions to bring it up-to-date with current
-Unicode support and to make it more readable. Notable is that Unicode
-7.0 changed what it should do with non-characters. Perl retains the old
-way of handling for reasons of backward compatibility. See
-L<perlunicode/Noncharacter code points>.
-
-=back
-
-=head3 L<perluniintro>
-
-=over 4
-
-=item *
-
-Advice for how to make sure your strings and regular expression patterns are
-interpreted as Unicode has been updated.
-
-=back
-
-=head3 L<perlvar>
-
-=over 4
-
-=item *
-
-C<$]> is no longer listed as being deprecated. Instead, discussion has
-been added on the advantages and disadvantages of using it versus
-C<$^V>.
-
-=item *
-
-C<${^ENCODING}> is now marked as deprecated.
-
-=item *
-
-The entry for C<%^H> has been clarified to indicate it can only handle
-simple values.
-
-=back
-
-=head3 L<perlvms>
-
-=over 4
-
-=item *
-
-Out-of-date and/or incorrect material has been removed.
-
-=item *
-
-Updated documentation on environment and shell interaction in VMS.
-
-=back
-
-=head3 L<perlxs>
-
-=over 4
-
-=item *
-
-Added a discussion of locale issues in XS code.
-
-=back
-
-=head1 Diagnostics
-
-The following additions or changes have been made to diagnostic output,
-including warnings and fatal error messages. For the complete list of
-diagnostic messages, see L<perldiag>.
-
-=head2 New Diagnostics
-
-=head3 New Errors
-
-=over 4
-
-=item *
-
-L<Bad symbol for scalar|perldiag/"Bad symbol for scalar">
-
-(P) An internal request asked to add a scalar entry to something that
-wasn't a symbol table entry.
-
-=item *
-
-L<Can't use a hash as a reference|perldiag/"Can't use a hash as a reference">
-
-(F) You tried to use a hash as a reference, as in
-C<< %foo->{"bar"} >> or C<< %$ref->{"hello"} >>. Versions of perl E<lt>= 5.6.1
-used to allow this syntax, but shouldn't have.
-
-=item *
-
-L<Can't use an array as a reference|perldiag/"Can't use an array as a reference">
-
-(F) You tried to use an array as a reference, as in
-C<< @foo->[23] >> or C<< @$ref->[99] >>. Versions of perl E<lt>= 5.6.1 used to
-allow this syntax, but shouldn't have.
-
-=item *
-
-L<Can't use 'defined(@array)' (Maybe you should just omit the defined()?)|perldiag/"Can't use 'defined(@array)' (Maybe you should just omit the defined()?)">
-
-(F) C<defined()> is not useful on arrays because it
-checks for an undefined I<scalar> value. If you want to see if the
-array is empty, just use S<C<if (@array) { # not empty }>> for example.
-
-=item *
-
-L<Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)|perldiag/"Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)">
-
-(F) C<defined()> is not usually right on hashes.
-
-Although S<C<defined %hash>> is false on a plain not-yet-used hash, it
-becomes true in several non-obvious circumstances, including iterators,
-weak references, stash names, even remaining true after S<C<undef %hash>>.
-These things make S<C<defined %hash>> fairly useless in practice, so it now
-generates a fatal error.
-
-If a check for non-empty is what you wanted then just put it in boolean
-context (see L<perldata/Scalar values>):
-
- if (%hash) {
- # not empty
- }
-
-If you had S<C<defined %Foo::Bar::QUUX>> to check whether such a package
-variable exists then that's never really been reliable, and isn't
-a good way to enquire about the features of a package, or whether
-it's loaded, etc.
-
-=item *
-
-L<Cannot chr %f|perldiag/"Cannot chr %f">
-
-(F) You passed an invalid number (like an infinity or not-a-number) to
-C<chr>.
-
-=item *
-
-L<Cannot compress %f in pack|perldiag/"Cannot compress %f in pack">
-
-(F) You tried converting an infinity or not-a-number to an unsigned
-character, which makes no sense.
-
-=item *
-
-L<Cannot pack %f with '%c'|perldiag/"Cannot pack %f with '%c'">
-
-(F) You tried converting an infinity or not-a-number to a character,
-which makes no sense.
-
-=item *
-
-L<Cannot print %f with '%c'|perldiag/"Cannot printf %f with '%c'">
-
-(F) You tried printing an infinity or not-a-number as a character (C<%c>),
-which makes no sense. Maybe you meant C<'%s'>, or just stringifying it?
-
-=item *
-
-L<charnames alias definitions may not contain a sequence of multiple spaces|perldiag/"charnames alias definitions may not contain a sequence of multiple spaces">
-
-(F) You defined a character name which had multiple space
-characters in a row. Change them to single spaces. Usually these
-names are defined in the C<:alias> import argument to C<use charnames>, but
-they could be defined by a translator installed into C<$^H{charnames}>.
-See L<charnames/CUSTOM ALIASES>.
-
-=item *
-
-L<charnames alias definitions may not contain trailing white-space|perldiag/"charnames alias definitions may not contain trailing white-space">
-
-(F) You defined a character name which ended in a space
-character. Remove the trailing space(s). Usually these names are
-defined in the C<:alias> import argument to C<use charnames>, but they
-could be defined by a translator installed into C<$^H{charnames}>.
-See L<charnames/CUSTOM ALIASES>.
-
-=item *
-
-L<:const is not permitted on named subroutines|perldiag/":const is not permitted on named subroutines">
-
-(F) The C<const> attribute causes an anonymous subroutine to be run and
-its value captured at the time that it is cloned. Named subroutines are
-not cloned like this, so the attribute does not make sense on them.
-
-=item *
-
-L<Hexadecimal float: internal error|perldiag/"Hexadecimal float: internal error">
-
-(F) Something went horribly bad in hexadecimal float handling.
-
-=item *
-
-L<Hexadecimal float: unsupported long double format|perldiag/"Hexadecimal float: unsupported long double format">
-
-(F) You have configured Perl to use long doubles but
-the internals of the long double format are unknown,
-therefore the hexadecimal float output is impossible.
-
-=item *
-
-L<Illegal suidscript|perldiag/"Illegal suidscript">
-
-(F) The script run under suidperl was somehow illegal.
-
-=item *
-
-L<In '(?...)', the '(' and '?' must be adjacent in regex; marked by S<<-- HERE> in mE<sol>%sE<sol>|perldiag/"In '(?...)', the '(' and '?' must be adjacent in regex; marked by <-- HERE in m/%s/">
-
-(F) The two-character sequence C<"(?"> in
-this context in a regular expression pattern should be an
-indivisible token, with nothing intervening between the C<"(">
-and the C<"?">, but you separated them.
-
-=item *
-
-L<In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by S<<-- HERE> in mE<sol>%sE<sol>|perldiag/"In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by <-- HERE in m/%s/">
-
-(F) The two-character sequence C<"(*"> in
-this context in a regular expression pattern should be an
-indivisible token, with nothing intervening between the C<"(">
-and the C<"*">, but you separated them.
-
-=item *
-
-L<Invalid quantifier in {,} in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/">
-
-(F) The pattern looks like a {min,max} quantifier, but the min or max could not
-be parsed as a valid number: either it has leading zeroes, or it represents
-too big a number to cope with. The S<<-- HERE> shows where in the regular
-expression the problem was discovered. See L<perlre>.
-
-=item *
-
-L<'%s' is an unknown bound type in regex|perldiag/"'%s' is an unknown bound type in regex; marked by <-- HERE in m/%s/">
-
-(F) You used C<\b{...}> or C<\B{...}> and the C<...> is not known to
-Perl. The current valid ones are given in
-L<perlrebackslash/\b{}, \b, \B{}, \B>.
-
-=item *
-
-L<Missing or undefined argument to require|perldiag/Missing or undefined argument to require>
-
-(F) You tried to call C<require> with no argument or with an undefined
-value as an argument. C<require> expects either a package name or a
-file-specification as an argument. See L<perlfunc/require>.
-
-Formerly, C<require> with no argument or C<undef> warned about a Null filename.
-
-=back
-
-=head3 New Warnings
-
-=over 4
-
-=item *
-
-L<\C is deprecated in regex|perldiag/"\C is deprecated in regex; marked by <-- HERE in m/%s/">
-
-(D deprecated) The C<< /\C/ >> character class was deprecated in v5.20, and
-now emits a warning. It is intended that it will become an error in v5.24.
-This character class matches a single byte even if it appears within a
-multi-byte character, breaks encapsulation, and can corrupt UTF-8
-strings.
-
-=item *
-
-L<"%s" is more clearly written simply as "%s" in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"%s" is more clearly written simply as "%s" in regex; marked by <-- HERE in mE<sol>%sE<sol>>
-
-(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
-
-You specified a character that has the given plainer way of writing it,
-and which is also portable to platforms running with different character
-sets.
-
-=item *
-
-L<Argument "%s" treated as 0 in increment (++)|perldiag/"Argument "%s" treated
-as 0 in increment (++)">
-
-(W numeric) The indicated string was fed as an argument to the C<++> operator
-which expects either a number or a string matching C</^[a-zA-Z]*[0-9]*\z/>.
-See L<perlop/Auto-increment and Auto-decrement> for details.
-
-=item *
-
-L<Both or neither range ends should be Unicode in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"Both or neither range ends should be Unicode in regex; marked by <-- HERE in m/%s/">
-
-(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
-
-In a bracketed character class in a regular expression pattern, you
-had a range which has exactly one end of it specified using C<\N{}>, and
-the other end is specified using a non-portable mechanism. Perl treats
-the range as a Unicode range, that is, all the characters in it are
-considered to be the Unicode characters, and which may be different code
-points on some platforms Perl runs on. For example, C<[\N{U+06}-\x08]>
-is treated as if you had instead said C<[\N{U+06}-\N{U+08}]>, that is it
-matches the characters whose code points in Unicode are 6, 7, and 8.
-But that C<\x08> might indicate that you meant something different, so
-the warning gets raised.
-
-=item *
-
-L<Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".|perldiag/Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".>
-
-(W locale) You are 1) running under "C<use locale>"; 2) the current
-locale is not a UTF-8 one; 3) you tried to do the designated case-change
-operation on the specified Unicode character; and 4) the result of this
-operation would mix Unicode and locale rules, which likely conflict.
-
-The warnings category C<locale> is new.
-
-=item *
-
-L<:const is experimental|perldiag/":const is experimental">
-
-(S experimental::const_attr) The C<const> attribute is experimental.
-If you want to use the feature, disable the warning with C<no warnings
-'experimental::const_attr'>, but know that in doing so you are taking
-the risk that your code may break in a future Perl version.
-
-=item *
-
-L<gmtime(%f) failed|perldiag/"gmtime(%f) failed">
-
-(W overflow) You called C<gmtime> with a number that it could not handle:
-too large, too small, or NaN. The returned value is C<undef>.
-
-=item *
-
-L<Hexadecimal float: exponent overflow|perldiag/"Hexadecimal float: exponent overflow">
-
-(W overflow) The hexadecimal floating point has larger exponent
-than the floating point supports.
-
-=item *
-
-L<Hexadecimal float: exponent underflow|perldiag/"Hexadecimal float: exponent underflow">
-
-(W overflow) The hexadecimal floating point has smaller exponent
-than the floating point supports.
-
-=item *
-
-L<Hexadecimal float: mantissa overflow|perldiag/"Hexadecimal float: mantissa overflow">
-
-(W overflow) The hexadecimal floating point literal had more bits in
-the mantissa (the part between the C<0x> and the exponent, also known as
-the fraction or the significand) than the floating point supports.
-
-=item *
-
-L<Hexadecimal float: precision loss|perldiag/"Hexadecimal float: precision loss">
-
-(W overflow) The hexadecimal floating point had internally more
-digits than could be output. This can be caused by unsupported
-long double formats, or by 64-bit integers not being available
-(needed to retrieve the digits under some configurations).
-
-=item *
-
-L<Locale '%s' may not work well.%s|perldiag/Locale '%s' may not work well.%s>
-
-(W locale) You are using the named locale, which is a non-UTF-8 one, and
-which perl has determined is not fully compatible with what it can
-handle. The second C<%s> gives a reason.
-
-The warnings category C<locale> is new.
