Adding upstream version 4.22.0.upstream/4.22.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 3128 insertions, 0 deletions

diff --git a/upstream/fedora-40/man1/perl5220delta.1 b/upstream/fedora-40/man1/perl5220delta.1
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+.\" -*- mode: troff; coding: utf-8 -*-
+.\" Automatically generated by Pod::Man 5.01 (Pod::Simple 3.43)
+.\"
+.\" Standard preamble:
+.\" ========================================================================
+.de Sp \" Vertical space (when we can't use .PP)
+.if t .sp .5v
+.if n .sp
+..
+.de Vb \" Begin verbatim text
+.ft CW
+.nf
+.ne \\$1
+..
+.de Ve \" End verbatim text
+.ft R
+.fi
+..
+.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>.
+.ie n \{\
+.    ds C` ""
+.    ds C' ""
+'br\}
+.el\{\
+.    ds C`
+.    ds C'
+'br\}
+.\"
+.\" Escape single quotes in literal strings from groff's Unicode transform.
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.\"
+.\" If the F register is >0, we'll generate index entries on stderr for
+.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
+.\" entries marked with X<> in POD.  Of course, you'll have to process the
+.\" output yourself in some meaningful fashion.
+.\"
+.\" Avoid warning from groff about undefined register 'F'.
+.de IX
+..
+.nr rF 0
+.if \n(.g .if rF .nr rF 1
+.if (\n(rF:(\n(.g==0)) \{\
+.    if \nF \{\
+.        de IX
+.        tm Index:\\$1\t\\n%\t"\\$2"
+..
+.        if !\nF==2 \{\
+.            nr % 0
+.            nr F 2
+.        \}
+.    \}
+.\}
+.rr rF
+.\" ========================================================================
+.\"
+.IX Title "PERL5220DELTA 1"
+.TH PERL5220DELTA 1 2024-01-25 "perl v5.38.2" "Perl Programmers Reference Guide"
+.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
+.\" way too many mistakes in technical documents.
+.if n .ad l
+.nh
+.SH NAME
+perl5220delta \- what is new for perl v5.22.0
+.SH DESCRIPTION
+.IX Header "DESCRIPTION"
+This document describes differences between the 5.20.0 release and the 5.22.0
+release.
+.PP
+If you are upgrading from an earlier release such as 5.18.0, first read
+perl5200delta, which describes differences between 5.18.0 and 5.20.0.
+.SH "Core Enhancements"
+.IX Header "Core Enhancements"
+.SS "New bitwise operators"
+.IX Subsection "New bitwise operators"
+A new experimental facility has been added that makes the four standard
+bitwise operators (\f(CW\*(C`& | ^ ~\*(C'\fR) treat their operands consistently as
+numbers, and introduces four new dotted operators (\f(CW\*(C`&. |. ^. ~.\*(C'\fR) that
+treat their operands consistently as strings.  The same applies to the
+assignment variants (\f(CW\*(C`&= |= ^= &.= |.= ^.=\*(C'\fR).
+.PP
+To use this, enable the "bitwise" feature and disable the
+"experimental::bitwise" warnings category.  See "Bitwise String
+Operators" in perlop for details.
+[GH #14348] <https://github.com/Perl/perl5/issues/14348>.
+.SS "New double-diamond operator"
+.IX Subsection "New double-diamond operator"
+\&\f(CW\*(C`<<>>\*(C'\fR is like \f(CW\*(C`<>\*(C'\fR but uses three-argument \f(CW\*(C`open\*(C'\fR to open
+each file in \f(CW@ARGV\fR.  This means that each element of \f(CW@ARGV\fR will be treated
+as an actual file name, and \f(CW"|foo"\fR won't be treated as a pipe open.
+.ie n .SS "New ""\eb"" boundaries in regular expressions"
+.el .SS "New \f(CW\eb\fP boundaries in regular expressions"
+.IX Subsection "New b boundaries in regular expressions"
+\fR\f(CI\*(C`qr/\eb{gcb}/\*(C'\fR\fI\fR
+.IX Subsection "qr/b{gcb}/"
+.PP
+\&\f(CW\*(C`gcb\*(C'\fR 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 \f(CW\*(C`\eX\*(C'\fR regular escape
+sequence.  Now, there is an alternative way of handling these.  See
+"\eb{}, \eb, \eB{}, \eB" in perlrebackslash for details.
+.PP
+\fR\f(CI\*(C`qr/\eb{wb}/\*(C'\fR\fI\fR
+.IX Subsection "qr/b{wb}/"
+.PP
+\&\f(CW\*(C`wb\*(C'\fR stands for Word Boundary.  It is a Unicode property
+that finds the boundary between words.  This is similar to the plain
+\&\f(CW\*(C`\eb\*(C'\fR (without braces) but is more suitable for natural language
+processing.  It knows, for example, that apostrophes can occur in the
+middle of words.  See "\eb{}, \eb, \eB{}, \eB" in perlrebackslash for details.
+.PP
+\fR\f(CI\*(C`qr/\eb{sb}/\*(C'\fR\fI\fR
+.IX Subsection "qr/b{sb}/"
+.PP
+\&\f(CW\*(C`sb\*(C'\fR stands for Sentence Boundary.  It is a Unicode property
+to aid in parsing natural language sentences.
+See "\eb{}, \eb, \eB{}, \eB" in perlrebackslash for details.
+.SS "Non-Capturing Regular Expression Flag"
+.IX Subsection "Non-Capturing Regular Expression Flag"
+Regular expressions now support a \f(CW\*(C`/n\*(C'\fR flag that disables capturing
+and filling in \f(CW$1\fR, \f(CW$2\fR, etc inside of groups:
+.PP
+.Vb 1
+\&  "hello" =~ /(hi|hello)/n; # $1 is not set
+.Ve
+.PP
+This is equivalent to putting \f(CW\*(C`?:\*(C'\fR at the beginning of every capturing group.
+.PP
+See "n" in perlre for more information.
+.ie n .SS """use re \*(Aqstrict\*(Aq"""
+.el .SS "\f(CWuse re \*(Aqstrict\*(Aq\fP"
+.IX Subsection "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
+\&\f(CW\*(C`experimental::re_strict\*(C'\fR.
+See 'strict' in re.
+.SS "Unicode 7.0 (with correction) is now supported"
+.IX Subsection "Unicode 7.0 (with correction) is now supported"
+For details on what is in this release, see
+<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 <http://www.unicode.org/errata/#current_errata>).
+.ie n .SS """use\ locale"" can restrict which locale categories are affected"
+.el .SS "\f(CWuse\ locale\fP can restrict which locale categories are affected"
+.IX Subsection "use locale can restrict which locale categories are affected"
+It is now possible to pass a parameter to \f(CW\*(C`use\ locale\*(C'\fR to specify
+a subset of locale categories to be locale-aware, with the remaining
+ones unaffected.  See "The "use locale" pragma" in perllocale for details.
+.SS "Perl now supports POSIX 2008 locale currency additions"
+.IX Subsection "Perl now supports POSIX 2008 locale currency additions"
+On platforms that are able to handle POSIX.1\-2008, the
+hash returned by
+\&\f(CWPOSIX::localeconv()\fR
+includes the international currency fields added by that version of the
+POSIX standard.  These are
+\&\f(CW\*(C`int_n_cs_precedes\*(C'\fR,
+\&\f(CW\*(C`int_n_sep_by_space\*(C'\fR,
+\&\f(CW\*(C`int_n_sign_posn\*(C'\fR,
+\&\f(CW\*(C`int_p_cs_precedes\*(C'\fR,
+\&\f(CW\*(C`int_p_sep_by_space\*(C'\fR,
+and
+\&\f(CW\*(C`int_p_sign_posn\*(C'\fR.
+.SS "Better heuristics on older platforms for determining locale UTF\-8ness"
+.IX Subsection "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.
+.SS "Aliasing via reference"
+.IX Subsection "Aliasing via reference"
+Variables and subroutines can now be aliased by assigning to a reference:
+.PP
+.Vb 2
+\&    \e$c = \e$d;
+\&    \e&x = \e&y;
+.Ve
+.PP
+Aliasing can also be accomplished
+by using a backslash before a \f(CW\*(C`foreach\*(C'\fR iterator variable; this is
+perhaps the most useful idiom this feature provides:
+.PP
+.Vb 1
+\&    foreach \e%hash (@array_of_hash_refs) { ... }
+.Ve
+.PP
+This feature is experimental and must be enabled via \f(CWuse\ feature\ \*(Aqrefaliasing\*(Aq\fR.  It will warn unless the \f(CW\*(C`experimental::refaliasing\*(C'\fR
+warnings category is disabled.
+.PP
+See "Assigning to References" in perlref
+.ie n .SS """prototype"" with no arguments"
+.el .SS "\f(CWprototype\fP with no arguments"
+.IX Subsection "prototype with no arguments"
+\&\f(CWprototype()\fR with no arguments now infers \f(CW$_\fR.
+[GH #14376] <https://github.com/Perl/perl5/issues/14376>.
+.ie n .SS "New "":const"" subroutine attribute"
+.el .SS "New \f(CW:const\fP subroutine attribute"
+.IX Subsection "New :const subroutine attribute"
+The \f(CW\*(C`const\*(C'\fR attribute can be applied to an anonymous subroutine.  It
+causes the new sub to be executed immediately whenever one is created
+(\fIi.e.\fR when the \f(CW\*(C`sub\*(C'\fR expression is evaluated).  Its value is captured
+and used to create a new constant subroutine that is returned.  This
+feature is experimental.  See "Constant Functions" in perlsub.
+.ie n .SS """fileno"" now works on directory handles"
+.el .SS "\f(CWfileno\fP now works on directory handles"
+.IX Subsection "fileno now works on directory handles"
+When the relevant support is available in the operating system, the
+\&\f(CW\*(C`fileno\*(C'\fR builtin now works on directory handles, yielding the
+underlying file descriptor in the same way as for filehandles. On
+operating systems without such support, \f(CW\*(C`fileno\*(C'\fR on a directory handle
+continues to return the undefined value, as before, but also sets \f(CW$!\fR to
+indicate that the operation is not supported.
+.PP
+Currently, this uses either a \f(CW\*(C`dd_fd\*(C'\fR member in the OS \f(CW\*(C`DIR\*(C'\fR
+structure, or a \f(CWdirfd(3)\fR function as specified by POSIX.1\-2008.
+.SS "List form of pipe open implemented for Win32"
+.IX Subsection "List form of pipe open implemented for Win32"
+The list form of pipe:
+.PP
+.Vb 1
+\&  open my $fh, "\-|", "program", @arguments;
+.Ve
+.PP
+is now implemented on Win32.  It has the same limitations as \f(CW\*(C`system
+LIST\*(C'\fR on Win32, since the Win32 API doesn't accept program arguments
+as a list.
+.SS "Assignment to list repetition"
+.IX Subsection "Assignment to list repetition"
+\&\f(CW\*(C`(...) x ...\*(C'\fR can now be used within a list that is assigned to, as long
+as the left-hand side is a valid lvalue.  This allows \f(CW\*(C`(undef,undef,$foo)\ =\ that_function()\*(C'\fR to be written as \f(CW\*(C`((undef)x2,\ $foo)\ =\ that_function()\*(C'\fR.
+.SS "Infinity and NaN (not-a-number) handling improved"
+.IX Subsection "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
+\&\f(CW\*(C`Inf\*(C'\fR, \f(CW\*(C`\-Inf\*(C'\fR, and \f(CW\*(C`NaN\*(C'\fR.
+.PP
+See also the POSIX enhancements.
+.SS "Floating point parsing has been improved"
+.IX Subsection "Floating point parsing has been improved"
+Parsing and printing of floating point values has been improved.
+.PP
+As a completely new feature, hexadecimal floating point literals
+(like \f(CW\*(C`0x1.23p\-4\*(C'\fR)  are now supported, and they can be output with
+\&\f(CW\*(C`printf\ "%a"\*(C'\fR. See "Scalar value constructors" in perldata for more
+details.
+.SS "Packing infinity or not-a-number into a character is now fatal"
+.IX Subsection "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 \f(CW0xFF\fR; if you gave it as an argument to \f(CW\*(C`chr\*(C'\fR,
+\&\f(CW\*(C`U+FFFD\*(C'\fR was returned.
+.PP
+But now, all such actions (\f(CW\*(C`pack\*(C'\fR, \f(CW\*(C`chr\*(C'\fR, and \f(CW\*(C`print \*(Aq%c\*(Aq\*(C'\fR)
+result in a fatal error.
+.SS "Experimental C Backtrace API"
+.IX Subsection "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).
+.PP
+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).
+.PP
+The supported platforms are Linux and OS X (some *BSD might work at
+least partly, but they have not yet been tested).
+.PP
+The feature needs to be enabled with \f(CW\*(C`Configure \-Dusecbacktrace\*(C'\fR.
+.PP
+See "C backtrace" in perlhacktips for more information.
+.SH Security
+.IX Header "Security"
+.ie n .SS "Perl is now compiled with ""\-fstack\-protector\-strong"" if available"
+.el .SS "Perl is now compiled with \f(CW\-fstack\-protector\-strong\fP if available"
+.IX Subsection "Perl is now compiled with -fstack-protector-strong if available"
+Perl has been compiled with the anti-stack-smashing option
+\&\f(CW\*(C`\-fstack\-protector\*(C'\fR since 5.10.1.  Now Perl uses the newer variant
+called \f(CW\*(C`\-fstack\-protector\-strong\*(C'\fR, if available.
+.SS "The Safe module could allow outside packages to be replaced"
+.IX Subsection "The Safe module could allow outside packages to be replaced"
+Critical bugfix: outside packages could be replaced.  Safe has
+been patched to 2.38 to address this.
+.ie n .SS "Perl is now always compiled with ""\-D_FORTIFY_SOURCE=2"" if available"
+.el .SS "Perl is now always compiled with \f(CW\-D_FORTIFY_SOURCE=2\fP if available"
+.IX Subsection "Perl is now always compiled with -D_FORTIFY_SOURCE=2 if available"
+The 'code hardening' option called \f(CW\*(C`_FORTIFY_SOURCE\*(C'\fR, available in
+gcc 4.*, is now always used for compiling Perl, if available.
+.PP
+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.
+.SH "Incompatible Changes"
+.IX Header "Incompatible Changes"
+.SS "Subroutine signatures moved before attributes"
+.IX Subsection "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).
+.ie n .SS """&"" and ""\e&"" prototypes accepts only subs"
+.el .SS "\f(CW&\fP and \f(CW\e&\fP prototypes accepts only subs"
+.IX Subsection "& and & prototypes accepts only subs"
+The \f(CW\*(C`&\*(C'\fR prototype character now accepts only anonymous subs (\f(CW\*(C`sub
+{...}\*(C'\fR), things beginning with \f(CW\*(C`\e&\*(C'\fR, or an explicit \f(CW\*(C`undef\*(C'\fR.  Formerly
+it erroneously also allowed references to arrays, hashes, and lists.
+[GH #2776] <https://github.com/Perl/perl5/issues/2776>.
+[GH #14186] <https://github.com/Perl/perl5/issues/14186>.
+[GH #14353] <https://github.com/Perl/perl5/issues/14353>.
+.PP
+In addition, the \f(CW\*(C`\e&\*(C'\fR prototype was allowing subroutine calls, whereas
+now it only allows subroutines: \f(CW&foo\fR is still permitted as an argument,
+while \f(CW&foo()\fR and \f(CWfoo()\fR no longer are.
+[GH #10633] <https://github.com/Perl/perl5/issues/10633>.
+.ie n .SS """use encoding"" is now lexical"
+.el .SS "\f(CWuse encoding\fP is now lexical"
+.IX Subsection "use encoding is now lexical"
+The 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.
+.SS "List slices returning empty lists"
+.IX Subsection "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 \f(CW\*(C`undef\*(C'\fR values in that case.
+[GH #12335] <https://github.com/Perl/perl5/issues/12335>.
+.ie n .SS """\eN{}"" with a sequence of multiple spaces is now a fatal error"
+.el .SS "\f(CW\eN{}\fP with a sequence of multiple spaces is now a fatal error"
+.IX Subsection "N{} with a sequence of multiple spaces is now a fatal error"
+E.g. \f(CW\*(C`\eN{TOO\ \ MANY\ SPACES}\*(C'\fR or \f(CW\*(C`\eN{TRAILING\ SPACE\ }\*(C'\fR.
+This has been deprecated since v5.18.
+.ie n .SS """use\ UNIVERSAL\ \*(Aq...\*(Aq"" is now a fatal error"
+.el .SS "\f(CWuse\ UNIVERSAL\ \*(Aq...\*(Aq\fP is now a fatal error"
+.IX Subsection "use UNIVERSAL ... is now a fatal error"
+Importing functions from \f(CW\*(C`UNIVERSAL\*(C'\fR has been deprecated since v5.12, and
+is now a fatal error.  \f(CW\*(C`use\ UNIVERSAL\*(C'\fR without any arguments is still
+allowed.
+.ie n .SS "In double-quotish ""\ec\fIX\fP"", \fIX\fP must now be a printable ASCII character"
+.el .SS "In double-quotish \f(CW\ec\fP\f(CIX\fP\f(CW\fP, \fIX\fP must now be a printable ASCII character"
+.IX Subsection "In double-quotish cX, X must now be a printable ASCII character"
+In prior releases, failure to do this raised a deprecation warning.
+.ie n .SS "Splitting the tokens ""(?"" and ""(*"" in regular expressions is now a fatal compilation error."
+.el .SS "Splitting the tokens \f(CW(?\fP and \f(CW(*\fP in regular expressions is now a fatal compilation error."
+.IX Subsection "Splitting the tokens (? and (* in regular expressions is now a fatal compilation error."
+These had been deprecated since v5.18.
+.ie n .SS """qr/foo/x"" now ignores all Unicode pattern white space"
+.el .SS "\f(CWqr/foo/x\fP now ignores all Unicode pattern white space"
+.IX Subsection "qr/foo/x now ignores all Unicode pattern white space"
+The \f(CW\*(C`/x\*(C'\fR 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:
+.PP
+.Vb 5
+\&    U+0085 NEXT LINE
+\&    U+200E LEFT\-TO\-RIGHT MARK
+\&    U+200F RIGHT\-TO\-LEFT MARK
+\&    U+2028 LINE SEPARATOR
+\&    U+2029 PARAGRAPH SEPARATOR
+.Ve
+.PP
+The use of these characters with \f(CW\*(C`/x\*(C'\fR outside bracketed character
+classes and when not preceded by a backslash has raised a deprecation
+warning since v5.18.  Now they will be ignored.
