X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/6a3ea89bf9ff596caed555010a5a2115f980312e..73247115beb59ea91539ef4f27f18d95029e381d:/pod/perldelta.pod

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index 2fef36b..c40962a 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -6,7 +6,7 @@ perldelta - what is new for perl v5.22.0
 
 =head1 DESCRIPTION
 
-This document describes differences between the 5.22.0 release and the 5.20.0
+This document describes differences between the 5.20.0 release and the 5.22.0
 release.
 
 If you are upgrading from an earlier release such as 5.18.0, first read
@@ -30,12 +30,12 @@ L<[perl #123466]|https://rt.perl.org/Ticket/Display.html?id=123466>.
 =head2 New double-diamond operator
 
 C<<< <<>> >>> is like C<< <> >> but uses three-argument C<open> to open
-each file in @ARGV.  So each element of @ARGV is an actual file name, and
-"|foo" won't be treated as a pipe open.
+each file in C<@ARGV>.  This means that each element of C<@ARGV> will be treated
+as an actual file name, and C<"|foo"> won't be treated as a pipe open.
 
-=head2 New \b boundaries in regular expressions
+=head2 New C<\b> boundaries in regular expressions
 
-=head3 qr/\b{gcb}/
+=head3 C<qr/\b{gcb}/>
 
 C<gcb> stands for Grapheme Cluster Boundary.  It is a Unicode property
 that finds the boundary between sequences of characters that look like a
@@ -44,30 +44,24 @@ the ability to deal with these through the C<\X> regular escape
 sequence.  Now, there is an alternative way of handling these.  See
 L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
 
-=head3 qr/\b{wb}/
+=head3 C<qr/\b{wb}/>
 
 C<wb> stands for Word Boundary.  It is a Unicode property
 that finds the boundary between words.  This is similar to the plain
 C<\b> (without braces) but is more suitable for natural language
-processing.  It knows, for example that apostrophes can occur in the
+processing.  It knows, for example, that apostrophes can occur in the
 middle of words.  See L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
 
-=head3 qr/\b{sb}/
+=head3 C<qr/\b{sb}/>
 
 C<sb> stands for Sentence Boundary.  It is a Unicode property
 to aid in parsing natural language sentences.
 See L<perlrebackslash/\b{}, \b, \B{}, \B> for details.
 
-=head2 C<no re> covers more and is lexical
-
-Previously running C<no re> would only turn off a few things. Now it
-turns off all the enabled things. For example, previously, you
-couldn't turn off debugging, once enabled, inside the same block.
-
 =head2 Non-Capturing Regular Expression Flag
 
 Regular expressions now support a C</n> flag that disables capturing
-and filling in C<$1>, C<$2>, etc... inside of groups:
+and filling in C<$1>, C<$2>, etc inside of groups:
 
   "hello" =~ /(hi|hello)/n; # $1 is not set
 
@@ -78,32 +72,22 @@ See L<perlre/"n"> for more information.
 =head2 C<use re 'strict'>
 
 This applies stricter syntax rules to regular expression patterns
-compiled within its scope, which hopefully will alert you to typos and
+compiled within its scope. This will hopefully alert you to typos and
 other unintentional behavior that backwards-compatibility issues prevent
-us from doing in normal regular expression compilations.  Because the
+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 category
-C<experimental::re_strict> warning.
+experience, using this pragma will raise a warning of category
+C<experimental::re_strict>.
 See L<'strict' in re|re/'strict' mode>.
 
-=head2 C<qr/foo/x> now ignores any Unicode pattern white space
-
-The C</x> regular expression modifier allows the pattern to contain
-white space and comments, both of which are ignored, for improved
-readability.  Until now, not all the white space characters that Unicode
-designates for this purpose were handled.  The additional ones now
-recognized are
-U+0085 NEXT LINE,
-U+200E LEFT-TO-RIGHT MARK,
-U+200F RIGHT-TO-LEFT MARK,
-U+2028 LINE SEPARATOR,
-and
-U+2029 PARAGRAPH SEPARATOR.
-
-=head2 Unicode 7.0 is now supported
+=head2 Unicode 7.0 (with correction) is now supported
 
 For details on what is in this release, see
 L<http://www.unicode.org/versions/Unicode7.0.0/>.
+The version of Unicode 7.0 that comes with Perl includes
+a correction dealing with glyph shaping in Arabic
+(see L<http://www.unicode.org/errata/#current_errata>).
+
 
 =head2 S<C<use locale>> can restrict which locale categories are affected
 
@@ -111,7 +95,7 @@ It is now possible to pass a parameter to S<C<use locale>> to specify
 a subset of locale categories to be locale-aware, with the remaining
 ones unaffected.  See L<perllocale/The "use locale" pragma> for details.
 
-=head2 Perl now supports POSIX 2008 locale currency additions.
+=head2 Perl now supports POSIX 2008 locale currency additions
 
 On platforms that are able to handle POSIX.1-2008, the
 hash returned by
@@ -126,10 +110,10 @@ C<int_p_sep_by_space>,
 and
 C<int_p_sign_posn>.
 
-=head2 Better heuristics on older platforms for determining locale UTF8ness
+=head2 Better heuristics on older platforms for determining locale UTF-8ness
 
 On platforms that implement neither the C99 standard nor the POSIX 2001
-standard, determining if the current locale is UTF8 or not depends on
+standard, determining if the current locale is UTF-8 or not depends on
 heuristics.  These are improved in this release.
 
 =head2 Aliasing via reference
@@ -139,13 +123,14 @@ Variables and subroutines can now be aliased by assigning to a reference:
     \$c = \$d;
     \&x = \&y;
 
-Or by using a backslash before a C<foreach> iterator variable, which is
+Aliasing can also be accomplished
+by using a backslash before a C<foreach> iterator variable; this is
 perhaps the most useful idiom this feature provides:
 
     foreach \%hash (@array_of_hash_refs) { ... }
 
-This feature is experimental and must be enabled via C<use feature
-'refaliasing'>.  It will warn unless the C<experimental::refaliasing>
+This feature is experimental and must be enabled via S<C<use feature
+'refaliasing'>>.  It will warn unless the C<experimental::refaliasing>
 warnings category is disabled.
 
 See L<perlref/Assigning to References>
@@ -155,12 +140,13 @@ See L<perlref/Assigning to References>
 C<prototype()> with no arguments now infers C<$_>.
 L<[perl #123514]|https://rt.perl.org/Ticket/Display.html?id=123514>.
 
-=head2 New "const" subroutine attribute
+=head2 New C<:const> subroutine attribute
 
-The "const" attribute can be applied to an anonymous subroutine.  It causes
-it to be executed immediately when it is cloned.  Its value is captured and
-used to create a new constant subroutine that is returned.  This feature is
-experimental.  See L<perlsub/Constant Functions>.
+The C<const> attribute can be applied to an anonymous subroutine.  It
+causes the new sub to be executed immediately whenever one is created
+(I<i.e.> when the C<sub> expression is evaluated).  Its value is captured
+and used to create a new constant subroutine that is returned.  This
+feature is experimental.  See L<perlsub/Constant Functions>.
 
 =head2 C<fileno> now works on directory handles
 
@@ -172,7 +158,7 @@ continues to return the undefined value, as before, but also sets C<$!> to
 indicate that the operation is not supported.
 
 Currently, this uses either a C<dd_fd> member in the OS C<DIR>
-structure, or a dirfd(3) function as specified by POSIX.1-2008.
+structure, or a C<dirfd(3)> function as specified by POSIX.1-2008.
 
 =head2 List form of pipe open implemented for Win32
 
@@ -184,26 +170,18 @@ is now implemented on Win32.  It has the same limitations as C<system
 LIST> on Win32, since the Win32 API doesn't accept program arguments
 as a list.
 
-=head2 C<close> now sets C<$!>
-
-When an I/O error occurs, the fact that there has been an error is recorded
-in the handle.  C<close> returns false for such a handle.  Previously, the
-value of C<$!> would be untouched by C<close>, so the common convention of
-writing C<close $fh or die $!> did not work reliably.  Now the handle
-records the value of C<$!>, too, and C<close> restores it.
-
 =head2 Assignment to list repetition
 
 C<(...) x ...> can now be used within a list that is assigned to, as long
-as the left-hand side is a valid lvalue.  This allows C<(undef,undef,$foo)
-= that_function()> to be written as C<((undef)x2, $foo) = that_function()>.
+as the left-hand side is a valid lvalue.  This allows S<C<(undef,undef,$foo)
+= that_function()>> to be written as S<C<((undef)x2, $foo) = that_function()>>.
 
 =head2 Infinity and NaN (not-a-number) handling improved
 
-Floating point values are able to hold the special values infinity (also
--infinity), and NaN (not-a-number).  Now we more robustly recognize and
-propagate the value in computations, and on output normalize them to C<Inf> and
-C<NaN>.
+Floating point values are able to hold the special values infinity, negative
+infinity, and NaN (not-a-number).  Now we more robustly recognize and
+propagate the value in computations, and on output normalize them to the strings
+C<Inf>, C<-Inf>, and C<NaN>.
 
 See also the L<POSIX> enhancements.
 
@@ -212,8 +190,9 @@ See also the L<POSIX> enhancements.
 Parsing and printing of floating point values has been improved.
 
 As a completely new feature, hexadecimal floating point literals
-(like 0x1.23p-4)  are now supported, and they can be output with
-C<printf %a>.
+(like C<0x1.23p-4>)  are now supported, and they can be output with
+S<C<printf "%a">>. See L<perldata/Scalar value constructors> for more
+details.
 
 =head2 Packing infinity or not-a-number into a character is now fatal
 
@@ -227,7 +206,7 @@ result in a fatal error.
 
 =head2 Experimental C Backtrace API
 
-Starting from Perl 5.21.1, on some platforms Perl supports retrieving
+Perl now supports (via a C level API) retrieving
 the C level backtrace (similar to what symbolic debuggers like gdb do).
 
 The backtrace returns the stack trace of the C call frames,
@@ -239,13 +218,11 @@ least partly, but they have not yet been tested).
 
 The feature needs to be enabled with C<Configure -Dusecbacktrace>.
 
-Also included is a C API to retrieve backtraces.
-
 See L<perlhacktips/"C backtrace"> for more information.
 
 =head1 Security
 
-=head2 Perl is now compiled with -fstack-protector-strong if available
+=head2 Perl is now compiled with C<-fstack-protector-strong> if available
 
 Perl has been compiled with the anti-stack-smashing option
 C<-fstack-protector> since 5.10.1.  Now Perl uses the newer variant
@@ -256,7 +233,7 @@ called C<-fstack-protector-strong>, if available.
 Critical bugfix: outside packages could be replaced.  L<Safe> has
 been patched to 2.38 to address this.
 
-=head2 Perl is now always compiled with -D_FORTIFY_SOURCE=2 if available
+=head2 Perl is now always compiled with C<-D_FORTIFY_SOURCE=2> if available
 
 The 'code hardening' option called C<_FORTIFY_SOURCE>, available in
 gcc 4.*, is now always used for compiling Perl, if available.
@@ -271,66 +248,81 @@ and OS X has enforced the same for many years.
 =head2 Subroutine signatures moved before attributes
 
 The experimental sub signatures feature, as introduced in 5.20, parsed
-signatures after attributes.  In this release, the positioning has been
-moved such that signatures occur after the subroutine name (if any) and
-before the attribute list (if any).
+signatures after attributes. In this release, following feedback from users
+of the experimental feature, the positioning has been moved such that
+signatures occur after the subroutine name (if any) and before the attribute
+list (if any).
 
 =head2 C<&> and C<\&> prototypes accepts only subs
 
-The C<&> prototype character now accepts only anonymous subs (C<sub {...}>)
-and things beginning with C<\&>.  Formerly it erroneously also allowed
-C<undef> and references to array, hashes, and lists.
+The C<&> prototype character now accepts only anonymous subs (C<sub
+{...}>), things beginning with C<\&>, or an explicit C<undef>.  Formerly
+it erroneously also allowed references to arrays, hashes, and lists.
 L<[perl #4539]|https://rt.perl.org/Ticket/Display.html?id=4539>.
 L<[perl #123062]|https://rt.perl.org/Ticket/Display.html?id=123062>.
+L<[perl #123062]|https://rt.perl.org/Ticket/Display.html?id=123475>.
 
-The C<\&> prototype was allowing subroutine calls, whereas now it only
-allows subroutines.  C<&foo> is permitted.  C<&foo()> and C<foo()> are not.
+In addition, the C<\&> prototype was allowing subroutine calls, whereas
+now it only allows subroutines: C<&foo> is still permitted as an argument,
+while C<&foo()> and C<foo()> no longer are.
 L<[perl #77860]|https://rt.perl.org/Ticket/Display.html?id=77860>.
 
 =head2 C<use encoding> is now lexical
 
 The L<encoding> pragma's effect is now limited to lexical scope.  This
 pragma is deprecated, but in the meantime, it could adversely affect
-unrelated modules that are included in the same program.
+unrelated modules that are included in the same program; this change
+fixes that.
 
 =head2 List slices returning empty lists
 
-List slices return an empty list now only if the original list was empty
+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.
+list if all indices fell outside the original list; now it returns a list
+of C<undef> values in that case.
 L<[perl #114498]|https://rt.perl.org/Ticket/Display.html?id=114498>.
 
-=head2 C<\N{}> with a sequence of multiple spaces is now a fatal error.
+=head2 C<\N{}> with a sequence of multiple spaces is now a fatal error
 
+E.g. S<C<\N{TOOE<nbsp>E<nbsp>MANY SPACES}>> or S<C<\N{TRAILING SPACE }>>.
 This has been deprecated since v5.18.
 
 =head2 S<C<use UNIVERSAL '...'>> is now a fatal error
 
 Importing functions from C<UNIVERSAL> has been deprecated since v5.12, and
-is now a fatal error.  S<C<"use UNIVERSAL">> without any arguments is still
+is now a fatal error.  S<C<use UNIVERSAL>> without any arguments is still
 allowed.
 
 =head2 In double-quotish C<\cI<X>>, I<X> must now be a printable ASCII character
 
 In prior releases, failure to do this raised a deprecation warning.
 
-=head2 Splitting the tokens C<(?> and C<(*> in regular expressions is
-now a fatal compilation error.
+=head2 Splitting the tokens C<(?> and C<(*> in regular expressions is now a fatal compilation error.
 
 These had been deprecated since v5.18.
 
-=head2 5 additional characters are treated as white space under C</x> in
-regex patterns (unless escaped)
+=head2 C<qr/foo/x> now ignores all Unicode pattern white space
+
+The C</x> regular expression modifier allows the pattern to contain
+white space and comments (both of which are ignored) for improved
+readability.  Until now, not all the white space characters that Unicode
+designates for this purpose were handled.  The additional ones now
+recognized are:
+
+    U+0085 NEXT LINE
+    U+200E LEFT-TO-RIGHT MARK
+    U+200F RIGHT-TO-LEFT MARK
+    U+2028 LINE SEPARATOR
+    U+2029 PARAGRAPH SEPARATOR
 
 The use of these characters with C</x> outside bracketed character
 classes and when not preceded by a backslash has raised a deprecation
-warning since v5.18.  Now they will be ignored.  See L</"qr/foo/x">
-for the list of the five characters.
+warning since v5.18.  Now they will be ignored.
 
-=head2 Comment lines within S<C<(?[ ])>> now are ended only by a C<\n>
+=head2 Comment lines within S<C<(?[ ])>> are now ended only by a C<\n>
 
 S<C<(?[ ])>>  is an experimental feature, introduced in v5.18.  It operates
-as if C</x> is always enabled.  But there was a difference, comment
+as if C</x> is always enabled.  But there was a difference: comment
 lines (following a C<#> character) were terminated by anything matching
 C<\R> which includes all vertical whitespace, such as form feeds.  For
 consistency, this is now changed to match what terminates comment lines
@@ -346,20 +338,20 @@ outcomes than existing code expects (though the documentation has always noted
 that this change might happen, recommending fully parenthesizing the
 expressions).  See L<perlrecharclass/Extended Bracketed Character Classes>.
 
-=head2 Omitting % and @ on hash and array names is no longer permitted
+=head2 Omitting C<%> and C<@> on hash and array names is no longer permitted
 
-Really old Perl let you omit the @ on array names and the % on hash
+Really old Perl let you omit the C<@> on array names and the C<%> on hash
 names in some spots.  This has issued a deprecation warning since Perl
-5.0, and is no longer permitted.
+5.000, and is no longer permitted.
 
-=head2 C<"$!"> text is now in English outside C<"use locale"> scope
+=head2 C<"$!"> text is now in English outside the scope of C<use locale>
 
 Previously, the text, unlike almost everything else, always came out
 based on the current underlying locale of the program.  (Also affected
-on some systems is C<"$^E>".)  For programs that are unprepared to
-handle locale, this can cause garbage text to be displayed.  It's better
-to display text that is translatable via some tool than garbage text
-which is much harder to figure out.
+on some systems is C<"$^E">.)  For programs that are unprepared to
+handle locale differences, this can cause garbage text to be displayed.
+It's better to display text that is translatable via some tool than
+garbage text which is much harder to figure out.
 
 =head2 C<"$!"> text will be returned in UTF-8 when appropriate
 
@@ -368,36 +360,37 @@ 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
-'use bytes' and 'use locale ":messages".  No other Perl operations will
+S<C<use bytes>> and S<C<use locale ":messages">>.  Within these two
+scopes, no other Perl operations will
 be affected by locale; only C<$!> and C<$^E> stringification.  The
-'bytes' pragma causes the UTF-8 flag to not be set, just as in previous
+C<bytes> pragma causes the UTF-8 flag to not be set, just as in previous
 Perl releases.  This resolves
 L<[perl #112208]|https://rt.perl.org/Ticket/Display.html?id=112208>.
 
 =head2 Support for C<?PATTERN?> without explicit operator has been removed
 
-Starting regular expressions matching only once directly with the
-question mark delimiter is now a syntax error, so that the question mark
-can be available for use in new operators.  Write C<m?PATTERN?> instead,
-explicitly using the C<m> operator: the question mark delimiter still
-invokes match-once behaviour.
+The C<m?PATTERN?> construct, which allows matching a regex only once,
+previously had an alternative form that was written directly with a question
+mark delimiter, omitting the explicit C<m> operator.  This usage has produced
+a deprecation warning since 5.14.0.  It is now a syntax error, so that the
+question mark can be available for use in new operators.
 