-
-=item *
-
-L<localtime(%f) failed|perldiag/"localtime(%f) failed">
-
-(W overflow) You called C<localtime> with a number that it could not handle:
-too large, too small, or NaN. The returned value is C<undef>.
-
-=item *
-
-L<Negative repeat count does nothing|perldiag/"Negative repeat count does nothing">
-
-(W numeric) You tried to execute the
-L<C<x>|perlop/Multiplicative Operators> repetition operator fewer than 0
-times, which doesn't make sense.
-
-=item *
-
-L<NO-BREAK SPACE in a charnames alias definition is deprecated|perldiag/"NO-BREAK SPACE in a charnames alias definition is deprecated">
-
-(D deprecated) You defined a character name which contained a no-break
-space character. Change it to a regular space. Usually these names are
-defined in the C<:alias> import argument to C<use charnames>, but they
-could be defined by a translator installed into C<$^H{charnames}>. See
-L<charnames/CUSTOM ALIASES>.
-
-=item *
-
-L<Non-finite repeat count does nothing|perldiag/"Non-finite repeat count does nothing">
-
-(W numeric) You tried to execute the
-L<C<x>|perlop/Multiplicative Operators> repetition operator C<Inf> (or
-C<-Inf>) or NaN times, which doesn't make sense.
-
-=item *
-
-L<PerlIO layer ':win32' is experimental|perldiag/"PerlIO layer ':win32' is experimental">
-
-(S experimental::win32_perlio) The C<:win32> PerlIO layer is
-experimental. If you want to take the risk of using this layer,
-simply disable this warning:
-
- no warnings "experimental::win32_perlio";
-
-=item *
-
-L<Ranges of ASCII printables should be some subset of "0-9", "A-Z", or "a-z" in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"Ranges of ASCII printables should be some subset of "0-9", "A-Z", or "a-z" in regex; marked by <-- HERE in mE<sol>%sE<sol>">
-
-(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
-
-Stricter rules help to find typos and other errors. Perhaps you didn't
-even intend a range here, if the C<"-"> was meant to be some other
-character, or should have been escaped (like C<"\-">). If you did
-intend a range, the one that was used is not portable between ASCII and
-EBCDIC platforms, and doesn't have an obvious meaning to a casual
-reader.
-
- [3-7] # OK; Obvious and portable
- [d-g] # OK; Obvious and portable
- [A-Y] # OK; Obvious and portable
- [A-z] # WRONG; Not portable; not clear what is meant
- [a-Z] # WRONG; Not portable; not clear what is meant
- [%-.] # WRONG; Not portable; not clear what is meant
- [\x41-Z] # WRONG; Not portable; not obvious to non-geek
-
-(You can force portability by specifying a Unicode range, which means that
-the endpoints are specified by
-L<C<\N{...}>|perlrecharclass/Character Ranges>, but the meaning may
-still not be obvious.)
-The stricter rules require that ranges that start or stop with an ASCII
-character that is not a control have all their endpoints be a literal
-character, and not some escape sequence (like C<"\x41">), and the ranges
-must be all digits, or all uppercase letters, or all lowercase letters.
-
-=item *
-
-L<Ranges of digits should be from the same group in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"Ranges of digits should be from the same group in regex; marked by <-- HERE in m/%s/">
-
-(W regexp) (only under C<S<use re 'strict'>> or within C<(?[...])>)
-
-Stricter rules help to find typos and other errors. You included a
-range, and at least one of the end points is a decimal digit. Under the
-stricter rules, when this happens, both end points should be digits in
-the same group of 10 consecutive digits.
-
-=item *
-
-L<Redundant argument in %s|perldiag/Redundant argument in %s>
-
-(W redundant) You called a function with more arguments than were
-needed, as indicated by information within other arguments you supplied
-(I<e.g>. a printf format). Currently only emitted when a printf-type format
-required fewer arguments than were supplied, but might be used in the
-future for I<e.g.> L<perlfunc/pack>.
-
-The warnings category C<< redundant >> is new. See also
-L<[perl #121025]|https://rt.perl.org/Ticket/Display.html?id=121025>.
-
-=item *
-
-L<Replacement list is longer than search list|perldiag/Replacement list is longer than search list>
-
-This is not a new diagnostic, but in earlier releases was accidentally
-not displayed if the transliteration contained wide characters. This is
-now fixed, so that you may see this diagnostic in places where you
-previously didn't (but should have).
-
-=item *
-
-L<Use of \b{} for non-UTF-8 locale is wrong. Assuming a UTF-8 locale|perldiag/"Use of \b{} for non-UTF-8 locale is wrong. Assuming a UTF-8 locale">
-
-(W locale) You are matching a regular expression using locale rules,
-and a Unicode boundary is being matched, but the locale is not a Unicode
-one. This doesn't make sense. Perl will continue, assuming a Unicode
-(UTF-8) locale, but the results could well be wrong except if the locale
-happens to be ISO-8859-1 (Latin1) where this message is spurious and can
-be ignored.
-
-The warnings category C<locale> is new.
-
-=item *
-
-L<< Using E<sol>u for '%s' instead of E<sol>%s in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"Using E<sol>u for '%s' instead of E<sol>%s in regex; marked by <-- HERE in mE<sol>%sE<sol>" >>
-
-(W regexp) You used a Unicode boundary (C<\b{...}> or C<\B{...}>) in a
-portion of a regular expression where the character set modifiers C</a>
-or C</aa> are in effect. These two modifiers indicate an ASCII
-interpretation, and this doesn't make sense for a Unicode definition.
-The generated regular expression will compile so that the boundary uses
-all of Unicode. No other portion of the regular expression is affected.
-
-=item *
-
-L<The bitwise feature is experimental|perldiag/"The bitwise feature is experimental">
-
-(S experimental::bitwise) This warning is emitted if you use bitwise
-operators (C<& | ^ ~ &. |. ^. ~.>) with the "bitwise" feature enabled.
-Simply suppress the warning if you want to use the feature, but know
-that in doing so you are taking the risk of using an experimental
-feature which may change or be removed in a future Perl version:
-
- no warnings "experimental::bitwise";
- use feature "bitwise";
- $x |.= $y;
-
-=item *
-
-L<Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Unescaped left brace in regex is deprecated, passed through in regex; marked by <-- HERE in m/%s/">
-
-(D deprecated, regexp) You used a literal C<"{"> character in a regular
-expression pattern. You should change to use C<"\{"> instead, because a future
-version of Perl (tentatively v5.26) will consider this to be a syntax error. If
-the pattern delimiters are also braces, any matching right brace
-(C<"}">) should also be escaped to avoid confusing the parser, for
-example,
-
- qr{abc\{def\}ghi}
-
-=item *
-
-L<Use of literal non-graphic characters in variable names is deprecated|perldiag/"Use of literal non-graphic characters in variable names is deprecated">
-
-(D deprecated) Using literal non-graphic (including control)
-characters in the source to refer to the I<^FOO> variables, like C<$^X> and
-C<${^GLOBAL_PHASE}> is now deprecated.
-
-=item *
-
-L<Useless use of attribute "const"|perldiag/Useless use of attribute "const">
-
-(W misc) The C<const> attribute has no effect except
-on anonymous closure prototypes. You applied it to
-a subroutine via L<attributes.pm|attributes>. This is only useful
-inside an attribute handler for an anonymous subroutine.
-
-=item *
-
-L<Useless use of E<sol>d modifier in transliteration operator|perldiag/"Useless use of /d modifier in transliteration operator">
-
-This is not a new diagnostic, but in earlier releases was accidentally
-not displayed if the transliteration contained wide characters. This is
-now fixed, so that you may see this diagnostic in places where you
-previously didn't (but should have).
-
-=item *
-
-L<E<quot>use re 'strict'E<quot> is experimental|perldiag/"use re 'strict'" is experimental>
-
-(S experimental::re_strict) The things that are different when a regular
-expression pattern is compiled under C<'strict'> are subject to change
-in future Perl releases in incompatible ways; there are also proposals
-to change how to enable strict checking instead of using this subpragma.
-This means that a pattern that compiles today may not in a future Perl
-release. This warning is to alert you to that risk.
-
-=item *
-
-L<Warning: unable to close filehandle properly: %s|perldiag/"Warning: unable to close filehandle properly: %s">
-
-L<Warning: unable to close filehandle %s properly: %s|perldiag/"Warning: unable to close filehandle %s properly: %s">
-
-(S io) Previously, perl silently ignored any errors when doing an implicit
-close of a filehandle, I<i.e.> where the reference count of the filehandle
-reached zero and the user's code hadn't already called C<close()>; I<e.g.>
-
- {
- open my $fh, '>', $file or die "open: '$file': $!\n";
- print $fh, $data or die;
- } # implicit close here
-
-In a situation such as disk full, due to buffering, the error may only be
-detected during the final close, so not checking the result of the close is
-dangerous.
-
-So perl now warns in such situations.
-
-=item *
-
-L<Wide character (U+%X) in %s|perldiag/"Wide character (U+%X) in %s">
-
-(W locale) While in a single-byte locale (I<i.e.>, a non-UTF-8
-one), a multi-byte character was encountered. Perl considers this
-character to be the specified Unicode code point. Combining non-UTF-8
-locales and Unicode is dangerous. Almost certainly some characters
-will have two different representations. For example, in the ISO 8859-7
-(Greek) locale, the code point 0xC3 represents a Capital Gamma. But so
-also does 0x393. This will make string comparisons unreliable.
-
-You likely need to figure out how this multi-byte character got mixed up
-with your single-byte locale (or perhaps you thought you had a UTF-8
-locale, but Perl disagrees).
-
-The warnings category C<locale> is new.
-
-=back
-
-=head2 Changes to Existing Diagnostics
-
-=over 4
-
-=item *
-
-<> should be quotes
-
-This warning has been changed to
-L<< <> at require-statement should be quotes|perldiag/"<> at require-statement should be quotes" >>
-to make the issue more identifiable.
-
-=item *
-
-L<Argument "%s" isn't numeric%s|perldiag/"Argument "%s" isn't numeric%s">
-
-The L<perldiag> entry for this warning has added this clarifying note:
-
- Note that for the Inf and NaN (infinity and not-a-number) the
- definition of "numeric" is somewhat unusual: the strings themselves
- (like "Inf") are considered numeric, and anything following them is
- considered non-numeric.
-
-=item *
-
-L<Global symbol "%s" requires explicit package name|perldiag/"Global symbol "%s" requires explicit package name (did you forget to declare "my %s"?)">
-
-This message has had '(did you forget to declare "my %s"?)' appended to it, to
-make it more helpful to new Perl programmers.
-L<[perl #121638]|https://rt.perl.org/Ticket/Display.html?id=121638>
-
-=item *
-
-'"my" variable &foo::bar can't be in a package' has been reworded to say
-'subroutine' instead of 'variable'.
-
-=item *
-
-L<<< \N{} in character class restricted to one character in regex; marked by
-S<< <-- HERE >> in mE<sol>%sE<sol>|perldiag/"\N{} in inverted character
-class or as a range end-point is restricted to one character in regex;
-marked by <-- HERE in m/%s/" >>>
-
-This message has had I<character class> changed to I<inverted character
-class or as a range end-point is> to reflect improvements in
-C<qr/[\N{named sequence}]/> (see under L</Selected Bug Fixes>).
-
-=item *
-
-L<panic: frexp|perldiag/"panic: frexp: %f">
-
-This message has had ': C<%f>' appended to it, to show what the offending
-floating point number is.
-
-=item *
-
-I<Possible precedence problem on bitwise %c operator> reworded as
-L<Possible precedence problem on bitwise %s operator|perldiag/"Possible precedence problem on bitwise %s operator">.
-
-=item *
-
-L<Unsuccessful %s on filename containing newline|perldiag/"Unsuccessful %s on filename containing newline">
-
-This warning is now only produced when the newline is at the end of
-the filename.
-
-=item *
-
-"Variable C<%s> will not stay shared" has been changed to say "Subroutine"
-when it is actually a lexical sub that will not stay shared.
-
-=item *
-
-L<Variable length lookbehind not implemented in regex mE<sol>%sE<sol>|perldiag/"Variable length lookbehind not implemented in regex m/%s/">
-
-The L<perldiag> entry for this warning has had information about Unicode
-behavior added.
