>From af36beb67d385dcb9afbca107248d16e3be3e2b7 Mon Sep 17 00:00:00 2001
From: Ikumi Keita <address@hidden>
Date: Fri, 3 May 2019 14:59:50 +0900
Subject: [PATCH] Improve comment syntax handling in docTeX mode

* font-latex.el (font-latex-set-syntactic-keywords):
(font-latex-doctex-^^A):
Assign comment ender syntax to the first "^" of ^^A, not its preceding
character.  Begin style b comment with the second "^".  These fix
bug#35140.
(font-latex-doctex-keywords): Add an entry so as to give the correct
fontification to the first "^" above.
(font-latex-find-matching-close): Add comments.
---
 font-latex.el | 29 +++++++++++++++++++----------
 1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/font-latex.el b/font-latex.el
index 486f39fe..cf84f261 100644
--- a/font-latex.el
+++ b/font-latex.el
@@ -1053,7 +1053,7 @@ have changed."
   (setq font-latex-doctex-syntactic-keywords
 	(append font-latex-syntactic-keywords
 		;; For docTeX comment-in-doc.
-		`(("\\(\\^\\)\\^A" (1 (font-latex-doctex-^^A)))))))
+		'(("\\^\\(\\^\\)A" (1 (font-latex-doctex-^^A)))))))
 
 
 ;;; Syntactic fontification
@@ -1464,6 +1464,10 @@ ignored during the search."
 	;; XXX: Do not look up syntax-table properties since they may
 	;; be misleading, e.g. in the case of "{foo}^^A" where the
 	;; closing brace gets a comment end syntax.
+	;; (Comment added on May 2019): This particular example is no
+	;; longer a problem with the modification on
+	;; `font-latex-doctex-^^A'.  Not sure there are other cases
+	;; that we can not rely on syntax property.
 	(parse-sexp-lookup-properties nil))
     (or
      (condition-case nil
@@ -2173,27 +2177,32 @@ END marks boundaries for searching for quotation ends."
 
 (defvar font-latex-doctex-keywords
   (append font-latex-keywords-2
-	  '(("^%<[^>]*>" (0 font-latex-doctex-preprocessor-face t)))))
+	  '(("^%<[^>]*>" (0 font-latex-doctex-preprocessor-face t))
+	    ("\\(\\^\\)\\^A" (1 (get-text-property (match-end 1) 'face) t)))))
 
 ;; Copy and adaptation of `doctex-font-lock-^^A' in `tex-mode.el' of
 ;; CVS Emacs (March 2004)
 (defun font-latex-doctex-^^A ()
   (if (eq (char-after (line-beginning-position)) ?\%)
       (progn
+	;; Assign comment ender syntax to the first "^" of ^^A.  It
+	;; used to be assigned to the character just before the "^",
+	;; but that sometimes caused trouble because the closing brace
+	;; in "{foo}^^A" didn't get the close paren syntax.  See
+	;; comment in `font-latex-find-matching-close' and bug#35140.
+	;; There is a hack in `font-latex-doctex-keywords' to restore
+	;; the correct fontification of this "^".
 	(put-text-property
-	 (1- (match-beginning 1)) (match-beginning 1) 'syntax-table
-	 (if (= (1+ (line-beginning-position)) (match-beginning 1))
-	     ;; The `%' is a single-char comment, which Emacs
-	     ;; syntax-table can't deal with.  We could turn it
-	     ;; into a non-comment, or use `\n%' or `%^' as the comment.
-	     ;; Instead, we include it in the ^^A comment.
-	     (eval-when-compile (string-to-syntax "< b"))
-	   (eval-when-compile (string-to-syntax ">"))))
+	 (match-beginning 0) (match-beginning 1) 'syntax-table
+	 (eval-when-compile (string-to-syntax ">")))
+	;; Make the EOL as the boundary of the style b comment which
+	;; begins with ^^A.
 	(let ((end (line-end-position)))
 	  (if (< end (point-max))
 	      (put-text-property end (1+ end) 'syntax-table
 				    (eval-when-compile
 				      (string-to-syntax "> b")))))
+	;; Begin style b comment with the second "^" of ^^A.
 	(eval-when-compile (string-to-syntax "< b")))))
 
 ;; Copy and adaptation of `doctex-font-lock-syntactic-face-function'
-- 
2.21.0