Minor perlreapi.pod cleanup

From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Message-ID: <51dd1af80705160938w13789b63m6d5f4710441ceac@mail.gmail.com>

p4raw-id: //depot/perl@31244

1 files changed, 11 insertions, 2 deletions

diff --git a/regexp.h b/regexp.h
index faec6564c1..1f72112ac8 100644
--- a/regexp.h
+++ b/regexp.h
@@ -55,8 +55,17 @@ typedef struct regexp_paren_pair {
     I32 end;
 } regexp_paren_pair;
 
-/* this is ordered such that the most commonly used 
-   fields are at the start of the struct */
+/*
+  The regexp/REGEXP struct, see L<perlreapi> for further documentation
+  on the individual fields. The struct is ordered so that the most
+  commonly used fields are placed at the start.
+
+  Any patch that adds items to this struct will need to include
+  changes to F<sv.c> (C<Perl_re_dup()>) and F<regcomp.c>
+  (C<pregfree()>). This involves freeing or cloning items in the
+  regexp's data array based on the data item's type.
+*/
+
 typedef struct regexp {
         /* what engine created this regexp? */
 	const struct regexp_engine* engine;