bug#49731: 28.0.50; Filter xref results by filename

["Daniel Martín via Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Juri Linkov <juri@linkov.net> writes:

>>> Now pushed to master in the commit 3573ebfa6d (it seems this is
>>> backward-compatible since it only sets buffer-local variables).
>>
>> Nice.
>>
>> Do you plan on adding an outline-[minor-]mode command to hide/show by
>> regexp?
>
> So now here are these two commands:
>
>   / s   outline-show-by-heading-regexp
>   / h   outline-hide-by-heading-regexp
>

Thanks.  Does it make sense for these commands to follow similar
semantics as Org Mode's sparse trees?  With C-c / / in an Org file, the
entire buffer is folded as much as possible, but the matching items are
made visible.  Here's a practical example:

* 1
abc
* 2
def
* 3
ghi

M-x org-mode
C-c / / ghi RET
(Only ghi section is visible.)
C-c / / abc RET
(Only abc section is visible.)
C-u C-c / / ghi RET <- Current folding status is kept.
(abc and ghi sections are visible.)

The main difference is that outline-show-by-heading-regexp would match
only headings, but that is clear given the name of the command.