 =head2 C<defined(@array)> and C<defined(%hash)> are now fatal errors
 
 These have been deprecated since v5.6.1 and have raised deprecation
 warnings since v5.16.
 
-=head2 Using a hash or an array as a reference are now fatal errors.
+=head2 Using a hash or an array as a reference are now fatal errors
 
-For example, C<%foo-E<gt>{"bar"}> now causes a fatal compilation
+For example, C<< %foo->{"bar"} >> now causes a fatal compilation
 error.  These have been deprecated since before v5.8, and have raised
 deprecation warnings since then.
 
 =head2 Changes to the C<*> prototype
 
 The C<*> character in a subroutine's prototype used to allow barewords to take
-precedence over most, but not all subroutines.  It was never consistent and
-exhibited buggy behaviour.
+precedence over most, but not all, subroutine names.  It was never
+consistent and exhibited buggy behavior.
 
 Now it has been changed, so subroutines always take precedence over barewords,
 which brings it into conformity with similarly prototyped built-in functions:
@@ -413,18 +406,11 @@ which brings it into conformity with similarly prototyped built-in functions:
 
 =head2 Setting C<${^ENCODING}> to anything but C<undef>
 
-This variable allows Perl scripts to be written in a non-ASCII,
-non-UTF-8 encoding.  However, it affects all modules globally, leading
+This variable allows Perl scripts to be written in an encoding other than
+ASCII or UTF-8.  However, it affects all modules globally, leading
 to wrong answers and segmentation faults.  New scripts should be written
 in UTF-8; old scripts should be converted to UTF-8, which is easily done
-with the L<encoding> pragma.
-
-=head2 C<< /\C/ >> character class
-
-This character class, which matches a single byte, even if it appears
-in a multi-byte character has been deprecated. Matching single bytes
-in a multi-byte character breaks encapsulation, and can corrupt utf8
-strings.
+with the L<piconv> utility.
 
 =head2 Use of non-graphic characters in single-character variable names
 
@@ -433,16 +419,18 @@ for longer variable names, allowing the one-character name to be a
 punctuation character or even invisible (a non-graphic).  Perl v5.20
 deprecated the ASCII-range controls as such a name.  Now, all
 non-graphic characters that formerly were allowed are deprecated.
-The practical effect of this occurs only when not under C<S<"use
-utf8">>, and affects just the C1 controls (code points 0x80 through
+The practical effect of this occurs only when not under C<S<use
+utf8>>, and affects just the C1 controls (code points 0x80 through
 0xFF), NO-BREAK SPACE, and SOFT HYPHEN.
 
 =head2 Inlining of C<sub () { $var }> with observable side-effects
 
-In many cases Perl makes sub () { $var } into an inlinable constant
-subroutine, capturing the value of $var at the time the C<sub> expression
-is evaluated.  This can break the closure behaviour in those cases where
-$var is subsequently modified.  The subroutine won't return the new value.
+In many cases Perl makes S<C<sub () { $var }>> into an inlinable constant
+subroutine, capturing the value of C<$var> at the time the C<sub> expression
+is evaluated.  This can break the closure behavior in those cases where
+C<$var> is subsequently modified, since the subroutine won't return the
+changed value. (Note that this all only applies to anonymous subroutines
+with an empty prototype (S<C<sub ()>>).)
 
 This usage is now deprecated in those cases where the variable could be
 modified elsewhere.  Perl detects those cases and emits a deprecation
@@ -469,18 +457,18 @@ Perl will continue to make the sub inlinable with no warnings.
         return sub () { $var }; # deprecated
     }
 
-In the second example above, detecting that $var is assigned to only once
+In the second example above, detecting that C<$var> is assigned to only once
 is too hard to detect.  That it happens in a spot other than the C<my>
 declaration is enough for Perl to find it suspicious.
 
 This deprecation warning happens only for a simple variable for the body of
 the sub.  (A C<BEGIN> block or C<use> statement inside the sub is ignored,
 because it does not become part of the sub's body.)  For more complex
-cases, such as C<sub () { do_something() if 0; $var }> the behaviour has
+cases, such as S<C<sub () { do_something() if 0; $var }>> the behavior has
 changed such that inlining does not happen if the variable is modifiable
 elsewhere.  Such cases should be rare.
 
-=head2 Use of multiple /x regexp modifiers
+=head2 Use of multiple C</x> regexp modifiers
 
 It is now deprecated to say something like any of the following:
 
@@ -491,12 +479,11 @@ It is now deprecated to say something like any of the following:
 That is, now C<x> should only occur once in any string of contiguous
 regular expression pattern modifiers.  We do not believe there are any
 occurrences of this in all of CPAN.  This is in preparation for a future
-Perl release having C</xx> mean to allow white-space for readability in
+Perl release having C</xx> permit white-space for readability in
 bracketed character classes (those enclosed in square brackets:
 C<[...]>).
 
-=head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now
-deprecated
+=head2 Using a NO-BREAK space in a character alias for C<\N{...}> is now deprecated
 
 This non-graphic character is essentially indistinguishable from a
 regular space, and so should not be allowed.  See
@@ -514,7 +501,7 @@ release; it will allow future extensions to the language to happen.
 =head2 Making all warnings fatal is discouraged
 
 The documentation for L<fatal warnings|warnings/Fatal Warnings> notes that
-C<< use warnings FATAL => 'all' >> is discouraged and provides stronger
+C<< use warnings FATAL => 'all' >> is discouraged, and provides stronger
 language about the risks of fatal warnings in general.
 
 =head1 Performance Enhancements
@@ -523,7 +510,7 @@ language about the risks of fatal warnings in general.
 
 =item *
 
-If method and class names are known at compile time, hashes are precomputed
+If a method or class name is known at compile time, a hash is precomputed
 to speed up run-time method lookup.  Also, compound method names like
 C<SUPER::new> are parsed at compile time, to save having to parse them at
 run time.
@@ -540,7 +527,8 @@ C<(...)x1>, C<("constant")x0> and C<($scalar)x0> are now optimised in list
 context.  If the right-hand argument is a constant 1, the repetition
 operator disappears.  If the right-hand argument is a constant 0, the whole
 expression is optimised to the empty list, so long as the left-hand
-argument is a simple scalar or constant.  C<(foo())x0> is not optimised.
+argument is a simple scalar or constant.  (That is, C<(foo())x0> is not
+subject to this optimisation.)
 
 =item *
 
@@ -550,16 +538,8 @@ optimisation only happened in void context.
 
 =item *
 
-Assignment to lexical variables is often optimised away.  For instance, in
-C<$lexical = chr $foo>, the C<chr> operator writes directly to the lexical
-variable instead of returning a value that gets copied.  This optimisation
-has been extended to C<split>, C<x> and C<vec> on the right-hand side.  It
-has also been made to work with state variable initialization.
-
-=item *
-
-In "\L...", "\Q...", etc., the extra "stringify" op is now optimised away,
-making these just as fast as C<lcfirst>, C<quotemeta>, etc.
+In C<"\L...">, C<"\Q...">, etc., the extra "stringify" op is now optimised
+away, making these just as fast as C<lcfirst>, C<quotemeta>, etc.
 
 =item *
 
@@ -569,39 +549,41 @@ used to sometimes.
 
 =item *
 
-C<length> is up to 20% faster for non-magical/non-tied scalars containing a
-string if it is a non-utf8 string or if C<use bytes;> is in scope.
+There is a performance improvement of up to 20% when C<length> is applied to
+a non-magical, non-tied string, and either C<use bytes> is in scope or the
+string doesn't use UTF-8 internally.
 
 =item *
 
-Non-magical/non-tied scalars that contain only a floating point value and are
-on most Perl builds with 64 bit integers now use 8-32 less bytes of memory
-depending on OS.
+On most perl builds with 64-bit integers, memory usage for non-magical,
+non-tied scalars containing only a floating point value has been reduced
+by between 8 and 32 bytes, depending on OS.
 
 =item *
 
-In C<@array = split>, the assignment can be optimized away with C<split>
-writing directly to the array.  This optimisation was happening only for
-package arrays other than @_ and only
-sometimes.  Now this optimisation happens
-almost all the time.
+In C<@array = split>, the assignment can be optimized away, so that C<split>
+writes directly to the array.  This optimisation was happening only for
+package arrays other than C<@_>, and only sometimes.  Now this
+optimisation happens almost all the time.
 
 =item *
 
-C<join> is now subject to constant folding.  Moreover, C<join> with a
-scalar or constant for the separator and a single-item list to join is
-simplified to a stringification.  The separator doesn't even get evaluated.
+C<join> is now subject to constant folding.  So for example
+S<C<join "-", "a", "b">> is converted at compile-time to C<"a-b">.
+Moreover, C<join> with a scalar or constant for the separator and a
+single-item list to join is simplified to a stringification, and the
+separator doesn't even get evaluated.
 
 =item *
 
 C<qq(@array)> is implemented using two ops: a stringify op and a join op.
-If the qq contains nothing but a single array, the stringification is
+If the C<qq> contains nothing but a single array, the stringification is
 optimized away.
 
 =item *
 
-C<our $var> and C<our($s,@a,%h)> in void context are no longer evaluated at
-run time.  Even a whole sequence of C<our $foo;> statements will simply be
+S<C<our $var>> and S<C<our($s,@a,%h)>> in void context are no longer evaluated at
+run time.  Even a whole sequence of S<C<our $foo;>> statements will simply be
 skipped over.  The same applies to C<state> variables.
 
 =item *
@@ -619,34 +601,24 @@ L<[perl #121489]|https://rt.perl.org/Ticket/Display.html?id=121489>
 
 =item *
 
-Refactoring of C<< pp_tied >> and CC<< pp_ref >> for small improvements.
-
-=item *
-
-Pathtools don't try to load XS on miniperl.
-
-=item *
-
-A typo fix reduces the size of the C<< OP >> structure.
-
-=item *
-
-Hash lookups where the key is a constant is faster.
+Hash lookups where the key is a constant are faster.
 
 =item *
 
-Subroutines with an empty prototype and bodies containing just C<undef> are now
+Subroutines with an empty prototype and a body containing just C<undef> are now
 eligible for inlining.
 L<[perl #122728]|https://rt.perl.org/Ticket/Display.html?id=122728>
 
 =item *
 
-Subroutines in packages no longer need to carry typeglobs around with them.
-Declaring a subroutine will now put a simple sub reference in the stash if
-possible, saving memory.  The typeglobs still notionally exist, so accessing
-them will cause the subroutine reference to be upgraded to a typeglob.  This
-optimization does not currently apply to XSUBs or exported subroutines, and
-method calls will undo it, since they cache things in typeglobs.
+Subroutines in packages no longer need to be stored in typeglobs:
+declaring a subroutine will now put a simple sub reference directly in the
+stash if possible, saving memory.  The typeglob still notionally exists,
+so accessing it will cause the stash entry to be upgraded to a typeglob
+(I<i.e.> this is just an internal implementation detail).
+This optimization does not currently apply to XSUBs or exported
+subroutines, and method calls will undo it, since they cache things in
+typeglobs.
 L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
 
 =item *
@@ -659,48 +631,575 @@ platforms.
 =item *
 
 Win32 Perl uses 8 KB less of per-process memory than before for every perl
-process of this version. This data is now memory mapped from disk and shared
-between perl processes from the same perl binary.
+process, because some data is now memory mapped from disk and shared
+between processes from the same perl binary.
 
 =back
 
 =head1 Modules and Pragmata
 
-XXX All changes to installed files in F<cpan/>, F<dist/>, F<ext/> and F<lib/>
-go here.  If Module::CoreList is updated, generate an initial draft of the
-following sections using F<Porting/corelist-perldelta.pl>.  A paragraph summary
-for important changes should then be added by hand.  In an ideal world,
-dual-life modules would have a F<Changes> file that could be cribbed.
+=head2 Updated Modules and Pragmata
+
+Many of the libraries distributed with perl have been upgraded since v5.20.0.
+For a complete list of changes, run:
 
-[ Within each section, list entries as a =item entry ]
+  corelist --diff 5.20.0 5.22.0
 
-=head2 New Modules and Pragmata
+You can substitute your favorite version in place of 5.20.0, too.
+
+Some notable changes include:
 
 =over 4
 
 =item *
 
-XXX
+L<Archive::Tar> has been upgraded to version 2.04.
 
-=back
+Tests can now be run in parallel.
 
