bug#32034: 26.1; [PACTH] better xref-location-marker for imperfect file locations

[João Távora]

Eli Zaretskii <eliz@gnu.org> writes:

>>            (beginning-of-line line)
>> -          (forward-char column)
>> +          (ignore-errors (forward-char column))
>> +          (unless (and (= (1+ (current-line)) line)
>> +                       (= (current-column) column))
>> +            (message "Intended xref location was line=%d, column=%d"
>> +                     line column))
>>            (point-marker))))))
>
> What will the last hunk do when a file changed, but the identifier was
> still found?

The function is completely oblivious to the identifier being found or
not.  So it would do what it does now: jump to the wrong location
(unless you're lucky and the change preserved the location of the
definition you're after).

> AFAIR, the etags back-end is capable of doing that
> (because it searches the file in the vicinity of the line/column if
> not found at the exact location), and it's a valuable feature, for
> obvious reasons.

IIUC, that's what I'm proposing in my point 3: add a "hint" field to
xref-file-location and default that hint to the identifier being looked
for.  If etags has code for that already, then great, we could try to
share it, but that would be for master right?  Or can 1, 2 and 3 go into
emacs-26?