+.ie n .SS "Comment lines within ""(?[\ ])"" are now ended only by a ""\en"""
+.el .SS "Comment lines within \f(CW(?[\ ])\fP are now ended only by a \f(CW\en\fP"
+.IX Subsection "Comment lines within (?[ ]) are now ended only by a n"
+\&\f(CW\*(C`(?[\ ])\*(C'\fR  is an experimental feature, introduced in v5.18.  It operates
+as if \f(CW\*(C`/x\*(C'\fR is always enabled.  But there was a difference: comment
+lines (following a \f(CW\*(C`#\*(C'\fR character) were terminated by anything matching
+\&\f(CW\*(C`\eR\*(C'\fR which includes all vertical whitespace, such as form feeds.  For
+consistency, this is now changed to match what terminates comment lines
+outside \f(CW\*(C`(?[\ ])\*(C'\fR, namely a \f(CW\*(C`\en\*(C'\fR (even if escaped), which is the
+same as what terminates a heredoc string and formats.
+.ie n .SS """(?[...])"" operators now follow standard Perl precedence"
+.el .SS "\f(CW(?[...])\fP operators now follow standard Perl precedence"
+.IX Subsection "(?[...]) 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 "Extended Bracketed Character Classes" in perlrecharclass.
+.ie n .SS "Omitting ""%"" and ""@"" on hash and array names is no longer permitted"
+.el .SS "Omitting \f(CW%\fP and \f(CW@\fP on hash and array names is no longer permitted"
+.IX Subsection "Omitting % and @ on hash and array names is no longer permitted"
+Really old Perl let you omit the \f(CW\*(C`@\*(C'\fR on array names and the \f(CW\*(C`%\*(C'\fR on hash
+names in some spots.  This has issued a deprecation warning since Perl
+5.000, and is no longer permitted.
+.ie n .SS """$!"" text is now in English outside the scope of ""use locale"""
+.el .SS "\f(CW""$!""\fP text is now in English outside the scope of \f(CWuse locale\fP"
+.IX Subsection """$!"" text is now in English outside the scope of 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 \f(CW"$^E"\fR.)  For programs that are unprepared to
+handle locale differences, this can cause garbage text to be displayed.
+It's better to display text that is translatable via some tool than
+garbage text which is much harder to figure out.
+.ie n .SS """$!"" text will be returned in UTF\-8 when appropriate"
+.el .SS "\f(CW""$!""\fP text will be returned in UTF\-8 when appropriate"
+.IX Subsection """$!"" text will be returned in UTF-8 when appropriate"
+The stringification of \f(CW$!\fR and \f(CW$^E\fR 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
+\&\f(CW\*(C`use\ bytes\*(C'\fR and \f(CW\*(C`use\ locale\ ":messages"\*(C'\fR.  Within these two
+scopes, no other Perl operations will
+be affected by locale; only \f(CW$!\fR and \f(CW$^E\fR stringification.  The
+\&\f(CW\*(C`bytes\*(C'\fR pragma causes the UTF\-8 flag to not be set, just as in previous
+Perl releases.  This resolves
+[GH #12035] <https://github.com/Perl/perl5/issues/12035>.
+.ie n .SS "Support for ""?PATTERN?"" without explicit operator has been removed"
+.el .SS "Support for \f(CW?PATTERN?\fP without explicit operator has been removed"
+.IX Subsection "Support for ?PATTERN? without explicit operator has been removed"
+The \f(CW\*(C`m?PATTERN?\*(C'\fR 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 \f(CW\*(C`m\*(C'\fR 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.
+.ie n .SS "defined(@array) and defined(%hash) are now fatal errors"
+.el .SS "\f(CWdefined(@array)\fP and \f(CWdefined(%hash)\fP are now fatal errors"
+.IX Subsection "defined(@array) and defined(%hash) are now fatal errors"
+These have been deprecated since v5.6.1 and have raised deprecation
+warnings since v5.16.
+.SS "Using a hash or an array as a reference are now fatal errors"
+.IX Subsection "Using a hash or an array as a reference are now fatal errors"
+For example, \f(CW\*(C`%foo\->{"bar"}\*(C'\fR now causes a fatal compilation
+error.  These have been deprecated since before v5.8, and have raised
+deprecation warnings since then.
+.ie n .SS "Changes to the ""*"" prototype"
+.el .SS "Changes to the \f(CW*\fP prototype"
+.IX Subsection "Changes to the * prototype"
+The \f(CW\*(C`*\*(C'\fR 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.
+.PP
+Now it has been changed, so subroutines always take precedence over barewords,
+which brings it into conformity with similarly prototyped built-in functions:
+.PP
+.Vb 6
+\&    sub splat(*) { ... }
+\&    sub foo { ... }
+\&    splat(foo); # now always splat(foo())
+\&    splat(bar); # still splat(\*(Aqbar\*(Aq) as before
+\&    close(foo); # close(foo())
+\&    close(bar); # close(\*(Aqbar\*(Aq)
+.Ve
+.SH Deprecations
+.IX Header "Deprecations"
+.ie n .SS "Setting ""${^ENCODING}"" to anything but ""undef"""
+.el .SS "Setting \f(CW${^ENCODING}\fP to anything but \f(CWundef\fP"
+.IX Subsection "Setting ${^ENCODING} to anything but 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 piconv utility.
+.SS "Use of non-graphic characters in single-character variable names"
+.IX Subsection "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 \f(CW\*(C`use\ utf8\*(C'\fR, and affects just the C1 controls (code points 0x80 through
+0xFF), NO-BREAK SPACE, and SOFT HYPHEN.
+.ie n .SS "Inlining of ""sub () { $var }"" with observable side-effects"
+.el .SS "Inlining of \f(CWsub () { $var }\fP with observable side-effects"
+.IX Subsection "Inlining of sub () { $var } with observable side-effects"
+In many cases Perl makes \f(CW\*(C`sub\ ()\ {\ $var\ }\*(C'\fR into an inlinable constant
+subroutine, capturing the value of \f(CW$var\fR at the time the \f(CW\*(C`sub\*(C'\fR expression
+is evaluated.  This can break the closure behavior in those cases where
+\&\f(CW$var\fR 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 (\f(CW\*(C`sub\ ()\*(C'\fR).)
+.PP
+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.
+.PP
+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.
+.PP
+.Vb 4
+\&    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 () { $var }; # deprecated
+\&    }
+.Ve
+.PP
+In the second example above, detecting that \f(CW$var\fR is assigned to only once
+is too hard to detect.  That it happens in a spot other than the \f(CW\*(C`my\*(C'\fR
+declaration is enough for Perl to find it suspicious.
+.PP
+This deprecation warning happens only for a simple variable for the body of
+the sub.  (A \f(CW\*(C`BEGIN\*(C'\fR block or \f(CW\*(C`use\*(C'\fR statement inside the sub is ignored,
+because it does not become part of the sub's body.)  For more complex
+cases, such as \f(CW\*(C`sub\ ()\ {\ do_something()\ if\ 0;\ $var\ }\*(C'\fR the behavior has
+changed such that inlining does not happen if the variable is modifiable
+elsewhere.  Such cases should be rare.
+.ie n .SS "Use of multiple ""/x"" regexp modifiers"
+.el .SS "Use of multiple \f(CW/x\fP regexp modifiers"
+.IX Subsection "Use of multiple /x regexp modifiers"
+It is now deprecated to say something like any of the following:
+.PP
+.Vb 3
+\&    qr/foo/xx;
+\&    /(?xax:foo)/;
+\&    use re qw(/amxx);
+.Ve
+.PP
+That is, now \f(CW\*(C`x\*(C'\fR 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 \f(CW\*(C`/xx\*(C'\fR permit white-space for readability in
+bracketed character classes (those enclosed in square brackets:
+\&\f(CW\*(C`[...]\*(C'\fR).
+.ie n .SS "Using a NO-BREAK space in a character alias for ""\eN{...}"" is now deprecated"
+.el .SS "Using a NO-BREAK space in a character alias for \f(CW\eN{...}\fP is now deprecated"
+.IX Subsection "Using a NO-BREAK space in a character alias for N{...} is now deprecated"
+This non-graphic character is essentially indistinguishable from a
+regular space, and so should not be allowed.  See
+"CUSTOM ALIASES" in charnames.
+.ie n .SS "A literal ""{"" should now be escaped in a pattern"
+.el .SS "A literal \f(CW""{""\fP should now be escaped in a pattern"
+.IX Subsection "A literal ""{"" 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 (\f(CW"\e{"\fR) or enclosing it within square
+brackets \f(CW"[{]"\fR, or by using \f(CW\*(C`\eQ\*(C'\fR; 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.
+.SS "Making all warnings fatal is discouraged"
+.IX Subsection "Making all warnings fatal is discouraged"
+The documentation for fatal warnings notes that
+\&\f(CW\*(C`use warnings FATAL => \*(Aqall\*(Aq\*(C'\fR is discouraged, and provides stronger
+language about the risks of fatal warnings in general.
+.SH "Performance Enhancements"
+.IX Header "Performance Enhancements"
+.IP \(bu 4
+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
+\&\f(CW\*(C`SUPER::new\*(C'\fR are parsed at compile time, to save having to parse them at
+run time.
+.IP \(bu 4
+Array and hash lookups (especially nested ones) that use only constants
+or simple variables as keys, are now considerably faster. See
+"Internal Changes" for more details.
+.IP \(bu 4
+\&\f(CW\*(C`(...)x1\*(C'\fR, \f(CW\*(C`("constant")x0\*(C'\fR and \f(CW\*(C`($scalar)x0\*(C'\fR 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, \f(CW\*(C`(foo())x0\*(C'\fR is not
+subject to this optimisation.)
+.IP \(bu 4
+\&\f(CW\*(C`substr\*(C'\fR assignment is now optimised into 4\-argument \f(CW\*(C`substr\*(C'\fR at the end
+of a subroutine (or as the argument to \f(CW\*(C`return\*(C'\fR).  Previously, this
+optimisation only happened in void context.
+.IP \(bu 4
+In \f(CW"\eL..."\fR, \f(CW"\eQ..."\fR, etc., the extra "stringify" op is now optimised
+away, making these just as fast as \f(CW\*(C`lcfirst\*(C'\fR, \f(CW\*(C`quotemeta\*(C'\fR, etc.
+.IP \(bu 4
+Assignment to an empty list is now sometimes faster.  In particular, it
+never calls \f(CW\*(C`FETCH\*(C'\fR on tied arguments on the right-hand side, whereas it
+used to sometimes.
+.IP \(bu 4
+There is a performance improvement of up to 20% when \f(CW\*(C`length\*(C'\fR is applied to
+a non-magical, non-tied string, and either \f(CW\*(C`use bytes\*(C'\fR is in scope or the
+string doesn't use UTF\-8 internally.
+.IP \(bu 4
+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.
+.IP \(bu 4
+In \f(CW\*(C`@array = split\*(C'\fR, the assignment can be optimized away, so that \f(CW\*(C`split\*(C'\fR
+writes directly to the array.  This optimisation was happening only for
+package arrays other than \f(CW@_\fR, and only sometimes.  Now this
+optimisation happens almost all the time.
+.IP \(bu 4
+\&\f(CW\*(C`join\*(C'\fR is now subject to constant folding.  So for example
+\&\f(CW\*(C`join\ "\-",\ "a",\ "b"\*(C'\fR is converted at compile-time to \f(CW"a\-b"\fR.
+Moreover, \f(CW\*(C`join\*(C'\fR 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.
+.IP \(bu 4
+\&\f(CWqq(@array)\fR is implemented using two ops: a stringify op and a join op.
+If the \f(CW\*(C`qq\*(C'\fR contains nothing but a single array, the stringification is
+optimized away.
+.IP \(bu 4
+\&\f(CW\*(C`our\ $var\*(C'\fR and \f(CW\*(C`our($s,@a,%h)\*(C'\fR in void context are no longer evaluated at
+run time.  Even a whole sequence of \f(CW\*(C`our\ $foo;\*(C'\fR statements will simply be
+skipped over.  The same applies to \f(CW\*(C`state\*(C'\fR variables.
+.IP \(bu 4
+Many internal functions have been refactored to improve performance and reduce
+their memory footprints.
+[GH #13659] <https://github.com/Perl/perl5/issues/13659>
+[GH #13856] <https://github.com/Perl/perl5/issues/13856>
+[GH #13874] <https://github.com/Perl/perl5/issues/13874>
+.IP \(bu 4
+\&\f(CW\*(C`\-T\*(C'\fR and \f(CW\*(C`\-B\*(C'\fR filetests will return sooner when an empty file is detected.
+[GH #13686] <https://github.com/Perl/perl5/issues/13686>
+.IP \(bu 4
+Hash lookups where the key is a constant are faster.
+.IP \(bu 4
+Subroutines with an empty prototype and a body containing just \f(CW\*(C`undef\*(C'\fR are now
+eligible for inlining.
+[GH #14077] <https://github.com/Perl/perl5/issues/14077>
+.IP \(bu 4
+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
+(\fIi.e.\fR 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.
+[GH #13392] <https://github.com/Perl/perl5/issues/13392>
+.IP \(bu 4
+The functions \f(CWutf8::native_to_unicode()\fR and \f(CWutf8::unicode_to_native()\fR
+(see 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.
+.IP \(bu 4
+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.
+.SH "Modules and Pragmata"
+.IX Header "Modules and Pragmata"
+.SS "Updated Modules and Pragmata"
+.IX Subsection "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:
+.PP
+.Vb 1
+\&  corelist \-\-diff 5.20.0 5.22.0
+.Ve
+.PP
+You can substitute your favorite version in place of 5.20.0, too.
+.PP
+Some notable changes include:
+.IP \(bu 4
+Archive::Tar has been upgraded to version 2.04.
+.Sp
+Tests can now be run in parallel.
+.IP \(bu 4
+attributes has been upgraded to version 0.27.
+.Sp
+The usage of \f(CW\*(C`memEQs\*(C'\fR in the XS has been corrected.
+[GH #14072] <https://github.com/Perl/perl5/issues/14072>
+.Sp
+Avoid reading beyond the end of a buffer. [perl #122629]
+.IP \(bu 4
+B has been upgraded to version 1.58.
+.Sp
+It provides a new \f(CW\*(C`B::safename\*(C'\fR function, based on the existing
+\&\f(CW\*(C`B::GV\->SAFENAME\*(C'\fR, that converts \f(CW\*(C`\ecOPEN\*(C'\fR to \f(CW\*(C`^OPEN\*(C'\fR.
+.Sp
+Nulled COPs are now of class \f(CW\*(C`B::COP\*(C'\fR, rather than \f(CW\*(C`B::OP\*(C'\fR.
+.Sp
+\&\f(CW\*(C`B::REGEXP\*(C'\fR objects now provide a \f(CW\*(C`qr_anoncv\*(C'\fR method for accessing the
+implicit CV associated with \f(CW\*(C`qr//\*(C'\fR things containing code blocks, and a
+\&\f(CW\*(C`compflags\*(C'\fR method that returns the pertinent flags originating from the
+\&\f(CW\*(C`qr//blahblah\*(C'\fR op.
+.Sp
+\&\f(CW\*(C`B::PMOP\*(C'\fR now provides a \f(CW\*(C`pmregexp\*(C'\fR method returning a \f(CW\*(C`B::REGEXP\*(C'\fR object.
+Two new classes, \f(CW\*(C`B::PADNAME\*(C'\fR and \f(CW\*(C`B::PADNAMELIST\*(C'\fR, have been introduced.
+.Sp
+A bug where, after an ithread creation or pseudofork, special/immortal SVs in
+the child ithread/pseudoprocess did not have the correct class of
+\&\f(CW\*(C`B::SPECIAL\*(C'\fR, has been fixed.
+The \f(CW\*(C`id\*(C'\fR and \f(CW\*(C`outid\*(C'\fR PADLIST methods have been added.
+.IP \(bu 4
+B::Concise has been upgraded to version 0.996.
+.Sp
+Null ops that are part of the execution chain are now given sequence
+numbers.
+.Sp
+Private flags for nulled ops are now dumped with mnemonics as they would be
+for the non-nulled counterparts.
+.IP \(bu 4
+B::Deparse has been upgraded to version 1.35.
+.Sp
+It now deparses \f(CW\*(C`+sub : attr { ... }\*(C'\fR correctly at the start of a
+statement.  Without the initial \f(CW\*(C`+\*(C'\fR, \f(CW\*(C`sub\*(C'\fR would be a statement label.
+.Sp
+\&\f(CW\*(C`BEGIN\*(C'\fR blocks are now emitted in the right place most of the time, but
+the change unfortunately introduced a regression, in that \f(CW\*(C`BEGIN\*(C'\fR blocks
+occurring just before the end of the enclosing block may appear below it
+instead.
+.Sp
+\&\f(CW\*(C`B::Deparse\*(C'\fR no longer puts erroneous \f(CW\*(C`local\*(C'\fR here and there, such as for
+\&\f(CW\*(C`LIST = tr/a//d\*(C'\fR.  [perl #119815]
+.Sp
+Adjacent \f(CW\*(C`use\*(C'\fR statements are no longer accidentally nested if one
+contains a \f(CW\*(C`do\*(C'\fR block.  [perl #115066]
+.Sp
+Parenthesised arrays in lists passed to \f(CW\*(C`\e\*(C'\fR are now correctly deparsed
+with parentheses (\fIe.g.\fR, \f(CW\*(C`\e(@a, (@b), @c)\*(C'\fR now retains the parentheses
+around \f(CW@b\fR), thus preserving the flattening behavior of referenced
+parenthesised arrays.  Formerly, it only worked for one array: \f(CW\*(C`\e(@a)\*(C'\fR.
+.Sp
+\&\f(CW\*(C`local our\*(C'\fR is now deparsed correctly, with the \f(CW\*(C`our\*(C'\fR included.
+.Sp
+\&\f(CW\*(C`for($foo; !$bar; $baz) {...}\*(C'\fR was deparsed without the \f(CW\*(C`!\*(C'\fR (or \f(CW\*(C`not\*(C'\fR).
+This has been fixed.
+.Sp
+Core keywords that conflict with lexical subroutines are now deparsed with
+the \f(CW\*(C`CORE::\*(C'\fR prefix.
+.Sp
+\&\f(CW\*(C`foreach state $x (...) {...}\*(C'\fR now deparses correctly with \f(CW\*(C`state\*(C'\fR and
+not \f(CW\*(C`my\*(C'\fR.
+.Sp
+\&\f(CW\*(C`our @array = split(...)\*(C'\fR now deparses correctly with \f(CW\*(C`our\*(C'\fR in those
+cases where the assignment is optimized away.
+.Sp
+It now deparses \f(CWour(\fR\f(CILIST\fR\f(CW)\fR and typed lexical (\f(CW\*(C`my Dog $spot\*(C'\fR) correctly.
+.Sp
+Deparse \f(CW$#_\fR as that instead of as \f(CW$#{_}\fR.
