Questionable code in handling of wordend in the regexp engine in regex-emacs.c

[Alan Mackenzie]

Hello, Emacs.

In function re_match_2_internal (in regex-emacs.c) in the handling of
case wordend: inside the large switch statement (approximately line 4800
in the file), there is some code, the look of which I don't like.

Primarily, there is an

    UPDATE_SYNTAX_TABLE (charpos);

before determining the syntax of the previous character, which seems OK.
Later on, before determining the syntax of the next character, we have:

    UPDATE_SYNTAX_TABLE_FORWARD (charpos);

.  Between these two calls, charpos hasn't been changed.  Surely the
argument to the second occurrence should be (charpos + 1)?



Also, probably less importantly, there is

    GET_CHAR_AFTER (c2, d, dummy);

, whereas at the same place in the handler for case symend: we have
instead

    c2 = RE_STRING_CHAR (d, target_multibyte);

.  Is the effect of these macros identical, or is one of them up to
date, and the other one really needs updating as well, for correct
functionality?



I came across these whilst investigating bug #34525.  Making the
indicated changes to regex-emacs.c sadly doesn't help solve the symptoms
of that bug.  :-(

-- 
Alan Mackenzie (Nuremberg, Germany).