-=head2 Updated Modules and Pragmata
+=item *
 
-=over 4
+L<attributes> has been upgraded to version 0.27.
+
+The usage of C<memEQs> in the XS has been corrected.
+L<[perl #122701]|https://rt.perl.org/Ticket/Display.html?id=122701>
+
+Avoid reading beyond the end of a buffer. [perl #122629]
+
+=item *
+
+L<B> has been upgraded to version 1.58.
+
+It provides a new C<B::safename> function, based on the existing
+C<< B::GV->SAFENAME >>, that converts C<\cOPEN> to C<^OPEN>.
+
+Nulled COPs are now of class C<B::COP>, rather than C<B::OP>.
+
+C<B::REGEXP> objects now provide a C<qr_anoncv> method for accessing the
+implicit CV associated with C<qr//> things containing code blocks, and a
+C<compflags> method that returns the pertinent flags originating from the
+C<qr//blahblah> op.
+
+C<B::PMOP> now provides a C<pmregexp> method returning a C<B::REGEXP> object.
+Two new classes, C<B::PADNAME> and C<B::PADNAMELIST>, have been introduced.
+
+A bug where, after an ithread creation or psuedofork, special/immortal SVs in
+the child ithread/psuedoprocess did not have the correct class of
+C<B::SPECIAL>, has been fixed.
+The C<id> and C<outid> PADLIST methods have been added.
+
+=item *
+
+L<B::Concise> has been upgraded to version 0.996.
+
+Null ops that are part of the execution chain are now given sequence
+numbers.
+
+Private flags for nulled ops are now dumped with mnemonics as they would be
+for the non-nulled counterparts.
+
+=item *
+
+L<B::Deparse> has been upgraded to version 1.35.
+
+It now deparses C<+sub : attr { ... }> correctly at the start of a
+statement.  Without the initial C<+>, C<sub> would be a statement label.
+
+C<BEGIN> blocks are now emitted in the right place most of the time, but
+the change unfortunately introduced a regression, in that C<BEGIN> blocks
+occurring just before the end of the enclosing block may appear below it
+instead.
+
+C<B::Deparse> no longer puts erroneous C<local> here and there, such as for
+C<LIST = tr/a//d>.  [perl #119815]
+
+Adjacent C<use> statements are no longer accidentally nested if one
+contains a C<do> block.  [perl #115066]
+
+Parenthesised arrays in lists passed to C<\> are now correctly deparsed
+with parentheses (I<e.g.>, C<\(@a, (@b), @c)> now retains the parentheses
+around @b), thus preserving the flattening behavior of referenced
+parenthesised arrays.  Formerly, it only worked for one array: C<\(@a)>.
+
+C<local our> is now deparsed correctly, with the C<our> included.
+
+C<for($foo; !$bar; $baz) {...}> was deparsed without the C<!> (or C<not>).
+This has been fixed.
+
+Core keywords that conflict with lexical subroutines are now deparsed with
+the C<CORE::> prefix.
+
+C<foreach state $x (...) {...}> now deparses correctly with C<state> and
+not C<my>.
+
+C<our @array = split(...)> now deparses correctly with C<our> in those
+cases where the assignment is optimized away.
+
+It now deparses C<our(I<LIST>)> and typed lexical (C<my Dog $spot>) correctly.
+
+Deparse C<$#_> as that instead of as C<$#{_}>.
+L<[perl #123947]|https://rt.perl.org/Ticket/Display.html?id=123947>
+
+BEGIN blocks at the end of the enclosing scope are now deparsed in the
+right place.  [perl #77452]
+
+BEGIN blocks were sometimes deparsed as __ANON__, but are now always called
+BEGIN.
+
+Lexical subroutines are now fully deparsed.  [perl #116553]
+
+C<Anything =~ y///r> with C</r> no longer omits the left-hand operand.
+
+The op trees that make up regexp code blocks are now deparsed for real.
+Formerly, the original string that made up the regular expression was used.
+That caused problems with C<qr/(?{E<lt>E<lt>heredoc})/> and multiline code blocks,
+which were deparsed incorrectly.  [perl #123217] [perl #115256]
+
+C<$;> at the end of a statement no longer loses its semicolon.
+[perl #123357]
+
+Some cases of subroutine declarations stored in the stash in shorthand form
+were being omitted.
+
+Non-ASCII characters are now consistently escaped in strings, instead of
+some of the time.  (There are still outstanding problems with regular
+expressions and identifiers that have not been fixed.)
+
+When prototype sub calls are deparsed with C<&> (I<e.g.>, under the B<-P>
+option), C<scalar> is now added where appropriate, to force the scalar
+context implied by the prototype.
+
+C<require(foo())>, C<do(foo())>, C<goto(foo())> and similar constructs with
+loop controls are now deparsed correctly.  The outer parentheses are not
+optional.
+
+Whitespace is no longer escaped in regular expressions, because it was
+getting erroneously escaped within C<(?x:...)> sections.
+
+C<sub foo { foo() }> is now deparsed with those mandatory parentheses.
+
+C</@array/> is now deparsed as a regular expression, and not just
+C<@array>.
+
+C</@{-}/>, C</@{+}/> and C<$#{1}> are now deparsed with the braces, which
+are mandatory in these cases.
+
+In deparsing feature bundles, C<B::Deparse> was emitting C<no feature;> first
+instead of C<no feature ':all';>.  This has been fixed.
+
+C<chdir FH> is now deparsed without quotation marks.
+
+C<\my @a> is now deparsed without parentheses.  (Parenthese would flatten
+the array.)
+
+C<system> and C<exec> followed by a block are now deparsed correctly.
+Formerly there was an erroneous C<do> before the block.
+
+C<< use constant QR =E<gt> qr/.../flags >> followed by C<"" =~ QR> is no longer
+without the flags.
+
+Deparsing C<BEGIN { undef &foo }> with the B<-w> switch enabled started to
+emit 'uninitialized' warnings in Perl 5.14.  This has been fixed.
+
+Deparsing calls to subs with a C<(;+)> prototype resulted in an infinite
+loop.  The C<(;$>) C<(_)> and C<(;_)> prototypes were given the wrong
+precedence, causing C<foo($aE<lt>$b)> to be deparsed without the parentheses.
+
+Deparse now provides a defined state sub in inner subs.
+
+=item *
+
+L<B::Op_private> has been added.
+
+L<B::Op_private> provides detailed information about the flags used in the
+C<op_private> field of perl opcodes.
+
+=item *
+
+L<bigint>, L<bignum>, L<bigrat> have been upgraded to version 0.39.
+
+Document in CAVEATS that using strings as numbers won't always invoke
+the big number overloading, and how to invoke it.  [rt.perl.org #123064]
+
+=item *
+
+L<Carp> has been upgraded to version 1.36.
+
+C<Carp::Heavy> now ignores version mismatches with Carp if Carp is newer
+than 1.12, since C<Carp::Heavy>'s guts were merged into Carp at that
+point.
+L<[perl #121574]|https://rt.perl.org/Ticket/Display.html?id=121574>
+
+Carp now handles non-ASCII platforms better.
+
+Off-by-one error fix for Perl E<lt> 5.14.
+
+=item *
+
+L<constant> has been upgraded to version 1.33.
+
+It now accepts fully-qualified constant names, allowing constants to be defined
+in packages other than the caller.
+
+=item *
+
+L<CPAN> has been upgraded to version 2.11.
+
+Add support for C<Cwd::getdcwd()> and introduce workaround for a misbehavior
+seen on Strawberry Perl 5.20.1.
+
+Fix C<chdir()> after building dependencies bug.
+
+Introduce experimental support for plugins/hooks.
+
+Integrate the C<App::Cpan> sources.
+
+Do not check recursion on optional dependencies.
+
+Sanity check F<META.yml> to contain a hash.
+L<[cpan #95271]|https://rt.cpan.org/Ticket/Display.html?id=95271>
+
+=item *
+
+L<CPAN::Meta::Requirements> has been upgraded to version 2.132.
+
+Works around limitations in C<version::vpp> detecting v-string magic and adds
+support for forthcoming L<ExtUtils::MakeMaker> bootstrap F<version.pm> for
+Perls older than 5.10.0.
+
+=item *
+
+L<Data::Dumper> has been upgraded to version 2.158.
+
+Fixes CVE-2014-4330 by adding a configuration variable/option to limit
+recursion when dumping deep data structures.
+
+Changes to resolve Coverity issues.
+XS dumps incorrectly stored the name of code references stored in a
+GLOB.
+L<[perl #122070]|https://rt.perl.org/Ticket/Display.html?id=122070>
+
+=item *
+
+L<DynaLoader> has been upgraded to version 1.32.
+
+Remove C<dl_nonlazy> global if unused in Dynaloader. [perl #122926]
+
+=item *
+
+L<Encode> has been upgraded to version 2.72.
+
+C<piconv> now has better error handling when the encoding name is nonexistent,
+and a build breakage when upgrading L<Encode> in perl-5.8.2 and earlier has
+been fixed.
+
+Building in C++ mode on Windows now works.
+
+=item *
+
+L<Errno> has been upgraded to version 1.23.
+
+Add C<-P> to the preprocessor command-line on GCC 5.  GCC added extra
+line directives, breaking parsing of error code definitions.  [rt.perl.org
+#123784]
+
+=item *
+
+L<experimental> has been upgraded to version 0.013.
+
+Hardcodes features for Perls older than 5.15.7.
+
+=item *
+
+L<ExtUtils::CBuilder> has been upgraded to version 0.280221.
+
+Fixes a regression on Android.
+L<[perl #122675]|https://rt.perl.org/Ticket/Display.html?id=122675>
+
+=item *
+
+L<ExtUtils::Manifest> has been upgraded to version 1.70.
+
+Fixes a bug with C<maniread()>'s handling of quoted filenames and improves
+C<manifind()> to follow symlinks.
+L<[perl #122415]|https://rt.perl.org/Ticket/Display.html?id=122415>
+
+=item *
+
+L<ExtUtils::ParseXS> has been upgraded to version 3.28.
+
+Only declare C<file> unused if we actually define it.
+Improve generated C<RETVAL> code generation to avoid repeated
+references to C<ST(0)>.  [perl #123278]
+Broaden and document the C</OBJ$/> to C</REF$/> typemap optimization
+for the C<DESTROY> method.  [perl #123418]
+
+=item *
+
+L<Fcntl> has been upgraded to version 1.13.
+
+Add support for the Linux pipe buffer size C<fcntl()> commands.
+
+=item *
+
+L<File::Find> has been upgraded to version 1.29.
+
+C<find()> and C<finddepth()> will now warn if passed inappropriate or
+misspelled options.
+
+=item *
+
+L<File::Glob> has been upgraded to version 1.24.
+
+Avoid C<SvIV()> expanding to call C<get_sv()> three times in a few
+places. [perl #123606]
+
+=item *
+
+L<HTTP::Tiny> has been upgraded to version 0.054.
+
+C<keep_alive> is now fork-safe and thread-safe.
+
+=item *
+
+L<IO> has been upgraded to version 1.35.
+
+The XS implementation has been fixed for the sake of older Perls.
+
+=item *
+
+L<IO::Socket> has been upgraded to version 1.38.
+
+Document the limitations of the C<connected()> method.  [perl #123096]
+
+=item *
+
+L<IO::Socket::IP> has been upgraded to version 0.37.
+
+A better fix for subclassing C<connect()>.
+L<[cpan #95983]|https://rt.cpan.org/Ticket/Display.html?id=95983>
+L<[cpan #97050]|https://rt.cpan.org/Ticket/Display.html?id=97050>
+
+Implements Timeout for C<connect()>.
+L<[cpan #92075]|https://rt.cpan.org/Ticket/Display.html?id=92075>
+
+=item *
+
+The libnet collection of modules has been upgraded to version 3.05.
+
+Support for IPv6 and SSL to C<Net::FTP>, C<Net::NNTP>, C<Net::POP3> and C<Net::SMTP>.
+Improvements in C<Net::SMTP> authentication.
+
+=item *
+
+L<Locale::Codes> has been upgraded to version 3.34.
+
+Fixed a bug in the scripts used to extract data from spreadsheets that
+prevented the SHP currency code from being found.
+L<[cpan #94229]|https://rt.cpan.org/Ticket/Display.html?id=94229>
+
+New codes have been added.
+
+=item *
+
+L<Math::BigInt> has been upgraded to version 1.9997.
+
+Synchronize POD changes from the CPAN release.
+C<< Math::BigFloat->blog(x) >> would sometimes return C<blog(2*x)> when
+the accuracy was greater than 70 digits.
+The result of C<< Math::BigFloat->bdiv() >> in list context now
+satisfies C<< x = quotient * divisor + remainder >>.
+
+Correct handling of subclasses.
+L<[cpan #96254]|https://rt.cpan.org/Ticket/Display.html?id=96254>
+L<[cpan #96329]|https://rt.cpan.org/Ticket/Display.html?id=96329>
+
+=item *
+
+L<Module::Metadata> has been upgraded to version 1.000026.
+
+Support installations on older perls with an L<ExtUtils::MakeMaker> earlier
+than 6.63_03
+
+=item *
+
+L<overload> has been upgraded to version 1.26.
+
+A redundant C<ref $sub> check has been removed.
+
+=item *
+
+The PathTools module collection has been upgraded to version 3.56.
+
+A warning from the B<gcc> compiler is now avoided when building the XS.
+
+Don't turn leading C<//> into C</> on Cygwin. [perl #122635]
+
+=item *
+
+L<perl5db.pl> has been upgraded to version 1.49.
+
+The debugger would cause an assertion failure.
+L<[perl #124127]|https://rt.perl.org/Ticket/Display.html?id=124127>
+
+C<fork()> in the debugger under C<tmux> will now create a new window for
+the forked process. L<[perl
+#121333]|https://rt.perl.org/Ticket/Display.html?id=121333>
+
+The debugger now saves the current working directory on startup and
+restores it when you restart your program with C<R> or C<rerun>. L<[perl
+#121509]|https://rt.perl.org/Ticket/Display.html?id=121509>
+
+=item *
+
+L<PerlIO::scalar> has been upgraded to version 0.22.
+
+Reading from a position well past the end of the scalar now correctly
+returns end of file.  [perl #123443]
+
+Seeking to a negative position still fails, but no longer leaves the
+file position set to a negation location.
+
+C<eof()> on a C<PerlIO::scalar> handle now properly returns true when
+the file position is past the 2GB mark on 32-bit systems.
+
+Attempting to write at file positions impossible for the platform now
+fail early rather than wrapping at 4GB.
+
+=item *
+
+L<Pod::Perldoc> has been upgraded to version 3.25.
+
+Filehandles opened for reading or writing now have C<:encoding(UTF-8)> set.
+L<[cpan #98019]|https://rt.cpan.org/Ticket/Display.html?id=98019>
+
+=item *
+
+L<POSIX> has been upgraded to version 1.53.
+
+The C99 math functions and constants (for example C<acosh>, C<isinf>, C<isnan>, C<round>,
+C<trunc>; C<M_E>, C<M_SQRT2>, C<M_PI>) have been added.
+
+C<POSIX::tmpnam()> now produces a deprecation warning.  [perl #122005]
+
+=item *
+
+L<Safe> has been upgraded to version 2.39.
+
+C<reval> was not propagating void context properly.
+
+=item *
+
+Scalar-List-Utils has been upgraded to version 1.41.
+
+A new module, L<Sub::Util>, has been added, containing functions related to
+CODE refs, including C<subname> (inspired by C<Sub::Identity>) and C<set_subname>
+(copied and renamed from C<Sub::Name>).
+The use of C<GetMagic> in C<List::Util::reduce()> has also been fixed.
+L<[cpan #63211]|https://rt.cpan.org/Ticket/Display.html?id=63211>
+
+=item *
+
+L<SDBM_File> has been upgraded to version 1.13.
+
+Simplified the build process.  [perl #123413]
+
+=item *
+
+L<Time::Piece> has been upgraded to version 1.29.
+
+When pretty printing negative C<Time::Seconds>, the "minus" is no longer lost.
+
+=item *
+
+L<Unicode::Collate> has been upgraded to version 1.12.
+
+Version 0.67's improved discontiguous contractions is invalidated by default
+and is supported as a parameter C<long_contraction>.
+
+=item *
+
+L<Unicode::Normalize> has been upgraded to version 1.18.
+
+The XSUB implementation has been removed in favor of pure Perl.
+
+=item *
+
+L<Unicode::UCD> has been upgraded to version 0.61.
+
+A new function L<property_values()|Unicode::UCD/prop_values()>
+has been added to return a given property's possible values.
+
+A new function L<charprop()|Unicode::UCD/charprop()>
+has been added to return the value of a given property for a given code
+point.
+
+A new function L<charprops_all()|Unicode::UCD/charprops_all()>
+has been added to return the values of all Unicode properties for a
+given code point.
+
+A bug has been fixed so that L<propaliases()|Unicode::UCD/prop_aliases()>
+returns the correct short and long names for the Perl extensions where
+it was incorrect.
+
+A bug has been fixed so that
+L<prop_value_aliases()|Unicode::UCD/prop_value_aliases()>
+returns C<undef> instead of a wrong result for properties that are Perl
+extensions.
+
+This module now works on EBCDIC platforms.
 
 =item *
 
-L<XXX> has been upgraded from version A.xx to B.yy.
+L<utf8> has been upgraded to version 1.17
+
+A mismatch between the documentation and the code in C<utf8::downgrade()>
+was fixed in favor of the documentation. The optional second argument
+is now correctly treated as a perl boolean (true/false semantics) and
+not as an integer.
+
+=item *
+
+L<version> has been upgraded to version 0.9909.
+
+Numerous changes.  See the F<Changes> file in the CPAN distribution for
+details.
+
+=item *
+
+L<Win32> has been upgraded to version 0.51.
+
+C<GetOSName()> now supports Windows 8.1, and building in C++ mode now works.
+
+=item *
+
+L<Win32API::File> has been upgraded to version 0.1202
+
+Building in C++ mode now works.
+
+=item *
+
+L<XSLoader> has been upgraded to version 0.20.
+
+Allow XSLoader to load modules from a different namespace.
+[perl #122455]
 
 =back
 
 =head2 Removed Modules and Pragmata
 
+The following modules (and associated modules) have been removed from the core
+perl distribution:
+
 =over 4
 
 =item *
 
-XXX
+L<CGI>
+
+=item *
+
+L<Module::Build>
 
 =back
 
@@ -715,6 +1214,17 @@ Perl.
 
 =head2 Changes to Existing Documentation
 
+=head3 L<perlaix>
+
+=over 4
+
+=item *
+
+A note on long doubles has been added.
+
+=back
+
+
 =head3 L<perlapi>
 
 =over 4
@@ -725,7 +1235,7 @@ Note that C<SvSetSV> doesn't do set magic.
 
 =item *
 
-C<sv_usepvn_flags> - Fix documentation to mention the use of C<NewX> instead of
+C<sv_usepvn_flags> - fix documentation to mention the use of C<Newx> instead of
 C<malloc>.
 
 L<[perl #121869]|https://rt.perl.org/Ticket/Display.html?id=121869>
@@ -736,16 +1246,18 @@ Clarify where C<NUL> may be embedded or is required to terminate a string.
 
 =item *
 
-Previously missing documentation due to formatting errors are now included.
+Some documentation that was previously missing due to formatting errors is
+now included.
 
 =item *
 
-Entries are now organized into groups rather than by file where they are found.
+Entries are now organized into groups rather than by the file where they
+are found.
 
 =item *
 
-Alphabetical sorting of entries is now handled by the POD generator to make
-entries easier to find when scanning.
+Alphabetical sorting of entries is now done consistently (automatically
+by the POD generator) to make entries easier to find when scanning.
 
 =back
 
@@ -758,6 +1270,11 @@ entries easier to find when scanning.
 The syntax of single-character variable names has been brought
 up-to-date and more fully explained.
 
+=item *
+
+Hexadecimal floating point numbers are described, as are infinity and
+NaN.
+
 =back
 
 =head3 L<perlebcdic>
@@ -766,92 +1283,177 @@ up-to-date and more fully explained.
 
 =item *
 
-This document has been significantly updated in the light of recent
-improvements to EBCDIC support.
+This document has been significantly updated in the light of recent
+improvements to EBCDIC support.
+
+=back
+
+=head3 L<perlfilter>
+
+=over 4
+
+=item *
+
+Added a L<LIMITATIONS|perlfilter/LIMITATIONS> section.
+
+=back
+
+
+=head3 L<perlfunc>
+
+=over 4
+
+=item *
+
+Mention that C<study()> is currently a no-op.
+
+=item *
+
+Calling C<delete> or C<exists> on array values is now described as "strongly
+discouraged" rather than "deprecated".
+
+=item *
+
+Improve documentation of C<< our >>.
+
+=item *
+
+C<-l> now notes that it will return false if symlinks aren't supported by the
+file system.
+L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523>
+
+=item *
+
+Note that C<exec LIST> and C<system LIST> may fall back to the shell on
+Win32. Only the indirect-object syntax C<exec PROGRAM LIST> and
+C<system PROGRAM LIST> will reliably avoid using the shell.
+
+This has also been noted in L<perlport>.
+
+L<[perl #122046]|https://rt.perl.org/Ticket/Display.html?id=122046>
+
+=back
+
+=head3 L<perlguts>
+
+=over 4
+
+=item *
+
+The OOK example has been updated to account for COW changes and a change in the
+storage of the offset.
+
+=item *
+
+Details on C level symbols and libperl.t added.
+
+=item *
+
+Information on Unicode handling has been added
+
+=item *
+
+Information on EBCDIC handling has been added
+
+=back
+
+=head3 L<perlhack>
+
+=over 4
+
+=item *
+
+A note has been added about running on platforms with non-ASCII
+character sets
+
+=item *
+
+A note has been added about performance testing
 
 =back
 
-=head3 L<perlfunc>
+=head3 L<perlhacktips>
 
 =over 4
 
 =item *
 
-Mention that C<study()> is currently a no-op.
+Documentation has been added illustrating the perils of assuming that
+there is no change to the contents of static memory pointed to by the
+return values of Perl's wrappers for C library functions.
 
 =item *
 
-Calling C<delete> or C<exists> on array values is now described as "strongly
-discouraged" rather than "deprecated".
+Replacements for C<tmpfile>, C<atoi>, C<strtol>, and C<strtoul> are now
+recommended.
 
 =item *
 
-Improve documentation of C<< our >>.
+Updated documentation for the C<test.valgrind> C<make> target.
+L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
 
 =item *
 
-C<-l> now notes that it will return false if symlinks aren't supported by the
-file system.
-
-L<[perl #121523]|https://rt.perl.org/Ticket/Display.html?id=121523>
+Information is given about writing test files portably to non-ASCII
+platforms.
 
 =item *
 
-Note that C<exec LIST> and C<system LIST> may fall back to the shell on
-Win32. Only C<exec PROGRAM LIST> and C<system PROGRAM LIST> indirect object
-syntax will reliably avoid using the shell.
-
-This has also been noted in L<perlport>.
-
-L<[perl #122046]|https://rt.perl.org/Ticket/Display.html?id=122046>
+A note has been added about how to get a C language stack backtrace.
 
 =back
 
-=head3 L<perlguts>
+=head3 L<perlhpux>
 
 =over 4
 
 =item *
 
-The OOK example has been updated to account for COW changes and a change in the
-storage of the offset.
+Note that the message "Redeclaration of "sendpath" with a different
+storage class specifier" is harmless.
+
+=back
+
+=head3 L<perllocale>
+
+=over 4
 
 =item *
 
-Details on C level symbols and libperl.t added.
+Updated for the enhancements in v5.22, along with some clarifications.
 