+[GH #14545] <https://github.com/Perl/perl5/issues/14545>
+.Sp
+BEGIN blocks at the end of the enclosing scope are now deparsed in the
+right place.  [perl #77452]
+.Sp
+BEGIN blocks were sometimes deparsed as _\|_ANON_\|_, but are now always called
+BEGIN.
+.Sp
+Lexical subroutines are now fully deparsed.  [perl #116553]
+.Sp
+\&\f(CW\*(C`Anything =~ y///r\*(C'\fR with \f(CW\*(C`/r\*(C'\fR no longer omits the left-hand operand.
+.Sp
+The op trees that make up regexp code blocks are now deparsed for real.
+Formerly, the original string that made up the regular expression was used.
+That caused problems with \f(CW\*(C`qr/(?{<<heredoc})/\*(C'\fR and multiline code blocks,
+which were deparsed incorrectly.  [perl #123217] [perl #115256]
+.Sp
+\&\f(CW$;\fR at the end of a statement no longer loses its semicolon.
+[perl #123357]
+.Sp
+Some cases of subroutine declarations stored in the stash in shorthand form
+were being omitted.
+.Sp
+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.)
+.Sp
+When prototype sub calls are deparsed with \f(CW\*(C`&\*(C'\fR (\fIe.g.\fR, under the \fB\-P\fR
+option), \f(CW\*(C`scalar\*(C'\fR is now added where appropriate, to force the scalar
+context implied by the prototype.
+.Sp
+\&\f(CW\*(C`require(foo())\*(C'\fR, \f(CW\*(C`do(foo())\*(C'\fR, \f(CW\*(C`goto(foo())\*(C'\fR and similar constructs with
+loop controls are now deparsed correctly.  The outer parentheses are not
+optional.
+.Sp
+Whitespace is no longer escaped in regular expressions, because it was
+getting erroneously escaped within \f(CW\*(C`(?x:...)\*(C'\fR sections.
+.Sp
+\&\f(CW\*(C`sub foo { foo() }\*(C'\fR is now deparsed with those mandatory parentheses.
+.Sp
+\&\f(CW\*(C`/@array/\*(C'\fR is now deparsed as a regular expression, and not just
+\&\f(CW@array\fR.
+.Sp
+\&\f(CW\*(C`/@{\-}/\*(C'\fR, \f(CW\*(C`/@{+}/\*(C'\fR and \f(CW$#{1}\fR are now deparsed with the braces, which
+are mandatory in these cases.
+.Sp
+In deparsing feature bundles, \f(CW\*(C`B::Deparse\*(C'\fR was emitting \f(CW\*(C`no feature;\*(C'\fR first
+instead of \f(CW\*(C`no feature \*(Aq:all\*(Aq;\*(C'\fR.  This has been fixed.
+.Sp
+\&\f(CW\*(C`chdir FH\*(C'\fR is now deparsed without quotation marks.
+.Sp
+\&\f(CW\*(C`\emy @a\*(C'\fR is now deparsed without parentheses.  (Parenthese would flatten
+the array.)
+.Sp
+\&\f(CW\*(C`system\*(C'\fR and \f(CW\*(C`exec\*(C'\fR followed by a block are now deparsed correctly.
+Formerly there was an erroneous \f(CW\*(C`do\*(C'\fR before the block.
+.Sp
+\&\f(CW\*(C`use constant QR => qr/.../flags\*(C'\fR followed by \f(CW\*(C`"" =~ QR\*(C'\fR is no longer
+without the flags.
+.Sp
+Deparsing \f(CW\*(C`BEGIN { undef &foo }\*(C'\fR with the \fB\-w\fR switch enabled started to
+emit 'uninitialized' warnings in Perl 5.14.  This has been fixed.
+.Sp
+Deparsing calls to subs with a \f(CW\*(C`(;+)\*(C'\fR prototype resulted in an infinite
+loop.  The \f(CW\*(C`(;$\*(C'\fR) \f(CW\*(C`(_)\*(C'\fR and \f(CW\*(C`(;_)\*(C'\fR prototypes were given the wrong
+precedence, causing \f(CWfoo($a<$b)\fR to be deparsed without the parentheses.
+.Sp
+Deparse now provides a defined state sub in inner subs.
+.IP \(bu 4
+B::Op_private has been added.
+.Sp
+B::Op_private provides detailed information about the flags used in the
+\&\f(CW\*(C`op_private\*(C'\fR field of perl opcodes.
+.IP \(bu 4
+bigint, bignum, bigrat have been upgraded to version 0.39.
+.Sp
+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]
+.IP \(bu 4
+Carp has been upgraded to version 1.36.
+.Sp
+\&\f(CW\*(C`Carp::Heavy\*(C'\fR now ignores version mismatches with Carp if Carp is newer
+than 1.12, since \f(CW\*(C`Carp::Heavy\*(C'\fR's guts were merged into Carp at that
+point.
+[GH #13708] <https://github.com/Perl/perl5/issues/13708>
+.Sp
+Carp now handles non-ASCII platforms better.
+.Sp
+Off-by-one error fix for Perl < 5.14.
+.IP \(bu 4
+constant has been upgraded to version 1.33.
+.Sp
+It now accepts fully-qualified constant names, allowing constants to be defined
+in packages other than the caller.
+.IP \(bu 4
+CPAN has been upgraded to version 2.11.
+.Sp
+Add support for \f(CWCwd::getdcwd()\fR and introduce workaround for a misbehavior
+seen on Strawberry Perl 5.20.1.
+.Sp
+Fix \f(CWchdir()\fR after building dependencies bug.
+.Sp
+Introduce experimental support for plugins/hooks.
+.Sp
+Integrate the \f(CW\*(C`App::Cpan\*(C'\fR sources.
+.Sp
+Do not check recursion on optional dependencies.
+.Sp
+Sanity check \fIMETA.yml\fR to contain a hash.
+[cpan #95271] <https://rt.cpan.org/Ticket/Display.html?id=95271>
+.IP \(bu 4
+CPAN::Meta::Requirements has been upgraded to version 2.132.
+.Sp
+Works around limitations in \f(CW\*(C`version::vpp\*(C'\fR detecting v\-string magic and adds
+support for forthcoming ExtUtils::MakeMaker bootstrap \fIversion.pm\fR for
+Perls older than 5.10.0.
+.IP \(bu 4
+Data::Dumper has been upgraded to version 2.158.
+.Sp
+Fixes CVE\-2014\-4330 by adding a configuration variable/option to limit
+recursion when dumping deep data structures.
+.Sp
+Changes to resolve Coverity issues.
+XS dumps incorrectly stored the name of code references stored in a
+GLOB.
+[GH #13911] <https://github.com/Perl/perl5/issues/13911>
+.IP \(bu 4
+DynaLoader has been upgraded to version 1.32.
+.Sp
+Remove \f(CW\*(C`dl_nonlazy\*(C'\fR global if unused in Dynaloader. [perl #122926]
+.IP \(bu 4
+Encode has been upgraded to version 2.72.
+.Sp
+\&\f(CW\*(C`piconv\*(C'\fR now has better error handling when the encoding name is nonexistent,
+and a build breakage when upgrading Encode in perl\-5.8.2 and earlier has
+been fixed.
+.Sp
+Building in C++ mode on Windows now works.
+.IP \(bu 4
+Errno has been upgraded to version 1.23.
+.Sp
+Add \f(CW\*(C`\-P\*(C'\fR to the preprocessor command-line on GCC 5.  GCC added extra
+line directives, breaking parsing of error code definitions.  [rt.perl.org
+#123784]
+.IP \(bu 4
+experimental has been upgraded to version 0.013.
+.Sp
+Hardcodes features for Perls older than 5.15.7.
+.IP \(bu 4
+ExtUtils::CBuilder has been upgraded to version 0.280221.
+.Sp
+Fixes a regression on Android.
+[GH #14064] <https://github.com/Perl/perl5/issues/14064>
+.IP \(bu 4
+ExtUtils::Manifest has been upgraded to version 1.70.
+.Sp
+Fixes a bug with \f(CWmaniread()\fR's handling of quoted filenames and improves
+\&\f(CWmanifind()\fR to follow symlinks.
+[GH #14003] <https://github.com/Perl/perl5/issues/14003>
+.IP \(bu 4
+ExtUtils::ParseXS has been upgraded to version 3.28.
+.Sp
+Only declare \f(CW\*(C`file\*(C'\fR unused if we actually define it.
+Improve generated \f(CW\*(C`RETVAL\*(C'\fR code generation to avoid repeated
+references to \f(CWST(0)\fR.  [perl #123278]
+Broaden and document the \f(CW\*(C`/OBJ$/\*(C'\fR to \f(CW\*(C`/REF$/\*(C'\fR typemap optimization
+for the \f(CW\*(C`DESTROY\*(C'\fR method.  [perl #123418]
+.IP \(bu 4
+Fcntl has been upgraded to version 1.13.
+.Sp
+Add support for the Linux pipe buffer size \f(CWfcntl()\fR commands.
+.IP \(bu 4
+File::Find has been upgraded to version 1.29.
+.Sp
+\&\f(CWfind()\fR and \f(CWfinddepth()\fR will now warn if passed inappropriate or
+misspelled options.
+.IP \(bu 4
+File::Glob has been upgraded to version 1.24.
+.Sp
+Avoid \f(CWSvIV()\fR expanding to call \f(CWget_sv()\fR three times in a few
+places. [perl #123606]
+.IP \(bu 4
+HTTP::Tiny has been upgraded to version 0.054.
+.Sp
+\&\f(CW\*(C`keep_alive\*(C'\fR is now fork-safe and thread-safe.
+.IP \(bu 4
+IO has been upgraded to version 1.35.
+.Sp
+The XS implementation has been fixed for the sake of older Perls.
+.IP \(bu 4
+IO::Socket has been upgraded to version 1.38.
+.Sp
+Document the limitations of the \f(CWconnected()\fR method.  [perl #123096]
+.IP \(bu 4
+IO::Socket::IP has been upgraded to version 0.37.
+.Sp
+A better fix for subclassing \f(CWconnect()\fR.
+[cpan #95983] <https://rt.cpan.org/Ticket/Display.html?id=95983>
+[cpan #97050] <https://rt.cpan.org/Ticket/Display.html?id=97050>
+.Sp
+Implements Timeout for \f(CWconnect()\fR.
+[cpan #92075] <https://rt.cpan.org/Ticket/Display.html?id=92075>
+.IP \(bu 4
+The libnet collection of modules has been upgraded to version 3.05.
+.Sp
+Support for IPv6 and SSL to \f(CW\*(C`Net::FTP\*(C'\fR, \f(CW\*(C`Net::NNTP\*(C'\fR, \f(CW\*(C`Net::POP3\*(C'\fR and \f(CW\*(C`Net::SMTP\*(C'\fR.
+Improvements in \f(CW\*(C`Net::SMTP\*(C'\fR authentication.
+.IP \(bu 4
+Locale::Codes has been upgraded to version 3.34.
+.Sp
+Fixed a bug in the scripts used to extract data from spreadsheets that
+prevented the SHP currency code from being found.
+[cpan #94229] <https://rt.cpan.org/Ticket/Display.html?id=94229>
+.Sp
+New codes have been added.
+.IP \(bu 4
+Math::BigInt has been upgraded to version 1.9997.
+.Sp
+Synchronize POD changes from the CPAN release.
+\&\f(CW\*(C`Math::BigFloat\->blog(x)\*(C'\fR would sometimes return \f(CWblog(2*x)\fR when
+the accuracy was greater than 70 digits.
+The result of \f(CW\*(C`Math::BigFloat\->bdiv()\*(C'\fR in list context now
+satisfies \f(CW\*(C`x = quotient * divisor + remainder\*(C'\fR.
+.Sp
+Correct handling of subclasses.
+[cpan #96254] <https://rt.cpan.org/Ticket/Display.html?id=96254>
+[cpan #96329] <https://rt.cpan.org/Ticket/Display.html?id=96329>
+.IP \(bu 4
+Module::Metadata has been upgraded to version 1.000026.
+.Sp
+Support installations on older perls with an ExtUtils::MakeMaker earlier
+than 6.63_03
+.IP \(bu 4
+overload has been upgraded to version 1.26.
+.Sp
+A redundant \f(CW\*(C`ref $sub\*(C'\fR check has been removed.
+.IP \(bu 4
+The PathTools module collection has been upgraded to version 3.56.
+.Sp
+A warning from the \fBgcc\fR compiler is now avoided when building the XS.
+.Sp
+Don't turn leading \f(CW\*(C`//\*(C'\fR into \f(CW\*(C`/\*(C'\fR on Cygwin. [perl #122635]
+.IP \(bu 4
+perl5db.pl has been upgraded to version 1.49.
+.Sp
+The debugger would cause an assertion failure.
+[GH #14605] <https://github.com/Perl/perl5/issues/14605>
+.Sp
+\&\f(CWfork()\fR in the debugger under \f(CW\*(C`tmux\*(C'\fR will now create a new window for
+the forked process. [GH #13602] <https://github.com/Perl/perl5/issues/13602>
+.Sp
+The debugger now saves the current working directory on startup and
+restores it when you restart your program with \f(CW\*(C`R\*(C'\fR or \f(CW\*(C`rerun\*(C'\fR.
+[GH #13691] <https://github.com/Perl/perl5/issues/13691>
+.IP \(bu 4
+PerlIO::scalar has been upgraded to version 0.22.
+.Sp
+Reading from a position well past the end of the scalar now correctly
+returns end of file.  [perl #123443]
+.Sp
+Seeking to a negative position still fails, but no longer leaves the
+file position set to a negation location.
+.Sp
+\&\f(CWeof()\fR on a \f(CW\*(C`PerlIO::scalar\*(C'\fR handle now properly returns true when
+the file position is past the 2GB mark on 32\-bit systems.
+.Sp
+Attempting to write at file positions impossible for the platform now
+fail early rather than wrapping at 4GB.
+.IP \(bu 4
+Pod::Perldoc has been upgraded to version 3.25.
+.Sp
+Filehandles opened for reading or writing now have \f(CW:encoding(UTF\-8)\fR set.
+[cpan #98019] <https://rt.cpan.org/Ticket/Display.html?id=98019>
+.IP \(bu 4
+POSIX has been upgraded to version 1.53.
+.Sp
+The C99 math functions and constants (for example \f(CW\*(C`acosh\*(C'\fR, \f(CW\*(C`isinf\*(C'\fR, \f(CW\*(C`isnan\*(C'\fR, \f(CW\*(C`round\*(C'\fR,
+\&\f(CW\*(C`trunc\*(C'\fR; \f(CW\*(C`M_E\*(C'\fR, \f(CW\*(C`M_SQRT2\*(C'\fR, \f(CW\*(C`M_PI\*(C'\fR) have been added.
+.Sp
+\&\f(CWPOSIX::tmpnam()\fR now produces a deprecation warning.  [perl #122005]
+.IP \(bu 4
+Safe has been upgraded to version 2.39.
+.Sp
+\&\f(CW\*(C`reval\*(C'\fR was not propagating void context properly.
+.IP \(bu 4
+Scalar-List-Utils has been upgraded to version 1.41.
+.Sp
+A new module, Sub::Util, has been added, containing functions related to
+CODE refs, including \f(CW\*(C`subname\*(C'\fR (inspired by \f(CW\*(C`Sub::Identity\*(C'\fR) and \f(CW\*(C`set_subname\*(C'\fR
+(copied and renamed from \f(CW\*(C`Sub::Name\*(C'\fR).
+The use of \f(CW\*(C`GetMagic\*(C'\fR in \f(CWList::Util::reduce()\fR has also been fixed.
+[cpan #63211] <https://rt.cpan.org/Ticket/Display.html?id=63211>
+.IP \(bu 4
+SDBM_File has been upgraded to version 1.13.
+.Sp
+Simplified the build process.  [perl #123413]
+.IP \(bu 4
+Time::Piece has been upgraded to version 1.29.
+.Sp
+When pretty printing negative \f(CW\*(C`Time::Seconds\*(C'\fR, the "minus" is no longer lost.
+.IP \(bu 4
+Unicode::Collate has been upgraded to version 1.12.
+.Sp
+Version 0.67's improved discontiguous contractions is invalidated by default
+and is supported as a parameter \f(CW\*(C`long_contraction\*(C'\fR.
+.IP \(bu 4
+Unicode::Normalize has been upgraded to version 1.18.
+.Sp
+The XSUB implementation has been removed in favor of pure Perl.
+.IP \(bu 4
+Unicode::UCD has been upgraded to version 0.61.
+.Sp
+A new function \fBproperty_values()\fR
+has been added to return a given property's possible values.
+.Sp
+A new function \fBcharprop()\fR
+has been added to return the value of a given property for a given code
+point.
+.Sp
+A new function \fBcharprops_all()\fR
+has been added to return the values of all Unicode properties for a
+given code point.
+.Sp
+A bug has been fixed so that \fBpropaliases()\fR
+returns the correct short and long names for the Perl extensions where
+it was incorrect.
+.Sp
+A bug has been fixed so that
+\&\fBprop_value_aliases()\fR
+returns \f(CW\*(C`undef\*(C'\fR instead of a wrong result for properties that are Perl
+extensions.
+.Sp
+This module now works on EBCDIC platforms.
+.IP \(bu 4
+utf8 has been upgraded to version 1.17
+.Sp
+A mismatch between the documentation and the code in \f(CWutf8::downgrade()\fR
+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.
+.IP \(bu 4
+version has been upgraded to version 0.9909.
+.Sp
+Numerous changes.  See the \fIChanges\fR file in the CPAN distribution for
+details.
+.IP \(bu 4
+Win32 has been upgraded to version 0.51.
+.Sp
+\&\f(CWGetOSName()\fR now supports Windows 8.1, and building in C++ mode now works.
+.IP \(bu 4
+Win32API::File has been upgraded to version 0.1202
+.Sp
+Building in C++ mode now works.
+.IP \(bu 4
+XSLoader has been upgraded to version 0.20.
+.Sp
+Allow XSLoader to load modules from a different namespace.
+[perl #122455]
+.SS "Removed Modules and Pragmata"
+.IX Subsection "Removed Modules and Pragmata"
+The following modules (and associated modules) have been removed from the core
+perl distribution:
+.IP \(bu 4
+CGI
+.IP \(bu 4
+Module::Build
+.SH Documentation
+.IX Header "Documentation"
+.SS "New Documentation"
+.IX Subsection "New Documentation"
+\fIperlunicook\fR
+.IX Subsection "perlunicook"
+.PP
+This document, by Tom Christiansen, provides examples of handling Unicode in
+Perl.
+.SS "Changes to Existing Documentation"
+.IX Subsection "Changes to Existing Documentation"
+\fIperlaix\fR
+.IX Subsection "perlaix"
+.IP \(bu 4
+A note on long doubles has been added.
