From cb2f5380e3e78b7d956c604c03c21122c8ced36d Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Sun, 23 Jun 2019 21:27:43 -0400
Subject: [PATCH] Fix sgml-mode handling of quotes within parens (Bug#36347)

* lisp/textmodes/sgml-mode.el (sgml-syntax-propertize): Use
syntax-ppss-table if set.  This is only needed on the release branch,
on master the caller (syntax-propertize) already does this.
(sgml-mode): Set syntax-ppss-table to sgml-tag-syntax-table.  This
correctly classifies parens as punctuation, so they won't confuse the
parser.
* test/lisp/textmodes/sgml-mode-tests.el (sgml-tests--quotes-syntax):
New test copied from master, with two cases added for this bug.
---
 lisp/textmodes/sgml-mode.el            | 10 ++++++----
 test/lisp/textmodes/sgml-mode-tests.el | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/lisp/textmodes/sgml-mode.el b/lisp/textmodes/sgml-mode.el
index 128e58810e..895ce844e9 100644
--- a/lisp/textmodes/sgml-mode.el
+++ b/lisp/textmodes/sgml-mode.el
@@ -357,10 +357,11 @@ (eval-and-compile
 (defun sgml-syntax-propertize (start end)
   "Syntactic keywords for `sgml-mode'."
   (goto-char start)
-  (sgml-syntax-propertize-inside end)
-  (funcall
-   (syntax-propertize-rules sgml-syntax-propertize-rules)
-   start end))
+  (with-syntax-table (or syntax-ppss-table (syntax-table)) ; Not needed on master.
+    (sgml-syntax-propertize-inside end)
+    (funcall
+     (syntax-propertize-rules sgml-syntax-propertize-rules)
+     start end)))
 
 (defun sgml-syntax-propertize-inside (end)
   (let ((ppss (syntax-ppss)))
@@ -568,6 +569,7 @@ (define-derived-mode sgml-mode text-mode '(sgml-xml-mode "XML" "SGML")
 			      sgml-font-lock-keywords-2)
 			     nil t))
   (setq-local syntax-propertize-function #'sgml-syntax-propertize)
+  (setq-local syntax-ppss-table sgml-tag-syntax-table)
   (setq-local facemenu-add-face-function 'sgml-mode-facemenu-add-face-function)
   (setq-local sgml-xml-mode (sgml-xml-guess))
   (unless sgml-xml-mode
diff --git a/test/lisp/textmodes/sgml-mode-tests.el b/test/lisp/textmodes/sgml-mode-tests.el
index 7318a667b3..0000b352ff 100644
--- a/test/lisp/textmodes/sgml-mode-tests.el
+++ b/test/lisp/textmodes/sgml-mode-tests.el
@@ -130,5 +130,27 @@ (ert-deftest sgml-delete-tag-bug-8203-should-not-delete-apostrophe ()
    (sgml-delete-tag 1)
    (should (string= "Winter is comin'" (buffer-string)))))
 
+(ert-deftest sgml-tests--quotes-syntax ()
+  (dolist (str '("a\"b <t>c'd</t>"
+                 "a'b <t>c\"d</t>"
+                 "<t>\"a'</t>"
+                 "<t>'a\"</t>"
+                 "<t>\"a'\"</t>"
+                 "<t>'a\"'</t>"
+                 "a\"b <tag>c'd</tag>"
+                 ;;"<tag>c>'d</tag>" Fixed in master.
+                 "<t><!-- \" --></t>"
+                 "<t><!-- ' --></t>"
+                 "<t>(')</t>"
+                 "<t>(\")</t>"
+                 ))
+   (with-temp-buffer
+     (sgml-mode)
+     (insert str)
+     (ert-info ((format "%S" str) :prefix "Test case: ")
+       ;; Check that last tag is parsed as a tag.
+       (should (= 1 (car (syntax-ppss (1- (point-max))))))
+       (should (= 0 (car (syntax-ppss (point-max)))))))))
+
 (provide 'sgml-mode-tests)
 ;;; sgml-mode-tests.el ends here
-- 
2.11.0