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;