+.PP
+\fIperlapi\fR
+.IX Subsection "perlapi"
+.IP \(bu 4
+Note that \f(CW\*(C`SvSetSV\*(C'\fR doesn't do set magic.
+.IP \(bu 4
+\&\f(CW\*(C`sv_usepvn_flags\*(C'\fR \- fix documentation to mention the use of \f(CW\*(C`Newx\*(C'\fR instead of
+\&\f(CW\*(C`malloc\*(C'\fR.
+.Sp
+[GH #13835] <https://github.com/Perl/perl5/issues/13835>
+.IP \(bu 4
+Clarify where \f(CW\*(C`NUL\*(C'\fR may be embedded or is required to terminate a string.
+.IP \(bu 4
+Some documentation that was previously missing due to formatting errors is
+now included.
+.IP \(bu 4
+Entries are now organized into groups rather than by the file where they
+are found.
+.IP \(bu 4
+Alphabetical sorting of entries is now done consistently (automatically
+by the POD generator) to make entries easier to find when scanning.
+.PP
+\fIperldata\fR
+.IX Subsection "perldata"
+.IP \(bu 4
+The syntax of single-character variable names has been brought
+up-to-date and more fully explained.
+.IP \(bu 4
+Hexadecimal floating point numbers are described, as are infinity and
+NaN.
+.PP
+\fIperlebcdic\fR
+.IX Subsection "perlebcdic"
+.IP \(bu 4
+This document has been significantly updated in the light of recent
+improvements to EBCDIC support.
+.PP
+\fIperlfilter\fR
+.IX Subsection "perlfilter"
+.IP \(bu 4
+Added a LIMITATIONS section.
+.PP
+\fIperlfunc\fR
+.IX Subsection "perlfunc"
+.IP \(bu 4
+Mention that \f(CWstudy()\fR is currently a no-op.
+.IP \(bu 4
+Calling \f(CW\*(C`delete\*(C'\fR or \f(CW\*(C`exists\*(C'\fR on array values is now described as "strongly
+discouraged" rather than "deprecated".
+.IP \(bu 4
+Improve documentation of \f(CW\*(C`our\*(C'\fR.
+.IP \(bu 4
+\&\f(CW\*(C`\-l\*(C'\fR now notes that it will return false if symlinks aren't supported by the
+file system.
+[GH #13695] <https://github.com/Perl/perl5/issues/13695>
+.IP \(bu 4
+Note that \f(CW\*(C`exec LIST\*(C'\fR and \f(CW\*(C`system LIST\*(C'\fR may fall back to the shell on
+Win32. Only the indirect-object syntax \f(CW\*(C`exec PROGRAM LIST\*(C'\fR and
+\&\f(CW\*(C`system PROGRAM LIST\*(C'\fR will reliably avoid using the shell.
+.Sp
+This has also been noted in perlport.
+.Sp
+[GH #13907] <https://github.com/Perl/perl5/issues/13907>
+.PP
+\fIperlguts\fR
+.IX Subsection "perlguts"
+.IP \(bu 4
+The OOK example has been updated to account for COW changes and a change in the
+storage of the offset.
+.IP \(bu 4
+Details on C level symbols and libperl.t added.
+.IP \(bu 4
+Information on Unicode handling has been added
+.IP \(bu 4
+Information on EBCDIC handling has been added
+.PP
+\fIperlhack\fR
+.IX Subsection "perlhack"
+.IP \(bu 4
+A note has been added about running on platforms with non-ASCII
+character sets
+.IP \(bu 4
+A note has been added about performance testing
+.PP
+\fIperlhacktips\fR
+.IX Subsection "perlhacktips"
+.IP \(bu 4
+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.
+.IP \(bu 4
+Replacements for \f(CW\*(C`tmpfile\*(C'\fR, \f(CW\*(C`atoi\*(C'\fR, \f(CW\*(C`strtol\*(C'\fR, and \f(CW\*(C`strtoul\*(C'\fR are now
+recommended.
+.IP \(bu 4
+Updated documentation for the \f(CW\*(C`test.valgrind\*(C'\fR \f(CW\*(C`make\*(C'\fR target.
+[GH #13658] <https://github.com/Perl/perl5/issues/13658>
+.IP \(bu 4
+Information is given about writing test files portably to non-ASCII
+platforms.
+.IP \(bu 4
+A note has been added about how to get a C language stack backtrace.
+.PP
+\fIperlhpux\fR
+.IX Subsection "perlhpux"
+.IP \(bu 4
+Note that the message "Redeclaration of "sendpath" with a different
+storage class specifier" is harmless.
+.PP
+\fIperllocale\fR
+.IX Subsection "perllocale"
+.IP \(bu 4
+Updated for the enhancements in v5.22, along with some clarifications.
+.PP
+\fIperlmodstyle\fR
+.IX Subsection "perlmodstyle"
+.IP \(bu 4
+Instead of pointing to the module list, we are now pointing to
+PrePAN <http://prepan.org/>.
+.PP
+\fIperlop\fR
+.IX Subsection "perlop"
+.IP \(bu 4
+Updated for the enhancements in v5.22, along with some clarifications.
+.PP
+\fIperlpodspec\fR
+.IX Subsection "perlpodspec"
+.IP \(bu 4
+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).
+.PP
+\fIperlpolicy\fR
+.IX Subsection "perlpolicy"
+.IP \(bu 4
+We now have a code of conduct for the \fIp5p\fR mailing list, as documented
+in "STANDARDS OF CONDUCT" in perlpolicy.
+.IP \(bu 4
+The conditions for marking an experimental feature as non-experimental are now
+set out.
+.IP \(bu 4
+Clarification has been made as to what sorts of changes are permissible in
+maintenance releases.
+.PP
+\fIperlport\fR
+.IX Subsection "perlport"
+.IP \(bu 4
+Out-of-date VMS-specific information has been fixed and/or simplified.
+.IP \(bu 4
+Notes about EBCDIC have been added.
+.PP
+\fIperlre\fR
+.IX Subsection "perlre"
+.IP \(bu 4
+The description of the \f(CW\*(C`/x\*(C'\fR 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.
+.IP \(bu 4
+The new \f(CW\*(C`/n\*(C'\fR modifier is described.
+.IP \(bu 4
+A note has been added on how to make bracketed character class ranges
+portable to non-ASCII machines.
+.PP
+\fIperlrebackslash\fR
+.IX Subsection "perlrebackslash"
+.IP \(bu 4
+Added documentation of \f(CW\*(C`\eb{sb}\*(C'\fR, \f(CW\*(C`\eb{wb}\*(C'\fR, \f(CW\*(C`\eb{gcb}\*(C'\fR, and \f(CW\*(C`\eb{g}\*(C'\fR.
+.PP
+\fIperlrecharclass\fR
+.IX Subsection "perlrecharclass"
+.IP \(bu 4
+Clarifications have been added to "Character Ranges" in perlrecharclass
+to the effect \f(CW\*(C`[A\-Z]\*(C'\fR, \f(CW\*(C`[a\-z]\*(C'\fR, \f(CW\*(C`[0\-9]\*(C'\fR 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.
+.IP \(bu 4
+The documentation of Bracketed Character Classes has been expanded to cover the
+improvements in \f(CW\*(C`qr/[\eN{named sequence}]/\*(C'\fR (see under "Selected Bug Fixes").
+.PP
+\fIperlref\fR
+.IX Subsection "perlref"
+.IP \(bu 4
+A new section has been added
+Assigning to References
+.PP
+\fIperlsec\fR
+.IX Subsection "perlsec"
+.IP \(bu 4
+Comments added on algorithmic complexity and tied hashes.
+.PP
+\fIperlsyn\fR
+.IX Subsection "perlsyn"
+.IP \(bu 4
+An ambiguity in the documentation of the \f(CW\*(C`...\*(C'\fR statement has been corrected.
+[GH #14054] <https://github.com/Perl/perl5/issues/14054>
+.IP \(bu 4
+The empty conditional in \f(CW\*(C`for\*(C'\fR and \f(CW\*(C`while\*(C'\fR is now documented
+in perlsyn.
+.PP
+\fIperlunicode\fR
+.IX Subsection "perlunicode"
+.IP \(bu 4
+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
+"Noncharacter code points" in perlunicode.
+.PP
+\fIperluniintro\fR
+.IX Subsection "perluniintro"
+.IP \(bu 4
+Advice for how to make sure your strings and regular expression patterns are
+interpreted as Unicode has been updated.
+.PP
+\fIperlvar\fR
+.IX Subsection "perlvar"
+.IP \(bu 4
+\&\f(CW$]\fR is no longer listed as being deprecated.  Instead, discussion has
+been added on the advantages and disadvantages of using it versus
+\&\f(CW$^V\fR.  \f(CW$OLD_PERL_VERSION\fR was re-added to the documentation as the long
+form of \f(CW$]\fR.
+.IP \(bu 4
+\&\f(CW\*(C`${^ENCODING}\*(C'\fR is now marked as deprecated.
+.IP \(bu 4
+The entry for \f(CW\*(C`%^H\*(C'\fR has been clarified to indicate it can only handle
+simple values.
+.PP
+\fIperlvms\fR
+.IX Subsection "perlvms"
+.IP \(bu 4
+Out-of-date and/or incorrect material has been removed.
+.IP \(bu 4
+Updated documentation on environment and shell interaction in VMS.
+.PP
+\fIperlxs\fR
+.IX Subsection "perlxs"
+.IP \(bu 4
+Added a discussion of locale issues in XS code.
+.SH Diagnostics
+.IX Header "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 perldiag.
+.SS "New Diagnostics"
+.IX Subsection "New Diagnostics"
+\fINew Errors\fR
+.IX Subsection "New Errors"
+.IP \(bu 4
+Bad symbol for scalar
+.Sp
+(P) An internal request asked to add a scalar entry to something that
+wasn't a symbol table entry.
+.IP \(bu 4
+Can't use a hash as a reference
+.Sp
+(F) You tried to use a hash as a reference, as in
+\&\f(CW\*(C`%foo\->{"bar"}\*(C'\fR or \f(CW\*(C`%$ref\->{"hello"}\*(C'\fR.  Versions of perl <= 5.6.1
+used to allow this syntax, but shouldn't have.
+.IP \(bu 4
+Can't use an array as a reference
+.Sp
+(F) You tried to use an array as a reference, as in
+\&\f(CW\*(C`@foo\->[23]\*(C'\fR or \f(CW\*(C`@$ref\->[99]\*(C'\fR.  Versions of perl <= 5.6.1 used to
+allow this syntax, but shouldn't have.
+.IP \(bu 4
+Can't use 'defined(@array)' (Maybe you should just omit the \fBdefined()\fR?)
+.Sp
+(F) \f(CWdefined()\fR is not useful on arrays because it
+checks for an undefined \fIscalar\fR value.  If you want to see if the
+array is empty, just use \f(CW\*(C`if\ (@array)\ {\ #\ not\ empty\ }\*(C'\fR for example.
+.IP \(bu 4
+Can't use 'defined(%hash)' (Maybe you should just omit the \fBdefined()\fR?)
+.Sp
+(F) \f(CWdefined()\fR is not usually right on hashes.
+.Sp
+Although \f(CW\*(C`defined\ %hash\*(C'\fR 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 \f(CW\*(C`undef\ %hash\*(C'\fR.
+These things make \f(CW\*(C`defined\ %hash\*(C'\fR fairly useless in practice, so it now
+generates a fatal error.
+.Sp
+If a check for non-empty is what you wanted then just put it in boolean
+context (see "Scalar values" in perldata):
+.Sp
+.Vb 3
+\&    if (%hash) {
+\&       # not empty
+\&    }
+.Ve
+.Sp
+If you had \f(CW\*(C`defined\ %Foo::Bar::QUUX\*(C'\fR 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.
+.IP \(bu 4
+Cannot chr \f(CW%f\fR
+.Sp
+(F) You passed an invalid number (like an infinity or not-a-number) to
+\&\f(CW\*(C`chr\*(C'\fR.
+.IP \(bu 4
+Cannot compress \f(CW%f\fR in pack
+.Sp
+(F) You tried converting an infinity or not-a-number to an unsigned
+character, which makes no sense.
+.IP \(bu 4
+Cannot pack \f(CW%f\fR with '%c'
+.Sp
+(F) You tried converting an infinity or not-a-number to a character,
+which makes no sense.
+.IP \(bu 4
+Cannot print \f(CW%f\fR with '%c'
+.Sp
+(F) You tried printing an infinity or not-a-number as a character (\f(CW%c\fR),
+which makes no sense.  Maybe you meant \f(CW\*(Aq%s\*(Aq\fR, or just stringifying it?
+.IP \(bu 4
+charnames alias definitions may not contain a sequence of multiple spaces
+.Sp
+(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 \f(CW\*(C`:alias\*(C'\fR import argument to \f(CW\*(C`use charnames\*(C'\fR, but
+they could be defined by a translator installed into \f(CW$^H{charnames}\fR.
+See "CUSTOM ALIASES" in charnames.
+.IP \(bu 4
+charnames alias definitions may not contain trailing white-space
+.Sp
+(F) You defined a character name which ended in a space
+character.  Remove the trailing space(s).  Usually these names are
+defined in the \f(CW\*(C`:alias\*(C'\fR import argument to \f(CW\*(C`use charnames\*(C'\fR, but they
+could be defined by a translator installed into \f(CW$^H{charnames}\fR.
+See "CUSTOM ALIASES" in charnames.
+.IP \(bu 4
+:const is not permitted on named subroutines
+.Sp
+(F) The \f(CW\*(C`const\*(C'\fR 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.
+.IP \(bu 4
+Hexadecimal float: internal error
+.Sp
+(F) Something went horribly bad in hexadecimal float handling.
+.IP \(bu 4
+Hexadecimal float: unsupported long double format
+.Sp
+(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.
+.IP \(bu 4
+Illegal suidscript
+.Sp
+(F) The script run under suidperl was somehow illegal.
+.IP \(bu 4
+In '(?...)', the '(' and '?' must be adjacent in regex; marked by <\-\-\ HERE in m/%s/
+.Sp
+(F) The two-character sequence \f(CW"(?"\fR in
+this context in a regular expression pattern should be an
+indivisible token, with nothing intervening between the \f(CW"("\fR
+and the \f(CW"?"\fR, but you separated them.
+.IP \(bu 4
+In '(*VERB...)', the '(' and '*' must be adjacent in regex; marked by <\-\-\ HERE in m/%s/
+.Sp
+(F) The two-character sequence \f(CW"(*"\fR in
+this context in a regular expression pattern should be an
+indivisible token, with nothing intervening between the \f(CW"("\fR
+and the \f(CW"*"\fR, but you separated them.
+.IP \(bu 4
+Invalid quantifier in {,} in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(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 <\-\-\ HERE shows where in the regular
+expression the problem was discovered.  See perlre.
+.IP \(bu 4
+\&'%s' is an unknown bound type in regex
+.Sp
+(F) You used \f(CW\*(C`\eb{...}\*(C'\fR or \f(CW\*(C`\eB{...}\*(C'\fR and the \f(CW\*(C`...\*(C'\fR is not known to
+Perl.  The current valid ones are given in
+"\eb{}, \eb, \eB{}, \eB" in perlrebackslash.
+.IP \(bu 4
+Missing or undefined argument to require
+.Sp
+(F) You tried to call \f(CW\*(C`require\*(C'\fR with no argument or with an undefined
+value as an argument.  \f(CW\*(C`require\*(C'\fR expects either a package name or a
+file-specification as an argument.  See "require" in perlfunc.
+.Sp
+Formerly, \f(CW\*(C`require\*(C'\fR with no argument or \f(CW\*(C`undef\*(C'\fR warned about a Null filename.
+.PP
+\fINew Warnings\fR
+.IX Subsection "New Warnings"
+.IP \(bu 4
+\&\eC is deprecated in regex
+.Sp
+(D deprecated) The \f(CW\*(C`/\eC/\*(C'\fR 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.
+.IP \(bu 4
+"%s" is more clearly written simply as "%s" in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(W regexp) (only under \f(CW\*(C`use\ re\ \*(Aqstrict\*(Aq\*(C'\fR or within \f(CW\*(C`(?[...])\*(C'\fR)
+.Sp
+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.
+.IP \(bu 4
+Argument "%s" treated as 0 in increment (++)
+.Sp
+(W numeric) The indicated string was fed as an argument to the \f(CW\*(C`++\*(C'\fR operator
+which expects either a number or a string matching \f(CW\*(C`/^[a\-zA\-Z]*[0\-9]*\ez/\*(C'\fR.
+See "Auto-increment and Auto-decrement" in perlop for details.
+.IP \(bu 4
+Both or neither range ends should be Unicode in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(W regexp) (only under \f(CW\*(C`use\ re\ \*(Aqstrict\*(Aq\*(C'\fR or within \f(CW\*(C`(?[...])\*(C'\fR)
+.Sp
+In a bracketed character class in a regular expression pattern, you
+had a range which has exactly one end of it specified using \f(CW\*(C`\eN{}\*(C'\fR, 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, \f(CW\*(C`[\eN{U+06}\-\ex08]\*(C'\fR
+is treated as if you had instead said \f(CW\*(C`[\eN{U+06}\-\eN{U+08}]\*(C'\fR, that is it
+matches the characters whose code points in Unicode are 6, 7, and 8.
+But that \f(CW\*(C`\ex08\*(C'\fR might indicate that you meant something different, so
+the warning gets raised.
+.IP \(bu 4
+Can't do %s("%s") on non\-UTF\-8 locale; resolved to "%s".
+.Sp
+(W locale) You are 1) running under "\f(CW\*(C`use locale\*(C'\fR"; 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.
+.Sp
+The warnings category \f(CW\*(C`locale\*(C'\fR is new.
+.IP \(bu 4
+:const is experimental
+.Sp
+(S experimental::const_attr) The \f(CW\*(C`const\*(C'\fR attribute is experimental.
+If you want to use the feature, disable the warning with \f(CWno warnings
+\&\*(Aqexperimental::const_attr\*(Aq\fR, but know that in doing so you are taking
+the risk that your code may break in a future Perl version.
+.IP \(bu 4
+gmtime(%f) failed
+.Sp
+(W overflow) You called \f(CW\*(C`gmtime\*(C'\fR with a number that it could not handle:
+too large, too small, or NaN.  The returned value is \f(CW\*(C`undef\*(C'\fR.
+.IP \(bu 4
+Hexadecimal float: exponent overflow
+.Sp
+(W overflow) The hexadecimal floating point has larger exponent
+than the floating point supports.
+.IP \(bu 4
+Hexadecimal float: exponent underflow
+.Sp
+(W overflow) The hexadecimal floating point has smaller exponent
+than the floating point supports.
