From a6be18461471b0889ded6084693664927a041704 Mon Sep 17 00:00:00 2001
From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Mon, 1 Feb 2021 10:42:22 +0100
Subject: [PATCH] Fix indentation of non-comment HTML with -- in it

* lisp/textmodes/sgml-mode.el (sgml-comment-indent-new-line): Only
indent as if we're in a comment if syntax-ppss says that we're in
a comment (bug#36227).
---
 lisp/textmodes/sgml-mode.el | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/lisp/textmodes/sgml-mode.el b/lisp/textmodes/sgml-mode.el
index 3e29f055ece..7051f520b90 100644
--- a/lisp/textmodes/sgml-mode.el
+++ b/lisp/textmodes/sgml-mode.el
@@ -510,10 +510,12 @@ an optional alist of possible values."
 (with-no-warnings (defvar v2))				; free for skeleton
 
 (defun sgml-comment-indent-new-line (&optional soft)
-  (let ((comment-start "-- ")
-	(comment-start-skip "\\(<!\\)?--[ \t]*")
-	(comment-end " --")
-	(comment-style 'plain))
+  (if (ppss-comment-depth (syntax-ppss))
+      (let ((comment-start "-- ")
+	    (comment-start-skip "\\(<!\\)?--[ \t]*")
+	    (comment-end " --")
+	    (comment-style 'plain))
+        (comment-indent-new-line soft))
     (comment-indent-new-line soft)))
 
 (defun sgml-mode-facemenu-add-face-function (face _end)
-- 
2.39.2