bug#25987: 25.2; support gcc fixit notes

[Dmitry Gutov]

On 05.03.2017 23:47, Tom Tromey wrote:

> * One way for this to work would be to display the buffer and
>    show the proposed change as an overlay; and then use y-or-n-p
>    to ask whether it should be applied.  I was thinking something like:
>
> (defun compilation--fixit-make-overlay (start end text)
>    (let ((overlay (make-overlay start end)))
>      (overlay-put overlay 'face 'diff-removed)
>      (overlay-put overlay 'after-string
>                   (propertize text 'face 'diff-added))
>      overlay))
>
>    With this approach perhaps nothing could be done if the fixit was
>    already visited, or if the buffer text already matches the
>    replacement.

I'm not sure we want to tie this feature to compilation-mode. Many modes 
that derive from it don't support fix-its, e.g. those of them that run 
the test suites. And even for those that do, Compilation provides a very 
basic UI.

Even to find and apply all fix-its, we'd need to add some new buffer, to 
show the list.

On the other hand, this can be a quick-and-dirty way to try out the 
feature and how handy it is. Showing the "quick fix" buttons on top of 
the fix-it text can be it (not sure it that's the UI you had in mind).