Update perlunicode base on Unicode UTS 18, regex reqs

Unicode is revising their document on what regular expression
implementations should do.  This includes retraction of a significant
part of it, which Perl did not handle (and apparently nobody else
either).  Thus we are much closer to implementing everything they say
than before.  The document is adding some new (manageable) things, which
we do not yet support.

1 files changed, 17 insertions, 37 deletions

diff --git a/pod/perlunicode.pod b/pod/perlunicode.pod
index 5a7938d5e6..b9be1924b4 100644
--- a/pod/perlunicode.pod
+++ b/pod/perlunicode.pod
@@ -1308,8 +1308,7 @@ version 18, October 2016.
 
 =item [2]
 C<\p{...}> C<\P{...}>.  This requirement is for a minimal list of
-properties.  Perl supports these and all other Unicode character
-properties, as R2.7 asks (see L</"Unicode Character Properties"> above).
+properties.  Perl supports these.  See R2.7 for other properties.
 
 =item [3]
 Perl has C<\d> C<\D> C<\s> C<\S> C<\w> C<\W> C<\X> C<[:I<prop>:]>
@@ -1416,12 +1415,14 @@ C<U+10FFFF> but also beyond C<U+10FFFF>
 
  RL2.1   Canonical Equivalents           - Retracted     [9]
                                            by Unicode
- RL2.2   Extended Grapheme Clusters      - Partial       [10]
+ RL2.2   Extended Grapheme Clusters and  - Partial       [10]
+         Character Classes with Strings
  RL2.3   Default Word Boundaries         - Done          [11]
  RL2.4   Default Case Conversion         - Done
  RL2.5   Name Properties                 - Done
  RL2.6   Wildcards in Property Values    - Partial       [12]
- RL2.7   Full Properties                 - Done
+ RL2.7   Full Properties                 - Partial       [13]
+ RL2.8   Optional Properties             - Partial       [14]
 
 =over 4
 
@@ -1434,7 +1435,9 @@ both your regular expressions and text to match them against (you
 can use L<Unicode::Normalize>).
 
 =item [10]
-Perl has C<\X> and C<\b{gcb}> but we don't have a "Grapheme Cluster Mode".
+Perl has C<\X> and C<\b{gcb}>.  Unicode has retracted their "Grapheme
+Cluster Mode", and recently added string properties, which Perl does not
+yet support.
 
 =item [11] see
 L<UAX#29 "Unicode Text Segmentation"|https://www.unicode.org/reports/tr29>,
@@ -1442,44 +1445,21 @@ L<UAX#29 "Unicode Text Segmentation"|https://www.unicode.org/reports/tr29>,
 =item [12] see
 L</Wildcards in Property Values> above.
 
-=back
-
-=head3 Level 3 - Tailored Support
-
- RL3.1   Tailored Punctuation            - Missing
- RL3.2   Tailored Grapheme Clusters      - Missing       [13]
- RL3.3   Tailored Word Boundaries        - Missing
- RL3.4   Tailored Loose Matches          - Retracted by Unicode
- RL3.5   Tailored Ranges                 - Retracted by Unicode
- RL3.6   Context Matching                - Partial       [14]
- RL3.7   Incremental Matches             - Missing
- RL3.8   Unicode Set Sharing             - Retracted by Unicode
- RL3.9   Possible Match Sets             - Missing
- RL3.10  Folded Matching                 - Retracted by Unicode
- RL3.11  Submatchers                     - Partial       [15]
-
-=over 4
-
 =item [13]
-Perl has L<Unicode::Collate>, but it isn't integrated with regular
-expressions.  See
-L<UTS#10 "Unicode Collation Algorithms"|https://www.unicode.org/reports/tr10>.
+Perl supports all the properties in the Unicode Character Database
+(UCD).  It does not yet support the listed properties that come from
+other Unicode sources.
 
 =item [14]
-Perl has C<(?<=x)> and C<(?=x)>, but this requirement says that it
-should be possible to specify that matches may occur only in a substring
-with the lookaheads and lookbehinds able to see beyond that matchable
-portion.
-
-=item [15]
-Perl has user-defined properties (L</"User-Defined Character
-Properties">) to look at single code points in ways beyond Unicode, and
-it might be possible, though probably not very clean, to use code blocks
-and things like C<(?(DEFINE)...)> (see L<perlre>) to do more specialized
-matching.
+The only optional property that Perl supports is Named Sequence.  None
+of these properties are in the UCD.
 
 =back
 
+=head3 Level 3 - Tailored Support
+
+This has been retracted by Unicode.
+
 =head2 Unicode Encodings
 
 Unicode characters are assigned to I<code points>, which are abstract