GNU bug report logs -
#77718
31.0.50; completion styles substring and flex are broken
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Reported by: Stephen Berman <stephen.berman <at> gmx.net>
Date: Thu, 10 Apr 2025 22:23:02 UTC
Severity: normal
Found in version 31.0.50
Done: Stefan Monnier <monnier <at> iro.umontreal.ca>
Bug is archived. No further changes may be made.
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Message #172 received at 77718 <at> debbugs.gnu.org (full text, mbox):
> Does the attached patch go in the direction you intended with your
> comments?
Yes, tho I think it's not quite right yet.
> From my initial testing it gives the same results as my patch
> with hardcoded "/", and I haven't seen bad results yet; however, I don't
> have a good understanding of `completion-boundaries' and may well have
> not used it as you meant. Also, even if it does do what you suggested,
> since it in effect reverts the substring completion display and behavior
> involving directories to what it was before Spencer's changes, I guess
> he wouldn't accept it, just as he rejected my first patch.
I can't remember what his change was trying to do, so I won't try to
guess what would be his opinion.
> That was why I proposed to make the behavior configurable, but you
> don't like that; why not?
I don't think Spencer specifically wants `/usr/` to complete to
`/usr//`. He's probably interested in a more general case. So I don't
think the two desires are fundamentally incompatible.
> @@ -4613,16 +4613,22 @@ completion-pcm--merge-completions
> ;; If prefix is one of the completions, there's no
> ;; suffix left to find.
> (not (assoc-string prefix comps t)))
> - (let ((suffix
> - (completion--common-suffix
> - (if (zerop (length prefix)) comps
> - ;; Ignore the chars in the common prefix, so we
> - ;; don't merge '("abc" "abbc") as "ab*bc".
> - (let ((skip (length prefix)))
> - (mapcar (lambda (str) (substring str skip))
> - comps))))))
> + (let* ((suffix
> + (completion--common-suffix
> + (if (zerop (length prefix)) comps
> + ;; Ignore the chars in the common prefix, so we
> + ;; don't merge '("abc" "abbc") as "ab*bc".
> + (let ((skip (length prefix)))
> + (mapcar (lambda (str) (substring str skip))
> + comps)))))
> + (bounds (completion-boundaries
> + prefix comps minibuffer-completion-predicate
> + suffix))
> + (sep (substring suffix (max 0 (1- (cdr bounds)))
> + (cdr bounds))))
> (cl-assert (stringp suffix))
> - (unless (equal suffix "")
> + (unless (or (equal suffix "")
> + (and (equal prefix "") (equal suffix sep)))
> (push suffix res))))
IIRC `prefix` here is just the longest common prefixes among the found
candidates for this specific part of the input pattern. E.g. for `/u
TAB`, `prefix` could be just "s" if there's `/usr/` and `/users/` among
the candidates. So testing if `prefix` is "" doesn't actually test
whether the text before `suffix` is another boundary separator
(e.g. "/"). For that you'd need to look also at `res` (which is where
the "/u" part would be stashed, tho possibly in pieces, with other
(non-string) elements interspersed).
Similarly, calling `completion-boundaries` on just `prefix` doesn't make
much sense. You'd want to call it on the combination of `prefix` and
`res` (i.e. on something like `(completion-pcm--pattern->string (reverse
(cons prefix res)))`).
BTW, if we want to fix the problem with a user-config, there is one part
that would make sense to be user-configurable, which is whether
`substring` completion should try and complete suffixes at all:
Depending on your habits and typing style, having a suffix inserted
after point can be a hindrance rather than a help because it can be
easier for you to type that suffix than to skip over it.
The "right" way to make this configurable (IMO) would be to have a new
completion style that's like `substring` but without the insertion of
common suffixes.
[ In my ideal UI, completion styles would not be limited to symbols, so
you could have `(substring nil)` and `(substring t)` be the two
alternatives, where `substring` would be a style that takes an
(optional) `inhibit-common-suffixes` arg. ]
Stefan
This bug report was last modified 10 days ago.
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