-
-=back
-
-=head2 Diagnostic Removals
-
-=over
-
-=item *
-
-"Ambiguous use of -foo resolved as -&foo()"
-
-There is actually no ambiguity here, and this impedes the use of negated
-constants; I<e.g.>, C<-Inf>.
-
-=item *
-
-"Constant is not a FOO reference"
-
-Compile-time checking of constant dereferencing (I<e.g.>, C<< my_constant->() >>)
-has been removed, since it was not taking overloading into account.
-L<[perl #69456]|https://rt.perl.org/Ticket/Display.html?id=69456>
-L<[perl #122607]|https://rt.perl.org/Ticket/Display.html?id=122607>
-
-=back
-
-=head1 Utility Changes
-
-=head2 F<find2perl>, F<s2p> and F<a2p> removal
-
-=over 4
-
-=item *
-
-The F<x2p/> directory has been removed from the Perl core.
-
-This removes find2perl, s2p and a2p. They have all been released to CPAN as
-separate distributions (C<App::find2perl>, C<App::s2p>, C<App::a2p>).
-
-=back
-
-=head2 L<h2ph>
-
-=over 4
-
-=item *
-
-F<h2ph> now handles hexadecimal constants in the compiler's predefined
-macro definitions, as visible in C<$Config{cppsymbols}>.
-L<[perl #123784]|https://rt.perl.org/Ticket/Display.html?id=123784>.
-
-=back
-
-=head2 L<encguess>
-
-=over 4
-
-=item *
-
-No longer depends on non-core modules.
-
-=back
-
-=head1 Configuration and Compilation
-
-=over 4
-
-=item *
-
-F<Configure> now checks for C<lrintl()>, C<lroundl()>, C<llrintl()>, and
-C<llroundl()>.
-
-=item *
-
-F<Configure> with C<-Dmksymlinks> should now be faster.
-L<[perl #122002]|https://rt.perl.org/Ticket/Display.html?id=122002>.
-
-=item *
-
-The C<pthreads> and C<cl> libraries will be linked by default if present.
-This allows XS modules that require threading to work on non-threaded
-perls. Note that you must still pass C<-Dusethreads> if you want a
-threaded perl.
-
-=item *
-
-For long doubles (to get more precision and range for floating point numbers)
-one can now use the GCC quadmath library which implements the quadruple
-precision floating point numbers on x86 and IA-64 platforms. See
-F<INSTALL> for details.
-
-=item *
-
-MurmurHash64A and MurmurHash64B can now be configured as the internal hash
-function.
-
-=item *
-
-C<make test.valgrind> now supports parallel testing.
-
-For example:
-
- TEST_JOBS=9 make test.valgrind
-
-See L<perlhacktips/valgrind> for more information.
-
-L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
-
-=item *
-
-The MAD (Misc Attribute Decoration) build option has been removed
-
-This was an unmaintained attempt at preserving
-the Perl parse tree more faithfully so that automatic conversion of
-Perl 5 to Perl 6 would have been easier.
-
-This build-time configuration option had been unmaintained for years,
-and had probably seriously diverged on both Perl 5 and Perl 6 sides.
-
-=item *
-
-A new compilation flag, C<< -DPERL_OP_PARENT >> is available. For details,
-see the discussion below at L<< /Internal Changes >>.
-
-=item *
-
-Pathtools no longer tries to load XS on miniperl. This speeds up building perl
-slightly.
-
-=back
-
-=head1 Testing
-
-=over 4
-
-=item *
-
-F<t/porting/re_context.t> has been added to test that L<utf8> and its
-dependencies only use the subset of the C<$1..$n> capture vars that
-C<Perl_save_re_context()> is hard-coded to localize, because that function
-has no efficient way of determining at runtime what vars to localize.
-
-=item *
-
-Tests for performance issues have been added in the file F<t/perf/taint.t>.
-
-=item *
-
-Some regular expression tests are written in such a way that they will
-run very slowly if certain optimizations break. These tests have been
-moved into new files, F<< t/re/speed.t >> and F<< t/re/speed_thr.t >>,
-and are run with a C<< watchdog() >>.
-
-=item *
-
-C<< test.pl >> now allows C<< plan skip_all => $reason >>, to make it
-more compatible with C<< Test::More >>.
-
-=item *
-
-A new test script, F<op/infnan.t>, has been added to test if infinity and NaN are
-working correctly. See L</Infinity and NaN (not-a-number) handling improved>.
-
-=back
-
-=head1 Platform Support
-
-=head2 Regained Platforms
-
-=over 4
-
-=item IRIX and Tru64 platforms are working again.
-
-Some C<make test> failures remain:
-L<[perl #123977]|https://rt.perl.org/Ticket/Display.html?id=123977>
-and L<[perl #125298]|https://rt.perl.org/Ticket/Display.html?id=125298>
-for IRIX; L<[perl #124212]|https://rt.perl.org/Ticket/Display.html?id=124212>,
-L<[cpan #99605]|https://rt.cpan.org/Public/Bug/Display.html?id=99605>, and
-L<[cpan #104836|https://rt.cpan.org/Ticket/Display.html?id=104836> for Tru64.
-
-=item z/OS running EBCDIC Code Page 1047
-
-Core perl now works on this EBCDIC platform. Earlier perls also worked, but,
-even though support wasn't officially withdrawn, recent perls would not compile
-and run well. Perl 5.20 would work, but had many bugs which have now been
-fixed. Many CPAN modules that ship with Perl still fail tests, including
-C<Pod::Simple>. However the version of C<Pod::Simple> currently on CPAN should work;
-it was fixed too late to include in Perl 5.22. Work is under way to fix many
-of the still-broken CPAN modules, which likely will be installed on CPAN when
-completed, so that you may not have to wait until Perl 5.24 to get a working
-version.
-
-=back
-
-=head2 Discontinued Platforms
-
-=over 4
-
-=item NeXTSTEP/OPENSTEP
-
-NeXTSTEP was a proprietary operating system bundled with NeXT's
-workstations in the early to mid 90s; OPENSTEP was an API specification
-that provided a NeXTSTEP-like environment on a non-NeXTSTEP system. Both
-are now long dead, so support for building Perl on them has been removed.
-
-=back
-
-=head2 Platform-Specific Notes
-
-=over 4
-
-=item EBCDIC
-
-Special handling is required of the perl interpreter on EBCDIC platforms
-to get C<qr/[i-j]/> to match only C<"i"> and C<"j">, since there are 7
-characters between the
-code points for C<"i"> and C<"j">. This special handling had only been
-invoked when both ends of the range are literals. Now it is also
-invoked if any of the C<\N{...}> forms for specifying a character by
-name or Unicode code point is used instead of a literal. See
-L<perlrecharclass/Character Ranges>.
-
-=item HP-UX
-
-The archname now distinguishes use64bitint from use64bitall.
-
-=item Android
-
-Build support has been improved for cross-compiling in general and for
-Android in particular.
-
-=item VMS
-
-=over 4
-
-=item *
-
-When spawning a subprocess without waiting, the return value is now
-the correct PID.
-
-=item *
-
-Fix a prototype so linking doesn't fail under the VMS C++ compiler.
-
-=item *
-
-C<finite>, C<finitel>, and C<isfinite> detection has been added to
-C<configure.com>, environment handling has had some minor changes, and
-a fix for legacy feature checking status.
-
-=back
-
-=item Win32
-
-=over 4
-
-=item *
-
-F<miniperl.exe> is now built with C<-fno-strict-aliasing>, allowing 64-bit
-builds to complete on GCC 4.8.
-L<[perl #123976]|https://rt.perl.org/Ticket/Display.html?id=123976>
-
-=item *
-
-C<nmake minitest> now works on Win32. Due to dependency issues you
-need to build C<nmake test-prep> first, and a small number of the
-tests fail.
-L<[perl #123394]|https://rt.perl.org/Ticket/Display.html?id=123394>
-
-=item *
-
-Perl can now be built in C++ mode on Windows by setting the makefile macro
-C<USE_CPLUSPLUS> to the value "define".
-
-=item *
-
-The list form of piped open has been implemented for Win32. Note: unlike
-C<system LIST> this does not fall back to the shell.
-L<[perl #121159]|https://rt.perl.org/Ticket/Display.html?id=121159>
-
-=item *
-
-New C<DebugSymbols> and C<DebugFull> configuration options added to
-Windows makefiles.
-
-=item *
-
-Previously, compiling XS modules (including CPAN ones) using Visual C++ for
-Win64 resulted in around a dozen warnings per file from F<hv_func.h>. These
-warnings have been silenced.
-
-=item *
-
-Support for building without PerlIO has been removed from the Windows
-makefiles. Non-PerlIO builds were all but deprecated in Perl 5.18.0 and are
-already not supported by F<Configure> on POSIX systems.
-
-=item *
-
-Between 2 and 6 milliseconds and seven I/O calls have been saved per attempt
-to open a perl module for each path in C<@INC>.
-
-=item *
-
-Intel C builds are now always built with C99 mode on.
-
-=item *
-
-C<%I64d> is now being used instead of C<%lld> for MinGW.
-
-=item *
-
-In the experimental C<:win32> layer, a crash in C<open> was fixed. Also
-opening F</dev/null> (which works under Win32 Perl's default C<:unix>
-layer) was implemented for C<:win32>.
-L<[perl #122224]|https://rt.perl.org/Ticket/Display.html?id=122224>
-
-=item *
-
-A new makefile option, C<USE_LONG_DOUBLE>, has been added to the Windows
-dmake makefile for gcc builds only. Set this to "define" if you want perl to
-use long doubles to give more accuracy and range for floating point numbers.
-
-=back
-
-=item OpenBSD
-
-On OpenBSD, Perl will now default to using the system C<malloc> due to the
-security features it provides. Perl's own malloc wrapper has been in use
-since v5.14 due to performance reasons, but the OpenBSD project believes
-the tradeoff is worth it and would prefer that users who need the speed
-specifically ask for it.
-
-L<[perl #122000]|https://rt.perl.org/Ticket/Display.html?id=122000>.
-
-=item Solaris
-
-=over 4
-
-=item *
-
-We now look for the Sun Studio compiler in both F</opt/solstudio*> and
-F</opt/solarisstudio*>.
-
-=item *
-
-Builds on Solaris 10 with C<-Dusedtrace> would fail early since make
-didn't follow implied dependencies to build C<perldtrace.h>. Added an
-explicit dependency to C<depend>.
-L<[perl #120120]|https://rt.perl.org/Ticket/Display.html?id=120120>
-
-=item *
-
-C99 options have been cleaned up; hints look for C<solstudio>
-as well as C<SUNWspro>; and support for native C<setenv> has been added.
-
-=back
-
-=back
-
-=head1 Internal Changes
-
-=over 4
-
-=item *
-
-Experimental support has been added to allow ops in the optree to locate
-their parent, if any. This is enabled by the non-default build option
-C<-DPERL_OP_PARENT>. It is envisaged that this will eventually become
-enabled by default, so XS code which directly accesses the C<op_sibling>
-field of ops should be updated to be future-proofed.
-
-On C<PERL_OP_PARENT> builds, the C<op_sibling> field has been renamed
-C<op_sibparent> and a new flag, C<op_moresib>, added. On the last op in a
-sibling chain, C<op_moresib> is false and C<op_sibparent> points to the
-parent (if any) rather than being C<NULL>.
-
-To make existing code work transparently whether using C<PERL_OP_PARENT>
-or not, a number of new macros and functions have been added that should
-be used, rather than directly manipulating C<op_sibling>.
-
-For the case of just reading C<op_sibling> to determine the next sibling,
-two new macros have been added. A simple scan through a sibling chain
-like this:
-
- for (; kid->op_sibling; kid = kid->op_sibling) { ... }
-
-should now be written as:
-
- for (; OpHAS_SIBLING(kid); kid = OpSIBLING(kid)) { ... }
-
-For altering optrees, a general-purpose function C<op_sibling_splice()>
-has been added, which allows for manipulation of a chain of sibling ops.
-By analogy with the Perl function C<splice()>, it allows you to cut out
-zero or more ops from a sibling chain and replace them with zero or more
-new ops. It transparently handles all the updating of sibling, parent,
-op_last pointers etc.
