From 41a42e631bd798151130097feafa6f535161b9de Mon Sep 17 00:00:00 2001
From: =?utf8?q?Jo=C3=A3o=20T=C3=A1vora?= <joaotavora@gmail.com>
Date: Thu, 8 Sep 2022 11:53:11 +0100
Subject: [PATCH] Don't return poorly supported "special elements" in
 eglot-imenu

Fix https://github.com/joaotavora/eglot/issues/758, https://github.com/joaotavora/eglot/issues/536, https://github.com/joaotavora/eglot/issues/535.

Eglot's eglot-imenu returned a structure compliant with the rules
outlined in imenu--index-alist.  In particular, it returned some
elements of the form

  (INDEX-NAME POSITION GOTO-FN ARGUMENTS...)

The original intention (mine) must have been to allow fancy
highlighting of the position navigated to with a custom GOTO-FN.

Not only was access to that fanciness never implemented, but many
other imenu frontends do not support such elements.

See for example https://github.com/joaotavora/eglot/issues/758, https://github.com/joaotavora/eglot/issues/536, https://github.com/joaotavora/eglot/issues/535.  And also related issues in other
packages:

https://github.com/IvanMalison/flimenu/issues/6
https://github.com/bmag/imenu-list/issues/58

So it's best to remove this problematic feature for now.  It can be
added back later.

* eglot.el (eglot-imenu): Simplify.

* NEWS.md: Mention change
---
 lisp/progmodes/eglot.el | 52 ++++++++++++++++++++---------------------
 1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/lisp/progmodes/eglot.el b/lisp/progmodes/eglot.el
index 80884903636..2ac9b0dff66 100644
--- a/lisp/progmodes/eglot.el
+++ b/lisp/progmodes/eglot.el
@@ -2916,39 +2916,37 @@ for which LSP on-type-formatting should be requested."
       nil)))
 
 (defun eglot-imenu ()
-  "EGLOT's `imenu-create-index-function'."
+  "EGLOT's `imenu-create-index-function'.
+Returns a list as described in docstring of `imenu--index-alist'."
   (cl-labels
-      ((visit (_name one-obj-array)
-              (imenu-default-goto-function
-               nil (car (eglot--range-region
-                         (eglot--dcase (aref one-obj-array 0)
-                           (((SymbolInformation) location)
-                            (plist-get location :range))
-                           (((DocumentSymbol) selectionRange)
-                            selectionRange))))))
-       (unfurl (obj)
-               (eglot--dcase obj
-                 (((SymbolInformation)) (list obj))
-                 (((DocumentSymbol) name children)
-                  (cons obj
-                        (mapcar
-                         (lambda (c)
-                           (plist-put
-                            c :containerName
-                            (let ((existing (plist-get c :containerName)))
-                              (if existing (format "%s::%s" name existing)
-                                name))))
-                         (mapcan #'unfurl children)))))))
+      ((unfurl (obj)
+         (eglot--dcase obj
+           (((SymbolInformation)) (list obj))
+           (((DocumentSymbol) name children)
+            (cons obj
+                  (mapcar
+                   (lambda (c)
+                     (plist-put
+                      c :containerName
+                      (let ((existing (plist-get c :containerName)))
+                        (if existing (format "%s::%s" name existing)
+                          name))))
+                   (mapcan #'unfurl children)))))))
     (mapcar
      (pcase-lambda (`(,kind . ,objs))
        (cons
         (alist-get kind eglot--symbol-kind-names "Unknown")
         (mapcan (pcase-lambda (`(,container . ,objs))
-                  (let ((elems (mapcar (lambda (obj)
-                                         (list (plist-get obj :name)
-                                               `[,obj] ;; trick
-                                               #'visit))
-                                       objs)))
+                  (let ((elems (mapcar
+                                (lambda (obj)
+                                  (cons (plist-get obj :name)
+                                        (car (eglot--range-region
+                                              (eglot--dcase obj
+                                                (((SymbolInformation) location)
+                                                 (plist-get location :range))
+                                                (((DocumentSymbol) selectionRange)
+                                                 selectionRange))))))
+                                objs)))
                     (if container (list (cons container elems)) elems)))
                 (seq-group-by
                  (lambda (e) (plist-get e :containerName)) objs))))
-- 
2.39.2