emacs-29 6fa9332e7cd 1/2: Ensure that EXTRA-DATA are always written when generating autoloads

[Philip Kaludercic]

branch: emacs-29
commit 6fa9332e7cdb28c3990f8d1444b02b65791713d6
Author: Philip Kaludercic <philipk@posteo.net>
Commit: Philip Kaludercic <philipk@posteo.net>

    Ensure that EXTRA-DATA are always written when generating autoloads
    
    * lisp/emacs-lisp/loaddefs-gen.el (loaddefs-generate): Handle
    edge-case where no autoloads are found.  (Bug#63260)
---
 lisp/emacs-lisp/loaddefs-gen.el | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lisp/emacs-lisp/loaddefs-gen.el b/lisp/emacs-lisp/loaddefs-gen.el
index 2a46fb7a022..5db9af21508 100644
--- a/lisp/emacs-lisp/loaddefs-gen.el
+++ b/lisp/emacs-lisp/loaddefs-gen.el
@@ -656,7 +656,20 @@ instead of just updating them with the new/changed 
autoloads."
             (write-region (point-min) (point-max) loaddefs-file nil 'silent)
             (byte-compile-info
              (file-relative-name loaddefs-file (car (ensure-list dir)))
-             t "GEN")))))))
+             t "GEN")))))
+
+    ;; If processing files without any autoloads, the above loop will
+    ;; not generate any files.  If the function was invoked with
+    ;; EXTRA-DATA, we want to ensure that even if no autoloads were
+    ;; found, that at least a file will have been generated containing
+    ;; the contents of EXTRA-DATA:
+    (when (and extra-data (not (file-exists-p output-file)))
+      (with-temp-buffer
+        (insert (loaddefs-generate--rubric output-file nil t))
+        (search-backward "\f")
+        (insert extra-data)
+        (ensure-empty-lines 1)
+        (write-region (point-min) (point-max) output-file nil 'silent)))))
 
 (defun loaddefs-generate--print-form (def)
   "Print DEF in a format that makes sense for version control."