 =back
 
-=head3 L<perlhacktips>
+=head3 L<perlmodstyle>
 
 =over 4
 
 =item *
 
-Documentation has been added illustrating the perils of assuming the contents
-of static memory pointed to by the return values of Perl wrappers for C library
-functions doesn't change.
+Instead of pointing to the module list, we are now pointing to
+L<PrePAN|http://prepan.org/>.
 
-=item *
+=back
 
-Recommended replacements for tmpfile, atoi, strtol, and strtoul added.
+=head3 L<perlop>
 
-=item *
+=over 4
 
-Updated documentation for the C<test.valgrind> C<make> target.
+=item *
 
-L<[perl #121431]|https://rt.perl.org/Ticket/Display.html?id=121431>
+Updated for the enhancements in v5.22, along with some clarifications.
 
 =back
 
-=head3 L<perlmodstyle>
+=head3 L<perlpodspec>
 
 =over 4
 
 =item *
 
-Instead of pointing to the module list, we are now pointing to
-L<PrePAN|http://prepan.org/>.
+The specification of the pod language is changing so that the default
+encoding of pods that aren't in UTF-8 (unless otherwise indicated) is
+CP1252 instead of ISO 8859-1 (Latin1).
 
 =back
 
@@ -869,6 +1471,11 @@ in L<< perlpolicy/STANDARDS OF CONDUCT >>.
 The conditions for marking an experimental feature as non-experimental are now
 set out.
 
+=item *
+
+Clarification has been made as to what sorts of changes are permissible in
+maintenance releases.
+
 =back
 
 =head3 L<perlport>
@@ -877,7 +1484,11 @@ set out.
 
 =item *
 
-Out-of-date VMS-specific information has been fixed/simplified.
+Out-of-date VMS-specific information has been fixed and/or simplified.
+
+=item *
+
+Notes about EBCDIC have been added.
 
 =back
 
@@ -887,8 +1498,19 @@ Out-of-date VMS-specific information has been fixed/simplified.
 
 =item *
 
-The C</x> modifier has been clarified to note that comments cannot be continued
-onto the next line by escaping them.
+The description of the C</x> modifier has been clarified to note that
+comments cannot be continued onto the next line by escaping them; and
+there is now a list of all the characters that are considered whitespace
+by this modifier.
+
+=item *
+
+The new C</n> modifier is described.
+
+=item *
+
+A note has been added on how to make bracketed character class ranges
+portable to non-ASCII machines.
 
 =back
 
@@ -909,11 +1531,11 @@ Added documentation of C<\b{sb}>, C<\b{wb}>, C<\b{gcb}>, and C<\b{g}>.
 =item *
 
 Clarifications have been added to L<perlrecharclass/Character Ranges>
-to the effect that Perl guarantees that C<[A-Z]>, C<[a-z]>, C<[0-9]> and
+to the effect C<[A-Z]>, C<[a-z]>, C<[0-9]> and
 any subranges thereof in regular expression bracketed character classes
 are guaranteed to match exactly what a naive English speaker would
-expect them to match, even on platforms (such as EBCDIC) where special
-handling is required to accomplish this.
+expect them to match, even on platforms (such as EBCDIC) where perl
+has to do extra work to accomplish this.
 
 =item *
 
@@ -922,6 +1544,17 @@ improvements in C<qr/[\N{named sequence}]/> (see under L</Selected Bug Fixes>).
 
 =back
 
+=head3 L<perlref>
+
+=over 4
+
+=item *
+
+A new section has been added
+L<Assigning to References|perlref/Assigning to References>
+
+=back
+
 =head3 L<perlsec>
 
 =over 4
@@ -954,9 +1587,11 @@ in L<< perlsyn >>.
 
 =item *
 
-Update B<Default Word Boundaries> under
-L<perlunicode/"Unicode Regular Expression Support Level">'s
-B<Extended Unicode Support>.
+This has had extensive revisions to bring it up-to-date with current
+Unicode support and to make it more readable.  Notable is that Unicode
+7.0 changed what it should do with non-characters.  Perl retains the old
+way of handling for reasons of backward compatibility.  See
+L<perlunicode/Noncharacter code points>.
 
 =back
 
@@ -967,8 +1602,7 @@ B<Extended Unicode Support>.
 =item *
 
 Advice for how to make sure your strings and regular expression patterns are
-interpreted as Unicode has been revised to account for the new Perl 5.22 EBCDIC
-handling.
+interpreted as Unicode has been updated.
 
 =back
 
@@ -978,7 +1612,18 @@ handling.
 
 =item *
 
-Further clarify version number representations and usage.
+C<$]> is no longer listed as being deprecated.  Instead, discussion has
+been added on the advantages and disadvantages of using it versus
+C<$^V>.
+
+=item *
+
+C<${^ENCODING}> is now marked as deprecated.
+
+=item *
+
+The entry for C<%^H> has been clarified to indicate it can only handle
+simple values.
 
 =back
 
@@ -1045,9 +1690,9 @@ allow this syntax, but shouldn't have.
 
 L<Can't use 'defined(@array)' (Maybe you should just omit the defined()?)|perldiag/"Can't use 'defined(@array)' (Maybe you should just omit the defined()?)">
 
-(F) defined() is not useful on arrays because it
+(F) C<defined()> is not useful on arrays because it
 checks for an undefined I<scalar> value.  If you want to see if the
-array is empty, just use C<if (@array) { # not empty }> for example.
+array is empty, just use S<C<if (@array) { # not empty }>> for example.
 
 =item *
 
@@ -1055,10 +1700,10 @@ L<Can't use 'defined(%hash)' (Maybe you should just omit the defined()?)|perldia
 
 (F) C<defined()> is not usually right on hashes.
 
-Although C<defined %hash> is false on a plain not-yet-used hash, it
+Although S<C<defined %hash>> is false on a plain not-yet-used hash, it
 becomes true in several non-obvious circumstances, including iterators,
-weak references, stash names, even remaining true after C<undef %hash>.
-These things make C<defined %hash> fairly useless in practice, so it now
+weak references, stash names, even remaining true after S<C<undef %hash>>.
+These things make S<C<defined %hash>> fairly useless in practice, so it now
 generates a fatal error.
 
 If a check for non-empty is what you wanted then just put it in boolean
@@ -1068,7 +1713,7 @@ context (see L<perldata/Scalar values>):
        # not empty
     }
 
-If you had C<defined %Foo::Bar::QUUX> to check whether such a package
+If you had S<C<defined %Foo::Bar::QUUX>> to check whether such a package
 variable exists then that's never really been reliable, and isn't
 a good way to enquire about the features of a package, or whether
 it's loaded, etc.
@@ -1098,8 +1743,8 @@ which makes no sense.
 
 L<Cannot print %f with '%c'|perldiag/"Cannot printf %f with '%c'">
 
-(F) You tried printing an infinity or not-a-number as a character (%c),
-which makes no sense.  Maybe you meant '%s', or just stringifying it?
+(F) You tried printing an infinity or not-a-number as a character (C<%c>),
+which makes no sense.  Maybe you meant C<'%s'>, or just stringifying it?
 
 =item *
 
@@ -1125,8 +1770,8 @@ See L<charnames/CUSTOM ALIASES>.
 
 L<:const is not permitted on named subroutines|perldiag/":const is not permitted on named subroutines">
 
-(F) The "const" attribute causes an anonymous subroutine to be run and
-its value captured at the time that it is cloned.  Names subroutines are
+(F) The C<const> attribute causes an anonymous subroutine to be run and
+its value captured at the time that it is cloned.  Named subroutines are
 not cloned like this, so the attribute does not make sense on them.
 
 =item *
@@ -1172,10 +1817,28 @@ and the C<"*">, but you separated them.
 L<Invalid quantifier in {,} in regex; marked by <-- HERE in mE<sol>%sE<sol>|perldiag/"Invalid quantifier in {,} in regex; marked by <-- HERE in m/%s/">
 
 (F) The pattern looks like a {min,max} quantifier, but the min or max could not
-be parsed as a valid number - either it has leading zeroes, or it represents
+be parsed as a valid number: either it has leading zeroes, or it represents
 too big a number to cope with.  The S<<-- HERE> shows where in the regular
 expression the problem was discovered.  See L<perlre>.
 
+=item *
+
+L<'%s' is an unknown bound type in regex|perldiag/"'%s' is an unknown bound type in regex; marked by <-- HERE in m/%s/">
+
+(F) You used C<\b{...}> or C<\B{...}> and the C<...> is not known to
+Perl.  The current valid ones are given in
+L<perlrebackslash/\b{}, \b, \B{}, \B>.
+
+=item *
+
+L<Missing or undefined argument to require|perldiag/Missing or undefined argument to require>
+
+(F) You tried to call C<require> with no argument or with an undefined
+value as an argument.  C<require> expects either a package name or a
+file-specification as an argument.  See L<perlfunc/require>.
+
+Formerly, C<require> with no argument or C<undef> warned about a Null filename.
+
 =back
 
 =head3 New Warnings
@@ -1184,11 +1847,13 @@ expression the problem was discovered.  See L<perlre>.
 
 =item *
 
-L<'%s' is an unknown bound type in regex|perldiag/"'%s' is an unknown bound type in regex; marked by <-- HERE in m/%s/">
+L<\C is deprecated in regex|perldiag/"\C is deprecated in regex; marked by <-- HERE in m/%s/">
 
-You used C<\b{...}> or C<\B{...}> and the C<...> is not known to
-Perl.  The current valid ones are given in
-L<perlrebackslash/\b{}, \b, \B{}, \B>.
+(D deprecated) The C<< /\C/ >> character class was deprecated in v5.20, and
+now emits a warning. It is intended that it will become an error in v5.24.
+This character class matches a single byte even if it appears within a
+multi-byte character, breaks encapsulation, and can corrupt UTF-8
+strings.
 
 =item *
 
@@ -1228,9 +1893,20 @@ the warning gets raised.
 
 =item *
 
+L<Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".|perldiag/Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".>
+
+(W locale) You are 1) running under "C<use locale>"; 2) the current
+locale is not a UTF-8 one; 3) you tried to do the designated case-change
+operation on the specified Unicode character; and 4) the result of this
+operation would mix Unicode and locale rules, which likely conflict.
+
+The warnings category C<locale> is new.
+
+=item *
+
 L<:const is experimental|perldiag/":const is experimental">
 
-(S experimental::const_attr) The "const" attribute is experimental.
+(S experimental::const_attr) The C<const> attribute is experimental.
 If you want to use the feature, disable the warning with C<no warnings
 'experimental::const_attr'>, but know that in doing so you are taking
 the risk that your code may break in a future Perl version.
@@ -1261,7 +1937,7 @@ than the floating point supports.
 L<Hexadecimal float: mantissa overflow|perldiag/"Hexadecimal float: mantissa overflow">
 
 (W overflow) The hexadecimal floating point literal had more bits in
-the mantissa (the part between the 0x and the exponent, also known as
+the mantissa (the part between the C<0x> and the exponent, also known as
 the fraction or the significand) than the floating point supports.
 
 =item *
@@ -1275,6 +1951,16 @@ long double formats, or by 64-bit integers not being available
 
 =item *
 
+L<Locale '%s' may not work well.%s|perldiag/Locale '%s' may not work well.%s>
+
+(W locale) You are using the named locale, which is a non-UTF-8 one, and
+which perl has determined is not fully compatible with what it can
+handle.  The second C<%s> gives a reason.
+
+The warnings category C<locale> is new.
+
+=item *
+
 L<localtime(%f) failed|perldiag/"localtime(%f) failed">
 
 (W overflow) You called C<localtime> with a number that it could not handle:
@@ -1304,7 +1990,7 @@ L<Non-finite repeat count does nothing|perldiag/"Non-finite repeat count does no
 
 (W numeric) You tried to execute the
 L<C<x>|perlop/Multiplicative Operators> repetition operator C<Inf> (or
-C<-Inf>) or C<NaN> times, which doesn't make sense.
+C<-Inf>) or NaN times, which doesn't make sense.
 
 =item *
 
@@ -1342,7 +2028,7 @@ the endpoints are specified by
 L<C<\N{...}>|perlrecharclass/Character Ranges>, but the meaning may
 still not be obvious.)
 The stricter rules require that ranges that start or stop with an ASCII
-character that is not a control have all their endpoints be the literal
+character that is not a control have all their endpoints be a literal
 character, and not some escape sequence (like C<"\x41">), and the ranges
 must be all digits, or all uppercase letters, or all lowercase letters.
 
@@ -1361,30 +2047,42 @@ the same group of 10 consecutive digits.
 
 L<Redundant argument in %s|perldiag/Redundant argument in %s>
 
-(W redundant) You called a function with more arguments than other
-arguments you supplied indicated would be needed. Currently only
-emitted when a printf-type format required fewer arguments than were
-supplied, but might be used in the future for e.g. L<perlfunc/pack>.
+(W redundant) You called a function with more arguments than were
+needed, as indicated by information within other arguments you supplied
+(I<e.g>. a printf format). Currently only emitted when a printf-type format
+required fewer arguments than were supplied, but might be used in the
+future for I<e.g.> L<perlfunc/pack>.
 
 The warnings category C<< redundant >> is new. See also
 L<[perl #121025]|https://rt.perl.org/Ticket/Display.html?id=121025>.
 
 =item *
 
+L<Replacement list is longer than search list|perldiag/Replacement list is longer than search list>
+
+This is not a new diagnostic, but in earlier releases was accidentally
+not displayed if the transliteration contained wide characters.  This is
+now fixed, so that you may see this diagnostic in places where you
+previously didn't (but should have).
+
+=item *
+
 L<Use of \b{} for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale|perldiag/"Use of \b{} for non-UTF-8 locale is wrong.  Assuming a UTF-8 locale">
 
-You are matching a regular expression using locale rules,
+(W locale) You are matching a regular expression using locale rules,
 and a Unicode boundary is being matched, but the locale is not a Unicode
 one.  This doesn't make sense.  Perl will continue, assuming a Unicode
 (UTF-8) locale, but the results could well be wrong except if the locale
 happens to be ISO-8859-1 (Latin1) where this message is spurious and can
 be ignored.
 
+The warnings category C<locale> is new.
+
 =item *
 
 L<< Using E<sol>u for '%s' instead of E<sol>%s in regex; marked by E<lt>-- HERE in mE<sol>%sE<sol>|perldiag/"Using E<sol>u for '%s' instead of E<sol>%s in regex; marked by <-- HERE in mE<sol>%sE<sol>" >>
 
-You used a Unicode boundary (C<\b{...}> or C<\B{...}>) in a
+(W regexp) You used a Unicode boundary (C<\b{...}> or C<\B{...}>) in a
 portion of a regular expression where the character set modifiers C</a>
 or C</aa> are in effect.  These two modifiers indicate an ASCII
 interpretation, and this doesn't make sense for a Unicode definition.
@@ -1395,7 +2093,7 @@ all of Unicode.  No other portion of the regular expression is affected.
 
 L<The bitwise feature is experimental|perldiag/"The bitwise feature is experimental">
 
-This warning is emitted if you use bitwise
+(S experimental::bitwise) This warning is emitted if you use bitwise
 operators (C<& | ^ ~ &. |. ^. ~.>) with the "bitwise" feature enabled.
 Simply suppress the warning if you want to use the feature, but know
 that in doing so you are taking the risk of using an experimental
@@ -1422,36 +2120,67 @@ example,
 
 L<Use of literal non-graphic characters in variable names is deprecated|perldiag/"Use of literal non-graphic characters in variable names is deprecated">
 
+(D deprecated) Using literal non-graphic (including control)
+characters in the source to refer to the I<^FOO> variables, like C<$^X> and
+C<${^GLOBAL_PHASE}> is now deprecated.
+
 =item *
 
 L<Useless use of attribute "const"|perldiag/Useless use of attribute "const">
 
-(W misc) The "const" attribute has no effect except
+(W misc) The C<const> attribute has no effect except
 on anonymous closure prototypes.  You applied it to
 a subroutine via L<attributes.pm|attributes>.  This is only useful
 inside an attribute handler for an anonymous subroutine.
 
 =item *
 
+L<Useless use of E<sol>d modifier in transliteration operator|perldiag/"Useless use of /d modifier in transliteration operator">
+
+This is not a new diagnostic, but in earlier releases was accidentally
+not displayed if the transliteration contained wide characters.  This is
+now fixed, so that you may see this diagnostic in places where you
+previously didn't (but should have).
+
+=item *
+
 L<E<quot>use re 'strict'E<quot> is experimental|perldiag/"use re 'strict'" is experimental>
 
 (S experimental::re_strict) The things that are different when a regular
 expression pattern is compiled under C<'strict'> are subject to change
-in future Perl releases in incompatible ways.  This means that a pattern
-that compiles today may not in a future Perl release.  This warning is
-to alert you to that risk.
+in future Perl releases in incompatible ways; there are also proposals
+to change how to enable strict checking instead of using this subpragma.
+This means that a pattern that compiles today may not in a future Perl
+release.  This warning is to alert you to that risk.
 
 =item *
 
+L<Warning: unable to close filehandle properly: %s|perldiag/"Warning: unable to close filehandle properly: %s">
+
 L<Warning: unable to close filehandle %s properly: %s|perldiag/"Warning: unable to close filehandle %s properly: %s">
 
+(S io) Previously, perl silently ignored any errors when doing an implicit
+close of a filehandle, I<i.e.> where the reference count of the filehandle
+reached zero and the user's code hadn't already called C<close()>; I<e.g.>
+
+    {
+        open my $fh, '>', $file  or die "open: '$file': $!\n";
+        print $fh, $data  or die;
+    } # implicit close here
+
+In a situation such as disk full, due to buffering, the error may only be
+detected during the final close, so not checking the result of the close is
+dangerous.
+
+So perl now warns in such situations.
+
 =item *
 
 L<Wide character (U+%X) in %s|perldiag/"Wide character (U+%X) in %s">
 
 (W locale) While in a single-byte locale (I<i.e.>, a non-UTF-8
 one), a multi-byte character was encountered.   Perl considers this
-character to be the specified Unicode code point.  Combining non-UTF8
+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
@@ -1461,32 +2190,7 @@ 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).
 
