perldelta: Improvements

This includes some small wording changes, reordering by importance,
collapsing near-duplicate entries.

1 files changed, 50 insertions, 66 deletions

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index eaa04d9df6..983ce88c10 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -19,6 +19,23 @@ L<[perl #133788]|https://rt.perl.org/Ticket/Display.html?id=133788>.
 
 =head1 Core Enhancements
 
+=head2 Limited variable length lookbehind in regular expression pattern matching is now experimentally supported
+
+Using a lookbehind assertion (like C<(?<=foo?)> or C<(?<!ba{1,9}r)> previously
+would generate an error and refuse to compile.  Now it compiles (if the
+maximum lookbehind is at most 255 characters), but raises a warning in
+the new C<experimental::vlb> warnings category.  This is to caution you
+that the precise behavior is subject to change based on feedback from
+use in the field.
+
+See L<perlre/(?<=pattern)> and L<perlre/(?<!pattern)>.
+
+=head2 The upper limit C<"n"> specifiable in a regular expression quantifier of the form C<"{m,n}"> has been doubled to 65534
+
+The meaning of an unbounded upper quantifier C<"{m,}"> remains unchanged.
+It matches 2**31 - 1 times on most platforms, and more on ones where a C
+language short variable is more than 4 bytes long.
+
 =head2 Unicode 12.1 is supported
 
 Because of a change in Unicode release cycles, Perl jumps from Unicode
@@ -41,23 +58,15 @@ as causing breaks: TAB, NO BREAK SPACE, and FIGURE SPACE (U+2007).  We
 have decided to continue to use the previous Perl tailoring with regards
 to these.
 
-=head2 The upper limit C<"n"> specifiable in a regular expression
-quantifier of the form C<"{m,n}"> has been doubled to 65534
-
-The meaning of an unbounded upper quantifier C<"{m,}"> remains unchanged.
-It matches 2**31 - 1 times on most platforms, and more on ones where a C
-language short variable is more than 4 bytes long.
-
-
-=head2 Wildcards in Unicode property value specifications are now
-partially supported
+=head2 Wildcards in Unicode property value specifications are now partially supported
 
 You can now do something like this in a regular expression pattern
 
  qr! \p{nv= /(?x) \A [0-5] \z / }!
 
-which matches all Unicode code points which have numeric value is
-between 0 and 5 inclusive.
+which matches all Unicode code points whose numeric value is
+between 0 and 5 inclusive.  So, it could match the Thai or Bengali
+digits whose numeric values are 0, 1, 2, 3, 4, or 5.
 
 This marks another step in implementing the regular expression features
 the Unicode Consortium suggests.
@@ -71,34 +80,6 @@ Previously it was an error to evaluate a named character C<\N{...}>
 within a single quoted regular expression pattern (whose evaluation is
 deferred from the normal place).  This restriction is now removed.
 
-=head2 It is now possible to compile perl to always use thread-safe
-locale operations.
-
-Previously, these calls were only used when the perl was compiled to be
-multi-threaded.  To always enable them, add
-
- -Accflags='-DUSE_THREAD_SAFE_LOCALE'
-
-to your F<Configure> flags.
-
-=head2 Limited variable length lookbehind in regular expression pattern matching
-is now experimentally supported
-
-Using a lookbehind assertion (like C<(?<=foo?)> or C<(?<!ba{1,9}r)> previously
-would generate an error and refuse to compile.  Now it compiles (if the
-maximum lookbehind is at most 255 characters), but raises a warning in
-the new C<experimental::vlb> warnings category.  This is to caution you
-that the precise behavior is subject to change based on feedback from
-use in the field.
-
-See L<perlre/(?<=pattern)> and L<perlre/(?<!pattern)>.
-
-=head2 Use faster method to convert to UTF-8
-
-There is a special inline function that's used when converting a single
-byte to UTF-8, that is faster than the more general one used prior to
-this commit.
-
 =head2 Turkic UTF-8 locales are now seamlessly supported
 
 Turkic languages have different casing rules than other languages for
@@ -109,6 +90,15 @@ rules for use with Turkic languages.  Previously, Perl ignored these,
 but now, it uses them when it detects that it is operating under a
 Turkic UTF-8 locale.
 
+=head2 It is now possible to compile perl to always use thread-safe locale operations.
+
+Previously, these calls were only used when the perl was compiled to be
+multi-threaded.  To always enable them, add
+
+ -Accflags='-DUSE_THREAD_SAFE_LOCALE'
+
+to your F<Configure> flags.
+
 =head2 Eliminate opASSIGN macro usage from core
 
 This macro is still defined but no longer used in core
@@ -120,11 +110,11 @@ possible regular expression debugging.
 
 =head1 Incompatible Changes
 
-=head2 Pattern delimiters must now be graphemes
+=head2 Assigning non-zero to C<$[> is fatal
 
-This usage has been deprecated and scheduled for removal in 5.30.  See
-L<perldeprecation/Use of unassigned code point or non-standalone
-grapheme for a delimiter.>
+Setting L<< C<$[>|perlvar/$[ >> to a non-zero value has been deprecated since
+Perl 5.12 and now throws a fatal error.
+See L<<< perldeprecation/Assigning non-zero to C<< $[ >> is fatal >>>.
 