-
-If you need to manipulate ops at a lower level, then three new macros,
-C<OpMORESIB_set>, C<OpLASTSIB_set> and C<OpMAYBESIB_set> are intended to
-be a low-level portable way to set C<op_sibling> / C<op_sibparent> while
-also updating C<op_moresib>. The first sets the sibling pointer to a new
-sibling, the second makes the op the last sibling, and the third
-conditionally does the first or second action. Note that unlike
-C<op_sibling_splice()> these macros won't maintain consistency in the
-parent at the same time (I<e.g.> by updating C<op_first> and C<op_last> where
-appropriate).
-
-A C-level C<Perl_op_parent()> function and a Perl-level C<B::OP::parent()>
-method have been added. The C function only exists under
-C<PERL_OP_PARENT> builds (using it is build-time error on vanilla
-perls). C<B::OP::parent()> exists always, but on a vanilla build it
-always returns C<NULL>. Under C<PERL_OP_PARENT>, they return the parent
-of the current op, if any. The variable C<$B::OP::does_parent> allows you
-to determine whether C<B> supports retrieving an op's parent.
-
-C<PERL_OP_PARENT> was introduced in 5.21.2, but the interface was
-changed considerably in 5.21.11. If you updated your code before the
-5.21.11 changes, it may require further revision. The main changes after
-5.21.2 were:
-
-=over 4
-
-=item *
-
-The C<OP_SIBLING> and C<OP_HAS_SIBLING> macros have been renamed
-C<OpSIBLING> and C<OpHAS_SIBLING> for consistency with other
-op-manipulating macros.
-
-=item *
-
-The C<op_lastsib> field has been renamed C<op_moresib>, and its meaning
-inverted.
-
-=item *
-
-The macro C<OpSIBLING_set> has been removed, and has been superseded by
-C<OpMORESIB_set> I<et al>.
-
-=item *
-
-The C<op_sibling_splice()> function now accepts a null C<parent> argument
-where the splicing doesn't affect the first or last ops in the sibling
-chain
-
-=back
-
-=item *
-
-Macros have been created to allow XS code to better manipulate the POSIX locale
-category C<LC_NUMERIC>. See L<perlapi/Locale-related functions and macros>.
-
-=item *
-
-The previous C<atoi> I<et al> replacement function, C<grok_atou>, has now been
-superseded by C<grok_atoUV>. See L<perlclib> for details.
-
-=item *
-
-A new function, C<Perl_sv_get_backrefs()>, has been added which allows you
-retrieve the weak references, if any, which point at an SV.
-
-=item *
-
-The C<screaminstr()> function has been removed. Although marked as
-public API, it was undocumented and had no usage in CPAN modules. Calling
-it has been fatal since 5.17.0.
-
-=item *
-
-The C<newDEFSVOP()>, C<block_start()>, C<block_end()> and C<intro_my()>
-functions have been added to the API.
-
-=item *
-
-The internal C<convert> function in F<op.c> has been renamed
-C<op_convert_list> and added to the API.
-
-=item *
-
-The C<sv_magic()> function no longer forbids "ext" magic on read-only
-values. After all, perl can't know whether the custom magic will modify
-the SV or not.
-L<[perl #123103]|https://rt.perl.org/Ticket/Display.html?id=123103>.
-
-=item *
-
-Accessing L<perlapi/CvPADLIST> on an XSUB is now forbidden.
-
-The C<CvPADLIST> field has been reused for a different internal purpose
-for XSUBs. So in particular, you can no longer rely on it being NULL as a
-test of whether a CV is an XSUB. Use C<CvISXSUB()> instead.
-
-=item *
-
-SVs of type C<SVt_NV> are now sometimes bodiless when the build
-configuration and platform allow it: specifically, when C<< sizeof(NV) <=
-sizeof(IV) >>. "Bodiless" means that the NV value is stored directly in
-the head of an SV, without requiring a separate body to be allocated. This
-trick has already been used for IVs since 5.9.2 (though in the case of
-IVs, it is always used, regardless of platform and build configuration).
-
-=item *
-
-The C<$DB::single>, C<$DB::signal> and C<$DB::trace> variables now have set- and
-get-magic that stores their values as IVs, and those IVs are used when
-testing their values in C<pp_dbstate()>. This prevents perl from
-recursing infinitely if an overloaded object is assigned to any of those
-variables.
-L<[perl #122445]|https://rt.perl.org/Ticket/Display.html?id=122445>.
-
-=item *
-
-C<Perl_tmps_grow()>, which is marked as public API but is undocumented, has
-been removed from the public API. This change does not affect XS code that
-uses the C<EXTEND_MORTAL> macro to pre-extend the mortal stack.
-
-=item *
-
-Perl's internals no longer sets or uses the C<SVs_PADMY> flag.
-C<SvPADMY()> now returns a true value for anything not marked C<PADTMP>
-and C<SVs_PADMY> is now defined as 0.
-
-=item *
-
-The macros C<SETsv> and C<SETsvUN> have been removed. They were no longer used
-in the core since commit 6f1401dc2a five years ago, and have not been
-found present on CPAN.
-
-=item *
-
-The C<< SvFAKE >> bit (unused on HVs) got informally reserved by
-David Mitchell for future work on vtables.
-
-=item *
-
-The C<sv_catpvn_flags()> function accepts C<SV_CATBYTES> and C<SV_CATUTF8>
-flags, which specify whether the appended string is bytes or UTF-8,
-respectively. (These flags have in fact been present since 5.16.0, but
-were formerly not regarded as part of the API.)
-
-=item *
-
-A new opcode class, C<< METHOP >>, has been introduced. It holds
-information used at runtime to improve the performance
-of class/object method calls.
-
-C<< OP_METHOD >> and C<< OP_METHOD_NAMED >> have changed from being
-C<< UNOP/SVOP >> to being C<< METHOP >>.
-
-=item *
-
-C<cv_name()> is a new API function that can be passed a CV or GV. It
-returns an SV containing the name of the subroutine, for use in
-diagnostics.
-
-L<[perl #116735]|https://rt.perl.org/Ticket/Display.html?id=116735>
-L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
-
-=item *
-
-C<cv_set_call_checker_flags()> is a new API function that works like
-C<cv_set_call_checker()>, except that it allows the caller to specify
-whether the call checker requires a full GV for reporting the subroutine's
-name, or whether it could be passed a CV instead. Whatever value is
-passed will be acceptable to C<cv_name()>. C<cv_set_call_checker()>
-guarantees there will be a GV, but it may have to create one on the fly,
-which is inefficient.
-L<[perl #116735]|https://rt.perl.org/Ticket/Display.html?id=116735>
-
-=item *
-
-C<CvGV> (which is not part of the API) is now a more complex macro, which may
-call a function and reify a GV. For those cases where it has been used as a
-boolean, C<CvHASGV> has been added, which will return true for CVs that
-notionally have GVs, but without reifying the GV. C<CvGV> also returns a GV
-now for lexical subs.
-L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
-
-=item *
-
-The L<perlapi/sync_locale> function has been added to the public API.
-Changing the program's locale should be avoided by XS code. Nevertheless,
-certain non-Perl libraries called from XS need to do so, such as C<Gtk>.
-When this happens, Perl needs to be told that the locale has
-changed. Use this function to do so, before returning to Perl.
-
-=item *
-
-The defines and labels for the flags in the C<op_private> field of OPs are now
-auto-generated from data in F<regen/op_private>. The noticeable effect of this
-is that some of the flag output of C<Concise> might differ slightly, and the
-flag output of S<C<perl -Dx>> may differ considerably (they both use the same set
-of labels now). Also, debugging builds now have a new assertion in
-C<op_free()> to ensure that the op doesn't have any unrecognized flags set in
-C<op_private>.
-
-=item *
-
-The deprecated variable C<PL_sv_objcount> has been removed.
-
-=item *
-
-Perl now tries to keep the locale category C<LC_NUMERIC> set to "C"
-except around operations that need it to be set to the program's
-underlying locale. This protects the many XS modules that cannot cope
-with the decimal radix character not being a dot. Prior to this
-release, Perl initialized this category to "C", but a call to
-C<POSIX::setlocale()> would change it. Now such a call will change the
-underlying locale of the C<LC_NUMERIC> category for the program, but the
-locale exposed to XS code will remain "C". There are new macros
-to manipulate the LC_NUMERIC locale, including
-C<STORE_LC_NUMERIC_SET_TO_NEEDED> and
-C<STORE_LC_NUMERIC_FORCE_TO_UNDERLYING>.
-See L<perlapi/Locale-related functions and macros>.
-
-=item *
-
-A new macro L<C<isUTF8_CHAR>|perlapi/isUTF8_CHAR> has been written which
-efficiently determines if the string given by its parameters begins
-with a well-formed UTF-8 encoded character.
-
-=item *
-
-The following private API functions had their context parameter removed:
-C<Perl_cast_ulong>, C<Perl_cast_i32>, C<Perl_cast_iv>, C<Perl_cast_uv>,
-C<Perl_cv_const_sv>, C<Perl_mg_find>, C<Perl_mg_findext>, C<Perl_mg_magical>,
-C<Perl_mini_mktime>, C<Perl_my_dirfd>, C<Perl_sv_backoff>, C<Perl_utf8_hop>.
-
-Note that the prefix-less versions of those functions that are part of the
-public API, such as C<cast_i32()>, remain unaffected.
-
-=item *
-
-The C<PADNAME> and C<PADNAMELIST> types are now separate types, and no
-longer simply aliases for SV and AV.
-L<[perl #123223]|https://rt.perl.org/Ticket/Display.html?id=123223>.
-
-=item *
-
-Pad names are now always UTF-8. The C<PadnameUTF8> macro always returns
-true. Previously, this was effectively the case already, but any support
-for two different internal representations of pad names has now been
-removed.
-
-=item *
-
-A new op class, C<UNOP_AUX>, has been added. This is a subclass of
-C<UNOP> with an C<op_aux> field added, which points to an array of unions
-of UV, SV* etc. It is intended for where an op needs to store more data
-than a simple C<op_sv> or whatever. Currently the only op of this type is
-C<OP_MULTIDEREF> (see next item).
-
-=item *
-
-A new op has been added, C<OP_MULTIDEREF>, which performs one or more
-nested array and hash lookups where the key is a constant or simple
-variable. For example the expression C<$a[0]{$k}[$i]>, which previously
-involved ten C<rv2Xv>, C<Xelem>, C<gvsv> and C<const> ops is now performed
-by a single C<multideref> op. It can also handle C<local>, C<exists> and
-C<delete>. A non-simple index expression, such as C<[$i+1]> is still done
-using C<aelem>/C<helem>, and single-level array lookup with a small constant
-index is still done using C<aelemfast>.
-
-=back
-
-=head1 Selected Bug Fixes
-
-=over 4
-
-=item *
-
-C<close> now sets C<$!>
-
-When an I/O error occurs, the fact that there has been an error is recorded
-in the handle. C<close> returns false for such a handle. Previously, the
-value of C<$!> would be untouched by C<close>, so the common convention of
-writing S<C<close $fh or die $!>> did not work reliably. Now the handle
-records the value of C<$!>, too, and C<close> restores it.
-
-=item *
-
-C<no re> now can turn off everything that C<use re> enables
-
-Previously, running C<no re> would turn off only a few things. Now it
-can turn off all the enabled things. For example, the only way to
-stop debugging, once enabled, was to exit the enclosing block; that is
-now fixed.
-
-=item *
-
-C<pack("D", $x)> and C<pack("F", $x)> now zero the padding on x86 long
-double builds. Under some build options on GCC 4.8 and later, they used
-to either overwrite the zero-initialized padding, or bypass the
-initialized buffer entirely. This caused F<op/pack.t> to fail.
-L<[perl #123971]|https://rt.perl.org/Ticket/Display.html?id=123971>
-
-=item *
-
-Extending an array cloned from a parent thread could result in "Modification of
-a read-only value attempted" errors when attempting to modify the new elements.
-L<[perl #124127]|https://rt.perl.org/Ticket/Display.html?id=124127>
-
-=item *
-
-An assertion failure and subsequent crash with C<< *x=<y> >> has been fixed.
-L<[perl #123790]|https://rt.perl.org/Ticket/Display.html?id=123790>
-
-=item *
-
-A possible crashing/looping bug related to compiling lexical subs has been
-fixed.