-=item *
-
-The following two warnings for C<tr///> used to be skipped if the
-transliteration contained wide characters, but now they occur regardless of
-whether there are wide characters or not:
-
-L<Useless use of E<sol>d modifier in transliteration operator|perldiag/"Useless use of /d modifier in transliteration operator">
-
-L<Replacement list is longer than search list|perldiag/Replacement list is longer than search list>
-
-=item *
-
-A new C<locale> warning category has been created, with the following warning
-messages currently in it:
-
-=over 4
-
-=item *
-
-L<Locale '%s' may not work well.%s|perldiag/Locale '%s' may not work well.%s>
-
-=item *
-
-L<Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".|perldiag/Can't do %s("%s") on non-UTF-8 locale; resolved to "%s".>
-
-=back
+The warnings category C<locale> is new.
 
 =back
 
@@ -1505,9 +2209,10 @@ to make the issue more identifiable.
 =item *
 
 L<Argument "%s" isn't numeric%s|perldiag/"Argument "%s" isn't numeric%s">
-now adds the following note:
 
- Note that for the C<Inf> and C<NaN> (infinity and not-a-number) the
+The L<perldiag> entry for this warning has added this clarifying note:
+
+ Note that for the Inf and NaN (infinity and not-a-number) the
  definition of "numeric" is somewhat unusual: the strings themselves
  (like "Inf") are considered numeric, and anything following them is
  considered non-numeric.
@@ -1527,31 +2232,29 @@ L<[perl #121638]|https://rt.perl.org/Ticket/Display.html?id=121638>
 
 =item *
 
-L<\N{} in character class restricted to one character in regex; marked by S<<-- HERE> in mE<sol>%sE<sol>|perldiag/"\N{} in inverted character class or as a range end-point is restricted to one character in regex; marked by <-- HERE in m/%s/">
+L<<< \N{} in character class restricted to one character in regex; marked by
+S<< <-- HERE >> in mE<sol>%sE<sol>|perldiag/"\N{} in inverted character
+class or as a range end-point is restricted to one character in regex;
+marked by <-- HERE in m/%s/" >>>
 
-This message has had 'character class' changed to 'inverted character class or
-as a range end-point is' to reflect improvements in C<qr/[\N{named sequence}]/>
-(see under L</Selected Bug Fixes>).
+This message has had I<character class> changed to I<inverted character
+class or as a range end-point is> to reflect improvements in
+C<qr/[\N{named sequence}]/> (see under L</Selected Bug Fixes>).
 
 =item *
 
 L<panic: frexp|perldiag/"panic: frexp: %f">
 
-This message has had ': %f' appended to it, to show what the offending floating
-point number is.
+This message has had ': C<%f>' appended to it, to show what the offending
+floating point number is.
 
 =item *
 
-B<Possible precedence problem on bitwise %c operator> reworded as
+I<Possible precedence problem on bitwise %c operator> reworded as
 L<Possible precedence problem on bitwise %s operator|perldiag/"Possible precedence problem on bitwise %s operator">.
 
 =item *
 
-C<require> with no argument or undef used to warn about a Null filename; now
-it dies with C<Missing or undefined argument to require>.
-
-=item *
-
 L<Unsuccessful %s on filename containing newline|perldiag/"Unsuccessful %s on filename containing newline">
 
 This warning is now only produced when the newline is at the end of
@@ -1559,14 +2262,15 @@ the filename.
 
 =item *
 
-"Variable %s will not stay shared" has been changed to say "Subroutine"
+"Variable C<%s> will not stay shared" has been changed to say "Subroutine"
 when it is actually a lexical sub that will not stay shared.
 
 =item *
 
 L<Variable length lookbehind not implemented in regex mE<sol>%sE<sol>|perldiag/"Variable length lookbehind not implemented in regex m/%s/">
 
-Information about Unicode behaviour has been added.
+The L<perldiag> entry for this warning has had information about Unicode
+behavior added.
 
 =back
 
@@ -1579,13 +2283,13 @@ Information about Unicode behaviour has been added.
 "Ambiguous use of -foo resolved as -&foo()"
 
 There is actually no ambiguity here, and this impedes the use of negated
-constants; e.g., C<-Inf>.
+constants; I<e.g.>, C<-Inf>.
 
 =item *
 
 "Constant is not a FOO reference"
 
-Compile-time checking of constant dereferencing (e.g., C<< my_constant->() >>)
+Compile-time checking of constant dereferencing (I<e.g.>, C<< my_constant->() >>)
 has been removed, since it was not taking overloading into account.
 L<[perl #69456]|https://rt.perl.org/Ticket/Display.html?id=69456>
 L<[perl #122607]|https://rt.perl.org/Ticket/Display.html?id=122607>
@@ -1594,7 +2298,7 @@ L<[perl #122607]|https://rt.perl.org/Ticket/Display.html?id=122607>
 
 =head1 Utility Changes
 
-=head2 F<x2p/>
+=head2 F<find2perl>, F<s2p> and F<a2p> removal
 
 =over 4
 
@@ -1603,7 +2307,7 @@ L<[perl #122607]|https://rt.perl.org/Ticket/Display.html?id=122607>
 The F<x2p/> directory has been removed from the Perl core.
 
 This removes find2perl, s2p and a2p. They have all been released to CPAN as
-separate distributions (App::find2perl, App::s2p, App::a2p).
+separate distributions (C<App::find2perl>, C<App::s2p>, C<App::a2p>).
 
 =back
 
@@ -1625,7 +2329,7 @@ L<[perl #123784]|https://rt.perl.org/Ticket/Display.html?id=123784>.
 
 =item *
 
-No longer depends on non-core module anymore.
+No longer depends on non-core modules.
 
 =back
 
@@ -1635,7 +2339,8 @@ No longer depends on non-core module anymore.
 
 =item *
 
-F<Configure> now checks for F<lrintl>, F<lroundl>, F<llrintl>, and F<llroundl>.
+F<Configure> now checks for C<lrintl()>, C<lroundl()>, C<llrintl()>, and
+C<llroundl()>.
 
 =item *
 
@@ -1644,16 +2349,17 @@ L<[perl #122002]|https://rt.perl.org/Ticket/Display.html?id=122002>.
 
 =item *
 
-pthreads and lcl will be linked by default if present. This allows XS modules
-that require threading to work on non-threaded perls. Note that you must still
-pass C<-Dusethreads> if you want a threaded perl.
+The C<pthreads> and C<cl> libraries will be linked by default if present.
+This allows XS modules that require threading to work on non-threaded
+perls. Note that you must still pass C<-Dusethreads> if you want a
+threaded perl.
 
 =item *
 
 For long doubles (to get more precision and range for floating point numbers)
 one can now use the GCC quadmath library which implements the quadruple
-precision floating point numbers in x86 and ia64 platforms.  See F<INSTALL> for
-details.
+precision floating point numbers on x86 and IA-64 platforms.  See
+F<INSTALL> for details.
 
 =item *
 
@@ -1688,6 +2394,11 @@ and had probably seriously diverged on both Perl 5 and Perl 6 sides.
 A new compilation flag, C<< -DPERL_OP_PARENT >> is available. For details,
 see the discussion below at L<< /Internal Changes >>.
 
+=item *
+
+Pathtools no longer tries to load XS on miniperl. This speeds up building perl
+slightly.
+
 =back
 
 =head1 Testing
@@ -1698,8 +2409,8 @@ see the discussion below at L<< /Internal Changes >>.
 
 F<t/porting/re_context.t> has been added to test that L<utf8> and its
 dependencies only use the subset of the C<$1..$n> capture vars that
-Perl_save_re_context() is hard-coded to localize, because that function has no
-efficient way of determining at runtime what vars to localize.
+C<Perl_save_re_context()> is hard-coded to localize, because that function
+has no efficient way of determining at runtime what vars to localize.
 
 =item *
 
@@ -1719,7 +2430,7 @@ more compatible with C<< Test::More >>.
 
 =item *
 
-A new test script, F<op/infnan.t>, has been added to test if Inf and NaN are
+A new test script, F<op/infnan.t>, has been added to test if infinity and NaN are
 working correctly.  See L</Infinity and NaN (not-a-number) handling improved>.
 
 =back
@@ -1732,7 +2443,11 @@ working correctly.  See L</Infinity and NaN (not-a-number) handling improved>.
 
 =item IRIX and Tru64 platforms are working again.
 
-(Some C<make test> failures remain.)
+Some C<make test> failures remain:
+L<[perl #123977]|https://rt.perl.org/Ticket/Display.html?id=123977>
+and L<[perl #125298]|https://rt.perl.org/Ticket/Display.html?id=125298>
+for IRIX; L<[perl #124212]|https://rt.perl.org/Ticket/Display.html?id=124212>
+for Tru64.
 
 =item z/OS running EBCDIC Code Page 1047
 
@@ -1740,7 +2455,7 @@ 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
-Pod::Simple.  However the version of Pod::Simple currently on CPAN should work;
+C<Pod::Simple>.  However the version of C<Pod::Simple> currently on CPAN should work;
 it was fixed too late to include in Perl 5.22.  Work is under way to fix many
 of the still-broken CPAN modules, which likely will be installed on CPAN when
 completed, so that you may not have to wait until Perl 5.24 to get a working
@@ -1754,10 +2469,10 @@ version.
 
 =item NeXTSTEP/OPENSTEP
 
-NeXTSTEP was proprietary OS 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.
+NeXTSTEP was a proprietary operating system bundled with NeXT's
+workstations in the early to mid 90s; OPENSTEP was an API specification
+that provided a NeXTSTEP-like environment on a non-NeXTSTEP system.  Both
+are now long dead, so support for building Perl on them has been removed.
 
 =back
 
@@ -1767,8 +2482,9 @@ for building Perl on them has been removed.
 
 =item EBCDIC
 
-Special handling is required on EBCDIC platforms to get C<qr/[i-j]/> to
-match only C<"i"> and C<"j">, since there are 7 characters between the
+Special handling is required of the perl interpreter on EBCDIC platforms
+to get C<qr/[i-j]/> to match only C<"i"> and C<"j">, since there are 7
+characters between the
 code points for C<"i"> and C<"j">.  This special handling had only been
 invoked when both ends of the range are literals.  Now it is also
 invoked if any of the C<\N{...}> forms for specifying a character by
@@ -1817,8 +2533,10 @@ L<[perl #123976]|https://rt.perl.org/Ticket/Display.html?id=123976>
 
 =item *
 
-C<test-prep> again depends on C<test-prep-gcc> for GCC builds.
-L<[perl #124221]|https://rt.perl.org/Ticket/Display.html?id=124221>
+C<nmake minitest> now works on Win32.  Due to dependency issues you
+need to build C<nmake test-prep> first, and a small number of the
+tests fail.
+L<[perl #123394]|https://rt.perl.org/Ticket/Display.html?id=123394>
 
 =item *
 
@@ -1827,11 +2545,9 @@ C<USE_CPLUSPLUS> to the value "define".
 
 =item *
 
-List form pipe open no longer falls back to the shell.
-
-=item *
-
-In release 5.21.8 compiling on VC with dmake was broken. Fixed.
+The list form of piped open has been implemented for Win32.  Note: unlike
+C<system LIST> this does not fall back to the shell.
+L<[perl #121159]|https://rt.perl.org/Ticket/Display.html?id=121159>
 
 =item *
 
@@ -1840,15 +2556,9 @@ Windows makefiles.
 
 =item *
 
-L<B> now compiles again on Windows.
-
-=item *
-
-Previously, on Visual C++ for Win64 built Perls only, when compiling every Perl
-XS module (including CPAN ones) and Perl aware .c file with a 64 bit Visual C++,
-would unconditionally have around a dozen warnings from hv_func.h.  These
-warnings have been silenced.  GCC all bitness and Visual C++ for Win32 were
-not affected.
+Previously, compiling XS modules (including CPAN ones) using Visual C++ for
+Win64 resulted in around a dozen warnings per file from F<hv_func.h>.  These
+warnings have been silenced.
 
 =item *
 
@@ -1858,8 +2568,8 @@ already not supported by F<Configure> on POSIX systems.
 
 =item *
 
-Between 2 and 6 ms and 7 I/O calls have been saved per attempt to open a perl
-module for each path in C<@INC>.
+Between 2 and 6 milliseconds and seven I/O calls have been saved per attempt
+to open a perl module for each path in C<@INC>.
 
 =item *
 
@@ -1872,8 +2582,8 @@ C<%I64d> is now being used instead of C<%lld> for MinGW.
 =item *
 
 In the experimental C<:win32> layer, a crash in C<open> was fixed. Also
-opening C</dev/null>, which works the Win32 Perl's normal C<:unix> layer, was
-implemented for C<:win32>.
+opening F</dev/null> (which works under Win32 Perl's default C<:unix>
+layer) was implemented for C<:win32>.
 L<[perl #122224]|https://rt.perl.org/Ticket/Display.html?id=122224>
 
 =item *
@@ -1912,8 +2622,8 @@ L<[perl #120120]|https://rt.perl.org/Ticket/Display.html?id=120120>
 
 =item *
 
-C<c99> options have been cleaned up, hints look for C<solstudio>
-as well as C<SUNWspro>, and support for native C<setenv> has been added.
+C99 options have been cleaned up; hints look for C<solstudio>
+as well as C<SUNWspro>; and support for native C<setenv> has been added.
 
 =back
 
@@ -1928,15 +2638,15 @@ as well as C<SUNWspro>, and support for native C<setenv> has been added.
 Experimental support has been added to allow ops in the optree to locate
 their parent, if any. This is enabled by the non-default build option
 C<-DPERL_OP_PARENT>. It is envisaged that this will eventually become
-enabled by default, so XS code which directly accesses the C<op_silbing>
+enabled by default, so XS code which directly accesses the C<op_sibling>
 field of ops should be updated to be future-proofed.
 
 On C<PERL_OP_PARENT> builds, the C<op_sibling> field has been renamed
 C<op_sibparent> and a new flag, C<op_moresib>, added. On the last op in a
 sibling chain, C<op_moresib> is false and C<op_sibparent> points to the
-parent (if any) rather than to being C<NULL>.
+parent (if any) rather than being C<NULL>.
 
-To make existing code work transparently whether using C<-DPERL_OP_PARENT>
+To make existing code work transparently whether using C<PERL_OP_PARENT>
 or not, a number of new macros and functions have been added that should
 be used, rather than directly manipulating C<op_sibling>.
 
@@ -1944,13 +2654,13 @@ For the case of just reading C<op_sibling> to determine the next sibling,
 two new macros have been added. A simple scan through a sibling chain
 like this:
 
-    for (; kid->op_sibling; kid = kid->op_sibling) { ...  }
+    for (; kid->op_sibling; kid = kid->op_sibling) { ... }
 
 should now be written as:
 
-    for (; OpHAS_SIBLING(kid); kid = OpSIBLING(kid)) { ...  }
+    for (; OpHAS_SIBLING(kid); kid = OpSIBLING(kid)) { ... }
 
-For altering optrees, A general-purpose function C<op_sibling_splice()>
+For altering optrees, a general-purpose function C<op_sibling_splice()>
 has been added, which allows for manipulation of a chain of sibling ops.
 By analogy with the Perl function C<splice()>, it allows you to cut out
 zero or more ops from a sibling chain and replace them with zero or more
@@ -1964,18 +2674,18 @@ also updating C<op_moresib>.  The first sets the sibling pointer to a new
 sibling, the second makes the op the last sibling, and the third
 conditionally does the first or second action.  Note that unlike
 C<op_sibling_splice()> these macros won't maintain consistency in the
-parent at the same time (e.g. by updating C<op_first> and C<op_last> where
+parent at the same time (I<e.g.> by updating C<op_first> and C<op_last> where
 appropriate).
 
-A C-level C<Perl_op_parent()> function and a perl-level C<B::OP::parent()>
+A C-level C<Perl_op_parent()> function and a Perl-level C<B::OP::parent()>
 method have been added. The C function only exists under
-C<-DPERL_OP_PARENT> builds (using it is build-time error on vanilla
+C<PERL_OP_PARENT> builds (using it is build-time error on vanilla
 perls).  C<B::OP::parent()> exists always, but on a vanilla build it
-always returns C<NULL>. Under C<-DPERL_OP_PARENT>, they return the parent
+always returns C<NULL>. Under C<PERL_OP_PARENT>, they return the parent
 of the current op, if any. The variable C<$B::OP::does_parent> allows you
 to determine whether C<B> supports retrieving an op's parent.
 
-C<-DPERL_OP_PARENT> was introduced in 5.21.2, but the interface was
+C<PERL_OP_PARENT> was introduced in 5.21.2, but the interface was
 changed considerably in 5.21.11. If you updated your code before the
 5.21.11 changes, it may require further revision. The main changes after
 5.21.2 were:
@@ -1996,7 +2706,7 @@ inverted.
 =item *
 
 The macro C<OpSIBLING_set> has been removed, and has been superseded by
-C<OpMORESIB_set> et al.
+C<OpMORESIB_set> I<et al>.
 
 =item *
 
@@ -2013,27 +2723,24 @@ category C<LC_NUMERIC>.  See L<perlapi/Locale-related functions and macros>.
 
 =item *
 
-The previous C<atoi> et al replacement function, C<grok_atou>, has now been
+The previous C<atoi> I<et al> replacement function, C<grok_atou>, has now been
 superseded by C<grok_atoUV>.  See L<perlclib> for details.
 
 =item *
 
-Added Perl_sv_get_backrefs() to determine if an SV is a weak-referent.
-
-Function either returns an SV * of type AV, which contains the set of
-weakreferences which reference the passed in SV, or a simple RV * which
-is the only weakref to this item.
+A new function, C<Perl_sv_get_backrefs()>, has been added which allows you
+retrieve the weak references, if any, which point at an SV.
 
 =item *
 
-C<screaminstr> has been removed. Although marked as public API, it is
-undocumented and has no usage in modern perl versions on CPAN Grep. Calling it
-has been fatal since 5.17.0.
+The C<screaminstr()> function has been removed. Although marked as
+public API, it was undocumented and had no usage in CPAN modules. Calling
+it has been fatal since 5.17.0.
 
