🚀 go-pugleaf

Piet van Oostrum writes:
 > When string-match matches an empty substring, (match-end 0) will report 1,
 > while it should report 0.
 > 
 > E.g: (string-match "x*" "abc") gives (match-end 0) => 1
 >      (string-match "x*" "xyz") also gives (match-end 0) => 1.
 > 
 > Probably the normal regexp match will also do this, but I
 > haven't checked it.

What version of Emacs are you using?  I tried this under v18.52
and match-end returned 0 for the first example, as it should.

On the other hand, the function `match-data' always returns
incorrect values if either end of the match is at the beginning
of the string or or if either match position is greater than
(point-max) in the current buffer.  This is because match-data
returns a list of _markers_ representing the match positions.
Marker positions are constrained by legal buffer positions and
positions less than (point-min) or greater than (point-max) are
rounded up or down to whichever end of the buffer is closest.

Bug?  Certainly, but I don't know if the behavior is worth
changing since you can write your own version of match-data that
returns a list of integers instead of markers.  E.g.

(defun match-data ()
  (let ((index '(9 8 7 6 5 4 3 2 1 0))
        (list))
    (while index
      (setq list (cons (match-beginning (car index))
		       (cons (match-end (car index)) list))
	    index (cdr index)))
    list ))