# What does this fix?
Currently, with non-exclusive completion functions, Emacs will do
`try-completion` on the current text, and decide whether to try next
completion function based on that. This makes completion functions that
can do non-prefix completions fails when the current text only occurs in
the middle of the candidates. This is a problem I found in a FIXME in
the code.
# How does this work?
I use `completion-all-completions` instead. As far as I know, this
respects the `completion-styles`.
Here's a simple test. Eval this:
```
(require 'thingatpt)
(defun my-completion-at-point ()
(let* ((symbol (thing-at-point 'symbol))
(bounds (bounds-of-thing-at-point 'symbol)))
(list (car bounds) (cdr bounds)
'("gnuemacs" "xemacs" "uemacs")
:exclusive 'no)))
(setq completion-at-point-functions
'(my-completion-at-point elisp-completion-at-point))
(setq completion-styles '(substring))
```
Now type "emacs" and press `C-M-i`, the candidates defined in
`my-completion-at-point` will show up correctly. Now change
`completion-styles` to `(basic)`, and complete "emacs" again, it
fallbacks to `elisp-completion-at-point`.
# The patch
See the attachment. Since I don't know much about email, I'm not sure if
gmail's attachment is permanent, so I'll also paste the diff and commit
log here:
## Diff
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -2244,18 +2244,11 @@ completion--capf-wrapper
(unless (member fun completion--capf-safe-funs)
(push fun completion--capf-safe-funs))
(and (eq 'no (plist-get (nthcdr 3 res) :exclusive))
- ;; FIXME: Here we'd need to decide whether there are
- ;; valid completions against the current text. But this depends
- ;; on the actual completion UI (e.g. with the default completion
- ;; it depends on completion-style) ;-(
- ;; We approximate this result by checking whether prefix
- ;; completion might work, which means that non-prefix completion
- ;; will not work (or not right) for completion functions that
- ;; are non-exclusive.
- (null (try-completion (buffer-substring-no-properties
- (car res) (point))
- (nth 2 res)
- (plist-get (nthcdr 3 res) :predicate)))
+ (null (completion-all-completions
+ (buffer-substring-no-properties (car res) (point))
+ (nth 2 res)
+ (plist-get (nthcdr 3 res) :predicate)
+ (- (point) (car res))))
(setq res nil)))
((not (or (listp res) (functionp res)))
(unless (member fun completion--capf-misbehave-funs)
## Commit Log
Fix handling for non-exclusive non-prefix completion functions
* lisp/minibuffer.el (completion--capf-wrapper):
use completion-all-completions to do the test.