bug#3717: M-x man completion

[Kevin Ryde]

Stefan Monnier <monnier@iro.umontreal.ca> writes:
>
> "boundary"

Speaking of boundaries, I wonder if perl "::" would be a good boundary,
since it's basically a directory separator in disguise.  I'll give it a
go - though I'm not a sophisticated completions user, so I wonder if
I'll notice the difference :).

    (cond ((eq (car-safe action) 'boundaries) ;; emacs23
           (let* ((suffix (cdr action))
                  ;; after last "::", or after start of string
                  ;; (page names don't have newlines, so ".*" is ok)
                  (start  (if (string-match ".*::" str) (match-end 0) 0))
                  ;; first "::", or end of string
                  (end    (string-match "::\\|\\'" suffix)))
             (cons 'boundaries (cons start end))))