+.IP \(bu 4
+Hexadecimal float: mantissa overflow
+.Sp
+(W overflow) The hexadecimal floating point literal had more bits in
+the mantissa (the part between the \f(CW\*(C`0x\*(C'\fR and the exponent, also known as
+the fraction or the significand) than the floating point supports.
+.IP \(bu 4
+Hexadecimal float: precision loss
+.Sp
+(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).
+.IP \(bu 4
+Locale '%s' may not work well.%s
+.Sp
+(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 \f(CW%s\fR gives a reason.
+.Sp
+The warnings category \f(CW\*(C`locale\*(C'\fR is new.
+.IP \(bu 4
+localtime(%f) failed
+.Sp
+(W overflow) You called \f(CW\*(C`localtime\*(C'\fR with a number that it could not handle:
+too large, too small, or NaN.  The returned value is \f(CW\*(C`undef\*(C'\fR.
+.IP \(bu 4
+Negative repeat count does nothing
+.Sp
+(W numeric) You tried to execute the
+\&\f(CW\*(C`x\*(C'\fR repetition operator fewer than 0
+times, which doesn't make sense.
+.IP \(bu 4
+NO-BREAK SPACE in a charnames alias definition is deprecated
+.Sp
+(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 \f(CW\*(C`:alias\*(C'\fR import argument to \f(CW\*(C`use charnames\*(C'\fR, but they
+could be defined by a translator installed into \f(CW$^H{charnames}\fR.  See
+"CUSTOM ALIASES" in charnames.
+.IP \(bu 4
+Non-finite repeat count does nothing
+.Sp
+(W numeric) You tried to execute the
+\&\f(CW\*(C`x\*(C'\fR repetition operator \f(CW\*(C`Inf\*(C'\fR (or
+\&\f(CW\*(C`\-Inf\*(C'\fR) or NaN times, which doesn't make sense.
+.IP \(bu 4
+PerlIO layer ':win32' is experimental
+.Sp
+(S experimental::win32_perlio) The \f(CW\*(C`:win32\*(C'\fR PerlIO layer is
+experimental.  If you want to take the risk of using this layer,
+simply disable this warning:
+.Sp
+.Vb 1
+\&    no warnings "experimental::win32_perlio";
+.Ve
+.IP \(bu 4
+Ranges of ASCII printables should be some subset of "0\-9", "A\-Z", or "a\-z" in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(W regexp) (only under \f(CW\*(C`use\ re\ \*(Aqstrict\*(Aq\*(C'\fR or within \f(CW\*(C`(?[...])\*(C'\fR)
+.Sp
+Stricter rules help to find typos and other errors.  Perhaps you didn't
+even intend a range here, if the \f(CW"\-"\fR was meant to be some other
+character, or should have been escaped (like \f(CW"\e\-"\fR).  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.
+.Sp
+.Vb 7
+\& [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
+\& [\ex41\-Z] # WRONG; Not portable; not obvious to non\-geek
+.Ve
+.Sp
+(You can force portability by specifying a Unicode range, which means that
+the endpoints are specified by
+\&\f(CW\*(C`\eN{...}\*(C'\fR, 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 \f(CW"\ex41"\fR), and the ranges
+must be all digits, or all uppercase letters, or all lowercase letters.
+.IP \(bu 4
+Ranges of digits should be from the same group in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(W regexp) (only under \f(CW\*(C`use\ re\ \*(Aqstrict\*(Aq\*(C'\fR or within \f(CW\*(C`(?[...])\*(C'\fR)
+.Sp
+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.
+.IP \(bu 4
+Redundant argument in \f(CW%s\fR
+.Sp
+(W redundant) You called a function with more arguments than were
+needed, as indicated by information within other arguments you supplied
+(\fIe.g\fR. 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 \fIe.g.\fR "pack" in perlfunc.
+.Sp
+The warnings category \f(CW\*(C`redundant\*(C'\fR is new. See also
+[GH #13534] <https://github.com/Perl/perl5/issues/13534>.
+.IP \(bu 4
+Replacement list is longer than search list
+.Sp
+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).
+.IP \(bu 4
+Use of \eb{} for non\-UTF\-8 locale is wrong.  Assuming a UTF\-8 locale
+.Sp
+(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.
+.Sp
+The warnings category \f(CW\*(C`locale\*(C'\fR is new.
+.IP \(bu 4
+Using /u for '%s' instead of /%s in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(W regexp) You used a Unicode boundary (\f(CW\*(C`\eb{...}\*(C'\fR or \f(CW\*(C`\eB{...}\*(C'\fR) in a
+portion of a regular expression where the character set modifiers \f(CW\*(C`/a\*(C'\fR
+or \f(CW\*(C`/aa\*(C'\fR 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.
+.IP \(bu 4
+The bitwise feature is experimental
+.Sp
+(S experimental::bitwise) This warning is emitted if you use bitwise
+operators (\f(CW\*(C`& | ^ ~ &. |. ^. ~.\*(C'\fR) 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:
+.Sp
+.Vb 3
+\&    no warnings "experimental::bitwise";
+\&    use feature "bitwise";
+\&    $x |.= $y;
+.Ve
+.IP \(bu 4
+Unescaped left brace in regex is deprecated, passed through in regex; marked by <\-\- HERE in m/%s/
+.Sp
+(D deprecated, regexp) You used a literal \f(CW"{"\fR character in a regular
+expression pattern. You should change to use \f(CW"\e{"\fR 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
+(\f(CW"}"\fR) should also be escaped to avoid confusing the parser, for
+example,
+.Sp
+.Vb 1
+\&    qr{abc\e{def\e}ghi}
+.Ve
+.IP \(bu 4
+Use of literal non-graphic characters in variable names is deprecated
+.Sp
+(D deprecated) Using literal non-graphic (including control)
+characters in the source to refer to the \fI^FOO\fR variables, like \f(CW$^X\fR and
+\&\f(CW\*(C`${^GLOBAL_PHASE}\*(C'\fR is now deprecated.
+.IP \(bu 4
+Useless use of attribute "const"
+.Sp
+(W misc) The \f(CW\*(C`const\*(C'\fR attribute has no effect except
+on anonymous closure prototypes.  You applied it to
+a subroutine via attributes.pm.  This is only useful
+inside an attribute handler for an anonymous subroutine.
+.IP \(bu 4
+Useless use of /d modifier in transliteration operator
+.Sp
+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).
+.IP \(bu 4
+"use re 'strict'" is experimental
+.Sp
+(S experimental::re_strict) The things that are different when a regular
+expression pattern is compiled under \f(CW\*(Aqstrict\*(Aq\fR 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.
+.IP \(bu 4
+Warning: unable to close filehandle properly: \f(CW%s\fR
+.Sp
+Warning: unable to close filehandle \f(CW%s\fR properly: \f(CW%s\fR
+.Sp
+(S io) Previously, perl silently ignored any errors when doing an implicit
+close of a filehandle, \fIi.e.\fR where the reference count of the filehandle
+reached zero and the user's code hadn't already called \f(CWclose()\fR; \fIe.g.\fR
+.Sp
+.Vb 4
+\&    {
+\&        open my $fh, \*(Aq>\*(Aq, $file  or die "open: \*(Aq$file\*(Aq: $!\en";
+\&        print $fh, $data  or die;
+\&    } # implicit close here
+.Ve
+.Sp
+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.
+.Sp
+So perl now warns in such situations.
+.IP \(bu 4
+Wide character (U+%X) in \f(CW%s\fR
+.Sp
+(W locale) While in a single-byte locale (\fIi.e.\fR, 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.
+.Sp
+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).
+.Sp
+The warnings category \f(CW\*(C`locale\*(C'\fR is new.
+.SS "Changes to Existing Diagnostics"
+.IX Subsection "Changes to Existing Diagnostics"
+.IP \(bu 4
+<> should be quotes
+.Sp
+This warning has been changed to
+<> at require-statement should be quotes
+to make the issue more identifiable.
+.IP \(bu 4
+Argument "%s" isn't numeric%s
+.Sp
+The perldiag entry for this warning has added this clarifying note:
+.Sp
+.Vb 4
+\& 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.
+.Ve
+.IP \(bu 4
+Global symbol "%s" requires explicit package name
+.Sp
+This message has had '(did you forget to declare "my \f(CW%s\fR"?)' appended to it, to
+make it more helpful to new Perl programmers.
+[GH #13732] <https://github.com/Perl/perl5/issues/13732>
+.IP \(bu 4
+\&'"my" variable &foo::bar can't be in a package' has been reworded to say
+\&'subroutine' instead of 'variable'.
+.IP \(bu 4
+\&\eN{} in character class restricted to one character in regex; marked by
+<\-\-\ HERE in m/%s/
+.Sp
+This message has had \fIcharacter class\fR changed to \fIinverted character
+class or as a range end-point is\fR to reflect improvements in
+\&\f(CW\*(C`qr/[\eN{named sequence}]/\*(C'\fR (see under "Selected Bug Fixes").
+.IP \(bu 4
+panic: frexp
+.Sp
+This message has had ': \f(CW%f\fR' appended to it, to show what the offending
+floating point number is.
+.IP \(bu 4
+\&\fIPossible precedence problem on bitwise \fR\f(CI%c\fR\fI operator\fR reworded as
+Possible precedence problem on bitwise \f(CW%s\fR operator.
+.IP \(bu 4
+Unsuccessful \f(CW%s\fR on filename containing newline
+.Sp
+This warning is now only produced when the newline is at the end of
+the filename.
+.IP \(bu 4
+"Variable \f(CW%s\fR will not stay shared" has been changed to say "Subroutine"
+when it is actually a lexical sub that will not stay shared.
+.IP \(bu 4
+Variable length lookbehind not implemented in regex m/%s/
+.Sp
+The perldiag entry for this warning has had information about Unicode
+behavior added.
+.SS "Diagnostic Removals"
+.IX Subsection "Diagnostic Removals"
+.IP \(bu 4
+"Ambiguous use of \-foo resolved as \-&\fBfoo()\fR"
+.Sp
+There is actually no ambiguity here, and this impedes the use of negated
+constants; \fIe.g.\fR, \f(CW\*(C`\-Inf\*(C'\fR.
+.IP \(bu 4
+"Constant is not a FOO reference"
+.Sp
+Compile-time checking of constant dereferencing (\fIe.g.\fR, \f(CWmy_constant\->()\fR)
+has been removed, since it was not taking overloading into account.
+[GH #9891] <https://github.com/Perl/perl5/issues/9891>
+[GH #14044] <https://github.com/Perl/perl5/issues/14044>
+.SH "Utility Changes"
+.IX Header "Utility Changes"
+.SS "\fIfind2perl\fP, \fIs2p\fP and \fIa2p\fP removal"
+.IX Subsection "find2perl, s2p and a2p removal"
+.IP \(bu 4
+The \fIx2p/\fR directory has been removed from the Perl core.
+.Sp
+This removes find2perl, s2p and a2p. They have all been released to CPAN as
+separate distributions (\f(CW\*(C`App::find2perl\*(C'\fR, \f(CW\*(C`App::s2p\*(C'\fR, \f(CW\*(C`App::a2p\*(C'\fR).
+.SS h2ph
+.IX Subsection "h2ph"
+.IP \(bu 4
+\&\fIh2ph\fR now handles hexadecimal constants in the compiler's predefined
+macro definitions, as visible in \f(CW$Config{cppsymbols}\fR.
+[GH #14491] <https://github.com/Perl/perl5/issues/14491>.
+.SS encguess
+.IX Subsection "encguess"
+.IP \(bu 4
+No longer depends on non-core modules.
+.SH "Configuration and Compilation"
+.IX Header "Configuration and Compilation"
+.IP \(bu 4
+\&\fIConfigure\fR now checks for \f(CWlrintl()\fR, \f(CWlroundl()\fR, \f(CWllrintl()\fR, and
+\&\f(CWllroundl()\fR.
+.IP \(bu 4
+\&\fIConfigure\fR with \f(CW\*(C`\-Dmksymlinks\*(C'\fR should now be faster.
+[GH #13890] <https://github.com/Perl/perl5/issues/13890>.
+.IP \(bu 4
+The \f(CW\*(C`pthreads\*(C'\fR and \f(CW\*(C`cl\*(C'\fR 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 \f(CW\*(C`\-Dusethreads\*(C'\fR if you want a
+threaded perl.
+.IP \(bu 4
+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 \fIINSTALL\fR for
+details.
+.IP \(bu 4
+MurmurHash64A and MurmurHash64B can now be configured as the internal hash
+function.
+.IP \(bu 4
+\&\f(CW\*(C`make test.valgrind\*(C'\fR now supports parallel testing.
+.Sp
+For example:
+.Sp
+.Vb 1
+\&    TEST_JOBS=9 make test.valgrind
+.Ve
+.Sp
+See "valgrind" in perlhacktips for more information.
+.Sp
+[GH #13658] <https://github.com/Perl/perl5/issues/13658>
+.IP \(bu 4
+The MAD (Misc Attribute Decoration) build option has been removed
+.Sp
+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.
+.Sp
+This build-time configuration option had been unmaintained for years,
+and had probably seriously diverged on both Perl 5 and Perl 6 sides.
+.IP \(bu 4
+A new compilation flag, \f(CW\*(C`\-DPERL_OP_PARENT\*(C'\fR is available. For details,
+see the discussion below at "Internal Changes".
+.IP \(bu 4
+Pathtools no longer tries to load XS on miniperl. This speeds up building perl
+slightly.
+.SH Testing
+.IX Header "Testing"
+.IP \(bu 4
+\&\fIt/porting/re_context.t\fR has been added to test that utf8 and its
+dependencies only use the subset of the \f(CW\*(C`$1..$n\*(C'\fR capture vars that
+\&\f(CWPerl_save_re_context()\fR is hard-coded to localize, because that function
+has no efficient way of determining at runtime what vars to localize.
+.IP \(bu 4
+Tests for performance issues have been added in the file \fIt/perf/taint.t\fR.
+.IP \(bu 4
+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, \fIt/re/speed.t\fR and \fIt/re/speed_thr.t\fR,
+and are run with a \f(CWwatchdog()\fR.
+.IP \(bu 4
+\&\f(CW\*(C`test.pl\*(C'\fR now allows \f(CW\*(C`plan skip_all => $reason\*(C'\fR, to make it
+more compatible with \f(CW\*(C`Test::More\*(C'\fR.
+.IP \(bu 4
+A new test script, \fIop/infnan.t\fR, has been added to test if infinity and NaN are
+working correctly.  See "Infinity and NaN (not-a-number) handling improved".
+.SH "Platform Support"
+.IX Header "Platform Support"
+.SS "Regained Platforms"
+.IX Subsection "Regained Platforms"
+.IP "IRIX and Tru64 platforms are working again." 4
+.IX Item "IRIX and Tru64 platforms are working again."
+Some \f(CW\*(C`make test\*(C'\fR failures remain:
+[GH #14557] <https://github.com/Perl/perl5/issues/14557>
+and [GH #14727] <https://github.com/Perl/perl5/issues/14727>
+for IRIX; [GH #14629] <https://github.com/Perl/perl5/issues/14629>,
+[cpan #99605] <https://rt.cpan.org/Public/Bug/Display.html?id=99605>, and
+[cpan #104836] <https://rt.cpan.org/Ticket/Display.html?id=104836> for Tru64.
+.IP "z/OS running EBCDIC Code Page 1047" 4
+.IX 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
+\&\f(CW\*(C`Pod::Simple\*(C'\fR.  However the version of \f(CW\*(C`Pod::Simple\*(C'\fR 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.
+.SS "Discontinued Platforms"
+.IX Subsection "Discontinued Platforms"
+.IP NeXTSTEP/OPENSTEP 4
+.IX 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.
+.SS "Platform-Specific Notes"
+.IX Subsection "Platform-Specific Notes"
+.IP EBCDIC 4
+.IX Item "EBCDIC"
+Special handling is required of the perl interpreter on EBCDIC platforms
+to get \f(CW\*(C`qr/[i\-j]/\*(C'\fR to match only \f(CW"i"\fR and \f(CW"j"\fR, since there are 7
+characters between the
+code points for \f(CW"i"\fR and \f(CW"j"\fR.  This special handling had only been
+invoked when both ends of the range are literals.  Now it is also
+invoked if any of the \f(CW\*(C`\eN{...}\*(C'\fR forms for specifying a character by
+name or Unicode code point is used instead of a literal.  See
+"Character Ranges" in perlrecharclass.
+.IP HP-UX 4
+.IX Item "HP-UX"
+The archname now distinguishes use64bitint from use64bitall.
+.IP Android 4
+.IX Item "Android"
+Build support has been improved for cross-compiling in general and for
+Android in particular.
+.IP VMS 4
+.IX Item "VMS"
+.RS 4
+.PD 0
+.IP \(bu 4
+.PD
+When spawning a subprocess without waiting, the return value is now
+the correct PID.
+.IP \(bu 4
+Fix a prototype so linking doesn't fail under the VMS C++ compiler.
+.IP \(bu 4
+\&\f(CW\*(C`finite\*(C'\fR, \f(CW\*(C`finitel\*(C'\fR, and \f(CW\*(C`isfinite\*(C'\fR detection has been added to
+\&\f(CW\*(C`configure.com\*(C'\fR, environment handling has had some minor changes, and
+a fix for legacy feature checking status.
+.RE
+.RS 4
+.RE
+.IP Win32 4
+.IX Item "Win32"
+.RS 4
+.PD 0
+.IP \(bu 4
+.PD
+\&\fIminiperl.exe\fR is now built with \f(CW\*(C`\-fno\-strict\-aliasing\*(C'\fR, allowing 64\-bit
+builds to complete on GCC 4.8.
+[GH #14556] <https://github.com/Perl/perl5/issues/14556>
+.IP \(bu 4
+\&\f(CW\*(C`nmake minitest\*(C'\fR now works on Win32.  Due to dependency issues you
+need to build \f(CW\*(C`nmake test\-prep\*(C'\fR first, and a small number of the
+tests fail.
+[GH #14318] <https://github.com/Perl/perl5/issues/14318>
+.IP \(bu 4
+Perl can now be built in C++ mode on Windows by setting the makefile macro
+\&\f(CW\*(C`USE_CPLUSPLUS\*(C'\fR to the value "define".
+.IP \(bu 4
+The list form of piped open has been implemented for Win32.  Note: unlike
+\&\f(CW\*(C`system LIST\*(C'\fR this does not fall back to the shell.
+[GH #13574] <https://github.com/Perl/perl5/issues/13574>
+.IP \(bu 4
+New \f(CW\*(C`DebugSymbols\*(C'\fR and \f(CW\*(C`DebugFull\*(C'\fR configuration options added to
+Windows makefiles.
+.IP \(bu 4
+Previously, compiling XS modules (including CPAN ones) using Visual C++ for
+Win64 resulted in around a dozen warnings per file from \fIhv_func.h\fR.  These
+warnings have been silenced.
