bug#65578: Eglot with mouse

[Dmitry Gutov]

On 28/08/2023 19:42, Juri Linkov wrote:
> > > xref-find-definitions-at-mouse uses save-excursion with
> > > mouse-set-point before calling xref-backend-identifier-at-point.
> > > But the same save-excursion with mouse-set-point can't be added
> > > around xref-find-definitions because save-excursion will restore
> > > the original position after visiting the found identifier.
> > Could we do that without additional save-excursion?
> >
> > diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
> > index 0666b18cba1..0c3e34fe0a5 100644
> > --- a/lisp/progmodes/xref.el
> > +++ b/lisp/progmodes/xref.el
> > @@ -1637,7 +1637,9 @@ xref-find-definitions-at-mouse
> >              (mouse-set-point event)
> >              (xref-backend-identifier-at-point (xref-find-backend)))))
> >       (if identifier
> > -        (xref-find-definitions identifier)
> > +        (progn
> > +          (mouse-set-point event)
> > +          (xref-find-definitions identifier))
> >         (user-error "No identifier here"))))
> The problem with this solution is that when it doesn't find
> the identifier then it leaves point at the wrong place.

I'm not sure is a big problem, but we could save the original position 
and restore it in case of error too:

diff --git a/lisp/progmodes/xref.el b/lisp/progmodes/xref.el
index 0666b18cba1..fb7380dee77 100644
--- a/lisp/progmodes/xref.el
+++ b/lisp/progmodes/xref.el
@@ -1635,9 +1635,18 @@ xref-find-definitions-at-mouse
   (let ((identifier
          (save-excursion
            (mouse-set-point event)
-           (xref-backend-identifier-at-point (xref-find-backend)))))
+           (xref-backend-identifier-at-point (xref-find-backend))))
+        (buf (current-buffer))
+        (pos (point)))
     (if identifier
-        (xref-find-definitions identifier)
+        (condition-case err
+          (progn
+            (mouse-set-point event)
+            (xref-find-definitions identifier))
+          (user-error
+           (set-buffer buf)
+           (goto-char pos)
+           (user-error (message (error-message-string err)))))
       (user-error "No identifier here"))))

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