 =item *
 
-C<newDEFSVOP>, C<block_start>, C<block_end> and C<intro_my> have been added
-to the API.
+The C<newDEFSVOP()>, C<block_start()>, C<block_end()> and C<intro_my()>
+functions have been added to the API.
 
 =item *
 
@@ -2042,56 +2749,54 @@ C<op_convert_list> and added to the API.
 
 =item *
 
-C<sv_magic> 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.
+The C<sv_magic()> function no longer forbids "ext" magic on read-only
+values.  After all, perl can't know whether the custom magic will modify
+the SV or not.
 L<[perl #123103]|https://rt.perl.org/Ticket/Display.html?id=123103>.
 
 =item *
 
-Starting in 5.21.6, accessing L<perlapi/CvPADLIST> in an XSUB is forbidden.
-CvPADLIST has been reused for a different internal purpose for XSUBs. Guard all
-CvPADLIST expressions with C<CvISXSUB()> if your code doesn't already block
-XSUB CV*s from going through optree CV* expecting code.
+Accessing L<perlapi/CvPADLIST> on an XSUB is now forbidden.
+
+The C<CvPADLIST> field has been reused for a different internal purpose
+for XSUBs. So in particular, you can no longer rely on it being NULL as a
+test of whether a CV is an XSUB. Use C<CvISXSUB()> instead.
 
 =item *
 
-SVs of type SVt_NV are now bodyless when a build configure and platform allow
-it, specifically C<sizeof(NV) <= sizeof(IV)>. The bodyless trick is the same one
-as for IVs since 5.9.2, but for NVs, unlike IVs, is not guaranteed on all
-platforms and build configurations.
+SVs of type C<SVt_NV> are now sometimes bodiless when the build
+configuration and platform allow it: specifically, when C<< sizeof(NV) <=
+sizeof(IV) >>. "Bodiless" means that the NV value is stored directly in
+the head of an SV, without requiring a separate body to be allocated. This
+trick has already been used for IVs since 5.9.2 (though in the case of
+IVs, it is always used, regardless of platform and build configuration).
 
 =item *
 
-The C<$DB::single>, C<$DB::signal> and C<$DB::trace> now have set and
-get magic that stores their values as IVs and those IVs are used when
-testing their values in C<pp_dbstate>.  This prevents perl from
-recursing infinity if an overloaded object is assigned to any of those
+The C<$DB::single>, C<$DB::signal> and C<$DB::trace> variables now have set- and
+get-magic that stores their values as IVs, and those IVs are used when
+testing their values in C<pp_dbstate()>.  This prevents perl from
+recursing infinitely if an overloaded object is assigned to any of those
 variables.
 L<[perl #122445]|https://rt.perl.org/Ticket/Display.html?id=122445>.
 
 =item *
 
-C<Perl_tmps_grow> which is marked as public API but undocumented has been
-removed from public API. If you use C<EXTEND_MORTAL> macro in your XS code to
-preextend the mortal stack, you are unaffected by this change.
-
-=item *
-
-C<cv_name>, which was introduced in 5.21.4, has been changed incompatibly.
-It now has a flags field that allows the caller to specify whether the name
-should be fully qualified.  See L<perlapi/cv_name>.
+C<Perl_tmps_grow()>, which is marked as public API but is undocumented, has
+been removed from the public API. This change does not affect XS code that
+uses the C<EXTEND_MORTAL> macro to pre-extend the mortal stack.
 
 =item *
 
-Internally Perl no longer uses the C<SVs_PADMY> flag.  C<SvPADMY()> now
-returns a true value for anything not marked PADTMP.  C<SVs_PADMY> is now
-defined as 0.
+Perl's internals no longer sets or uses the C<SVs_PADMY> flag.
+C<SvPADMY()> now returns a true value for anything not marked C<PADTMP>
+and C<SVs_PADMY> is now defined as 0.
 
 =item *
 
-The macros SETsv and SETsvUN have been removed. They were no longer used
-in the core since commit 6f1401dc2a, and have not been found present on
-CPAN.
+The macros C<SETsv> and C<SETsvUN> have been removed. They were no longer used
+in the core since commit 6f1401dc2a five years ago, and have not been
+found present on CPAN.
 
 =item *
 
@@ -2100,44 +2805,44 @@ David Mitchell for future work on vtables.
 
 =item *
 
-The C<sv_catpvn_flags> function accepts C<SV_CATBYTES> and C<SV_CATUTF8>
-flags, which specify whether the appended string is bytes or utf8,
-respectively.
+The C<sv_catpvn_flags()> function accepts C<SV_CATBYTES> and C<SV_CATUTF8>
+flags, which specify whether the appended string is bytes or UTF-8,
+respectively. (These flags have in fact been present since 5.16.0, but
+were formerly not regarded as part of the API.)
 
 =item *
 
-A new opcode class, C<< METHOP >> has been introduced, which holds
-class/method related info needed at runtime to improve performance
+A new opcode class, C<< METHOP >>, has been introduced. It holds
+information used at runtime to improve the performance
 of class/object method calls.
 
-C<< OP_METHOD >> and C<< OP_METHOD_NAMED >> are moved from being
+C<< OP_METHOD >> and C<< OP_METHOD_NAMED >> have changed from being
 C<< UNOP/SVOP >> to being C<< METHOP >>.
 
 =item *
 
-C<save_re_context> no longer does anything and has been moved to F<mathoms.c>.
-
-=item *
+C<cv_name()> is a new API function that can be passed a CV or GV.  It
+returns an SV containing the name of the subroutine, for use in
+diagnostics.
 
-C<cv_name> is a new API function that can be passed a CV or GV.  It returns an
-SV containing the name of the subroutine for use in diagnostics.
 L<[perl #116735]|https://rt.perl.org/Ticket/Display.html?id=116735>
 L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
 
 =item *
 
-C<cv_set_call_checker_flags> is a new API function that works like
-C<cv_set_call_checker>, except that it allows the caller to specify whether the
-call checker requires a full GV for reporting the subroutine's name, or whether
-it could be passed a CV instead.  Whatever value is passed will be acceptable
-to C<cv_name>.  C<cv_set_call_checker> guarantees there will be a GV, but it
-may have to create one on the fly, which is inefficient.
+C<cv_set_call_checker_flags()> is a new API function that works like
+C<cv_set_call_checker()>, except that it allows the caller to specify
+whether the call checker requires a full GV for reporting the subroutine's
+name, or whether it could be passed a CV instead.  Whatever value is
+passed will be acceptable to C<cv_name()>.  C<cv_set_call_checker()>
+guarantees there will be a GV, but it may have to create one on the fly,
+which is inefficient.
 L<[perl #116735]|https://rt.perl.org/Ticket/Display.html?id=116735>
 
 =item *
 
 C<CvGV> (which is not part of the API) is now a more complex macro, which may
-call a function and reify a GV.  For those cases where is has been used as a
+call a function and reify a GV.  For those cases where it has been used as a
 boolean, C<CvHASGV> has been added, which will return true for CVs that
 notionally have GVs, but without reifying the GV.  C<CvGV> also returns a GV
 now for lexical subs.
@@ -2145,9 +2850,10 @@ L<[perl #120441]|https://rt.perl.org/Ticket/Display.html?id=120441>
 
 =item *
 
-Added L<perlapi/sync_locale>.  Changing the program's locale should be avoided
-by XS code.  Nevertheless, certain non-Perl libraries called from XS, such as
-C<Gtk> do so.  When this happens, Perl needs to be told that the locale has
+The L<perlapi/sync_locale> function has been added to the public API.
+Changing the program's locale should be avoided by XS code. Nevertheless,
+certain non-Perl libraries called from XS need to do so, such as C<Gtk>.
+When this happens, Perl needs to be told that the locale has
 changed.  Use this function to do so, before returning to Perl.
 
 =item *
@@ -2155,21 +2861,13 @@ changed.  Use this function to do so, before returning to Perl.
 The defines and labels for the flags in the C<op_private> field of OPs are now
 auto-generated from data in F<regen/op_private>.  The noticeable effect of this
 is that some of the flag output of C<Concise> might differ slightly, and the
-flag output of C<perl -Dx> may differ considerably (they both use the same set
-of labels now).  Also in debugging builds, there is a new assert in
-C<op_free()> that checks that the op doesn't have any unrecognized flags set in
+flag output of S<C<perl -Dx>> may differ considerably (they both use the same set
+of labels now).  Also, debugging builds now have a new assertion in
+C<op_free()> to ensure that the op doesn't have any unrecognized flags set in
 C<op_private>.
 
 =item *
 
-Added L<perlapi/sync_locale>.
-Changing the program's locale should be avoided by XS code.  Nevertheless,
-certain non-Perl libraries called from XS, such as C<Gtk> do so.  When this
-happens, Perl needs to be told that the locale has changed.  Use this function
-to do so, before returning to Perl.
-
-=item *
-
 The deprecated variable C<PL_sv_objcount> has been removed.
 
 =item *
@@ -2181,11 +2879,11 @@ with the decimal radix character not being a dot.  Prior to this
 release, Perl initialized this category to "C", but a call to
 C<POSIX::setlocale()> would change it.  Now such a call will change the
 underlying locale of the C<LC_NUMERIC> category for the program, but the
-locale exposed to XS code will remain "C".  There is an API under
-development for those relatively few modules that need to use the
-underlying locale.  This API will be nailed down during the course of
-developing v5.21.  Send email to L<mailto:perl5-porters@perl.org> for
-guidance.
+locale exposed to XS code will remain "C".  There are new macros
+to manipulate the LC_NUMERIC locale, including
+C<STORE_LC_NUMERIC_SET_TO_NEEDED> and
+C<STORE_LC_NUMERIC_FORCE_TO_UNDERLYING>.
+See L<perlapi/Locale-related functions and macros>.
 
 =item *
 
@@ -2195,22 +2893,23 @@ with a well-formed UTF-8 encoded character.
 
 =item *
 
-The following private API functions had their context parameter removed,
+The following private API functions had their context parameter removed:
 C<Perl_cast_ulong>,  C<Perl_cast_i32>, C<Perl_cast_iv>,    C<Perl_cast_uv>,
 C<Perl_cv_const_sv>, C<Perl_mg_find>,  C<Perl_mg_findext>, C<Perl_mg_magical>,
 C<Perl_mini_mktime>, C<Perl_my_dirfd>, C<Perl_sv_backoff>, C<Perl_utf8_hop>.
 
-Users of the public API prefix-less calls remain unaffected.
+Note that the prefix-less versions of those functions that are part of the
+public API, such as C<cast_i32()>, remain unaffected.
 
 =item *
 
-The PADNAME and PADNAMELIST types are now separate types, and no longer
-simply aliases for SV and AV.
+The C<PADNAME> and C<PADNAMELIST> types are now separate types, and no
+longer simply aliases for SV and AV.
 L<[perl #123223]|https://rt.perl.org/Ticket/Display.html?id=123223>.
 
 =item *
 
-Pad names are now always UTF8.  The C<PadnameUTF8> macro always returns
+Pad names are now always UTF-8.  The C<PadnameUTF8> macro always returns
 true.  Previously, this was effectively the case already, but any support
 for two different internal representations of pad names has now been
 removed.
@@ -2219,9 +2918,9 @@ removed.
 
 A new op class, C<UNOP_AUX>, has been added. This is a subclass of
 C<UNOP> with an C<op_aux> field added, which points to an array of unions
-of C<UV>, C<SV*> etc. It is intended for where an op needs to store more data
+of UV, SV* etc. It is intended for where an op needs to store more data
 than a simple C<op_sv> or whatever. Currently the only op of this type is
-C<OP_MULTIDEREF> (see below).
+C<OP_MULTIDEREF> (see next item).
 
 =item *
 
@@ -2242,51 +2941,52 @@ index is still done using C<aelemfast>.
 
 =item *
 
-C<pack("D", $x)> and C<pack("F", $x)> now zero the padding on x86 long double
-builds.  GCC 4.8 and later, under some build options, would either overwrite
-the zero-initialized padding, or bypass the initialized buffer entirely.  This
-caused F<op/pack.t> to fail.
-L<[perl #123971]|https://rt.perl.org/Ticket/Display.html?id=123971>
-
-=item *
+C<close> now sets C<$!>
 
-Extending an array cloned from a parent thread could result in "Modification of
-a read-only value attempted" errors when attempting to modify the new elements.
-L<[perl #124127]|https://rt.perl.org/Ticket/Display.html?id=124127>
+When an I/O error occurs, the fact that there has been an error is recorded
+in the handle.  C<close> returns false for such a handle.  Previously, the
+value of C<$!> would be untouched by C<close>, so the common convention of
+writing S<C<close $fh or die $!>> did not work reliably.  Now the handle
+records the value of C<$!>, too, and C<close> restores it.
 
 =item *
 
-An assertion failure and subsequent crash with C<< *x=<y> >> has been fixed.
-L<[perl #123790]|https://rt.perl.org/Ticket/Display.html?id=123790>
+C<no re> now can turn off everything that C<use re> enables
+
+Previously, running C<no re> would turn off only a few things. Now it
+can turn off all the enabled things. For example, the only way to
+stop debugging, once enabled, was to exit the enclosing block; that is
+now fixed.
 
 =item *
 
-An optimization for state variable initialization introduced in Perl 5.21.6 has
-been reverted because it was found to exacerbate some other existing buggy
-behaviour.
-L<[perl #124160]|https://rt.perl.org/Ticket/Display.html?id=124160>
+C<pack("D", $x)> and C<pack("F", $x)> now zero the padding on x86 long
+double builds.  Under some build options on GCC 4.8 and later, they used
+to either overwrite the zero-initialized padding, or bypass the
+initialized buffer entirely.  This caused F<op/pack.t> to fail.
+L<[perl #123971]|https://rt.perl.org/Ticket/Display.html?id=123971>
 
 =item *
 
-The extension of another optimization to cover more ops in Perl 5.21 has also
-been reverted to its Perl 5.20 state as a temporary fix for regression issues
-that it caused.
-L<[perl #123790]|https://rt.perl.org/Ticket/Display.html?id=123790>
+Extending an array cloned from a parent thread could result in "Modification of
+a read-only value attempted" errors when attempting to modify the new elements.
+L<[perl #124127]|https://rt.perl.org/Ticket/Display.html?id=124127>
 
 =item *
 
-New bitwise ops added in Perl 5.21.9 accidentally caused C<$^H |= 0x1c020000>
-to enable all features.  This has now been fixed.
+An assertion failure and subsequent crash with C<< *x=<y> >> has been fixed.
+L<[perl #123790]|https://rt.perl.org/Ticket/Display.html?id=123790>
 
 =item *
 
-A possible crashing/looping bug has been fixed.
+A possible crashing/looping bug related to compiling lexical subs has been
+fixed.
 L<[perl #124099]|https://rt.perl.org/Ticket/Display.html?id=124099>
 
 =item *
 
-UTF-8 variable names used in array indexes, unquoted UTF-8 HERE-document
-terminators and UTF-8 function names all now work correctly.
+UTF-8 now works correctly in function names, in unquoted HERE-document
+terminators, and in variable names used as array indexes.
 L<[perl #124113]|https://rt.perl.org/Ticket/Display.html?id=124113>
 
 =item *
@@ -2306,7 +3006,7 @@ L<[perl #123995]|https://rt.perl.org/Ticket/Display.html?id=123995>
 
 =item *
 
-C<split> in the scope of lexical $_ has been fixed not to fail assertions.
+C<split> in the scope of lexical C<$_> has been fixed not to fail assertions.
 L<[perl #123763]|https://rt.perl.org/Ticket/Display.html?id=123763>
 
 =item *
@@ -2317,9 +3017,9 @@ L<[perl #123817]|https://rt.perl.org/Ticket/Display.html?id=123817>
 
 =item *
 
-An @ 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 @ as
-literal.  This has been fixed.
+An C<@> sign in quotes followed by a non-ASCII digit (which is not a valid
+identifier) would cause the parser to crash, instead of simply trying the
+C<@> as literal.  This has been fixed.
 L<[perl #123963]|https://rt.perl.org/Ticket/Display.html?id=123963>
 
 =item *
@@ -2331,30 +3031,21 @@ L<[perl #123847]|https://rt.perl.org/Ticket/Display.html?id=123847>
 =item *
 
 C<foreach> in scalar context was not pushing an item on to the stack, resulting
-in bugs.  (C<print 4, scalar do { foreach(@x){} } + 1> would print 5.)  It has
-been fixed to return C<undef>.
+in bugs.  (S<C<print 4, scalar do { foreach(@x){} } + 1>> would print 5.)
+It has been fixed to return C<undef>.
 L<[perl #124004]|https://rt.perl.org/Ticket/Display.html?id=124004>
 
 =item *
 
-A memory leak introduced in Perl 5.21.6 has been fixed.
-L<[perl #123922]|https://rt.perl.org/Ticket/Display.html?id=123922>
-
-=item *
-
-A regression in the behaviour of the C<readline> built-in function, caused by
-the introduction of the C<< <<>> >> operator, has been fixed.
-L<[perl #123990]|https://rt.perl.org/Ticket/Display.html?id=123990>
-
-=item *
-
 Several cases of data used to store environment variable contents in core C
 code being potentially overwritten before being used have been fixed.
 L<[perl #123748]|https://rt.perl.org/Ticket/Display.html?id=123748>
 
 =item *
 
-Patterns starting with C</.*/> are now fast again.
+Some patterns starting with C</.*..../> matched against long strings have
+been slow since v5.8, and some of the form C</.*..../i> have been slow
+since v5.18. They are now all fast again.
 L<[perl #123743]|https://rt.perl.org/Ticket/Display.html?id=123743>.
 
 =item *
@@ -2362,32 +3053,21 @@ L<[perl #123743]|https://rt.perl.org/Ticket/Display.html?id=123743>.
 The original visible value of C<$/> is now preserved when it is set to
 an invalid value.  Previously if you set C<$/> to a reference to an
 array, for example, perl would produce a runtime error and not set
-C<PL_rs>, but perl code that checked C<$/> would see the array
+C<PL_rs>, but Perl code that checked C<$/> would see the array
 reference.
 L<[perl #123218]|https://rt.perl.org/Ticket/Display.html?id=123218>.
 