+.IP \(bu 4
+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 \fIConfigure\fR on POSIX systems.
+.IP \(bu 4
+Between 2 and 6 milliseconds and seven I/O calls have been saved per attempt
+to open a perl module for each path in \f(CW@INC\fR.
+.IP \(bu 4
+Intel C builds are now always built with C99 mode on.
+.IP \(bu 4
+\&\f(CW%I64d\fR is now being used instead of \f(CW%lld\fR for MinGW.
+.IP \(bu 4
+In the experimental \f(CW\*(C`:win32\*(C'\fR layer, a crash in \f(CW\*(C`open\*(C'\fR was fixed. Also
+opening \fI/dev/null\fR (which works under Win32 Perl's default \f(CW\*(C`:unix\*(C'\fR
+layer) was implemented for \f(CW\*(C`:win32\*(C'\fR.
+[GH #13968] <https://github.com/Perl/perl5/issues/13968>
+.IP \(bu 4
+A new makefile option, \f(CW\*(C`USE_LONG_DOUBLE\*(C'\fR, 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.
+.RE
+.RS 4
+.RE
+.IP OpenBSD 4
+.IX Item "OpenBSD"
+On OpenBSD, Perl will now default to using the system \f(CW\*(C`malloc\*(C'\fR 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.
+.Sp
+[GH #13888] <https://github.com/Perl/perl5/issues/13888>.
+.IP Solaris 4
+.IX Item "Solaris"
+.RS 4
+.PD 0
+.IP \(bu 4
+.PD
+We now look for the Sun Studio compiler in both \fI/opt/solstudio*\fR and
+\&\fI/opt/solarisstudio*\fR.
+.IP \(bu 4
+Builds on Solaris 10 with \f(CW\*(C`\-Dusedtrace\*(C'\fR would fail early since make
+didn't follow implied dependencies to build \f(CW\*(C`perldtrace.h\*(C'\fR.  Added an
+explicit dependency to \f(CW\*(C`depend\*(C'\fR.
+[GH #13334] <https://github.com/Perl/perl5/issues/13334>
+.IP \(bu 4
+C99 options have been cleaned up; hints look for \f(CW\*(C`solstudio\*(C'\fR
+as well as \f(CW\*(C`SUNWspro\*(C'\fR; and support for native \f(CW\*(C`setenv\*(C'\fR has been added.
+.RE
+.RS 4
+.RE
+.SH "Internal Changes"
+.IX Header "Internal Changes"
+.IP \(bu 4
+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
+\&\f(CW\*(C`\-DPERL_OP_PARENT\*(C'\fR. It is envisaged that this will eventually become
+enabled by default, so XS code which directly accesses the \f(CW\*(C`op_sibling\*(C'\fR
+field of ops should be updated to be future-proofed.
+.Sp
+On \f(CW\*(C`PERL_OP_PARENT\*(C'\fR builds, the \f(CW\*(C`op_sibling\*(C'\fR field has been renamed
+\&\f(CW\*(C`op_sibparent\*(C'\fR and a new flag, \f(CW\*(C`op_moresib\*(C'\fR, added. On the last op in a
+sibling chain, \f(CW\*(C`op_moresib\*(C'\fR is false and \f(CW\*(C`op_sibparent\*(C'\fR points to the
+parent (if any) rather than being \f(CW\*(C`NULL\*(C'\fR.
+.Sp
+To make existing code work transparently whether using \f(CW\*(C`PERL_OP_PARENT\*(C'\fR
+or not, a number of new macros and functions have been added that should
+be used, rather than directly manipulating \f(CW\*(C`op_sibling\*(C'\fR.
+.Sp
+For the case of just reading \f(CW\*(C`op_sibling\*(C'\fR to determine the next sibling,
+two new macros have been added. A simple scan through a sibling chain
+like this:
+.Sp
+.Vb 1
+\&    for (; kid\->op_sibling; kid = kid\->op_sibling) { ... }
+.Ve
+.Sp
+should now be written as:
+.Sp
+.Vb 1
+\&    for (; OpHAS_SIBLING(kid); kid = OpSIBLING(kid)) { ... }
+.Ve
+.Sp
+For altering optrees, a general-purpose function \f(CWop_sibling_splice()\fR
+has been added, which allows for manipulation of a chain of sibling ops.
+By analogy with the Perl function \f(CWsplice()\fR, 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.
+.Sp
+If you need to manipulate ops at a lower level, then three new macros,
+\&\f(CW\*(C`OpMORESIB_set\*(C'\fR, \f(CW\*(C`OpLASTSIB_set\*(C'\fR and \f(CW\*(C`OpMAYBESIB_set\*(C'\fR are intended to
+be a low-level portable way to set \f(CW\*(C`op_sibling\*(C'\fR / \f(CW\*(C`op_sibparent\*(C'\fR while
+also updating \f(CW\*(C`op_moresib\*(C'\fR.  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
+\&\f(CWop_sibling_splice()\fR these macros won't maintain consistency in the
+parent at the same time (\fIe.g.\fR by updating \f(CW\*(C`op_first\*(C'\fR and \f(CW\*(C`op_last\*(C'\fR where
+appropriate).
+.Sp
+A C\-level \f(CWPerl_op_parent()\fR function and a Perl-level \f(CWB::OP::parent()\fR
+method have been added. The C function only exists under
+\&\f(CW\*(C`PERL_OP_PARENT\*(C'\fR builds (using it is build-time error on vanilla
+perls).  \f(CWB::OP::parent()\fR exists always, but on a vanilla build it
+always returns \f(CW\*(C`NULL\*(C'\fR. Under \f(CW\*(C`PERL_OP_PARENT\*(C'\fR, they return the parent
+of the current op, if any. The variable \f(CW$B::OP::does_parent\fR allows you
+to determine whether \f(CW\*(C`B\*(C'\fR supports retrieving an op's parent.
+.Sp
+\&\f(CW\*(C`PERL_OP_PARENT\*(C'\fR 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:
+.RS 4
+.IP \(bu 4
+The \f(CW\*(C`OP_SIBLING\*(C'\fR and \f(CW\*(C`OP_HAS_SIBLING\*(C'\fR macros have been renamed
+\&\f(CW\*(C`OpSIBLING\*(C'\fR and \f(CW\*(C`OpHAS_SIBLING\*(C'\fR for consistency with other
+op-manipulating macros.
+.IP \(bu 4
+The \f(CW\*(C`op_lastsib\*(C'\fR field has been renamed \f(CW\*(C`op_moresib\*(C'\fR, and its meaning
+inverted.
+.IP \(bu 4
+The macro \f(CW\*(C`OpSIBLING_set\*(C'\fR has been removed, and has been superseded by
+\&\f(CW\*(C`OpMORESIB_set\*(C'\fR \fIet al\fR.
+.IP \(bu 4
+The \f(CWop_sibling_splice()\fR function now accepts a null \f(CW\*(C`parent\*(C'\fR argument
+where the splicing doesn't affect the first or last ops in the sibling
+chain
+.RE
+.RS 4
+.RE
+.IP \(bu 4
+Macros have been created to allow XS code to better manipulate the POSIX locale
+category \f(CW\*(C`LC_NUMERIC\*(C'\fR.  See "Locale-related functions and macros" in perlapi.
+.IP \(bu 4
+The previous \f(CW\*(C`atoi\*(C'\fR \fIet al\fR replacement function, \f(CW\*(C`grok_atou\*(C'\fR, has now been
+superseded by \f(CW\*(C`grok_atoUV\*(C'\fR.  See perlclib for details.
+.IP \(bu 4
+A new function, \f(CWPerl_sv_get_backrefs()\fR, has been added which allows you
+retrieve the weak references, if any, which point at an SV.
+.IP \(bu 4
+The \f(CWscreaminstr()\fR 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.
+.IP \(bu 4
+The \f(CWnewDEFSVOP()\fR, \f(CWblock_start()\fR, \f(CWblock_end()\fR and \f(CWintro_my()\fR
+functions have been added to the API.
+.IP \(bu 4
+The internal \f(CW\*(C`convert\*(C'\fR function in \fIop.c\fR has been renamed
+\&\f(CW\*(C`op_convert_list\*(C'\fR and added to the API.
+.IP \(bu 4
+The \f(CWsv_magic()\fR 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.
+[GH #14202] <https://github.com/Perl/perl5/issues/14202>.
+.IP \(bu 4
+Accessing "CvPADLIST" in perlapi on an XSUB is now forbidden.
+.Sp
+The \f(CW\*(C`CvPADLIST\*(C'\fR 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 \f(CWCvISXSUB()\fR instead.
+.IP \(bu 4
+SVs of type \f(CW\*(C`SVt_NV\*(C'\fR are now sometimes bodiless when the build
+configuration and platform allow it: specifically, when \f(CWsizeof(NV) <=
+sizeof(IV)\fR. "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).
+.IP \(bu 4
+The \f(CW$DB::single\fR, \f(CW$DB::signal\fR and \f(CW$DB::trace\fR variables now have set\- and
+get-magic that stores their values as IVs, and those IVs are used when
+testing their values in \f(CWpp_dbstate()\fR.  This prevents perl from
+recursing infinitely if an overloaded object is assigned to any of those
+variables.
+[GH #14013] <https://github.com/Perl/perl5/issues/14013>.
+.IP \(bu 4
+\&\f(CWPerl_tmps_grow()\fR, 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 \f(CW\*(C`EXTEND_MORTAL\*(C'\fR macro to pre-extend the mortal stack.
+.IP \(bu 4
+Perl's internals no longer sets or uses the \f(CW\*(C`SVs_PADMY\*(C'\fR flag.
+\&\f(CWSvPADMY()\fR now returns a true value for anything not marked \f(CW\*(C`PADTMP\*(C'\fR
+and \f(CW\*(C`SVs_PADMY\*(C'\fR is now defined as 0.
+.IP \(bu 4
+The macros \f(CW\*(C`SETsv\*(C'\fR and \f(CW\*(C`SETsvUN\*(C'\fR 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.
+.IP \(bu 4
+The \f(CW\*(C`SvFAKE\*(C'\fR bit (unused on HVs) got informally reserved by
+David Mitchell for future work on vtables.
+.IP \(bu 4
+The \f(CWsv_catpvn_flags()\fR function accepts \f(CW\*(C`SV_CATBYTES\*(C'\fR and \f(CW\*(C`SV_CATUTF8\*(C'\fR
+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.)
+.IP \(bu 4
+A new opcode class, \f(CW\*(C`METHOP\*(C'\fR, has been introduced. It holds
+information used at runtime to improve the performance
+of class/object method calls.
+.Sp
+\&\f(CW\*(C`OP_METHOD\*(C'\fR and \f(CW\*(C`OP_METHOD_NAMED\*(C'\fR have changed from being
+\&\f(CW\*(C`UNOP/SVOP\*(C'\fR to being \f(CW\*(C`METHOP\*(C'\fR.
+.IP \(bu 4
+\&\f(CWcv_name()\fR 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.
+.Sp
+[GH #12767] <https://github.com/Perl/perl5/issues/12767>
+[GH #13392] <https://github.com/Perl/perl5/issues/13392>
+.IP \(bu 4
+\&\f(CWcv_set_call_checker_flags()\fR is a new API function that works like
+\&\f(CWcv_set_call_checker()\fR, 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 \f(CWcv_name()\fR.  \f(CWcv_set_call_checker()\fR
+guarantees there will be a GV, but it may have to create one on the fly,
+which is inefficient.
+[GH #12767] <https://github.com/Perl/perl5/issues/12767>
+.IP \(bu 4
+\&\f(CW\*(C`CvGV\*(C'\fR (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, \f(CW\*(C`CvHASGV\*(C'\fR has been added, which will return true for CVs that
+notionally have GVs, but without reifying the GV.  \f(CW\*(C`CvGV\*(C'\fR also returns a GV
+now for lexical subs.
+[GH #13392] <https://github.com/Perl/perl5/issues/13392>
+.IP \(bu 4
+The "sync_locale" in perlapi 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 \f(CW\*(C`Gtk\*(C'\fR.
+When this happens, Perl needs to be told that the locale has
+changed.  Use this function to do so, before returning to Perl.
+.IP \(bu 4
+The defines and labels for the flags in the \f(CW\*(C`op_private\*(C'\fR field of OPs are now
+auto-generated from data in \fIregen/op_private\fR.  The noticeable effect of this
+is that some of the flag output of \f(CW\*(C`Concise\*(C'\fR might differ slightly, and the
+flag output of \f(CW\*(C`perl\ \-Dx\*(C'\fR may differ considerably (they both use the same set
+of labels now).  Also, debugging builds now have a new assertion in
+\&\f(CWop_free()\fR to ensure that the op doesn't have any unrecognized flags set in
+\&\f(CW\*(C`op_private\*(C'\fR.
+.IP \(bu 4
+The deprecated variable \f(CW\*(C`PL_sv_objcount\*(C'\fR has been removed.
+.IP \(bu 4
+Perl now tries to keep the locale category \f(CW\*(C`LC_NUMERIC\*(C'\fR 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
+\&\f(CWPOSIX::setlocale()\fR would change it.  Now such a call will change the
+underlying locale of the \f(CW\*(C`LC_NUMERIC\*(C'\fR 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
+\&\f(CW\*(C`STORE_LC_NUMERIC_SET_TO_NEEDED\*(C'\fR and
+\&\f(CW\*(C`STORE_LC_NUMERIC_FORCE_TO_UNDERLYING\*(C'\fR.
+See "Locale-related functions and macros" in perlapi.
+.IP \(bu 4
+A new macro \f(CW\*(C`isUTF8_CHAR\*(C'\fR has been written which
+efficiently determines if the string given by its parameters begins
+with a well-formed UTF\-8 encoded character.
+.IP \(bu 4
+The following private API functions had their context parameter removed:
+\&\f(CW\*(C`Perl_cast_ulong\*(C'\fR,  \f(CW\*(C`Perl_cast_i32\*(C'\fR, \f(CW\*(C`Perl_cast_iv\*(C'\fR,    \f(CW\*(C`Perl_cast_uv\*(C'\fR,
+\&\f(CW\*(C`Perl_cv_const_sv\*(C'\fR, \f(CW\*(C`Perl_mg_find\*(C'\fR,  \f(CW\*(C`Perl_mg_findext\*(C'\fR, \f(CW\*(C`Perl_mg_magical\*(C'\fR,
+\&\f(CW\*(C`Perl_mini_mktime\*(C'\fR, \f(CW\*(C`Perl_my_dirfd\*(C'\fR, \f(CW\*(C`Perl_sv_backoff\*(C'\fR, \f(CW\*(C`Perl_utf8_hop\*(C'\fR.
+.Sp
+Note that the prefix-less versions of those functions that are part of the
+public API, such as \f(CWcast_i32()\fR, remain unaffected.
+.IP \(bu 4
+The \f(CW\*(C`PADNAME\*(C'\fR and \f(CW\*(C`PADNAMELIST\*(C'\fR types are now separate types, and no
+longer simply aliases for SV and AV.
+[GH #14250] <https://github.com/Perl/perl5/issues/14250>.
+.IP \(bu 4
+Pad names are now always UTF\-8.  The \f(CW\*(C`PadnameUTF8\*(C'\fR 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.
+.IP \(bu 4
+A new op class, \f(CW\*(C`UNOP_AUX\*(C'\fR, has been added. This is a subclass of
+\&\f(CW\*(C`UNOP\*(C'\fR with an \f(CW\*(C`op_aux\*(C'\fR 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 \f(CW\*(C`op_sv\*(C'\fR or whatever. Currently the only op of this type is
+\&\f(CW\*(C`OP_MULTIDEREF\*(C'\fR (see next item).
+.IP \(bu 4
+A new op has been added, \f(CW\*(C`OP_MULTIDEREF\*(C'\fR, which performs one or more
+nested array and hash lookups where the key is a constant or simple
+variable. For example the expression \f(CW\*(C`$a[0]{$k}[$i]\*(C'\fR, which previously
+involved ten \f(CW\*(C`rv2Xv\*(C'\fR, \f(CW\*(C`Xelem\*(C'\fR, \f(CW\*(C`gvsv\*(C'\fR and \f(CW\*(C`const\*(C'\fR ops is now performed
+by a single \f(CW\*(C`multideref\*(C'\fR op. It can also handle \f(CW\*(C`local\*(C'\fR, \f(CW\*(C`exists\*(C'\fR and
+\&\f(CW\*(C`delete\*(C'\fR. A non-simple index expression, such as \f(CW\*(C`[$i+1]\*(C'\fR is still done
+using \f(CW\*(C`aelem\*(C'\fR/\f(CW\*(C`helem\*(C'\fR, and single-level array lookup with a small constant
+index is still done using \f(CW\*(C`aelemfast\*(C'\fR.
+.SH "Selected Bug Fixes"
+.IX Header "Selected Bug Fixes"
+.IP \(bu 4
+\&\f(CW\*(C`close\*(C'\fR now sets \f(CW$!\fR
+.Sp
+When an I/O error occurs, the fact that there has been an error is recorded
+in the handle.  \f(CW\*(C`close\*(C'\fR returns false for such a handle.  Previously, the
+value of \f(CW$!\fR would be untouched by \f(CW\*(C`close\*(C'\fR, so the common convention of
+writing \f(CW\*(C`close\ $fh\ or\ die\ $!\*(C'\fR did not work reliably.  Now the handle
+records the value of \f(CW$!\fR, too, and \f(CW\*(C`close\*(C'\fR restores it.
+.IP \(bu 4
+\&\f(CW\*(C`no re\*(C'\fR now can turn off everything that \f(CW\*(C`use re\*(C'\fR enables
+.Sp
+Previously, running \f(CW\*(C`no re\*(C'\fR 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.
+.IP \(bu 4
+\&\f(CW\*(C`pack("D", $x)\*(C'\fR and \f(CW\*(C`pack("F", $x)\*(C'\fR 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 \fIop/pack.t\fR to fail.
+[GH #14554] <https://github.com/Perl/perl5/issues/14554>
+.IP \(bu 4
+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.
+[GH #14605] <https://github.com/Perl/perl5/issues/14605>
+.IP \(bu 4
+An assertion failure and subsequent crash with \f(CW\*(C`*x=<y>\*(C'\fR has been fixed.
+[GH #14493] <https://github.com/Perl/perl5/issues/14493>
+.IP \(bu 4
+A possible crashing/looping bug related to compiling lexical subs has been
+fixed.
+[GH #14596] <https://github.com/Perl/perl5/issues/14596>
+.IP \(bu 4
+UTF\-8 now works correctly in function names, in unquoted HERE-document
+terminators, and in variable names used as array indexes.
+[GH #14601] <https://github.com/Perl/perl5/issues/14601>
+.IP \(bu 4
+Repeated global pattern matches in scalar context on large tainted strings were
+exponentially slow depending on the current match position in the string.
