bug#66041: 30.0.50; Should 'flymake-note-echo' inherit from 'compilation-info'?

[João Távora]

On Mon, Sep 18, 2023 at 12:42 PM Eli Zaretskii <eliz@gnu.org> wrote:
>
> > From: João Távora <joaotavora@gmail.com>
> > Date: Mon, 18 Sep 2023 11:46:55 +0100
> > Cc: Jim Porter <jporterbugs@gmail.com>, 66041@debbugs.gnu.org
> >
> > On Mon, Sep 18, 2023, 11:44 Eli Zaretskii <eliz@gnu.org> wrote:
> >
> >  > Cc: 66041@debbugs.gnu.org
> >  > From: João Távora <joaotavora@gmail.com>
> >  > Date: Sun, 17 Sep 2023 23:15:31 +0100
> >  >
> >  > emacs -Q
> >  > M-x flymake-mode RET
> >  > M-: (setq flymake-show-diagnostics-at-end-of-line t) RET
> >  > M-x erase-buffer RET
> >  > h e l l o
> >  >
> >  > The first bug I find is that the exclamation mark on the fringe is
> >  > green, but it should be yellow, since, presumably a warning is
> >  > more important than a note.
> >  >
> >  > The second bug has to do with the placement of the cursor when
> >  > two "eol overlays" are present.  The cursor shouldn't be placed
> >  > in the middle of them, since they represent unreachable areas of
> >  > the buffer.
> >
> >  When I try the above, the cursor is at the end of "hello", and the
> >  overlay with the warning is displayed after it.  So I don't think I
> >  understand what you mean by "in the middle of them".
> >
> > Sorry. The recipe is missing a single SPC character after the hello, so 
> > that the style warning is
> > triggered.
>
> You have there two overlays, each one with a before-string, and each
> string has its first character propertized with (cursor t).  So Emacs
> picks up one of the two overlay strings to place the cursor, and it
> just happens to be not the one you wanted.

Yes, something like that.  Skimming the code, I think I meant for only
one overlay, not two, to be the end-of-line overlay containing the two
strings.  But this was tricky to implement and I probably missed an
edge case.  There is a FIXME there, have to investigate.

Anyway, since I have your interest, any suggestions on how you would
implement this? Knowing that this feature is upposed to display
multiple pieces of relatively short cursor-unreachable text visually
after the end -of-line (the text being the diagnostic text, naturally).

Currently I'm placing them exactly between (line-end-position) and the
character after that.  There is a link between this eol overlay and
the origin diagnostic.  If you delete the latter, the former should
be recalculated asap, i.e. it should ideally not wait another 1s or two
before Flymake re-contacts the backend for up-to-date info.

João