-L<[perl #124099]|https://rt.perl.org/Ticket/Display.html?id=124099>
-
-=item *
-
-UTF-8 now works correctly in function names, in unquoted HERE-document
-terminators, and in variable names used as array indexes.
-L<[perl #124113]|https://rt.perl.org/Ticket/Display.html?id=124113>
-
-=item *
-
-Repeated global pattern matches in scalar context on large tainted strings were
-exponentially slow depending on the current match position in the string.
-L<[perl #123202]|https://rt.perl.org/Ticket/Display.html?id=123202>
-
-=item *
-
-Various crashes due to the parser getting confused by syntax errors have been
-fixed.
-L<[perl #123801]|https://rt.perl.org/Ticket/Display.html?id=123801>
-L<[perl #123802]|https://rt.perl.org/Ticket/Display.html?id=123802>
-L<[perl #123955]|https://rt.perl.org/Ticket/Display.html?id=123955>
-L<[perl #123995]|https://rt.perl.org/Ticket/Display.html?id=123995>
-
-=item *
-
-C<split> in the scope of lexical C<$_> has been fixed not to fail assertions.
-L<[perl #123763]|https://rt.perl.org/Ticket/Display.html?id=123763>
-
-=item *
-
-C<my $x : attr> syntax inside various list operators no longer fails
-assertions.
-L<[perl #123817]|https://rt.perl.org/Ticket/Display.html?id=123817>
-
-=item *
-
-An C<@> sign in quotes followed by a non-ASCII digit (which is not a valid
-identifier) would cause the parser to crash, instead of simply trying the
-C<@> as literal. This has been fixed.
-L<[perl #123963]|https://rt.perl.org/Ticket/Display.html?id=123963>
-
-=item *
-
-C<*bar::=*foo::=*glob_with_hash> has been crashing since Perl 5.14, but no
-longer does.
-L<[perl #123847]|https://rt.perl.org/Ticket/Display.html?id=123847>
-
-=item *
-
-C<foreach> in scalar context was not pushing an item on to the stack, resulting
-in bugs. (S<C<print 4, scalar do { foreach(@x){} } + 1>> would print 5.)
-It has been fixed to return C<undef>.
-L<[perl #124004]|https://rt.perl.org/Ticket/Display.html?id=124004>
-
-=item *
-
-Several cases of data used to store environment variable contents in core C
-code being potentially overwritten before being used have been fixed.
-L<[perl #123748]|https://rt.perl.org/Ticket/Display.html?id=123748>
-
-=item *
-
-Some patterns starting with C</.*..../> matched against long strings have
-been slow since v5.8, and some of the form C</.*..../i> have been slow
-since v5.18. They are now all fast again.
-L<[perl #123743]|https://rt.perl.org/Ticket/Display.html?id=123743>.
-
-=item *
-
-The original visible value of C<$/> is now preserved when it is set to
-an invalid value. Previously if you set C<$/> to a reference to an
-array, for example, perl would produce a runtime error and not set
-C<PL_rs>, but Perl code that checked C<$/> would see the array
-reference.
-L<[perl #123218]|https://rt.perl.org/Ticket/Display.html?id=123218>.
-
-=item *
-
-In a regular expression pattern, a POSIX class, like C<[:ascii:]>, must
-be inside a bracketed character class, like C<qr/[[:ascii:]]/>. A
-warning is issued when something looking like a POSIX class is not
-inside a bracketed class. That warning wasn't getting generated when
-the POSIX class was negated: C<[:^ascii:]>. This is now fixed.
-
-=item *
-
-Perl 5.14.0 introduced a bug whereby S<C<eval { LABEL: }>> would crash. This
-has been fixed.
-L<[perl #123652]|https://rt.perl.org/Ticket/Display.html?id=123652>.
-
-=item *
-
-Various crashes due to the parser getting confused by syntax errors have
-been fixed.
-L<[perl #123617]|https://rt.perl.org/Ticket/Display.html?id=123617>.
-L<[perl #123737]|https://rt.perl.org/Ticket/Display.html?id=123737>.
-L<[perl #123753]|https://rt.perl.org/Ticket/Display.html?id=123753>.
-L<[perl #123677]|https://rt.perl.org/Ticket/Display.html?id=123677>.
-
-=item *
-
-Code like C</$a[/> used to read the next line of input and treat it as
-though it came immediately after the opening bracket. Some invalid code
-consequently would parse and run, but some code caused crashes, so this is
-now disallowed.
-L<[perl #123712]|https://rt.perl.org/Ticket/Display.html?id=123712>.
-
-=item *
-
-Fix argument underflow for C<pack>.
-L<[perl #123874]|https://rt.perl.org/Ticket/Display.html?id=123874>.
-
-=item *
-
-Fix handling of non-strict C<\x{}>. Now C<\x{}> is equivalent to C<\x{0}>
-instead of faulting.
-
-=item *
-
-C<stat -t> is now no longer treated as stackable, just like C<-t stat>.
-L<[perl #123816]|https://rt.perl.org/Ticket/Display.html?id=123816>.
-
-=item *
-
-The following no longer causes a SEGV: C<qr{x+(y(?0))*}>.
-
-=item *
-
-Fixed infinite loop in parsing backrefs in regexp patterns.
-
-=item *
-
-Several minor bug fixes in behavior of Infinity and NaN, including
-warnings when stringifying Infinity-like or NaN-like strings. For example,
-"NaNcy" doesn't numify to NaN anymore.
-
-=item *
+perldelta - what is new for perl v5.23.4
-A bug in regular expression patterns that could lead to segfaults and
-other crashes has been fixed. This occurred only in patterns compiled
-with C</i> while taking into account the current POSIX locale (which usually
-means they have to be compiled within the scope of C<S<use locale>>),
-and there must be a string of at least 128 consecutive bytes to match.
-L<[perl #123539]|https://rt.perl.org/Ticket/Display.html?id=123539>.
-
-=item *
-
-C<s///g> now works on very long strings (where there are more than 2
-billion iterations) instead of dying with 'Substitution loop'.
-L<[perl #103260]|https://rt.perl.org/Ticket/Display.html?id=103260>.
-L<[perl #123071]|https://rt.perl.org/Ticket/Display.html?id=123071>.
-
-=item *
-
-C<gmtime> no longer crashes with not-a-number values.
-L<[perl #123495]|https://rt.perl.org/Ticket/Display.html?id=123495>.
-
-=item *
-
-C<\()> (a reference to an empty list), and C<y///> with lexical C<$_> in
-scope, could both do a bad write past the end of the stack. They have
-both been fixed to extend the stack first.
-
-=item *
-
-C<prototype()> with no arguments used to read the previous item on the
-stack, so S<C<print "foo", prototype()>> would print foo's prototype.
-It has been fixed to infer C<$_> instead.
-L<[perl #123514]|https://rt.perl.org/Ticket/Display.html?id=123514>.
-
-=item *
-
-Some cases of lexical state subs declared inside predeclared subs could
-crash, for example when evalling a string including the name of an outer
-variable, but no longer do.
-
-=item *
-
-Some cases of nested lexical state subs inside anonymous subs could cause
-'Bizarre copy' errors or possibly even crashes.
-
-=item *
-
-When trying to emit warnings, perl's default debugger (F<perl5db.pl>) was
-sometimes giving 'Undefined subroutine &DB::db_warn called' instead. This
-bug, which started to occur in Perl 5.18, has been fixed.
-L<[perl #123553]|https://rt.perl.org/Ticket/Display.html?id=123553>.
-
-=item *
-
-Certain syntax errors in substitutions, such as C<< s/${<>{})// >>, would
-crash, and had done so since Perl 5.10. (In some cases the crash did not
-start happening till 5.16.) The crash has, of course, been fixed.
-L<[perl #123542]|https://rt.perl.org/Ticket/Display.html?id=123542>.
-
-=item *
-
-Fix a couple of string grow size calculation overflows; in particular,
-a repeat expression like S<C<33 x ~3>> could cause a large buffer
-overflow since the new output buffer size was not correctly handled by
-C<SvGROW()>. An expression like this now properly produces a memory wrap
-panic.
-L<[perl #123554]|https://rt.perl.org/Ticket/Display.html?id=123554>.
-
-=item *
-
-C<< formline("@...", "a"); >> would crash. The C<FF_CHECKNL> case in
-C<pp_formline()> didn't set the pointer used to mark the chop position,
-which led to the C<FF_MORE> case crashing with a segmentation fault.
-This has been fixed.
-L<[perl #123538]|https://rt.perl.org/Ticket/Display.html?id=123538>.
-
-=item *
-
-A possible buffer overrun and crash when parsing a literal pattern during
-regular expression compilation has been fixed.
-L<[perl #123604]|https://rt.perl.org/Ticket/Display.html?id=123604>.
-
-=item *
-
-C<fchmod()> and C<futimes()> now set C<$!> when they fail due to being
-passed a closed file handle.
-L<[perl #122703]|https://rt.perl.org/Ticket/Display.html?id=122703>.
-
-=item *
-
-C<op_free()> and C<scalarvoid()> no longer crash due to a stack overflow
-when freeing a deeply recursive op tree.
-L<[perl #108276]|https://rt.perl.org/Ticket/Display.html?id=108276>.
-
-=item *
-
-In Perl 5.20.0, C<$^N> accidentally had the internal UTF-8 flag turned off
-if accessed from a code block within a regular expression, effectively
-UTF-8-encoding the value. This has been fixed.
-L<[perl #123135]|https://rt.perl.org/Ticket/Display.html?id=123135>.
-
-=item *
-
-A failed C<semctl> call no longer overwrites existing items on the stack,
-which means that C<(semctl(-1,0,0,0))[0]> no longer gives an
-"uninitialized" warning.
-
-=item *
-
-C<else{foo()}> with no space before C<foo> is now better at assigning the
-right line number to that statement.
-L<[perl #122695]|https://rt.perl.org/Ticket/Display.html?id=122695>.
-
-=item *
-
-Sometimes the assignment in C<@array = split> gets optimised so that C<split>
-itself writes directly to the array. This caused a bug, preventing this
-assignment from being used in lvalue context. So
-C<(@a=split//,"foo")=bar()> was an error. (This bug probably goes back to
-Perl 3, when the optimisation was added.) It has now been fixed.
-L<[perl #123057]|https://rt.perl.org/Ticket/Display.html?id=123057>.
-
-=item *
-
-When an argument list fails the checks specified by a subroutine
-signature (which is still an experimental feature), the resulting error
-messages now give the file and line number of the caller, not of the
-called subroutine.
-L<[perl #121374]|https://rt.perl.org/Ticket/Display.html?id=121374>.
+=head1 DESCRIPTION
-=item *
+This document describes differences between the 5.23.3 release and the 5.23.4
+release.
-The flip-flop operators (C<..> and C<...> in scalar context) used to maintain
-a separate state for each recursion level (the number of times the
-enclosing sub was called recursively), contrary to the documentation. Now
-each closure has one internal state for each flip-flop.
-L<[perl #122829]|https://rt.perl.org/Ticket/Display.html?id=122829>.
+If you are upgrading from an earlier release such as 5.23.2, first read
+L<perl5233delta>, which describes differences between 5.23.2 and 5.23.3.
-=item *
+=head1 Notice
-The flip-flop operator (C<..> in scalar context) would return the same
-scalar each time, unless the containing subroutine was called recursively.
-Now it always returns a new scalar.
-L<[perl #122829]|https://rt.perl.org/Ticket/Display.html?id=122829>.
+XXX Any important notices here
-=item *
+=head1 Core Enhancements
-C<use>, C<no>, statement labels, special blocks (C<BEGIN>) and pod are now
-permitted as the first thing in a C<map> or C<grep> block, the block after
-C<print> or C<say> (or other functions) returning a handle, and within
-C<${...}>, C<@{...}>, etc.
-L<[perl #122782]|https://rt.perl.org/Ticket/Display.html?id=122782>.
+XXX New core language features go here. Summarize user-visible core language
+enhancements. Particularly prominent performance optimisations could go
+here, but most should go in the L</Performance Enhancements> section.
-=item *
+[ List each enhancement as a =head2 entry ]
-The repetition operator C<x> now propagates lvalue context to its left-hand
-argument when used in contexts like C<foreach>. That allows
-S<C<for(($#that_array)x2) { ... }>> to work as expected if the loop modifies
-C<$_>.