+[GH #14238] <https://github.com/Perl/perl5/issues/14238>
+.IP \(bu 4
+Various crashes due to the parser getting confused by syntax errors have been
+fixed.
+[GH #14496] <https://github.com/Perl/perl5/issues/14496>
+[GH #14497] <https://github.com/Perl/perl5/issues/14497>
+[GH #14548] <https://github.com/Perl/perl5/issues/14548>
+[GH #14564] <https://github.com/Perl/perl5/issues/14564>
+.IP \(bu 4
+\&\f(CW\*(C`split\*(C'\fR in the scope of lexical \f(CW$_\fR has been fixed not to fail assertions.
+[GH #14483] <https://github.com/Perl/perl5/issues/14483>
+.IP \(bu 4
+\&\f(CW\*(C`my $x : attr\*(C'\fR syntax inside various list operators no longer fails
+assertions.
+[GH #14500] <https://github.com/Perl/perl5/issues/14500>
+.IP \(bu 4
+An \f(CW\*(C`@\*(C'\fR 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
+\&\f(CW\*(C`@\*(C'\fR as literal.  This has been fixed.
+[GH #14553] <https://github.com/Perl/perl5/issues/14553>
+.IP \(bu 4
+\&\f(CW\*(C`*bar::=*foo::=*glob_with_hash\*(C'\fR has been crashing since Perl 5.14, but no
+longer does.
+[GH #14512] <https://github.com/Perl/perl5/issues/14512>
+.IP \(bu 4
+\&\f(CW\*(C`foreach\*(C'\fR in scalar context was not pushing an item on to the stack, resulting
+in bugs.  (\f(CW\*(C`print\ 4,\ scalar\ do\ {\ foreach(@x){}\ }\ +\ 1\*(C'\fR would print 5.)
+It has been fixed to return \f(CW\*(C`undef\*(C'\fR.
+[GH #14569] <https://github.com/Perl/perl5/issues/14569>
+.IP \(bu 4
+Several cases of data used to store environment variable contents in core C
+code being potentially overwritten before being used have been fixed.
+[GH #14476] <https://github.com/Perl/perl5/issues/14476>
+.IP \(bu 4
+Some patterns starting with \f(CW\*(C`/.*..../\*(C'\fR matched against long strings have
+been slow since v5.8, and some of the form \f(CW\*(C`/.*..../i\*(C'\fR have been slow
+since v5.18. They are now all fast again.
+[GH #14475] <https://github.com/Perl/perl5/issues/14475>.
+.IP \(bu 4
+The original visible value of \f(CW$/\fR is now preserved when it is set to
+an invalid value.  Previously if you set \f(CW$/\fR to a reference to an
+array, for example, perl would produce a runtime error and not set
+\&\f(CW\*(C`PL_rs\*(C'\fR, but Perl code that checked \f(CW$/\fR would see the array
+reference.
+[GH #14245] <https://github.com/Perl/perl5/issues/14245>.
+.IP \(bu 4
+In a regular expression pattern, a POSIX class, like \f(CW\*(C`[:ascii:]\*(C'\fR, must
+be inside a bracketed character class, like \f(CW\*(C`qr/[[:ascii:]]/\*(C'\fR.  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: \f(CW\*(C`[:^ascii:]\*(C'\fR.  This is now fixed.
+.IP \(bu 4
+Perl 5.14.0 introduced a bug whereby \f(CW\*(C`eval\ {\ LABEL:\ }\*(C'\fR would crash.  This
+has been fixed.
+[GH #14438] <https://github.com/Perl/perl5/issues/14438>.
+.IP \(bu 4
+Various crashes due to the parser getting confused by syntax errors have
+been fixed.
+[GH #14421] <https://github.com/Perl/perl5/issues/14421>.
+[GH #14472] <https://github.com/Perl/perl5/issues/14472>.
+[GH #14480] <https://github.com/Perl/perl5/issues/14480>.
+[GH #14447] <https://github.com/Perl/perl5/issues/14447>.
+.IP \(bu 4
+Code like \f(CW\*(C`/$a[/\*(C'\fR 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.
+[GH #14462] <https://github.com/Perl/perl5/issues/14462>.
+.IP \(bu 4
+Fix argument underflow for \f(CW\*(C`pack\*(C'\fR.
+[GH #14525] <https://github.com/Perl/perl5/issues/14525>.
+.IP \(bu 4
+Fix handling of non-strict \f(CW\*(C`\ex{}\*(C'\fR. Now \f(CW\*(C`\ex{}\*(C'\fR is equivalent to \f(CW\*(C`\ex{0}\*(C'\fR
+instead of faulting.
+.IP \(bu 4
+\&\f(CW\*(C`stat \-t\*(C'\fR is now no longer treated as stackable, just like \f(CW\*(C`\-t stat\*(C'\fR.
+[GH #14499] <https://github.com/Perl/perl5/issues/14499>.
+.IP \(bu 4
+The following no longer causes a SEGV: \f(CW\*(C`qr{x+(y(?0))*}\*(C'\fR.
+.IP \(bu 4
+Fixed infinite loop in parsing backrefs in regexp patterns.
+.IP \(bu 4
+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.
+.IP \(bu 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 \f(CW\*(C`/i\*(C'\fR while taking into account the current POSIX locale (which usually
+means they have to be compiled within the scope of \f(CW\*(C`use\ locale\*(C'\fR),
+and there must be a string of at least 128 consecutive bytes to match.
+[GH #14389] <https://github.com/Perl/perl5/issues/14389>.
+.IP \(bu 4
+\&\f(CW\*(C`s///g\*(C'\fR now works on very long strings (where there are more than 2
+billion iterations) instead of dying with 'Substitution loop'.
+[GH #11742] <https://github.com/Perl/perl5/issues/11742>.
+[GH #14190] <https://github.com/Perl/perl5/issues/14190>.
+.IP \(bu 4
+\&\f(CW\*(C`gmtime\*(C'\fR no longer crashes with not-a-number values.
+[GH #14365] <https://github.com/Perl/perl5/issues/14365>.
+.IP \(bu 4
+\&\f(CW\*(C`\e()\*(C'\fR (a reference to an empty list), and \f(CW\*(C`y///\*(C'\fR with lexical \f(CW$_\fR in
+scope, could both do a bad write past the end of the stack.  They have
+both been fixed to extend the stack first.
+.IP \(bu 4
+\&\f(CWprototype()\fR with no arguments used to read the previous item on the
+stack, so \f(CW\*(C`print\ "foo",\ prototype()\*(C'\fR would print foo's prototype.
+It has been fixed to infer \f(CW$_\fR instead.
+[GH #14376] <https://github.com/Perl/perl5/issues/14376>.
+.IP \(bu 4
+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.
+.IP \(bu 4
+Some cases of nested lexical state subs inside anonymous subs could cause
+\&'Bizarre copy' errors or possibly even crashes.
+.IP \(bu 4
+When trying to emit warnings, perl's default debugger (\fIperl5db.pl\fR) was
+sometimes giving 'Undefined subroutine &DB::db_warn called' instead.  This
+bug, which started to occur in Perl 5.18, has been fixed.
+[GH #14400] <https://github.com/Perl/perl5/issues/14400>.
+.IP \(bu 4
+Certain syntax errors in substitutions, such as \f(CW\*(C`s/${<>{})//\*(C'\fR, 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.
+[GH #14391] <https://github.com/Perl/perl5/issues/14391>.
+.IP \(bu 4
+Fix a couple of string grow size calculation overflows; in particular,
+a repeat expression like \f(CW\*(C`33\ x\ ~3\*(C'\fR could cause a large buffer
+overflow since the new output buffer size was not correctly handled by
+\&\f(CWSvGROW()\fR.  An expression like this now properly produces a memory wrap
+panic.
+[GH #14401] <https://github.com/Perl/perl5/issues/14401>.
+.IP \(bu 4
+\&\f(CW\*(C`formline("@...", "a");\*(C'\fR would crash.  The \f(CW\*(C`FF_CHECKNL\*(C'\fR case in
+\&\f(CWpp_formline()\fR didn't set the pointer used to mark the chop position,
+which led to the \f(CW\*(C`FF_MORE\*(C'\fR case crashing with a segmentation fault.
+This has been fixed.
+[GH #14388] <https://github.com/Perl/perl5/issues/14388>.
+.IP \(bu 4
+A possible buffer overrun and crash when parsing a literal pattern during
+regular expression compilation has been fixed.
+[GH #14416] <https://github.com/Perl/perl5/issues/14416>.
+.IP \(bu 4
+\&\f(CWfchmod()\fR and \f(CWfutimes()\fR now set \f(CW$!\fR when they fail due to being
+passed a closed file handle.
+[GH #14073] <https://github.com/Perl/perl5/issues/14073>.
+.IP \(bu 4
+\&\f(CWop_free()\fR and \f(CWscalarvoid()\fR no longer crash due to a stack overflow
+when freeing a deeply recursive op tree.
+[GH #11866] <https://github.com/Perl/perl5/issues/11866>.
+.IP \(bu 4
+In Perl 5.20.0, \f(CW$^N\fR 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.
+[GH #14211] <https://github.com/Perl/perl5/issues/14211>.
+.IP \(bu 4
+A failed \f(CW\*(C`semctl\*(C'\fR call no longer overwrites existing items on the stack,
+which means that \f(CW\*(C`(semctl(\-1,0,0,0))[0]\*(C'\fR no longer gives an
+"uninitialized" warning.
+.IP \(bu 4
+\&\f(CW\*(C`else{foo()}\*(C'\fR with no space before \f(CW\*(C`foo\*(C'\fR is now better at assigning the
+right line number to that statement.
+[GH #14070] <https://github.com/Perl/perl5/issues/14070>.
+.IP \(bu 4
+Sometimes the assignment in \f(CW\*(C`@array = split\*(C'\fR gets optimised so that \f(CW\*(C`split\*(C'\fR
+itself writes directly to the array.  This caused a bug, preventing this
+assignment from being used in lvalue context.  So
+\&\f(CW\*(C`(@a=split//,"foo")=bar()\*(C'\fR was an error.  (This bug probably goes back to
+Perl 3, when the optimisation was added.) It has now been fixed.
+[GH #14183] <https://github.com/Perl/perl5/issues/14183>.
+.IP \(bu 4
+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.
+[GH #13643] <https://github.com/Perl/perl5/issues/13643>.
+.IP \(bu 4
+The flip-flop operators (\f(CW\*(C`..\*(C'\fR and \f(CW\*(C`...\*(C'\fR 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.
+[GH #14110] <https://github.com/Perl/perl5/issues/14110>.
+.IP \(bu 4
+The flip-flop operator (\f(CW\*(C`..\*(C'\fR in scalar context) would return the same
+scalar each time, unless the containing subroutine was called recursively.
+Now it always returns a new scalar.
+[GH #14110] <https://github.com/Perl/perl5/issues/14110>.
+.IP \(bu 4
+\&\f(CW\*(C`use\*(C'\fR, \f(CW\*(C`no\*(C'\fR, statement labels, special blocks (\f(CW\*(C`BEGIN\*(C'\fR) and pod are now
+permitted as the first thing in a \f(CW\*(C`map\*(C'\fR or \f(CW\*(C`grep\*(C'\fR block, the block after
+\&\f(CW\*(C`print\*(C'\fR or \f(CW\*(C`say\*(C'\fR (or other functions) returning a handle, and within
+\&\f(CW\*(C`${...}\*(C'\fR, \f(CW\*(C`@{...}\*(C'\fR, etc.
+[GH #14088] <https://github.com/Perl/perl5/issues/14088>.
+.IP \(bu 4
+The repetition operator \f(CW\*(C`x\*(C'\fR now propagates lvalue context to its left-hand
+argument when used in contexts like \f(CW\*(C`foreach\*(C'\fR.  That allows
+\&\f(CW\*(C`for(($#that_array)x2)\ {\ ...\ }\*(C'\fR to work as expected if the loop modifies
+\&\f(CW$_\fR.
+.IP \(bu 4
+\&\f(CW\*(C`(...) x ...\*(C'\fR in scalar context used to corrupt the stack if one operand
+was an object with "x" overloading, causing erratic behavior.
+[GH #13811] <https://github.com/Perl/perl5/issues/13811>.
+.IP \(bu 4
+Assignment to a lexical scalar is often optimised away; for example in
+\&\f(CW\*(C`my $x; $x = $y + $z\*(C'\fR, the assign operator is optimised away and the add
+operator writes its result directly to \f(CW$x\fR.  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 \f(CW\*(C`$foo++\*(C'\fR, \f(CW\*(C`$foo\-\-\*(C'\fR, and \f(CW\*(C`\-$foo\*(C'\fR under \f(CW\*(C`use
+integer\*(C'\fR, \f(CW\*(C`chomp\*(C'\fR, \f(CW\*(C`chr\*(C'\fR and \f(CW\*(C`setpgrp\*(C'\fR.
+.IP \(bu 4
+List assignments were sometimes buggy if the same scalar ended up on both
+sides of the assignment due to use of \f(CW\*(C`tied\*(C'\fR, \f(CW\*(C`values\*(C'\fR or \f(CW\*(C`each\*(C'\fR.  The
+result would be the wrong value getting assigned.
+.IP \(bu 4
+\&\f(CWsetpgrp($nonzero)\fR (with one argument) was accidentally changed in 5.16
+to mean \f(CWsetpgrp(0)\fR.  This has been fixed.
+.IP \(bu 4
+\&\f(CW\*(C`_\|_SUB_\|_\*(C'\fR could return the wrong value or even corrupt memory under the
+debugger (the \f(CW\*(C`\-d\*(C'\fR switch) and in subs containing \f(CW\*(C`eval $string\*(C'\fR.
+.IP \(bu 4
+When \f(CW\*(C`sub\ ()\ {\ $var\ }\*(C'\fR 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.
+.IP \(bu 4
+\&\f(CW\*(C`my\ sub\ f\ ()\ {\ $var\ }\*(C'\fR and \f(CW\*(C`sub\ ()\ :\ attr\ {\ $var\ }\*(C'\fR 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
+\&\f(CW\*(C`:method\*(C'\fR attribute, which does nothing much.
+.IP \(bu 4
+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 \f(CW\*(C`eval\*(C'\fR or \f(CW\*(C`state\*(C'\fR 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 \f(CW\*(C`sub
+() { jabber() if DEBUG; 42 }\*(C'\fR.
+.Sp
+Some subroutines with an explicit \f(CW\*(C`return\*(C'\fR were being made inlinable,
+contrary to the documentation,  Now \f(CW\*(C`return\*(C'\fR always prevents inlining.
+.IP \(bu 4
+On some systems, such as VMS, \f(CW\*(C`crypt\*(C'\fR can return a non-ASCII string.  If a
+scalar assigned to had contained a UTF\-8 string previously, then \f(CW\*(C`crypt\*(C'\fR
+would not turn off the UTF\-8 flag, thus corrupting the return value.  This
+would happen with \f(CW\*(C`$lexical\ =\ crypt\ ...\*(C'\fR.
+.IP \(bu 4
+\&\f(CW\*(C`crypt\*(C'\fR no longer calls \f(CW\*(C`FETCH\*(C'\fR twice on a tied first argument.
+.IP \(bu 4
+An unterminated here-doc on the last line of a quote-like operator
+(\f(CW\*(C`qq[${ <<END }]\*(C'\fR, \f(CW\*(C`/(?{ <<END })/\*(C'\fR) no longer causes a double free.  It
+started doing so in 5.18.
+.IP \(bu 4
+\&\f(CWindex()\fR and \f(CWrindex()\fR no longer crash when used on strings over 2GB in
+size.
+[GH #13700] <https://github.com/Perl/perl5/issues/13700>.
+.IP \(bu 4
+A small, previously intentional, memory leak in
+\&\f(CW\*(C`PERL_SYS_INIT\*(C'\fR/\f(CW\*(C`PERL_SYS_INIT3\*(C'\fR on Win32 builds was fixed. This might
+affect embedders who repeatedly create and destroy perl engines within
+the same process.
+.IP \(bu 4
+\&\f(CWPOSIX::localeconv()\fR now returns the data for the program's underlying
+locale even when called from outside the scope of \f(CW\*(C`use\ locale\*(C'\fR.
+.IP \(bu 4
+\&\f(CWPOSIX::localeconv()\fR now works properly on platforms which don't have
+\&\f(CW\*(C`LC_NUMERIC\*(C'\fR and/or \f(CW\*(C`LC_MONETARY\*(C'\fR, 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 \f(CWlocaleconv()\fR.
+.IP \(bu 4
+\&\f(CWPOSIX::localeconv()\fR 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.
+.IP \(bu 4
+On Microsoft Windows, within the scope of \f(CW\*(C`use\ locale\*(C'\fR, the following
+POSIX character classes gave results for many locales that did not
+conform to the POSIX standard:
+\&\f(CW\*(C`[[:alnum:]]\*(C'\fR,
+\&\f(CW\*(C`[[:alpha:]]\*(C'\fR,
+\&\f(CW\*(C`[[:blank:]]\*(C'\fR,
+\&\f(CW\*(C`[[:digit:]]\*(C'\fR,
+\&\f(CW\*(C`[[:graph:]]\*(C'\fR,
+\&\f(CW\*(C`[[:lower:]]\*(C'\fR,
+\&\f(CW\*(C`[[:print:]]\*(C'\fR,
+\&\f(CW\*(C`[[:punct:]]\*(C'\fR,
+\&\f(CW\*(C`[[:upper:]]\*(C'\fR,
+\&\f(CW\*(C`[[:word:]]\*(C'\fR,
+and
+\&\f(CW\*(C`[[:xdigit:]]\*(C'\fR.
+This was because the underlying Microsoft implementation does not
+follow the standard.  Perl now takes special precautions to correct for
+this.
+.IP \(bu 4
+Many issues have been detected by Coverity <http://www.coverity.com/> and
+fixed.
+.IP \(bu 4
+\&\f(CWsystem()\fR and friends should now work properly on more Android builds.
+.Sp
+Due to an oversight, the value specified through \f(CW\*(C`\-Dtargetsh\*(C'\fR to \fIConfigure\fR
+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 \f(CWsystem()\fR,
+\&\f(CWexec()\fR and backticks: the commands would end up looking for \f(CW\*(C`/bin/sh\*(C'\fR
+instead of \f(CW\*(C`/system/bin/sh\*(C'\fR, and so would fail for the vast majority
+of devices, leaving \f(CW$!\fR as \f(CW\*(C`ENOENT\*(C'\fR.
+.IP \(bu 4
+\&\f(CW\*(C`qr(...\e(...\e)...)\*(C'\fR,
+\&\f(CW\*(C`qr[...\e[...\e]...]\*(C'\fR,
+and
+\&\f(CW\*(C`qr{...\e{...\e}...}\*(C'\fR
+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.
