Revert to defadvice for sh-must-be-shell-mode

* ebuild-mode.el (sh-must-be-shell-mode): Test if the function is
defined at compile time. This should only be the case for Emacs
versions where defadvice is unobsolete.

Signed-off-by: Ulrich Müller <ulm@gentoo.org>

2 files changed, 8 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index 0052228..68a5be8 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2023-09-16  Ulrich Müller  <ulm@gentoo.org>
 
+	* ebuild-mode.el (sh-must-be-shell-mode): Test if the function is
+	defined at compile time. This should only be the case for Emacs
+	versions where defadvice is unobsolete.
+
 	* glep-mode.el (rst-classify-adornment)
 	(glep-mode-ignore-preamble): Use :before-while instead of :around
 	as advice combinator.
diff --git a/ebuild-mode.el b/ebuild-mode.el
index d49c931..416758d 100644
--- a/ebuild-mode.el
+++ b/ebuild-mode.el
@@ -901,12 +901,11 @@ in a Gentoo profile."
     ["Insert package.mask tag line" ebuild-mode-insert-tag-line]
     ["Customize ebuild-mode" (customize-group 'ebuild)]))
 
-(if (fboundp 'sh-must-be-shell-mode)
+(if (eval-when-compile (fboundp 'sh-must-be-shell-mode))
     ;; make TAB key work
-    (defun sh-must-be-shell-mode ()
-      "Signal an error if not in Shell-script mode."
-      (unless (derived-mode-p 'sh-mode)
-	(error "This buffer is not in Shell-script mode"))))
+    (defadvice sh-must-be-shell-mode
+	(around ebuild-mode-sh-must-be-shell-mode activate)
+      (unless (derived-mode-p 'sh-mode) ad-do-it)))
 
 ;;;###autoload
 (add-to-list 'auto-mode-alist '("\\.\\(ebuild\\|eclass\\)\\'" . ebuild-mode))