 =head2 Delimiters must now be graphemes
 
@@ -138,12 +128,6 @@ But to avoid breaking code unnecessarily, most instances that issued a
 deprecation warning, remain legal and now have a non-deprecation warning
 raised.  See L<perldeprecation/Unescaped left braces in regular expressions>.
 
-=head2 Assigning non-zero to C<$[> is fatal
-
-Setting L<< C<$[>|perlvar/$[ >> to a non-zero value has been deprecated since
-Perl 5.12 and now throws a fatal error.
-See L<<< perldeprecation/Assigning non-zero to C<< $[ >> is fatal >>>.
-
 =head2 Previously deprecated sysread()/syswrite() on :utf8 handles is now fatal
 
 Calling sysread(), syswrite(), send() or recv() on a C<:utf8> handle,
@@ -206,8 +190,7 @@ malformed UTF-8.  This protects agains potential security threats.  This
 is considered a bug fix as well.
 L<[perl #131642]|https://rt.perl.org/Ticket/Display.html?id=131642>.
 
-=head2 Any set of digits in the Common script are legal in a script run
-of another script
+=head2 Any set of digits in the Common script are legal in a script run of another script
 
 There are several sets of digits in the Common script.  C<[0-9]> is the
 most familiar.  But there are also C<[\x{FF10}-\x{FF19}]> (FULLWIDTH
@@ -245,7 +228,7 @@ Translating from UTF-8 into the code point it represents now is done via a
 deterministic finite automaton, speeding it up.  As a typical example,
 C<ord("\x7fff")> now requires 12% fewer instructions than before.  The
 performance of checking that a sequence of bytes is valid UTF-8 is similarly
-improved, again by using a dfa.
+improved, again by using a DFA.
 
 =item *
 
@@ -282,11 +265,11 @@ Code optimizations in F<regcomp.c>, F<regcomp.h>, F<regexec.c>.
 =item *
 
 Regular expression pattern matching of things like C<qr/[^I<a>]/> is
-significantly sped up, where I<a> is any ASCII character.  Which classes
-will get this speed up is complicated and depends on the underlying bit
-patterns of those characters, so differs between ASCII and EBCDIC
-platforms, but all case pairs, like C<qr/[Gg]/> are included, as is
-C<[^01]>.
+significantly sped up, where I<a> is any ASCII character.  Other classes
+can get this speed up, but which ones is complicated and depends on the
+underlying bit patterns of those characters, so differs between ASCII
+and EBCDIC platforms, but all case pairs, like C<qr/[Gg]/> are included,
+as is C<[^01]>.
 
 =back
 
@@ -354,7 +337,7 @@ L<CPAN> has been upgraded from version 2.20 to 2.22.
 
 L<Data::Dumper> has been upgraded from version 2.170 to 2.174
 
-L<Data::Dumper> now avoids leak when C<croak>ing.
+L<Data::Dumper> now avoids leaking when C<croak>ing.
 
 =item *
 
@@ -370,7 +353,7 @@ L<Devel::Peek> has been upgraded from version 1.27 to 1.28.
 
 =item *
 
-L<Devel::PPPort> has been upgraded from version 3.40 to 3.51.
+L<Devel::PPPort> has been upgraded from version 3.40 to 3.52.
 
 =item *
 
@@ -862,7 +845,8 @@ L<[perl #133524]|https://rt.perl.org/Ticket/Display.html?id=133524>
 =item *
 
 Under C<< -Dr >> (or C<< use re 'Debug' >>) the compiled regex engine
-program is displayed. It used two different spellings for I<< infinity >>,
+program is displayed. It used to use two different spellings for I<<
+infinity >>,
 C<< INFINITY >>, and C<< INFTY >>. It now uses the latter exclusively,
 as that spelling has been around the longest.
 
@@ -889,9 +873,9 @@ L<[perl #133654]|https://rt.perl.org/Ticket/Display.html?id=133654>.
 
 =item *
 
-Normally the thread-safe functions are used only on threaded builds.
-It is now possible to force their use on unthreaded builds on systems
-that have them available, by including the
+Normally the thread-safe locale functions are used only on threaded
+builds.  It is now possible to force their use on unthreaded builds on
+systems that have them available, by including the
 C<-Accflags='-DUSE_THREAD_SAFE_LOCALE'> option to F<Configure>.
 
 =item *
@@ -905,11 +889,11 @@ L<[perl #133760]|https://rt.perl.org/Ticket/Display.html?id=133760>.
 
 =item *
 
-Fix -DPERL_GLOBAL_STRUCT_PRIVATE build option.
+Multiple improvements and fixes for -DPERL_GLOBAL_STRUCT build option.
 
 =item *
 
-Multiple improvements and fixes for -DPERL_GLOBAL_STRUCT build option.
+Fix -DPERL_GLOBAL_STRUCT_PRIVATE build option.
 
 =back