bug#63759: 29.0.91; dockerfile-ts-mode--imenu returns invalid index

[Randy Taylor <dev@rjt.dev>]

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On Saturday, May 27th, 2023 at 14:33, Eli Zaretskii <eliz@gnu.org> wrote:
> > From: Jimmy Yuen Ho Wong wyuenho@gmail.com
> 
> > Date: Sat, 27 May 2023 18:38:29 +0100
> > 
> > Reproduction:
> > 
> > 0. Open a Emacs GUI, i.e. NS port
> > 1. C-x C-f /some/nonexistent/Dockerfile
> > 2. M-x toggle-debug-on-error
> > 2. M-x imenu-add-menubar-index
> > 3. Click on the Index > Stage menu item
> > 4. Observe the following error pops up
> > 
> > Expectation:
> > 
> > If the dockerfile-ts-mode buffer is empty, there should not be an extra
> > item preset in the imenu index that when clicked on will jump to a
> > non-existent location and result in an error.
> > 
> > `Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil) imenu-default-goto-function("Stage" nil) imenu(("Stage" nil imenu-default-goto-function)) imenu(("Stage")) imenu--menubar-select(("Stage")) #f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>)() funcall-interactively(#f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>)) #<subr call-interactively>(#f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>) nil nil) call-interactively@ido-cr+-record-current-command(#<subr call-interactively> #f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>) nil nil) apply(call-interactively@ido-cr+-record-current-command #<subr call-interactively> (#f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>) nil nil)) call-interactively(#f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>) nil nil) command-execute(#f(compiled-function () (interactive nil) #<bytecode 0xcfe8182542f4cbd>))`
> 
> 
> Thanks.
> 
> Randy, can you p-lease look into this?

Thanks for the report Jimmy.

Patch attached.

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From 479d474153a71753391ae3323416cdadfe79638d Mon Sep 17 00:00:00 2001
From: Randy Taylor <dev@rjt.dev>
Date: Sat, 27 May 2023 20:52:37 -0400
Subject: [PATCH] dockerfile-ts-mode: Prevent empty categories in imenu
 (Bug#63759)

* lisp/progmodes/dockerfile-ts-mode.el (dockerfile-ts-mode--imenu):
Don't include empty categories.
---
 lisp/progmodes/dockerfile-ts-mode.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/progmodes/dockerfile-ts-mode.el b/lisp/progmodes/dockerfile-ts-mode.el
index f2f30cf2617..078f5965341 100644
--- a/lisp/progmodes/dockerfile-ts-mode.el
+++ b/lisp/progmodes/dockerfile-ts-mode.el
@@ -123,8 +123,10 @@ dockerfile-ts-mode--imenu
   (let* ((node (treesit-buffer-root-node))
          (stage-tree (treesit-induce-sparse-tree
                       node "from_instruction"
-                      nil 1000)))
-    `(("Stage" . ,(dockerfile-ts-mode--imenu-1 stage-tree)))))
+                      nil 1000))
+         (stage-index (dockerfile-ts-mode--imenu-1 stage-tree)))
+    (append
+     (when stage-index `(("Stage" . ,stage-index))))))
 
 (defun dockerfile-ts-mode--imenu-1 (node)
   "Helper for `dockerfile-ts-mode--imenu'.
-- 
2.40.1