Re: TAGS completion with (setq-local completion-ignore-case t)

[Morgan Willcock <morgan@ice9.digital>]

Eli Zaretskii <eliz@gnu.org> writes:

>> I rebuilt from the latest commit on the master branch to incorporate the
>> patch.  Unfortunately, I do not see any change in the result of the
>> failing test case; the completion still appears to be case-sensitive.
>> 
>>   printf "Function IsSingle\nFunction IsString\n" > functions
>>   etags --lang=none --regex='/^function[ \t]+\([0-9A-Za-z:_]+\)/\1/i' functions
>>   emacs -Q --eval "(progn \
>>                      (pop-to-buffer (get-buffer-create \"test\")) \
>>                      (setq-local completion-ignore-case t) \
>>                      (visit-tags-table \"TAGS\") \
>>                      (insert \"is\") \
>>                      (complete-tag) \
>>                      (complete-tag))"
>> 
>>   # No completions.
>
> You need to set tags-case-fold-search, not the buffer-local value of
> completion-ignore-case.  That's because the commands in etags.el look
> at tags-case-fold-search to decide whether they should ignore
> letter-case.

Setting tags-case-fold-search to t (buffer-local or not) doesn't seem to
have any effect when completion-ignore-case is also set to t.

  emacs -Q --eval "(progn \
                     (pop-to-buffer (get-buffer-create \"test\")) \
                     (setq-local completion-ignore-case t) \
                     (setq-local tags-case-fold-search t) \
                     (visit-tags-table \"TAGS\") \
                     (insert \"is\") \
                     (complete-tag) \
                     (complete-tag))"

  # No completions.

  emacs -Q --eval "(progn \
                     (pop-to-buffer (get-buffer-create \"test\")) \
                     (setq-local completion-ignore-case t) \
                     (setq tags-case-fold-search t) \
                     (visit-tags-table \"TAGS\") \
                     (insert \"is\") \
                     (complete-tag) \
                     (complete-tag))"

  # No completions.

I would still need to set completion-ignore-case to t because that is
still relevant for other capf backends for the buffer (but not for all
buffers).

It also pretty strange that setting completion-ignore-case to t has done
the opposite of what it advertises.

-- 
Morgan Willcock