+=head1 Security
-=item *
+XXX Any security-related notices go here. In particular, any security
+vulnerabilities closed should be noted here rather than in the
+L</Selected Bug Fixes> section.
-C<(...) x ...> in scalar context used to corrupt the stack if one operand
-was an object with "x" overloading, causing erratic behavior.
-L<[perl #121827]|https://rt.perl.org/Ticket/Display.html?id=121827>.
+[ List each security issue as a =head2 entry ]
-=item *
+=head1 Incompatible Changes
-Assignment to a lexical scalar is often optimised away; for example in
-C<my $x; $x = $y + $z>, the assign operator is optimised away and the add
-operator writes its result directly to C<$x>. Various bugs related to
-this optimisation have been fixed. Certain operators on the right-hand
-side would sometimes fail to assign the value at all or assign the wrong
-value, or would call STORE twice or not at all on tied variables. The
-operators affected were C<$foo++>, C<$foo-->, and C<-$foo> under C<use
-integer>, C<chomp>, C<chr> and C<setpgrp>.
+=head2 Lexical $_ has been removed
-=item *
+C<my $_> was introduced in Perl 5.10, and subsequently caused much confusion
+with no obvious solution. In Perl 5.18.0, it was made experimental on the
+theory that it would either be removed or redesigned in a less confusing (but
+backward-incompatible) way. Over the following years, no alternatives were
+proposed. The feature has now been removed and will fail to compile.
-List assignments were sometimes buggy if the same scalar ended up on both
-sides of the assignment due to use of C<tied>, C<values> or C<each>. The
-result would be the wrong value getting assigned.
+=head2 Only blanks and tabs are now allowed within C<[...]> within C<(?[...])>.
-=item *
+The experimental Extended Bracketed Character Classes can contain regular
+bracketed character classes within them. These differ from regular ones in
+that white space is generally ignored, unless escaped by preceding it with a
+backslash. The white space that is ignored is now limited to just tab C<\t>
+and SPACE characters. Previously, it was any white space. See
+L<perlrecharclass/Extended Bracketed Character Classes>.
-C<setpgrp($nonzero)> (with one argument) was accidentally changed in 5.16
-to mean C<setpgrp(0)>. This has been fixed.
+=head1 Deprecations
-=item *
+XXX Any deprecated features, syntax, modules etc. should be listed here.
-C<__SUB__> could return the wrong value or even corrupt memory under the
-debugger (the C<-d> switch) and in subs containing C<eval $string>.
+=head2 Module removals
-=item *
+XXX Remove this section if inapplicable.
-When S<C<sub () { $var }>> becomes inlinable, it now returns a different
-scalar each time, just as a non-inlinable sub would, though Perl still
-optimises the copy away in cases where it would make no observable
-difference.
+The following modules will be removed from the core distribution in a
+future release, and will at that time need to be installed from CPAN.
+Distributions on CPAN which require these modules will need to list them as
+prerequisites.
-=item *
+The core versions of these modules will now issue C<"deprecated">-category
+warnings to alert you to this fact. To silence these deprecation warnings,
+install the modules in question from CPAN.
-S<C<my sub f () { $var }>> and S<C<sub () : attr { $var }>> are no longer
-eligible for inlining. The former would crash; the latter would just
-throw the attributes away. An exception is made for the little-known
-C<:method> attribute, which does nothing much.
+Note that these are (with rare exceptions) fine modules that you are encouraged
+to continue to use. Their disinclusion from core primarily hinges on their
+necessity to bootstrapping a fully functional, CPAN-capable Perl installation,
+not usually on concerns over their design.
-=item *
+=over
-Inlining of subs with an empty prototype is now more consistent than
-before. Previously, a sub with multiple statements, of which all but the last
-were optimised away, would be inlinable only if it were an anonymous sub
-containing a string C<eval> or C<state> declaration or closing over an
-outer lexical variable (or any anonymous sub under the debugger). Now any
-sub that gets folded to a single constant after statements have been
-optimised away is eligible for inlining. This applies to things like C<sub
-() { jabber() if DEBUG; 42 }>.
+=item XXX
-Some subroutines with an explicit C<return> were being made inlinable,
-contrary to the documentation, Now C<return> always prevents inlining.
+XXX Note that deprecated modules should be listed here even if they are listed
+as an updated module in the L</Modules and Pragmata> section.
-=item *
+=back
-On some systems, such as VMS, C<crypt> can return a non-ASCII string. If a
-scalar assigned to had contained a UTF-8 string previously, then C<crypt>
-would not turn off the UTF-8 flag, thus corrupting the return value. This
-would happen with S<C<$lexical = crypt ...>>.
+[ List each other deprecation as a =head2 entry ]
-=item *
+=head1 Performance Enhancements
-C<crypt> no longer calls C<FETCH> twice on a tied first argument.
+XXX Changes which enhance performance without changing behaviour go here.
+There may well be none in a stable release.
-=item *
+[ List each enhancement as a =item entry ]
-An unterminated here-doc on the last line of a quote-like operator
-(C<qq[${ <<END }]>, C</(?{ <<END })/>) no longer causes a double free. It
-started doing so in 5.18.
+=over 4
=item *
-C<index()> and C<rindex()> no longer crash when used on strings over 2GB in
-size.
-L<[perl #121562]|https://rt.perl.org/Ticket/Display.html?id=121562>.
+XXX
-=item *
+=back
-A small, previously intentional, memory leak in
-C<PERL_SYS_INIT>/C<PERL_SYS_INIT3> on Win32 builds was fixed. This might
-affect embedders who repeatedly create and destroy perl engines within
-the same process.
+=head1 Modules and Pragmata
-=item *
+XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
+go here. If Module::CoreList is updated, generate an initial draft of the
+following sections using F<Porting/corelist-perldelta.pl>. A paragraph summary
+for important changes should then be added by hand. In an ideal world,
+dual-life modules would have a F<Changes> file that could be cribbed.
-C<POSIX::localeconv()> now returns the data for the program's underlying
-locale even when called from outside the scope of S<C<use locale>>.
+[ Within each section, list entries as a =item entry ]
-=item *
+=head2 New Modules and Pragmata
-C<POSIX::localeconv()> now works properly on platforms which don't have
-C<LC_NUMERIC> and/or C<LC_MONETARY>, or for which Perl has been compiled
-to disregard either or both of these locale categories. In such
-circumstances, there are now no entries for the corresponding values in
-the hash returned by C<localeconv()>.
+=over 4
=item *
-C<POSIX::localeconv()> now marks appropriately the values it returns as
-UTF-8 or not. Previously they were always returned as bytes, even if
-they were supposed to be encoded as UTF-8.
-
-=item *
+XXX
-On Microsoft Windows, within the scope of C<S<use locale>>, the following
-POSIX character classes gave results for many locales that did not
-conform to the POSIX standard:
-C<[[:alnum:]]>,
-C<[[:alpha:]]>,
-C<[[:blank:]]>,
-C<[[:digit:]]>,
-C<[[:graph:]]>,
-C<[[:lower:]]>,
-C<[[:print:]]>,
-C<[[:punct:]]>,
-C<[[:upper:]]>,
-C<[[:word:]]>,
-and
-C<[[:xdigit:]]>.
-This was because the underlying Microsoft implementation does not
-follow the standard. Perl now takes special precautions to correct for
-this.
+=back
-=item *
+=head2 Updated Modules and Pragmata
-Many issues have been detected by L<Coverity|http://www.coverity.com/> and
-fixed.
+=over 4
=item *
-C<system()> and friends should now work properly on more Android builds.
+L<XXX> has been upgraded from version A.xx to B.yy.
-Due to an oversight, the value specified through C<-Dtargetsh> to F<Configure>
-would end up being ignored by some of the build process. This caused perls
-cross-compiled for Android to end up with defective versions of C<system()>,
-C<exec()> and backticks: the commands would end up looking for C</bin/sh>
-instead of C</system/bin/sh>, and so would fail for the vast majority
-of devices, leaving C<$!> as C<ENOENT>.
+=back
-=item *
+=head2 Removed Modules and Pragmata
-C<qr(...\(...\)...)>,
-C<qr[...\[...\]...]>,
-and
-C<qr{...\{...\}...}>
-now work. Previously it was impossible to escape these three
-left-characters with a backslash within a regular expression pattern
-where otherwise they would be considered metacharacters, and the pattern
-opening delimiter was the character, and the closing delimiter was its
-mirror character.
+=over 4
=item *
-C<< s///e >> on tainted UTF-8 strings corrupted C<< pos() >>. This bug,
-introduced in 5.20, is now fixed.
-L<[perl #122148]|https://rt.perl.org/Ticket/Display.html?id=122148>.
-
-=item *
+XXX
-A non-word boundary in a regular expression (C<< \B >>) did not always
-match the end of the string; in particular C<< q{} =~ /\B/ >> did not
-match. This bug, introduced in perl 5.14, is now fixed.
-L<[perl #122090]|https://rt.perl.org/Ticket/Display.html?id=122090>.
+=back
-=item *
+=head1 Documentation
-C<< " P" =~ /(?=.*P)P/ >> should match, but did not. This is now fixed.
-L<[perl #122171]|https://rt.perl.org/Ticket/Display.html?id=122171>.
+XXX Changes to files in F<pod/> go here. Consider grouping entries by
+file and be sure to link to the appropriate page, e.g. L<perlfunc>.
-=item *
+=head2 New Documentation
-Failing to compile C<use Foo> in an C<eval> could leave a spurious
-C<BEGIN> subroutine definition, which would produce a "Subroutine
-BEGIN redefined" warning on the next use of C<use>, or other C<BEGIN>
-block.
-L<[perl #122107]|https://rt.perl.org/Ticket/Display.html?id=122107>.
+XXX Changes which create B<new> files in F<pod/> go here.
-=item *
+=head3 L<XXX>
-C<method { BLOCK } ARGS> syntax now correctly parses the arguments if they
-begin with an opening brace.
-L<[perl #46947]|https://rt.perl.org/Ticket/Display.html?id=46947>.
+XXX Description of the purpose of the new file here
-=item *
+=head2 Changes to Existing Documentation
-External libraries and Perl may have different ideas of what the locale is.
-This is problematic when parsing version strings if the locale's numeric
-separator has been changed. Version parsing has been patched to ensure
-it handles the locales correctly.
-L<[perl #121930]|https://rt.perl.org/Ticket/Display.html?id=121930>.
+XXX Changes which significantly change existing files in F<pod/> go here.
+However, any changes to F<pod/perldiag.pod> should go in the L</Diagnostics>
+section.
-=item *
+=head3 L<XXX>
-A bug has been fixed where zero-length assertions and code blocks inside of a
-regex could cause C<pos> to see an incorrect value.
-L<[perl #122460]|https://rt.perl.org/Ticket/Display.html?id=122460>.
+=over 4
=item *
-Dereferencing of constants now works correctly for typeglob constants. Previously
-the glob was stringified and its name looked up. Now the glob itself is used.
-L<[perl #69456]|https://rt.perl.org/Ticket/Display.html?id=69456>
+XXX Description of the change here
-=item *
+=back
-When parsing a sigil (C<$> C<@> C<%> C<&)> followed by braces,
-the parser no
-longer tries to guess whether it is a block or a hash constructor (causing a
-syntax error when it guesses the latter), since it can only be a block.
+=head1 Diagnostics
-=item *
+The following additions or changes have been made to diagnostic output,
+including warnings and fatal error messages. For the complete list of
+diagnostic messages, see L<perldiag>.
-S<C<undef $reference>> now frees the referent immediately, instead of hanging on
-to it until the next statement.
-L<[perl #122556]|https://rt.perl.org/Ticket/Display.html?id=122556>
+XXX New or changed warnings emitted by the core's C<C> code go here. Also
+include any changes in L<perldiag> that reconcile it to the C<C> code.
-=item *
+=head2 New Diagnostics
-Various cases where the name of a sub is used (autoload, overloading, error
-messages) used to crash for lexical subs, but have been fixed.
+XXX Newly added diagnostic messages go under here, separated into New Errors
+and New Warnings
-=item *
+=head3 New Errors
-Bareword lookup now tries to avoid vivifying packages if it turns out the
-bareword is not going to be a subroutine name.