+.IP \(bu 4
+\&\f(CW\*(C`s///e\*(C'\fR on tainted UTF\-8 strings corrupted \f(CWpos()\fR. This bug,
+introduced in 5.20, is now fixed.
+[GH #13948] <https://github.com/Perl/perl5/issues/13948>.
+.IP \(bu 4
+A non-word boundary in a regular expression (\f(CW\*(C`\eB\*(C'\fR) did not always
+match the end of the string; in particular \f(CW\*(C`q{} =~ /\eB/\*(C'\fR did not
+match. This bug, introduced in perl 5.14, is now fixed.
+[GH #13917] <https://github.com/Perl/perl5/issues/13917>.
+.IP \(bu 4
+\&\f(CW\*(C`" P" =~ /(?=.*P)P/\*(C'\fR should match, but did not. This is now fixed.
+[GH #13954] <https://github.com/Perl/perl5/issues/13954>.
+.IP \(bu 4
+Failing to compile \f(CW\*(C`use Foo\*(C'\fR in an \f(CW\*(C`eval\*(C'\fR could leave a spurious
+\&\f(CW\*(C`BEGIN\*(C'\fR subroutine definition, which would produce a "Subroutine
+BEGIN redefined" warning on the next use of \f(CW\*(C`use\*(C'\fR, or other \f(CW\*(C`BEGIN\*(C'\fR
+block.
+[GH #13926] <https://github.com/Perl/perl5/issues/13926>.
+.IP \(bu 4
+\&\f(CW\*(C`method { BLOCK } ARGS\*(C'\fR syntax now correctly parses the arguments if they
+begin with an opening brace.
+[GH #9085] <https://github.com/Perl/perl5/issues/9085>.
+.IP \(bu 4
+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.
+[GH #13863] <https://github.com/Perl/perl5/issues/13863>.
+.IP \(bu 4
+A bug has been fixed where zero-length assertions and code blocks inside of a
+regex could cause \f(CW\*(C`pos\*(C'\fR to see an incorrect value.
+[GH #14016] <https://github.com/Perl/perl5/issues/14016>.
+.IP \(bu 4
+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.
+[GH #9891] <https://github.com/Perl/perl5/issues/9891>
+.IP \(bu 4
+When parsing a sigil (\f(CW\*(C`$\*(C'\fR \f(CW\*(C`@\*(C'\fR \f(CW\*(C`%\*(C'\fR \f(CW\*(C`&)\*(C'\fR 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.
+.IP \(bu 4
+\&\f(CW\*(C`undef\ $reference\*(C'\fR now frees the referent immediately, instead of hanging on
+to it until the next statement.
+[GH #14032] <https://github.com/Perl/perl5/issues/14032>
+.IP \(bu 4
+Various cases where the name of a sub is used (autoload, overloading, error
+messages) used to crash for lexical subs, but have been fixed.
+.IP \(bu 4
+Bareword lookup now tries to avoid vivifying packages if it turns out the
+bareword is not going to be a subroutine name.
+.IP \(bu 4
+Compilation of anonymous constants (\fIe.g.\fR, \f(CW\*(C`sub () { 3 }\*(C'\fR) no longer deletes
+any subroutine named \f(CW\*(C`_\|_ANON_\|_\*(C'\fR in the current package.  Not only was
+\&\f(CW\*(C`*_\|_ANON_\|_{CODE}\*(C'\fR cleared, but there was a memory leak, too.  This bug goes
+back to Perl 5.8.0.
+.IP \(bu 4
+Stub declarations like \f(CW\*(C`sub f;\*(C'\fR and \f(CW\*(C`sub f ();\*(C'\fR no longer wipe out constants
+of the same name declared by \f(CW\*(C`use constant\*(C'\fR.  This bug was introduced in Perl
+5.10.0.
+.IP \(bu 4
+\&\f(CW\*(C`qr/[\eN{named sequence}]/\*(C'\fR now works properly in many instances.
+.Sp
+Some names
+known to \f(CW\*(C`\eN{...}\*(C'\fR 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 \f(CW\*(C`?[...])\*(C'\fR construct.  When the \f(CW\*(C`[...]\*(C'\fR
+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.
+.IP \(bu 4
+Tainted constants evaluated at compile time no longer cause unrelated
+statements to become tainted.
+[GH #14059] <https://github.com/Perl/perl5/issues/14059>
+.IP \(bu 4
+\&\f(CW\*(C`open\ $$fh,\ ...\*(C'\fR, which vivifies a handle with a name like
+\&\f(CW"main::_GEN_0"\fR, was not giving the handle the right reference count, so
+a double free could happen.
+.IP \(bu 4
+When deciding that a bareword was a method name, the parser would get confused
+if an \f(CW\*(C`our\*(C'\fR sub with the same name existed, and look up the method in the
+package of the \f(CW\*(C`our\*(C'\fR sub, instead of the package of the invocant.
+.IP \(bu 4
+The parser no longer gets confused by \f(CW\*(C`\eU=\*(C'\fR within a double-quoted string.  It
+used to produce a syntax error, but now compiles it correctly.
+[GH #10882] <https://github.com/Perl/perl5/issues/10882>
+.IP \(bu 4
+It has always been the intention for the \f(CW\*(C`\-B\*(C'\fR and \f(CW\*(C`\-T\*(C'\fR file test operators to
+treat UTF\-8 encoded files as text.  (perlfunc 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.
+.IP \(bu 4
+Under some conditions warning messages raised during regular expression pattern
+compilation were being output more than once.  This has now been fixed.
+.IP \(bu 4
+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.
+[GH #14051] <https://github.com/Perl/perl5/issues/14051>
+.IP \(bu 4
+Constant folding could incorrectly suppress warnings if lexical warnings
+(\f(CW\*(C`use warnings\*(C'\fR or \f(CW\*(C`no warnings\*(C'\fR) were not in effect and \f(CW$^W\fR were
+false at compile time and true at run time.
+.IP \(bu 4
+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.
+[GH #14081] <https://github.com/Perl/perl5/issues/14081>
+.IP \(bu 4
+Thread cloning used to work incorrectly for lexical subs, possibly causing
+crashes or double frees on exit.
+.IP \(bu 4
+Since Perl 5.14.0, deleting \f(CW$SomePackage::{_\|_ANON_\|_}\fR and then undefining an
+anonymous subroutine could corrupt things internally, resulting in
+Devel::Peek crashing or B.pm giving nonsensical data.  This has been
+fixed.
+.IP \(bu 4
+\&\f(CW\*(C`(caller\ $n)[3]\*(C'\fR now reports names of lexical subs, instead of
+treating them as \f(CW"(unknown)"\fR.
+.IP \(bu 4
+\&\f(CW\*(C`sort subname LIST\*(C'\fR now supports using a lexical sub as the comparison
+routine.
+.IP \(bu 4
+Aliasing (\fIe.g.\fR, via \f(CW\*(C`*x\ =\ *y\*(C'\fR) could confuse list assignments that mention the
+two names for the same variable on either side, causing wrong values to be
+assigned.
+[GH #5788] <https://github.com/Perl/perl5/issues/5788>
+.IP \(bu 4
+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.
+.IP \(bu 4
+An optimization in \f(CW\*(C`split\*(C'\fR to treat \f(CW\*(C`split\ /^/\*(C'\fR like \f(CW\*(C`split\ /^/m\*(C'\fR had the
+unfortunate side-effect of also treating \f(CW\*(C`split\ /\eA/\*(C'\fR like \f(CW\*(C`split\ /^/m\*(C'\fR,
+which it should not.  This has been fixed.  (Note, however, that \f(CW\*(C`split\ /^x/\*(C'\fR
+does not behave like \f(CW\*(C`split\ /^x/m\*(C'\fR, which is also considered to be a bug and
+will be fixed in a future version.)
+[GH #14086] <https://github.com/Perl/perl5/issues/14086>
+.IP \(bu 4
+The little-known \f(CW\*(C`my\ Class\ $var\*(C'\fR syntax (see fields and attributes)
+could get confused in the scope of \f(CW\*(C`use utf8\*(C'\fR if \f(CW\*(C`Class\*(C'\fR were a constant
+whose value contained Latin\-1 characters.
+.IP \(bu 4
+Locking and unlocking values via Hash::Util or \f(CW\*(C`Internals::SvREADONLY\*(C'\fR
+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.
+.IP \(bu 4
+Some unterminated \f(CW\*(C`(?(...)...)\*(C'\fR constructs in regular expressions would
+either crash or give erroneous error messages.  \f(CW\*(C`/(?(1)/\*(C'\fR is one such
+example.
+.IP \(bu 4
+\&\f(CW\*(C`pack\ "w",\ $tied\*(C'\fR no longer calls FETCH twice.
+.IP \(bu 4
+List assignments like \f(CW\*(C`($x,\ $z)\ =\ (1,\ $y)\*(C'\fR now work correctly if \f(CW$x\fR and
+\&\f(CW$y\fR have been aliased by \f(CW\*(C`foreach\*(C'\fR.
+.IP \(bu 4
+Some patterns including code blocks with syntax errors, such as
+\&\f(CW\*(C`/\ (?{(^{})/\*(C'\fR, would hang or fail assertions on debugging builds.  Now
+they produce errors.
+.IP \(bu 4
+An assertion failure when parsing \f(CW\*(C`sort\*(C'\fR with debugging enabled has been
+fixed.
+[GH #14087] <https://github.com/Perl/perl5/issues/14087>.
+.IP \(bu 4
+\&\f(CW\*(C`*a\ =\ *b;\ @a\ =\ split\ //,\ $b[1]\*(C'\fR could do a bad read and produce junk
+results.
+.IP \(bu 4
+In \f(CW\*(C`()\ =\ @array\ =\ split\*(C'\fR, the \f(CW\*(C`()\ =\*(C'\fR at the beginning no longer confuses
+the optimizer into assuming a limit of 1.
+.IP \(bu 4
+Fatal warnings no longer prevent the output of syntax errors.
+[GH #14155] <https://github.com/Perl/perl5/issues/14155>.
+.IP \(bu 4
+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.
+.IP \(bu 4
+Fixed the issue that caused \f(CW\*(C`make distclean\*(C'\fR to incorrectly leave some
+files behind.
+[GH #14108] <https://github.com/Perl/perl5/issues/14108>.
+.IP \(bu 4
+AIX now sets the length in \f(CW\*(C`getsockopt\*(C'\fR correctly.
+[GH #13484] <https://github.com/Perl/perl5/issues/13484>.
+[cpan #91183] <https://rt.cpan.org/Ticket/Display.html?id=91183>.
+[cpan #85570] <https://rt.cpan.org/Ticket/Display.html?id=85570>.
+.IP \(bu 4
+The optimization phase of a regexp compilation could run "forever" and
+exhaust all memory under certain circumstances; now fixed.
+[GH #13984] <https://github.com/Perl/perl5/issues/13984>.
+.IP \(bu 4
+The test script \fIt/op/crypt.t\fR now uses the SHA\-256 algorithm if the
+default one is disabled, rather than giving failures.
+[GH #13715] <https://github.com/Perl/perl5/issues/13715>.
+.IP \(bu 4
+Fixed an off-by-one error when setting the size of a shared array.
+[GH #14151] <https://github.com/Perl/perl5/issues/14151>.
+.IP \(bu 4
+Fixed a bug that could cause perl to enter an infinite loop during
+compilation. In particular, a \f(CWwhile(1)\fR within a sublist, \fIe.g.\fR
+.Sp
+.Vb 1
+\&    sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }
+.Ve
+.Sp
+The bug was introduced in 5.20.0
+[GH #14165] <https://github.com/Perl/perl5/issues/14165>.
+.IP \(bu 4
+On Win32, if a variable was \f(CW\*(C`local\*(C'\fR\-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).
+[GH #8641] <https://github.com/Perl/perl5/issues/8641>.
+.IP \(bu 4
+Calling \f(CW\*(C`write\*(C'\fR on a format with a \f(CW\*(C`^**\*(C'\fR field could produce a panic
+in \f(CWsv_chop()\fR if there were insufficient arguments or if the variable
+used to fill the field was empty.
+[GH #14255] <https://github.com/Perl/perl5/issues/14255>.
+.IP \(bu 4
+Non-ASCII lexical sub names now appear without trailing junk when they
+appear in error messages.
+.IP \(bu 4
+The \f(CW\*(C`\e@\*(C'\fR subroutine prototype no longer flattens parenthesized arrays
+(taking a reference to each element), but takes a reference to the array
+itself.
+[GH #9111] <https://github.com/Perl/perl5/issues/9111>.
+.IP \(bu 4
+A block containing nothing except a C\-style \f(CW\*(C`for\*(C'\fR loop could corrupt the
+stack, causing lists outside the block to lose elements or have elements
+overwritten.  This could happen with \f(CW\*(C`map { for(...){...} } ...\*(C'\fR and with
+lists containing \f(CW\*(C`do { for(...){...} }\*(C'\fR.
+[GH #14269] <https://github.com/Perl/perl5/issues/14269>.
+.IP \(bu 4
+\&\f(CWscalar()\fR now propagates lvalue context, so that
+\&\f(CW\*(C`for(scalar($#foo))\ {\ ...\ }\*(C'\fR can modify \f(CW$#foo\fR through \f(CW$_\fR.
+.IP \(bu 4
+\&\f(CW\*(C`qr/@array(?{block})/\*(C'\fR no longer dies with "Bizarre copy of ARRAY".
+[GH #14292] <https://github.com/Perl/perl5/issues/14292>.
+.IP \(bu 4
+\&\f(CW\*(C`eval\ \*(Aq$variable\*(Aq\*(C'\fR in nested named subroutines would sometimes look up a
+global variable even with a lexical variable in scope.
+.IP \(bu 4
+In perl 5.20.0, \f(CW\*(C`sort CORE::fake\*(C'\fR 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 \f(CW\*(C`CORE::fake\*(C'\fR as a
+sort sub name has been restored.
+[GH #14323] <https://github.com/Perl/perl5/issues/14323>.
+.IP \(bu 4
+Outside of \f(CW\*(C`use utf8\*(C'\fR, a single-character Latin\-1 lexical variable is
+disallowed.  The error message for it, "Can't use global \f(CW$foo\fR...", was
+giving garbage instead of the variable name.
+.IP \(bu 4
+\&\f(CW\*(C`readline\*(C'\fR on a nonexistent handle was causing \f(CW\*(C`${^LAST_FH}\*(C'\fR to produce a
+reference to an undefined scalar (or fail an assertion).  Now
+\&\f(CW\*(C`${^LAST_FH}\*(C'\fR ends up undefined.
+.IP \(bu 4
+\&\f(CW\*(C`(...) x ...\*(C'\fR in void context now applies scalar context to the left-hand
+argument, instead of the context the current sub was called in.
+[GH #14174] <https://github.com/Perl/perl5/issues/14174>.
+.SH "Known Problems"
+.IX Header "Known Problems"
+.IP \(bu 4
+\&\f(CW\*(C`pack\*(C'\fR\-ing a NaN on a perl compiled with Visual C 6 does not behave properly,
+leading to a test failure in \fIt/op/infnan.t\fR.
+[GH #14705] <https://github.com/Perl/perl5/issues/14705>
+.IP \(bu 4
+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).
+.IP \(bu 4
+EBCDIC platforms
+.RS 4
+.IP \(bu 4
+The \f(CW\*(C`cmp\*(C'\fR (and hence \f(CW\*(C`sort\*(C'\fR) 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.
+.IP \(bu 4
+Ranges containing \f(CW\*(C`\eN{...}\*(C'\fR in the \f(CW\*(C`tr///\*(C'\fR (and \f(CW\*(C`y///\*(C'\fR)
+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.  ("Version 8 Regular Expressions" in perlre gives
+details as to how it should work.)
+.IP \(bu 4
+Encode and encoding are mostly broken.
+.IP \(bu 4
+Many CPAN modules that are shipped with core show failing tests.
+.IP \(bu 4
+\&\f(CW\*(C`pack\*(C'\fR/\f(CW\*(C`unpack\*(C'\fR with \f(CW"U0"\fR format may not work properly.
+.RE
+.RS 4
+.RE
+.IP \(bu 4
+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:
+.RS 4
+.IP \(bu 4
+B::Generate version 1.50
+.IP \(bu 4
+B::Utils version 0.25
+.IP \(bu 4
+Coro version 6.42
+.IP \(bu 4
+Dancer version 1.3130
+.IP \(bu 4
+Data::Alias version 1.18
+.IP \(bu 4
+Data::Dump::Streamer version 2.38
+.IP \(bu 4
+Data::Util version 0.63
+.IP \(bu 4
+Devel::Spy version 0.07
+.IP \(bu 4
+invoker version 0.34
+.IP \(bu 4
+Lexical::Var version 0.009
+.IP \(bu 4
+LWP::ConsoleLogger version 0.000018
+.IP \(bu 4
+Mason version 2.22
+.IP \(bu 4
+NgxQueue version 0.02
+.IP \(bu 4
+Padre version 1.00
+.IP \(bu 4
+Parse::Keyword 0.08
+.RE
+.RS 4
+.RE
+.SH Obituary
+.IX Header "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.
+.SH Acknowledgements
+.IX Header "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.
+.PP
+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.
+.PP
+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:
+.PP
+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.
+.PP
+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.
+.PP
+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.
+.PP
+For a more complete list of all of Perl's historical contributors, please see
+the \fIAUTHORS\fR file in the Perl source distribution.
+.SH "Reporting Bugs"
+.IX Header "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
+<https://rt.perl.org/>.  There may also be information at
+<http://www.perl.org/>, the Perl Home Page.
+.PP
+If you believe you have an unreported bug, please run the perlbug program
+included with your release.  Be sure to trim your bug down to a tiny but
+sufficient test case.  Your bug report, along with the output of \f(CW\*(C`perl \-V\*(C'\fR,
+will be sent off to perlbug@perl.org to be analysed by the Perl porting team.
+.PP
+If the bug you are reporting has security implications, which make it
+inappropriate to send to a publicly archived mailing list, then please send it
+to perl5\-security\-report@perl.org.  This points to a closed subscription
+unarchived mailing list, which includes all the core committers, who will be
+able to help assess the impact of issues, figure out a resolution, and help
+co-ordinate the release of patches to mitigate or fix the problem across all
+platforms on which Perl is supported.  Please only use this address for
+security issues in the Perl core, not for modules independently distributed on
+CPAN.
+.SH "SEE ALSO"
+.IX Header "SEE ALSO"
+The \fIChanges\fR file for an explanation of how to view exhaustive details on
+what changed.
+.PP
+The \fIINSTALL\fR file for how to build Perl.
+.PP
+The \fIREADME\fR file for general stuff.
+.PP
+The \fIArtistic\fR and \fICopying\fR files for copyright information.