 =item *
 
 In a regular expression pattern, a POSIX class, like C<[:ascii:]>, must
-be inside a bracketed character class, like C</qr[[:ascii:]]>.  A
+be inside a bracketed character class, like C<qr/[[:ascii:]]/>.  A
 warning is issued when something looking like a POSIX class is not
 inside a bracketed class.  That warning wasn't getting generated when
 the POSIX class was negated: C<[:^ascii:]>.  This is now fixed.
 
 =item *
 
-Fix a couple of other size calculation overflows.
-L<[perl #123554]|https://rt.perl.org/Ticket/Display.html?id=123554>.
-
-=item *
-
-A bug introduced in 5.21.6, C<dump LABEL> acted the same as C<goto
-LABEL>.  This has been fixed.
-L<[perl #123836]|https://rt.perl.org/Ticket/Display.html?id=123836>.
-
-=item *
-
-Perl 5.14.0 introduced a bug whereby C<eval { LABEL: }> would crash.  This
+Perl 5.14.0 introduced a bug whereby S<C<eval { LABEL: }>> would crash.  This
 has been fixed.
 L<[perl #123652]|https://rt.perl.org/Ticket/Display.html?id=123652>.
 
@@ -2433,28 +3113,23 @@ Fixed infinite loop in parsing backrefs in regexp patterns.
 
 =item *
 
-Several minor bug fixes in behavior of Inf and NaN, including
-warnings when stringifying Inf-like or NaN-like strings. For example,
+Several minor bug fixes in behavior of Infinity and NaN, including
+warnings when stringifying Infinity-like or NaN-like strings. For example,
 "NaNcy" doesn't numify to NaN anymore.
 
 =item *
 
-Only stringy classnames are now shared. This fixes some failures in L<autobox>.
-L<[perl #100819]|https://rt.cpan.org/Ticket/Display.html?id=100819>.
-
-=item *
-
 A bug in regular expression patterns that could lead to segfaults and
 other crashes has been fixed.  This occurred only in patterns compiled
-with C<"/i">, while taking into account the current POSIX locale (this usually
-means they have to be compiled within the scope of C<S<"use locale">>),
+with C</i> while taking into account the current POSIX locale (which usually
+means they have to be compiled within the scope of C<S<use locale>>),
 and there must be a string of at least 128 consecutive bytes to match.
 L<[perl #123539]|https://rt.perl.org/Ticket/Display.html?id=123539>.
 
 =item *
 
-C<s///> now works on very long strings instead of dying with 'Substitution
-loop'.
+C<s///g> now works on very long strings (where there are more than 2
+billion iterations) instead of dying with 'Substitution loop'.
 L<[perl #103260]|https://rt.perl.org/Ticket/Display.html?id=103260>.
 L<[perl #123071]|https://rt.perl.org/Ticket/Display.html?id=123071>.
 
@@ -2465,26 +3140,27 @@ L<[perl #123495]|https://rt.perl.org/Ticket/Display.html?id=123495>.
 
 =item *
 
-C<\()> (reference to an empty list) and C<y///> with lexical $_ in scope
-could do a bad write past the end of the stack.  They have been fixed
-to extend the stack first.
+C<\()> (a reference to an empty list), and C<y///> with lexical C<$_> in
+scope, could both do a bad write past the end of the stack.  They have
+both been fixed to extend the stack first.
 
 =item *
 
 C<prototype()> with no arguments used to read the previous item on the
-stack, so C<print "foo", prototype()> would print foo's prototype.  It has
-been fixed to infer $_ instead.
+stack, so S<C<print "foo", prototype()>> would print foo's prototype.
+It has been fixed to infer C<$_> instead.
 L<[perl #123514]|https://rt.perl.org/Ticket/Display.html?id=123514>.
 
 =item *
 
-Some cases of lexical state subs inside predeclared subs could crash but no
-longer do.
+Some cases of lexical state subs declared inside predeclared subs could
+crash, for example when evalling a string including the name of an outer
+variable, but no longer do.
 
 =item *
 
 Some cases of nested lexical state subs inside anonymous subs could cause
-'Bizarre copy' errors or possibly even crash.
+'Bizarre copy' errors or possibly even crashes.
 
 =item *
 
@@ -2495,23 +3171,24 @@ L<[perl #123553]|https://rt.perl.org/Ticket/Display.html?id=123553>.
 
 =item *
 
-Certain syntax errors in substitutions, such as C<< s/${E<lt>E<gt>{})// >>, would
+Certain syntax errors in substitutions, such as C<< s/${<>{})// >>, would
 crash, and had done so since Perl 5.10.  (In some cases the crash did not
 start happening till 5.16.)  The crash has, of course, been fixed.
 L<[perl #123542]|https://rt.perl.org/Ticket/Display.html?id=123542>.
 
 =item *
 
-A repeat expression like C<33 x ~3> could cause a large buffer
+Fix a couple of string grow size calculation overflows; in particular,
+a repeat expression like S<C<33 x ~3>> could cause a large buffer
 overflow since the new output buffer size was not correctly handled by
-SvGROW().  An expression like this now properly produces a memory wrap
+C<SvGROW()>.  An expression like this now properly produces a memory wrap
 panic.
 L<[perl #123554]|https://rt.perl.org/Ticket/Display.html?id=123554>.
 
 =item *
 
 C<< formline("@...", "a"); >> would crash.  The C<FF_CHECKNL> case in
-pp_formline() didn't set the pointer used to mark the chop position,
+C<pp_formline()> didn't set the pointer used to mark the chop position,
 which led to the C<FF_MORE> case crashing with a segmentation fault.
 This has been fixed.
 L<[perl #123538]|https://rt.perl.org/Ticket/Display.html?id=123538>.
@@ -2524,39 +3201,28 @@ L<[perl #123604]|https://rt.perl.org/Ticket/Display.html?id=123604>.
 
 =item *
 
-fchmod() and futimes() now set C<$!> when they fail due to being
+C<fchmod()> and C<futimes()> now set C<$!> when they fail due to being
 passed a closed file handle.
 L<[perl #122703]|https://rt.perl.org/Ticket/Display.html?id=122703>.
 
 =item *
 
-Perl now comes with a corrected Unicode 7.0 for the erratum issued on
-October 21, 2014 (see L<http://www.unicode.org/errata/#current_errata>),
-dealing with glyph shaping in Arabic.
-
-=item *
-
-op_free() no longer crashes due to a stack overflow when freeing a
-deeply recursive op tree.
-L<[perl #108276]|https://rt.perl.org/Ticket/Display.html?id=108276>.
-
-=item *
-
-scalarvoid() would crash due to a stack overflow when processing a
-deeply recursive op tree.
+C<op_free()> and C<scalarvoid()> no longer crash due to a stack overflow
+when freeing a deeply recursive op tree.
 L<[perl #108276]|https://rt.perl.org/Ticket/Display.html?id=108276>.
 
 =item *
 
-In Perl 5.20.0, C<$^N> accidentally had the internal UTF8 flag turned off
+In Perl 5.20.0, C<$^N> accidentally had the internal UTF-8 flag turned off
 if accessed from a code block within a regular expression, effectively
-UTF8-encoding the value.  This has been fixed.
+UTF-8-encoding the value.  This has been fixed.
 L<[perl #123135]|https://rt.perl.org/Ticket/Display.html?id=123135>.
 
 =item *
 
 A failed C<semctl> call no longer overwrites existing items on the stack,
-causing C<(semctl(-1,0,0,0))[0]> to give an "uninitialized" warning.
+which means that C<(semctl(-1,0,0,0))[0]> no longer gives an
+"uninitialized" warning.
 
 =item *
 
@@ -2566,24 +3232,24 @@ L<[perl #122695]|https://rt.perl.org/Ticket/Display.html?id=122695>.
 
 =item *
 
-Sometimes the assignment in C<@array = split> gets optimised and C<split>
+Sometimes the assignment in C<@array = split> gets optimised so that C<split>
 itself writes directly to the array.  This caused a bug, preventing this
 assignment from being used in lvalue context.  So
 C<(@a=split//,"foo")=bar()> was an error.  (This bug probably goes back to
-Perl 3, when the optimisation was added.)  This optimisation, and the bug,
-started to happen in more cases in 5.21.5.  It has now been fixed.
+Perl 3, when the optimisation was added.) It has now been fixed.
 L<[perl #123057]|https://rt.perl.org/Ticket/Display.html?id=123057>.
 
 =item *
 
-When argument lists that fail the checks installed by subroutine
-signatures, the resulting error messages now give the file and line number
-of the caller, not of the called subroutine.
+When an argument list fails the checks specified by a subroutine
+signature (which is still an experimental feature), the resulting error
+messages now give the file and line number of the caller, not of the
+called subroutine.
 L<[perl #121374]|https://rt.perl.org/Ticket/Display.html?id=121374>.
 
 =item *
 
-Flip-flop operators (C<..> and C<...> in scalar context) used to maintain
+The flip-flop operators (C<..> and C<...> in scalar context) used to maintain
 a separate state for each recursion level (the number of times the
 enclosing sub was called recursively), contrary to the documentation.  Now
 each closure has one internal state for each flip-flop.
@@ -2591,6 +3257,13 @@ L<[perl #122829]|https://rt.perl.org/Ticket/Display.html?id=122829>.
 
 =item *
 
+The flip-flop operator (C<..> in scalar context) would return the same
+scalar each time, unless the containing subroutine was called recursively.
+Now it always returns a new scalar.
+L<[perl #122829]|https://rt.perl.org/Ticket/Display.html?id=122829>.
+
+=item *
+
 C<use>, C<no>, statement labels, special blocks (C<BEGIN>) and pod are now
 permitted as the first thing in a C<map> or C<grep> block, the block after
 C<print> or C<say> (or other functions) returning a handle, and within
@@ -2601,29 +3274,30 @@ L<[perl #122782]|https://rt.perl.org/Ticket/Display.html?id=122782>.
 
 The repetition operator C<x> now propagates lvalue context to its left-hand
 argument when used in contexts like C<foreach>.  That allows
-C<for(($#that_array)x2) { ... }> to work as expected if the loop modifies
-$_.
+S<C<for(($#that_array)x2) { ... }>> to work as expected if the loop modifies
+C<$_>.
 
 =item *
 
 C<(...) x ...> in scalar context used to corrupt the stack if one operand
-were an object with "x" overloading, causing erratic behaviour.
+was an object with "x" overloading, causing erratic behavior.
 L<[perl #121827]|https://rt.perl.org/Ticket/Display.html?id=121827>.
 
 =item *
 
-Assignment to a lexical scalar is often optimised away (as mentioned under
-L</Performance Enhancements>).  Various bugs related to this optimisation
-have been fixed.  Certain operators on the right-hand side would sometimes
-fail to assign the value at all or assign the wrong value, or would call
-STORE twice or not at all on tied variables.  The operators affected were
-C<$foo++>, C<$foo-->, and C<-$foo> under C<use integer>, C<chomp>, C<chr>
-and C<setpgrp>.
+Assignment to a lexical scalar is often optimised away; for example in
+C<my $x; $x = $y + $z>, the assign operator is optimised away and the add
+operator writes its result directly to C<$x>.  Various bugs related to
+this optimisation have been fixed.  Certain operators on the right-hand
+side would sometimes fail to assign the value at all or assign the wrong
+value, or would call STORE twice or not at all on tied variables.  The
+operators affected were C<$foo++>, C<$foo-->, and C<-$foo> under C<use
+integer>, C<chomp>, C<chr> and C<setpgrp>.
 
 =item *
 
 List assignments were sometimes buggy if the same scalar ended up on both
-sides of the assignment due to used of C<tied>, C<values> or C<each>.  The
+sides of the assignment due to use of C<tied>, C<values> or C<each>.  The
 result would be the wrong value getting assigned.
 
 =item *
@@ -2634,27 +3308,27 @@ to mean C<setpgrp(0)>.  This has been fixed.
 =item *
 
 C<__SUB__> could return the wrong value or even corrupt memory under the
-debugger (the B<-d> switch) and in subs containing C<eval $string>.
+debugger (the C<-d> switch) and in subs containing C<eval $string>.
 
 =item *
 
-When C<sub () { $var }> becomes inlinable, it now returns a different
+When S<C<sub () { $var }>> becomes inlinable, it now returns a different
 scalar each time, just as a non-inlinable sub would, though Perl still
 optimises the copy away in cases where it would make no observable
 difference.
 
 =item *
 
-C<my sub f () { $var }> and C<sub () : attr { $var }> are no longer
+S<C<my sub f () { $var }>> and S<C<sub () : attr { $var }>> are no longer
 eligible for inlining.  The former would crash; the latter would just
 throw the attributes away.  An exception is made for the little-known
-":method" attribute, which does nothing much.
+C<:method> attribute, which does nothing much.
 
 =item *
 
 Inlining of subs with an empty prototype is now more consistent than
-before.  Previously, a sub with multiple statements, all but the last
-optimised away, would be inlinable only if it were an anonymous sub
+before. Previously, a sub with multiple statements, of which all but the last
+were optimised away, would be inlinable only if it were an anonymous sub
 containing a string C<eval> or C<state> declaration or closing over an
 outer lexical variable (or any anonymous sub under the debugger).  Now any
 sub that gets folded to a single constant after statements have been
@@ -2667,9 +3341,9 @@ contrary to the documentation,  Now C<return> always prevents inlining.
 =item *
 
 On some systems, such as VMS, C<crypt> can return a non-ASCII string.  If a
-scalar assigned to had contained a UTF8 string previously, then C<crypt>
-would not turn off the UTF8 flag, thus corrupting the return value.  This
-would happen with C<$lexical = crypt ...>.
+scalar assigned to had contained a UTF-8 string previously, then C<crypt>
+would not turn off the UTF-8 flag, thus corrupting the return value.  This
+would happen with S<C<$lexical = crypt ...>>.
 
 =item *
 
@@ -2683,21 +3357,16 @@ started doing so in 5.18.
 
 =item *
 
-Fixed two assertion failures introduced into C<-DPERL_OP_PARENT>
-builds.
-L<[perl #108276]|https://rt.perl.org/Ticket/Display.html?id=108276>.
-
-=item *
-
-index() and rindex() no longer crash when used on strings over 2GB in
+C<index()> and C<rindex()> no longer crash when used on strings over 2GB in
 size.
 L<[perl #121562]|https://rt.perl.org/Ticket/Display.html?id=121562>.
 
 =item *
 
-A small previously intentional memory leak in PERL_SYS_INIT/PERL_SYS_INIT3 on
-Win32 builds was fixed. This might affect embedders who repeatedly create and
-destroy perl engines within the same process.
+A small, previously intentional, memory leak in
+C<PERL_SYS_INIT>/C<PERL_SYS_INIT3> on Win32 builds was fixed. This might
+affect embedders who repeatedly create and destroy perl engines within
+the same process.
 
 =item *
 
@@ -2735,7 +3404,7 @@ C<[[:upper:]]>,
 C<[[:word:]]>,
 and
 C<[[:xdigit:]]>.
-These are because the underlying Microsoft implementation does not
+This was because the underlying Microsoft implementation does not
 follow the standard.  Perl now takes special precautions to correct for
 this.
 
@@ -2746,12 +3415,12 @@ fixed.
 
 =item *
 
-system() and friends should now work properly on more Android builds.
+C<system()> and friends should now work properly on more Android builds.
 
-Due to an oversight, the value specified through -Dtargetsh to Configure
+Due to an oversight, the value specified through C<-Dtargetsh> to F<Configure>
 would end up being ignored by some of the build process.  This caused perls
-cross-compiled for Android to end up with defective versions of system(),
-exec() and backticks: the commands would end up looking for C</bin/sh>
+cross-compiled for Android to end up with defective versions of C<system()>,
+C<exec()> and backticks: the commands would end up looking for C</bin/sh>
 instead of C</system/bin/sh>, and so would fail for the vast majority
 of devices, leaving C<$!> as C<ENOENT>.
 
@@ -2769,7 +3438,7 @@ mirror character.
 
 =item *
 
-C<< s///e >> on tainted utf8 strings got C<< pos() >> messed up. This bug,
+C<< s///e >> on tainted UTF-8 strings corrupted C<< pos() >>. This bug,
 introduced in 5.20, is now fixed.
 L<[perl #122148]|https://rt.perl.org/Ticket/Display.html?id=122148>.
 
@@ -2787,7 +3456,7 @@ L<[perl #122171]|https://rt.perl.org/Ticket/Display.html?id=122171>.
 
 =item *
 
-Failing to compile C<use Foo> in an eval could leave a spurious
+Failing to compile C<use Foo> in an C<eval> could leave a spurious
 C<BEGIN> subroutine definition, which would produce a "Subroutine
 BEGIN redefined" warning on the next use of C<use>, or other C<BEGIN>
 block.
@@ -2815,19 +3484,20 @@ L<[perl #122460]|https://rt.perl.org/Ticket/Display.html?id=122460>.
 
 =item *
 
-Constant dereferencing now works correctly for typeglob constants.  Previously
+Dereferencing of constants now works correctly for typeglob constants.  Previously
 the glob was stringified and its name looked up.  Now the glob itself is used.
 L<[perl #69456]|https://rt.perl.org/Ticket/Display.html?id=69456>
 
 =item *
 
-When parsing a funny character ($ @ % &) followed by braces, the parser no
+When parsing a sigil (C<$> C<@> C<%> C<&)> followed by braces,
+the parser no
 longer tries to guess whether it is a block or a hash constructor (causing a
 syntax error when it guesses the latter), since it can only be a block.
 
 =item *
 
-C<undef $reference> now frees the referent immediately, instead of hanging on
+S<C<undef $reference>> now frees the referent immediately, instead of hanging on
 to it until the next statement.
 L<[perl #122556]|https://rt.perl.org/Ticket/Display.html?id=122556>
 
@@ -2843,7 +3513,7 @@ bareword is not going to be a subroutine name.
 
 =item *
 
-Compilation of anonymous constants (e.g., C<sub () { 3 }>) no longer deletes
+Compilation of anonymous constants (I<e.g.>, C<sub () { 3 }>) no longer deletes
 any subroutine named C<__ANON__> in the current package.  Not only was
 C<*__ANON__{CODE}> cleared, but there was a memory leak, too.  This bug goes
 back to Perl 5.8.0.
@@ -2856,12 +3526,9 @@ of the same name declared by C<use constant>.  This bug was introduced in Perl
 
 =item *
 
-Under some conditions a warning raised in compilation of regular expression
-patterns could be displayed multiple times.  This is now fixed.
-
-=item *
+C<qr/[\N{named sequence}]/> now works properly in many instances.
 