+=over 4
=item *
-Compilation of anonymous constants (I<e.g.>, C<sub () { 3 }>) no longer deletes
-any subroutine named C<__ANON__> in the current package. Not only was
-C<*__ANON__{CODE}> cleared, but there was a memory leak, too. This bug goes
-back to Perl 5.8.0.
+L<Character following \p must be '{' or a single-character Unicode property name in regex;|perldiag/"Character following \%c must be '{' or a single-character Unicode property name in regex; marked by <-- HERE in m/%s/">
=item *
-Stub declarations like C<sub f;> and C<sub f ();> no longer wipe out constants
-of the same name declared by C<use constant>. This bug was introduced in Perl
-5.10.0.
+L<perldiag/"Illegal user-defined property name">
-=item *
+=back
-C<qr/[\N{named sequence}]/> now works properly in many instances.
+=head3 New Warnings
-Some names
-known to C<\N{...}> refer to a sequence of multiple characters, instead of the
-usual single character. Bracketed character classes generally only match
-single characters, but now special handling has been added so that they can
-match named sequences, but not if the class is inverted or the sequence is
-specified as the beginning or end of a range. In these cases, the only
-behavior change from before is a slight rewording of the fatal error message
-given when this class is part of a C<?[...])> construct. When the C<[...]>
-stands alone, the same non-fatal warning as before is raised, and only the
-first character in the sequence is used, again just as before.
+=over 4
=item *
-Tainted constants evaluated at compile time no longer cause unrelated
-statements to become tainted.
-L<[perl #122669]|https://rt.perl.org/Ticket/Display.html?id=122669>
+XXX L<message|perldiag/"message">
-=item *
+=back
-S<C<open $$fh, ...>>, which vivifies a handle with a name like
-C<"main::_GEN_0">, was not giving the handle the right reference count, so
-a double free could happen.
+=head2 Changes to Existing Diagnostics
-=item *
+XXX Changes (i.e. rewording) of diagnostic messages go here
-When deciding that a bareword was a method name, the parser would get confused
-if an C<our> sub with the same name existed, and look up the method in the
-package of the C<our> sub, instead of the package of the invocant.
+=over 4
=item *
-The parser no longer gets confused by C<\U=> within a double-quoted string. It
-used to produce a syntax error, but now compiles it correctly.
-L<[perl #80368]|https://rt.perl.org/Ticket/Display.html?id=80368>
+L<"Can't modify non-lvalue subroutine call of &%s"|perldiag/"Can't modify non-lvalue subroutine call of &%s">
-=item *
-
-It has always been the intention for the C<-B> and C<-T> file test operators to
-treat UTF-8 encoded files as text. (L<perlfunc|perlfunc/-X FILEHANDLE> has
-been updated to say this.) Previously, it was possible for some files to be
-considered UTF-8 that actually weren't valid UTF-8. This is now fixed. The
-operators now work on EBCDIC platforms as well.
+This error now reports the name of the non-lvalue subroutine you attempted to
+use as an lvalue.
-=item *
+=back
-Under some conditions warning messages raised during regular expression pattern
-compilation were being output more than once. This has now been fixed.
+=head1 Utility Changes
-=item *
+XXX Changes to installed programs such as F<perlbug> and F<xsubpp> go here.
+Most of these are built within the directory F<utils>.
-Perl 5.20.0 introduced a regression in which a UTF-8 encoded regular
-expression pattern that contains a single ASCII lowercase letter did not
-match its uppercase counterpart. That has been fixed in both 5.20.1 and
-5.22.0.
-L<[perl #122655]|https://rt.perl.org/Ticket/Display.html?id=122655>
+[ List utility changes as a =head2 entry for each utility and =item
+entries for each change
+Use L<XXX> with program names to get proper documentation linking. ]
-=item *
+=head2 L<XXX>
-Constant folding could incorrectly suppress warnings if lexical warnings
-(C<use warnings> or C<no warnings>) were not in effect and C<$^W> were
-false at compile time and true at run time.
+=over 4
=item *
-Loading Unicode tables during a regular expression match could cause assertion
-failures under debugging builds if the previous match used the very same
-regular expression.
-L<[perl #122747]|https://rt.perl.org/Ticket/Display.html?id=122747>
+Using the C<NO_HASH_SEED> define in combination with the default hash algorithm
+C<PERL_HASH_FUNC_ONE_AT_A_TIME_HARD> resulted in a fatal error while compiling
+the interpreter, since Perl 5.17.10. This has been fixed.
-=item *
-
-Thread cloning used to work incorrectly for lexical subs, possibly causing
-crashes or double frees on exit.
+=back
-=item *
+=head1 Configuration and Compilation
-Since Perl 5.14.0, deleting C<$SomePackage::{__ANON__}> and then undefining an
-anonymous subroutine could corrupt things internally, resulting in
-L<Devel::Peek> crashing or L<B.pm|B> giving nonsensical data. This has been
-fixed.
+XXX Changes to F<Configure>, F<installperl>, F<installman>, and analogous tools
+go here. Any other changes to the Perl build process should be listed here.
+However, any platform-specific changes should be listed in the
+L</Platform Support> section, instead.
-=item *
+[ List changes as a =item entry ].
-S<C<(caller $n)[3]>> now reports names of lexical subs, instead of
-treating them as C<"(unknown)">.
+=over 4
=item *
-C<sort subname LIST> now supports using a lexical sub as the comparison
-routine.
-
-=item *
+XXX
-Aliasing (I<e.g.>, via S<C<*x = *y>>) could confuse list assignments that mention the
-two names for the same variable on either side, causing wrong values to be
-assigned.
-L<[perl #15667]|https://rt.perl.org/Ticket/Display.html?id=15667>
+=back
-=item *
+=head1 Testing
-Long here-doc terminators could cause a bad read on short lines of input. This
-has been fixed. It is doubtful that any crash could have occurred. This bug
-goes back to when here-docs were introduced in Perl 3.000 twenty-five years
-ago.
+XXX Any significant changes to the testing of a freshly built perl should be
+listed here. Changes which create B<new> files in F<t/> go here as do any
+large changes to the testing harness (e.g. when parallel testing was added).
+Changes to existing files in F<t/> aren't worth summarizing, although the bugs
+that they represent may be covered elsewhere.
-=item *
+[ List each test improvement as a =item entry ]
-An optimization in C<split> to treat S<C<split /^/>> like S<C<split /^/m>> had the
-unfortunate side-effect of also treating S<C<split /\A/>> like S<C<split /^/m>>,
-which it should not. This has been fixed. (Note, however, that S<C<split /^x/>>
-does not behave like S<C<split /^x/m>>, which is also considered to be a bug and
-will be fixed in a future version.)
-L<[perl #122761]|https://rt.perl.org/Ticket/Display.html?id=122761>
+=over 4
=item *
-The little-known S<C<my Class $var>> syntax (see L<fields> and L<attributes>)
-could get confused in the scope of C<use utf8> if C<Class> were a constant
-whose value contained Latin-1 characters.
-
-=item *
+XXX
-Locking and unlocking values via L<Hash::Util> or C<Internals::SvREADONLY>
-no longer has any effect on values that were read-only to begin with.
-Previously, unlocking such values could result in crashes, hangs or
-other erratic behavior.
+=back
-=item *
+=head1 Platform Support
-Some unterminated C<(?(...)...)> constructs in regular expressions would
-either crash or give erroneous error messages. C</(?(1)/> is one such
-example.
+XXX Any changes to platform support should be listed in the sections below.
-=item *
+[ Within the sections, list each platform as a =item entry with specific
+changes as paragraphs below it. ]
-S<C<pack "w", $tied>> no longer calls FETCH twice.
+=head2 New Platforms
-=item *
+XXX List any platforms that this version of perl compiles on, that previous
+versions did not. These will either be enabled by new files in the F<hints/>
+directories, or new subdirectories and F<README> files at the top level of the
+source tree.
-List assignments like S<C<($x, $z) = (1, $y)>> now work correctly if C<$x> and
-C<$y> have been aliased by C<foreach>.
+=over 4
-=item *
+=item XXX-some-platform
-Some patterns including code blocks with syntax errors, such as
-S<C</ (?{(^{})/>>, would hang or fail assertions on debugging builds. Now
-they produce errors.
+XXX
-=item *
+=back
-An assertion failure when parsing C<sort> with debugging enabled has been
-fixed.
-L<[perl #122771]|https://rt.perl.org/Ticket/Display.html?id=122771>.
+=head2 Discontinued Platforms
-=item *
+XXX List any platforms that this version of perl no longer compiles on.
-S<C<*a = *b; @a = split //, $b[1]>> could do a bad read and produce junk
-results.
+=over 4
-=item *
+=item XXX-some-platform
-In S<C<() = @array = split>>, the S<C<() =>> at the beginning no longer confuses
-the optimizer into assuming a limit of 1.
+XXX
-=item *
+=back
-Fatal warnings no longer prevent the output of syntax errors.
-L<[perl #122966]|https://rt.perl.org/Ticket/Display.html?id=122966>.
+=head2 Platform-Specific Notes
-=item *
+XXX List any changes for specific platforms. This could include configuration
+and compilation changes or changes in portability/compatibility. However,
+changes within modules for platforms should generally be listed in the
+L</Modules and Pragmata> section.
-Fixed a NaN double-to-long-double conversion error on VMS. For quiet NaNs
-(and only on Itanium, not Alpha) negative infinity instead of NaN was
-produced.
+=over 4
-=item *
+=item XXX-some-platform
-Fixed the issue that caused C<< make distclean >> to incorrectly leave some
-files behind.
-L<[perl #122820]|https://rt.perl.org/Ticket/Display.html?id=122820>.
+XXX
-=item *
+=item Win32
-AIX now sets the length in C<< getsockopt >> correctly.
-L<[perl #120835]|https://rt.perl.org/Ticket/Display.html?id=120835>.
-L<[cpan #91183]|https://rt.cpan.org/Ticket/Display.html?id=91183>.
-L<[cpan #85570]|https://rt.cpan.org/Ticket/Display.html?id=85570>.
+=over
=item *
-The optimization phase of a regexp compilation could run "forever" and
-exhaust all memory under certain circumstances; now fixed.
-L<[perl #122283]|https://rt.perl.org/Ticket/Display.html?id=122283>.
+A new build option C<USE_NO_REGISTRY> has been added to the makefiles. This
+option is off by default, meaning the default is to do Windows registry
+lookups. This option stops Perl from looking inside the registry for anything.
+For what values are looked up in the registry see L<perlwin32>. Internally, in
+C, the name of this option is C<WIN32_NO_REGISTRY>.
=item *
-The test script F<< t/op/crypt.t >> now uses the SHA-256 algorithm if the
-default one is disabled, rather than giving failures.
-L<[perl #121591]|https://rt.perl.org/Ticket/Display.html?id=121591>.
+The behavior of Perl using C<HKEY_CURRENT_USER\Software\Perl> and
+C<HKEY_LOCAL_MACHINE\Software\Perl> to lookup certain values, including C<%ENV>
+vars starting with C<PERL> has changed. Previously, the 2 keys were checked
+for entries at all times through Perl processes life time even if they did not
+exist. For performance reasons, now, if the root key (i.e.
+C<HKEY_CURRENT_USER\Software\Perl> or C<HKEY_LOCAL_MACHINE\Software\Perl>) does
+not exist at process start time, it will not be checked again for C<%ENV>
+override entries for the remainder of the Perl processes life. This more
+closely matches Unix behaviour in that the environment is copied or inherited
+on startup and changing the variable in the parent process or another process
+or editing <.bashrc> will not change the environmental variable in other
+existing, running, processes.
=item *
-Fixed an off-by-one error when setting the size of a shared array.
-L<[perl #122950]|https://rt.perl.org/Ticket/Display.html?id=122950>.
+One glob fetch was removed for each C<-X> or C<stat> call whether done from
+Perl code or internally from Perl's C code. The glob being looked up was
+C<${^WIN32_SLOPPY_STAT}> which is a special variable. This makes C<-X> and
+C<stat> slightly faster.
=item *
-Fixed a bug that could cause perl to enter an infinite loop during
-compilation. In particular, a C<while(1)> within a sublist, I<e.g.>
-
- sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }
-
-The bug was introduced in 5.20.0
-L<[perl #122995]|https://rt.perl.org/Ticket/Display.html?id=122995>.
