bug#64516: [PATCH] docview: Only enable imenu when supported

[Morgan Smith <Morgan.J.Smith@outlook.com>]

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Tassilo Horn <tsdh@gnu.org> writes:

>
> Yes, almost.  I'd rather handle the error rather putting the setup
> function in a hook and let the error hit top-level and flash the screen.
>

I've made the requested change.  Please see attached.

Thank you,

Morgan


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From 7de1362395597d2d7210dc78dcdb104071d758ab Mon Sep 17 00:00:00 2001
From: Morgan Smith <Morgan.J.Smith@outlook.com>
Date: Tue, 11 Jul 2023 14:08:24 -0400
Subject: [PATCH] docview: imenu: check return value of 'mutool'

While 'mutool' supports many filetypes, 'mutool show' only supports
PDF files.  This would lead to cryptic imenu errors when opening other
file types (like EPUB) since we would parse the error output.  During
my testing this caused 'imenu--index-alist' to have a value of '(nil).

* lisp/doc-view.el (doc-view--pdf-outline): Error when 'mutool' returns
an error.  Use 'call-process' to get the return value and remove the
call to 'shell-quote-argument' as 'call-process' doesn't want any
escapes.
(doc-view-mode): Ignore imenu-unavailable errors when calling
'doc-view-imenu-setup'.
---
 lisp/doc-view.el | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lisp/doc-view.el b/lisp/doc-view.el
index b14655fb274..7d604a7bc86 100644
--- a/lisp/doc-view.el
+++ b/lisp/doc-view.el
@@ -147,6 +147,8 @@
 (require 'filenotify)
 (eval-when-compile (require 'subr-x))
 
+(autoload 'imenu-unavailable-error "imenu")
+
 ;;;; Customization Options
 
 (defgroup doc-view nil
@@ -1910,9 +1912,10 @@ doc-view--pdf-outline
   (let ((fn (or file-name (buffer-file-name))))
     (when fn
       (let ((outline nil)
-            (fn (shell-quote-argument (expand-file-name fn))))
+            (fn (expand-file-name fn)))
         (with-temp-buffer
-          (insert (shell-command-to-string (format "mutool show %s outline" fn)))
+          (unless (= 0 (call-process "mutool" nil (current-buffer) nil "show" fn "outline"))
+            (imenu-unavailable-error "Unable to create imenu index using `mutool'"))
           (goto-char (point-min))
           (while (re-search-forward doc-view--outline-rx nil t)
             (push `((level . ,(length (match-string 1)))
@@ -2236,7 +2239,7 @@ doc-view-mode
     (setq mode-name "DocView"
 	  buffer-read-only t
 	  major-mode 'doc-view-mode)
-    (doc-view-imenu-setup)
+    (ignore-error imenu-unavailable (doc-view-imenu-setup))
     (doc-view-initiate-display)
     ;; Switch off view-mode explicitly, because doc-view-mode is the
     ;; canonical view mode for PDF/PS/DVI files.  This could be
-- 
2.41.0