perldiag: Document ‘Zero length \N{}’

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 9121e06..521a0ea 100644 (file)
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -6462,6 +6462,14 @@ what you want, put an & in front.)
 not get any randomness out of your system.  This usually indicates
 Something Very Wrong.
 
+=item Zero length \N{} in regex; marked by <-- HERE in m/%s/
+
+(F) Named Unicode character escapes C<(\N{...})> may return a zero-length
+sequence.  Such an escape was used in an extended character class, i.e.
+C<(?[...])>, which is not permitted.  Check that the correct escape has
+been used, and the correct charnames handler is in scope.  The <-- HERE
+shows whereabouts in the regular expression the problem was discovered.
+
 =back
 
 =head1 SEE ALSO

diff --git a/t/porting/diag.t b/t/porting/diag.t
index 6925872..d359ecf 100644 (file)
--- a/t/porting/diag.t
+++ b/t/porting/diag.t
@@ -637,7 +637,6 @@ Wrong size of loadOrdinals array: expected %d, actual %d
 Wrong syntax (suid) fd script name "%s"
 'X' outside of string in %s
 'X' outside of string in unpack
-Zero length \N{} in regex; marked by <-- HERE in m/%s/
 
 __CATEGORIES__
 Code point 0x%X is not Unicode, all \p{} matches fail; all \P{} matches succeed