*************************************************/
/* This function runs a regular expression match, and sets up the pointers to
-the matched substrings. The matched strings are copied.
-
-We might consider tracing the uses of expand_nstring to see if consitification
-is viable, and save the copy cost by just using the pointers into the subject string.
-Pre-pcre2 we did that without noticing, so it might just work - or might have been
-a bug. It was certainly a risk in the implemenation.
+the matched substrings. The matched strings are copied so the lifetime of
+the subject is not a problem.
Arguments:
re the compiled expression