PATCH GH #17025 \p{user-defined} overrides official Unicode

Prior to this patch, they only sometimes overrode.

2 files changed, 17 insertions, 1 deletions

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index 7ce4cf8f01..23d3fe7656 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -45,6 +45,20 @@ XXX For a release on a stable branch, this section aspires to be:
 
 [ List each incompatible change as a =head2 entry ]
 
+=head2 C<\p{I<user-defined>}> properties now always override official
+Unicode ones
+
+Previously, if and only if a user-defined property was declared prior to
+the compilation of the regular expression pattern containing it, its
+definition was used instead of any official Unicode property with the
+same name.  Now, it always overrides the offical property.  This
+change could break existing code that relied (likely unwittingly) on the
+previous behavior.  Without this fix, if Unicode released a new version
+with a new property that happens to have the same name as the one you
+had long been using, your program would break when you upgraded to a
+perl that used that new Unicode version.  See L<perlunicode/User-Defined
+Character Properties>.  [GH #17205]
+
 =head1 Deprecations
 
 XXX Any deprecated features, syntax, modules etc. should be listed here.
diff --git a/pod/perlunicode.pod b/pod/perlunicode.pod
index e048df6df6..59058225b7 100644
--- a/pod/perlunicode.pod
+++ b/pod/perlunicode.pod
@@ -1066,7 +1066,9 @@ You can define your own binary character properties by defining subroutines
 whose names begin with C<"In"> or C<"Is">.  (The experimental feature
 L<perlre/(?[ ])> provides an alternative which allows more complex
 definitions.)  The subroutines can be defined in any
-package.  The user-defined properties can be used in the regular expression
+package.  They override any Unicode properties expressed as the same
+names.  The user-defined properties can be used in the regular
+expression
 C<\p{}> and C<\P{}> constructs; if you are using a user-defined property from a
 package other than the one you are in, you must specify its package in the
 C<\p{}> or C<\P{}> construct.