bug#29193: 26.0.90; Using (thing-at-point 'sexp) in flymake-diag-region might be suboptimal

[Dmitry Gutov <dgutov@yandex.ru>]

On 12.12.2020 13:39, Lars Ingebrigtsen wrote:
> Dmitry Gutov <dgutov@yandex.ru> writes:
> 
>> Rubocop can report warning when 'end' is at wrong column. It just
>> reports the beginning column, of course.
>>
>> In ruby-mode, (thing-at-point 'sexp) signals an error at this position.
>> I'm not sure exactly whether it's a problem in ruby-mode.
>>
>> But Flycheck uses (thing-at-poing 'symbol) for the same purpose, and the
>> whole 'end' token gets highlighted (which is probably what we expect).
>>
>> In contrast, Flymake only highlights its first character ('e').
> 
> I had a look at the current `flymake-diag-region', and it does not use
> (thing-at-point 'sexp) at present.  It does use (end-of-thing 'sexp),
> though.

The behavior is the same: when 'end' is misindented, only 'e' in 'end' 
is highlighted.

Whereas the message is:

Layout/EndAlignment: ‘end‘ at 23, 3 is not aligned with ‘class‘ at 5, 4.

That highlighting is not too hard to interpret, but we could do better, 
probably.