-C<qr/[\N{named sequence}]/> now works properly in many instances.  Some names
+Some names
 known to C<\N{...}> refer to a sequence of multiple characters, instead of the
 usual single character.  Bracketed character classes generally only match
 single characters, but now special handling has been added so that they can
@@ -2880,14 +3547,15 @@ L<[perl #122669]|https://rt.perl.org/Ticket/Display.html?id=122669>
 
 =item *
 
-C<open $$fh, ...>, which vivifies a handle with a name like "main::_GEN_0", was
-not giving the handle the right reference count, so a double free could happen.
+S<C<open $$fh, ...>>, which vivifies a handle with a name like
+C<"main::_GEN_0">, was not giving the handle the right reference count, so
+a double free could happen.
 
 =item *
 
 When deciding that a bareword was a method name, the parser would get confused
-if an "our" sub with the same name existed, and look up the method in the
-package of the "our" sub, instead of the package of the invocant.
+if an C<our> sub with the same name existed, and look up the method in the
+package of the C<our> sub, instead of the package of the invocant.
 
 =item *
 
@@ -2910,21 +3578,21 @@ compilation were being output more than once.  This has now been fixed.
 
 =item *
 
-A regression has been fixed that was introduced in Perl 5.20.0 (fixed in Perl
-5.20.1 as well as here) in which a UTF-8 encoded regular expression pattern
-that contains a single ASCII lowercase letter does not match its uppercase
-counterpart.
+Perl 5.20.0 introduced a regression in which a UTF-8 encoded regular
+expression pattern that contains a single ASCII lowercase letter did not
+match its uppercase counterpart. That has been fixed in both 5.20.1 and
+5.22.0.
 L<[perl #122655]|https://rt.perl.org/Ticket/Display.html?id=122655>
 
 =item *
 
-Constant folding could incorrectly suppress warnings if lexical warnings (C<use
-warnings> or C<no warnings>) were not in effect and C<$^W> were false at
-compile time and true at run time.
+Constant folding could incorrectly suppress warnings if lexical warnings
+(C<use warnings> or C<no warnings>) were not in effect and C<$^W> were
+false at compile time and true at run time.
 
 =item *
 
-Loading UTF8 tables during a regular expression match could cause assertion
+Loading Unicode tables during a regular expression match could cause assertion
 failures under debugging builds if the previous match used the very same
 regular expression.
 L<[perl #122747]|https://rt.perl.org/Ticket/Display.html?id=122747>
@@ -2943,16 +3611,17 @@ fixed.
 
 =item *
 
-C<(caller $n)[3]> now reports names of lexical subs, instead of treating them
-as "(unknown)".
+S<C<(caller $n)[3]>> now reports names of lexical subs, instead of
+treating them as C<"(unknown)">.
 
 =item *
 
-C<sort subname LIST> now supports lexical subs for the comparison routine.
+C<sort subname LIST> now supports using a lexical sub as the comparison
+routine.
 
 =item *
 
-Aliasing (e.g., via C<*x = *y>) could confuse list assignments that mention the
+Aliasing (I<e.g.>, via S<C<*x = *y>>) could confuse list assignments that mention the
 two names for the same variable on either side, causing wrong values to be
 assigned.
 L<[perl #15667]|https://rt.perl.org/Ticket/Display.html?id=15667>
@@ -2966,38 +3635,25 @@ ago.
 
 =item *
 
-An optimization in C<split> to treat C<split/^/> like C<split/^/m> had the
-unfortunate side-effect of also treating C<split/\A/> like C<split/^/m>, which
-it should not.  This has been fixed.  (Note, however, that C<split/^x/> does
-not behave like C<split/^x/m>, which is also considered to be a bug and will be
-fixed in a future version.)
+An optimization in C<split> to treat S<C<split /^/>> like S<C<split /^/m>> had the
+unfortunate side-effect of also treating S<C<split /\A/>> like S<C<split /^/m>>,
+which it should not.  This has been fixed.  (Note, however, that S<C<split /^x/>>
+does not behave like S<C<split /^x/m>>, which is also considered to be a bug and
+will be fixed in a future version.)
 L<[perl #122761]|https://rt.perl.org/Ticket/Display.html?id=122761>
 
 =item *
 
-The little-known C<my Class $var> syntax (see L<fields> and L<attributes>)
+The little-known S<C<my Class $var>> syntax (see L<fields> and L<attributes>)
 could get confused in the scope of C<use utf8> if C<Class> were a constant
 whose value contained Latin-1 characters.
 
 =item *
 
 Locking and unlocking values via L<Hash::Util> or C<Internals::SvREADONLY>
-no longer has any effect on values that are read-only to begin.
+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 behaviour.
-
-=item *
-
-The internal C<looks_like_number> function (which L<Scalar::Util> provides
-access to) began erroneously to return true for "-e1" in 5.21.4, affecting
-also C<-'-e1'>.  This has been fixed.
-
-=item *
-
-The flip-flop operator (C<..> in scalar context) would return the same
-scalar each time, unless the containing subroutine was called recursively.
-Now it always returns a new scalar.
-L<[perl #122829]|https://rt.perl.org/Ticket/Display.html?id=122829>.
+other erratic behavior.
 
 =item *
 
@@ -3007,17 +3663,17 @@ example.
 
 =item *
 
-C<pack "w", $tied> no longer calls FETCH twice.
+S<C<pack "w", $tied>> no longer calls FETCH twice.
 
 =item *
 
-List assignments like C<($x, $z) = (1, $y)> now work correctly if $x and $y
-have been aliased by C<foreach>.
+List assignments like S<C<($x, $z) = (1, $y)>> now work correctly if C<$x> and
+C<$y> have been aliased by C<foreach>.
 
 =item *
 
 Some patterns including code blocks with syntax errors, such as
-C</ (?{(^{})/>, would hang or fail assertions on debugging builds.  Now
+S<C</ (?{(^{})/>>, would hang or fail assertions on debugging builds.  Now
 they produce errors.
 
 =item *
@@ -3028,13 +3684,13 @@ L<[perl #122771]|https://rt.perl.org/Ticket/Display.html?id=122771>.
 
 =item *
 
-C<*a = *b; @a = split //, $b[1]> could do a bad read and produce junk
+S<C<*a = *b; @a = split //, $b[1]>> could do a bad read and produce junk
 results.
 
 =item *
 
-In C<() = @array = split>, the C<() => at the beginning no longer confuses
-the optimizer, making it assume a limit of 1.
+In S<C<() = @array = split>>, the S<C<() =>> at the beginning no longer confuses
+the optimizer into assuming a limit of 1.
 
 =item *
 
@@ -3043,14 +3699,14 @@ L<[perl #122966]|https://rt.perl.org/Ticket/Display.html?id=122966>.
 
 =item *
 
-Fixed a NaN double to long double conversion error on VMS. For quiet NaNs
+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.
 
 =item *
 
-Fixed the issue that caused C<< make distclean >> to leave files behind
-that shouldn't.
+Fixed the issue that caused C<< make distclean >> to incorrectly leave some
+files behind.
 L<[perl #122820]|https://rt.perl.org/Ticket/Display.html?id=122820>.
 
 =item *
@@ -3062,47 +3718,50 @@ L<[cpan #85570]|https://rt.cpan.org/Ticket/Display.html?id=85570>.
 
 =item *
 
-During the pattern optimization phase, we no longer recurse into
-GOSUB/GOSTART when not SCF_DO_SUBSTR. This prevents the optimizer
-to run "forever" and exhaust all memory.
+The optimization phase of a regexp compilation could run "forever" and
+exhaust all memory under certain circumstances; now fixed.
 L<[perl #122283]|https://rt.perl.org/Ticket/Display.html?id=122283>.
 
 =item *
 
-F<< t/op/crypt.t >> now performs SHA-256 algorithm if the default one
-is disabled.
+The test script F<< t/op/crypt.t >> now uses the SHA-256 algorithm if the
+default one is disabled, rather than giving failures.
 L<[perl #121591]|https://rt.perl.org/Ticket/Display.html?id=121591>.
 
 =item *
 
-Fixed an off-by-one error when setting the size of shared array.
+Fixed an off-by-one error when setting the size of a shared array.
 L<[perl #122950]|https://rt.perl.org/Ticket/Display.html?id=122950>.
 
 =item *
 
-Fixed a bug that could cause perl to execute an infinite loop during
-compilation.
+Fixed a bug that could cause perl to enter an infinite loop during
+compilation. In particular, a C<while(1)> within a sublist, I<e.g.>
+
+    sub foo { () = ($a, my $b, ($c, do { while(1) {} })) }
+
+The bug was introduced in 5.20.0
 L<[perl #122995]|https://rt.perl.org/Ticket/Display.html?id=122995>.
 
 =item *
 
-On Win32, restoring in a child pseudo-process a variable that was
-C<local()>ed in a parent pseudo-process before the C<fork> happened caused
-memory corruption and a crash in the child pseudo-process (and therefore OS
-process).
+On Win32, if a variable was C<local>-ized in a pseudo-process that later
+forked, restoring the original value in the child pseudo-process caused
+memory corruption and a crash in the child pseudo-process (and therefore the
+OS process).
 L<[perl #40565]|https://rt.perl.org/Ticket/Display.html?id=40565>.
 
 =item *
 
 Calling C<write> on a format with a C<^**> field could produce a panic
-in sv_chop() if there were insufficient arguments or if the variable
+in C<sv_chop()> if there were insufficient arguments or if the variable
 used to fill the field was empty.
 L<[perl #123245]|https://rt.perl.org/Ticket/Display.html?id=123245>.
 
 =item *
 
-Non-ASCII lexical sub names (use in error messages) on longer have extra
-junk on the end.
+Non-ASCII lexical sub names now appear without trailing junk when they
+appear in error messages.
 
 =item *
 
@@ -3122,7 +3781,7 @@ L<[perl #123286]|https://rt.perl.org/Ticket/Display.html?id=123286>.
 =item *
 
 C<scalar()> now propagates lvalue context, so that
-C<for(scalar($#foo)) { ... }> can modify C<$#foo> through C<$_>.
+S<C<for(scalar($#foo)) { ... }>> can modify C<$#foo> through C<$_>.
 
 =item *
 
@@ -3131,21 +3790,21 @@ L<[perl #123344]|https://rt.perl.org/Ticket/Display.html?id=123344>.
 
 =item *
 
-C<eval '$variable'> in nested named subroutines would sometimes look up a
+S<C<eval '$variable'>> in nested named subroutines would sometimes look up a
 global variable even with a lexical variable in scope.
 
 =item *
 
 In perl 5.20.0, C<sort CORE::fake> where 'fake' is anything other than a
-keyword started chopping of the last 6 characters and treating the result
-as a sort sub name.  The previous behaviour of treating "CORE::fake" as a
+keyword, started chopping off the last 6 characters and treating the result
+as a sort sub name.  The previous behavior of treating C<CORE::fake> as a
 sort sub name has been restored.
 L<[perl #123410]|https://rt.perl.org/Ticket/Display.html?id=123410>.
 
 =item *
 
 Outside of C<use utf8>, a single-character Latin-1 lexical variable is
-disallowed.  The error message for it, "Can't use global $foo...", was
+disallowed.  The error message for it, "Can't use global C<$foo>...", was
 giving garbage instead of the variable name.
 
 =item *
@@ -3156,7 +3815,7 @@ C<${^LAST_FH}> ends up undefined.
 
 =item *
 
-C<(...)x...> in void context now applies scalar context to the left-hand
+C<(...) x ...> in void context now applies scalar context to the left-hand
 argument, instead of the context the current sub was called in.
 L<[perl #123020]|https://rt.perl.org/Ticket/Display.html?id=123020>.
 
@@ -3168,6 +3827,12 @@ L<[perl #123020]|https://rt.perl.org/Ticket/Display.html?id=123020>.
 
 =item *
 
+C<pack>-ing a NaN on a perl compiled with Visual C 6 does not behave properly,
+leading to a test failure in F<t/op/infnan.t>.
+L<[perl 125203]|https://rt.perl.org/Ticket/Display.html?id=125203>
+
+=item *
+
 A goal is for Perl to be able to be recompiled to work reasonably well on any
 Unicode version.  In Perl 5.22, though, the earliest such version is Unicode
 5.1 (current is 7.0).
@@ -3180,6 +3845,22 @@ EBCDIC platforms
 
 =item *
 
+The C<cmp> (and hence C<sort>) operators do not necessarily give the
+correct results when both operands are UTF-EBCDIC encoded strings and
+there is a mixture of ASCII and/or control characters, along with other
+characters.
+
+=item *
+
+Ranges containing C<\N{...}> in the C<tr///> (and C<y///>)
+transliteration operators are treated differently than the equivalent
+ranges in regular expression patterns.  They should, but don't, cause
+the values in the ranges to all be treated as Unicode code points, and
+not native ones.  (L<perlre/Version 8 Regular Expressions> gives
+details as to how it should work.)
+
+=item *
+
 Encode and encoding are mostly broken.
 
 =item *
@@ -3195,8 +3876,8 @@ C<pack>/C<unpack> with C<"U0"> format may not work properly.
 =item *
 
 The following modules are known to have test failures with this version of
-Perl.  Patches have been submitted, so there will hopefully be new releases
-soon:
+Perl.  In many cases, patches have been submitted, so there will hopefully be
+new releases soon:
 
 =over
 
@@ -3218,6 +3899,10 @@ L<Data::Alias> version 1.18
 
 =item *
 
+L<Data::Dump::Streamer> version 2.38
+
+=item *
+
 L<Data::Util> version 0.63
 
 =item *
@@ -3226,14 +3911,26 @@ L<Devel::Spy> version 0.07
 
 =item *
 
+L<invoker> version 0.34
+
+=item *
+
 L<Lexical::Var> version 0.009
 
 =item *
 
+L<LWP::ConsoleLogger> version 0.000018
+
+=item *
+
 L<Mason> version 2.22
 
 =item *
 
+L<NgxQueue> version 0.02
+
+=item *
+
 L<Padre> version 1.00
 
 =item *
@@ -3244,18 +3941,68 @@ L<Parse::Keyword> 0.08
 
 =back
 
-=head1 Acknowledgements
+=head1 Obituary
 
-XXX Generate this with:
+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.
+
+=head1 Acknowledgements
 
-  perl Porting/acknowledgements.pl v5.20.0..HEAD
+Perl 5.22.0 represents approximately 12 months of development since Perl 5.20.0
+and contains approximately 590,000 lines of changes across 2,400 files from 94
+authors.
+
+Excluding auto-generated files, documentation and release tools, there were
+approximately 370,000 lines of changes to 1,500 .pm, .t, .c and .h files.
+
+Perl continues to flourish into its third decade thanks to a vibrant community
+of users and developers. The following people are known to have contributed the
+improvements that became Perl 5.22.0:
+
+Aaron Crane, Abhijit Menon-Sen, Abigail, Alberto Simões, Alex Solovey, Alex
+Vandiver, Alexandr Ciornii, Alexandre (Midnite) Jousset, Andreas König,
+Andreas Voegele, Andrew Fresh, Andy Dougherty, Anthony Heading, Aristotle
+Pagaltzis, brian d foy, Brian Fraser, Chad Granum, Chris 'BinGOs' Williams,
+Craig A. Berry, Dagfinn Ilmari Mannsåker, Daniel Dragan, Darin McBride, Dave
+Rolsky, David Golden, David Mitchell, David Wheeler, Dmitri Tikhonov, Doug
+Bell, E. Choroba, Ed J, Eric Herman, Father Chrysostomos, George Greer, Glenn
+D. Golden, Graham Knop, H.Merijn Brand, Herbert Breunung, Hugo van der Sanden,
+James E Keenan, James McCoy, James Raspass, Jan Dubois, Jarkko Hietaniemi,
+Jasmine Ngan, Jerry D. Hedden, Jim Cromie, John Goodyear, kafka, Karen
+Etheridge, Karl Williamson, Kent Fredric, kmx, Lajos Veres, Leon Timmermans,
+Lukas Mai, Mathieu Arnold, Matthew Horsfall, Max Maischein, Michael Bunk,
+Nicholas Clark, Niels Thykier, Niko Tyni, Norman Koch, Olivier Mengué, Peter
+John Acklam, Peter Martini, Petr Písař, Philippe Bruhat (BooK), Pierre
+Bogossian, Rafael Garcia-Suarez, Randy Stauner, Reini Urban, Ricardo Signes,
+Rob Hoelz, Rostislav Skudnov, Sawyer X, Shirakata Kentaro, Shlomi Fish,
+Sisyphus, Slaven Rezic, Smylers, Steffen Müller, Steve Hay, Sullivan Beck,
+syber, Tadeusz Sośnierz, Thomas Sibley, Todd Rinaldo, Tony Cook, Vincent Pit,
+Vladimir Marek, Yaroslav Kuzmin, Yves Orton, Ævar Arnfjörð Bjarmason.
+
+The list above is almost certainly incomplete as it is automatically generated
+from version control history. In particular, it does not include the names of
+the (very much appreciated) contributors who reported issues to the Perl bug
+tracker.
+
+Many of the changes included in this version originated in the CPAN modules
+included in Perl's core. We're grateful to the entire CPAN community for
+helping Perl to flourish.
+
+For a more complete list of all of Perl's historical contributors, please see
+the F<AUTHORS> file in the Perl source distribution.
 
 =head1 Reporting Bugs
 
 If you find what you think is a bug, you might check the articles recently
 posted to the comp.lang.perl.misc newsgroup and the perl bug database at
-https://rt.perl.org/ .  There may also be information at
-http://www.perl.org/ , the Perl Home Page.
+L<https://rt.perl.org/>.  There may also be information at
+L<http://www.perl.org/>, the Perl Home Page.
 
 If you believe you have an unreported bug, please run the L<perlbug> program
 included with your release.  Be sure to trim your bug down to a tiny but