Previously, one could select a completion via M-<up>/M-<down>,
but then RET would not actually select the chosen completion.
With the addition of completion-auto-deselect, this is not
actually necessary: we can reasonably assume that when a
completion is selected, the user wants to use that, since their
last action must have been to select it. So, just choose the
selected completion on RET. This lets us default
minibuffer-completion-auto-choose to nil.
For minibuffers with require-match completion, this can be done
by changing the existing command bound to RET. For minibuffers
with nil require-match completion, RET was previously bound to
exit-minibuffer, and changing exit-minibuffer to have this logic
is risky. We handle that case by adding a new
minibuffer-completion-exit which wraps exit-minibuffer and bind
RET to it.
* lisp/minibuffer.el (minibuffer-insert-completion-if-selected)
(minibuffer-completion-exit, completion--selected-candidate):
Add.
(minibuffer-complete-and-exit): Call
minibuffer-choose-completion. (bug#77253)
(minibuffer-local-completion-map): Bind RET to
minibuffer-completion-exit, overriding exit-minibuffer.
(completion-in-region-mode-map): Bind RET to
minibuffer-choose-completion when there's a selected candidate.
(minibuffer-completion-auto-choose): Default to nil.
(minibuffer-visible-completions--filter)
(minibuffer-visible-completions-map): Delete RET binding, no
longer necessary.
* lisp/simple.el (completion-setup-function): Update completion
help text to show more correct bindings.
* test/lisp/minibuffer-tests.el (completions-header-format-test)
(minibuffer-next-completion): Set
minibuffer-completion-auto-choose=t explicitly.
(with-minibuffer-setup, minibuffer-completion-RET-prefix)
(completion-in-region-next-completion): Add new tests.
* etc/NEWS: Announce.
e46471ed07