+During miniperl's process startup, during the build process, 4 to 8 IO calls
+related to the process starting F<.pl> and the F<buildcustomize.pl> file were
+removed from the code opening and executing the first 1 or 2 F<.pl> files.
-=item *
+=back
-On Win32, if a variable was C<local>-ized in a pseudo-process that later
-forked, restoring the original value in the child pseudo-process caused
-memory corruption and a crash in the child pseudo-process (and therefore the
-OS process).
-L<[perl #40565]|https://rt.perl.org/Ticket/Display.html?id=40565>.
+=back
-=item *
+=head1 Internal Changes
-Calling C<write> on a format with a C<^**> field could produce a panic
-in C<sv_chop()> if there were insufficient arguments or if the variable
-used to fill the field was empty.
-L<[perl #123245]|https://rt.perl.org/Ticket/Display.html?id=123245>.
+XXX Changes which affect the interface available to C<XS> code go here. Other
+significant internal changes for future core maintainers should be noted as
+well.
-=item *
+[ List each change as a =item entry ]
-Non-ASCII lexical sub names now appear without trailing junk when they
-appear in error messages.
+=over 4
=item *
-The C<\@> subroutine prototype no longer flattens parenthesized arrays
-(taking a reference to each element), but takes a reference to the array
-itself.
-L<[perl #47363]|https://rt.perl.org/Ticket/Display.html?id=47363>.
+L<perlapi/sv_backoff> had its return type changed from C<int> to C<void>. It
+previously has always returned C<0> since Perl 5.000 stable but that was
+undocumented. Although C<sv_backoff> is marked as public API, XS code is not
+expected to be impacted since the proper API call would be through public API
+C<sv_setsv(sv, &PL_sv_undef)>, or quasi-public C<SvOOK_off>, or non-public
+C<SvOK_off> calls, and the return value of C<sv_backoff> was previously a
+meaningless constant that can be rewritten as C<(sv_backoff(sv),0)>.
=item *
-A block containing nothing except a C-style C<for> loop could corrupt the
-stack, causing lists outside the block to lose elements or have elements
-overwritten. This could happen with C<map { for(...){...} } ...> and with
-lists containing C<do { for(...){...} }>.
-L<[perl #123286]|https://rt.perl.org/Ticket/Display.html?id=123286>.
-
-=item *
+The C<EXTEND> and C<MEXTEND> macros have been improved to avoid various issues
+with integer truncation and wrapping. In particular, some casts formerly used
+within the macros have been removed. This means for example that passing an
+unsigned nitems arg is likely to raise a compiler warning now (it's always been
+documented to require a signed value; formerly int, lately SSize_t).
-C<scalar()> now propagates lvalue context, so that
-S<C<for(scalar($#foo)) { ... }>> can modify C<$#foo> through C<$_>.
+=back
-=item *
+=head1 Selected Bug Fixes
-C<qr/@array(?{block})/> no longer dies with "Bizarre copy of ARRAY".
-L<[perl #123344]|https://rt.perl.org/Ticket/Display.html?id=123344>.
+XXX Important bug fixes in the core language are summarized here. Bug fixes in
+files in F<ext/> and F<lib/> are best summarized in L</Modules and Pragmata>.
-=item *
+[ List each fix as a =item entry ]
-S<C<eval '$variable'>> in nested named subroutines would sometimes look up a
-global variable even with a lexical variable in scope.
+=over 4
=item *
-In perl 5.20.0, C<sort CORE::fake> where 'fake' is anything other than a
-keyword, started chopping off the last 6 characters and treating the result
-as a sort sub name. The previous behavior of treating C<CORE::fake> as a
-sort sub name has been restored.
-L<[perl #123410]|https://rt.perl.org/Ticket/Display.html?id=123410>.
+There were places in regular expression patterns where comments (C<(?#...)>)
+weren't allowed, but should have been. This is now fixed.
+L<[perl #116639]|https://rt.perl.org/Ticket/Display.html?id=116639>
=item *
-Outside of C<use utf8>, a single-character Latin-1 lexical variable is
-disallowed. The error message for it, "Can't use global C<$foo>...", was
-giving garbage instead of the variable name.
+A regression from perl Perl 5.20 has been fixed, in which some syntax errors in
+L<C<(?[...])>|perlrecharclass/Extended Bracketed Character Classes> constructs
+within regular expression patterns could cause a segfault instead of a proper
+error message.
+L<[perl #126180]|https://rt.perl.org/Ticket/Display.html?id=126180>
=item *
-C<readline> on a nonexistent handle was causing C<${^LAST_FH}> to produce a
-reference to an undefined scalar (or fail an assertion). Now
-C<${^LAST_FH}> ends up undefined.
+Some problems with attempting to extend the perl stack to around 2G or 4G
+entries have been fixed. This was particularly an issue on 32-bit perls built
+to use 64-bit integers, and was easily noticeable with the list repetition
+operator, e.g.
-=item *
+ @a = (1) x $big_number
-C<(...) x ...> in void context now applies scalar context to the left-hand
-argument, instead of the context the current sub was called in.
-L<[perl #123020]|https://rt.perl.org/Ticket/Display.html?id=123020>.
+Formerly perl may have crashed, depending on the exact value of C<$big_number>;
+now it will typically raise an exception.
+L<[perl #125937]|https://rt.perl.org/Ticket/Display.html?id=125937>
=back
=head1 Known Problems
-=over 4
-
-=item *
-
-C<pack>-ing a NaN on a perl compiled with Visual C 6 does not behave properly,
-leading to a test failure in F<t/op/infnan.t>.
-L<[perl 125203]|https://rt.perl.org/Ticket/Display.html?id=125203>
-
-=item *
-
-A goal is for Perl to be able to be recompiled to work reasonably well on any
-Unicode version. In Perl 5.22, though, the earliest such version is Unicode
-5.1 (current is 7.0).
-
-=item *
+XXX Descriptions of platform agnostic bugs we know we can't fix go here. Any
+tests that had to be C<TODO>ed for the release would be noted here. Unfixed
+platform specific bugs also go here.
-EBCDIC platforms
+[ List each fix as a =item entry ]
=over 4
=item *
-The C<cmp> (and hence C<sort>) operators do not necessarily give the
-correct results when both operands are UTF-EBCDIC encoded strings and
-there is a mixture of ASCII and/or control characters, along with other
-characters.
-
-=item *
-
-Ranges containing C<\N{...}> in the C<tr///> (and C<y///>)
-transliteration operators are treated differently than the equivalent
-ranges in regular expression patterns. They should, but don't, cause
-the values in the ranges to all be treated as Unicode code points, and
-not native ones. (L<perlre/Version 8 Regular Expressions> gives
-details as to how it should work.)
-
-=item *
-
-Encode and encoding are mostly broken.
-
-=item *
-
-Many CPAN modules that are shipped with core show failing tests.
-
-=item *
-
-C<pack>/C<unpack> with C<"U0"> format may not work properly.
+XXX
=back
-=item *
-
-The following modules are known to have test failures with this version of
-Perl. In many cases, patches have been submitted, so there will hopefully be
-new releases soon:
-
-=over
-
-=item *
-
-L<B::Generate> version 1.50
-
-=item *
-
-L<B::Utils> version 0.25
-
-=item *
-
-L<Dancer> version 1.3130
-
-=item *
-
-L<Data::Alias> version 1.18
-
-=item *
-
-L<Data::Dump::Streamer> version 2.38
-
-=item *
-
-L<Data::Util> version 0.63
-
-=item *
-
-L<Devel::Spy> version 0.07
-
-=item *
-
-L<invoker> version 0.34
+=head1 Errata From Previous Releases
-=item *
-
-L<Lexical::Var> version 0.009
-
-=item *
-
-L<LWP::ConsoleLogger> version 0.000018
-
-=item *
-
-L<Mason> version 2.22
-
-=item *
-
-L<NgxQueue> version 0.02
+=over 4
=item *
-L<Padre> version 1.00
+(This was actually done in Perl 5.23.2, but the perldelta entry got missed.)
+The way that C<OP_AASSIGN> handles assignment with potentially common values
+(e.g. C<($a,$b) = ($b, $a)> has changed. In particular the C<OPpASSIGN_COMMON>
+flag has been replaced with three more specific flags:
-=item *
-
-L<Parse::Keyword> 0.08
+ OPpASSIGN_COMMON_AGG
+ OPpASSIGN_COMMON_RC1
+ OPpASSIGN_COMMON_SCALAR
-=back
+and the runtime now sometimes does a mark and sweep using the C<SVf_BREAK> to
+detect common elements.
=back
=head1 Obituary
-Brian McCauley died on May 8, 2015. He was a frequent poster to Usenet, Perl
-Monks, and other Perl forums, and made several CPAN contributions under the
-nick NOBULL, including to the Perl FAQ. He attended almost every
-YAPC::Europe, and indeed, helped organise YAPC::Europe 2006 and the QA
-Hackathon 2009. His wit and his delight in intricate systems were
-particularly apparent in his love of board games; many Perl mongers will
-have fond memories of playing Fluxx and other games with Brian. He will be
-missed.
+XXX If any significant core contributor has died, we've added a short obituary
+here.
=head1 Acknowledgements
-Perl 5.22.0 represents approximately 12 months of development since Perl 5.20.0
-and contains approximately 590,000 lines of changes across 2,400 files from 94
-authors.
-
-Excluding auto-generated files, documentation and release tools, there were
-approximately 370,000 lines of changes to 1,500 .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
-improvements that became Perl 5.22.0:
-
-Aaron Crane, Abhijit Menon-Sen, Abigail, Alberto Simões, Alex Solovey, Alex
-Vandiver, Alexandr Ciornii, Alexandre (Midnite) Jousset, Andreas König,
-Andreas Voegele, Andrew Fresh, Andy Dougherty, Anthony Heading, Aristotle
-Pagaltzis, brian d foy, Brian Fraser, Chad Granum, Chris 'BinGOs' Williams,
-Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, Darin McBride, Dave
-Rolsky, David Golden, David Mitchell, David Wheeler, Dmitri Tikhonov, Doug
-Bell, E. Choroba, Ed J, Eric Herman, Father Chrysostomos, George Greer, Glenn
-D. Golden, Graham Knop, H.Merijn Brand, Herbert Breunung, Hugo van der Sanden,
-James E Keenan, James McCoy, James Raspass, Jan Dubois, Jarkko Hietaniemi,
-Jasmine Ngan, Jerry D. Hedden, Jim Cromie, John Goodyear, kafka, Karen
-Etheridge, Karl Williamson, Kent Fredric, kmx, Lajos Veres, Leon Timmermans,
-Lukas Mai, Mathieu Arnold, Matthew Horsfall, Max Maischein, Michael Bunk,
-Nicholas Clark, Niels Thykier, Niko Tyni, Norman Koch, Olivier Mengué, Peter
-John Acklam, Peter Martini, Petr Písař, Philippe Bruhat (BooK), Pierre
-Bogossian, Rafael Garcia-Suarez, Randy Stauner, Reini Urban, Ricardo Signes,
-Rob Hoelz, Rostislav Skudnov, Sawyer X, Shirakata Kentaro, Shlomi Fish,
-Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steve Hay, Sullivan Beck,
-syber, Tadeusz Sośnierz, Thomas Sibley, Todd Rinaldo, Tony Cook, Vincent Pit,
-Vladimir Marek, Yaroslav Kuzmin, Yves Orton, Ævar Arnfjörð Bjarmason.
-
-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
-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
-helping Perl to flourish.
-
-For a more complete list of all of Perl's historical contributors, please see
-the F<AUTHORS> file in the Perl source distribution.
+XXX Generate this with:
+
+ perl Porting/acknowledgements.pl v5.23.3..HEAD
=head1 Reporting Bugs
If you find what you think is a bug, you might check the articles recently
posted to the comp.lang.perl.misc newsgroup and the perl bug database at
-L<https://rt.perl.org/>. There may also be information at
-L<http://www.perl.org/>, the Perl Home Page.
+L<https://rt.perl.org/> . There may also be information at
+L<http://www.perl.org/> , the Perl Home Page.
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
https://perl5.git.perl.org / perl5.git / blobdiff