Reformulate c-end-of-macro, handling multiline block comments better

* lisp/progmodes/cc-langs.el (c-last-open-c-comment-start-on-line-re): Comment
out.
(c-open-c-comment-on-logical-line-re): Remove.

* lisp/progmodes/cc-engine.el (c-end-of-macro): Handle multiline block
comments lacking escaped newlines using parse-partial-sexp rather than the
former variables removed from cc-langs.el.

2 files changed, 38 insertions, 56 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 23fb1effdd4..0964c04b899 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -358,7 +358,8 @@ comment at the start of cc-engine.el for more info."
   "Go to the end of a preprocessor directive.
 More accurately, move the point to the end of the closest following
 line that doesn't end with a line continuation backslash - no check is
-done that the point is inside a cpp directive to begin with.
+done that the point is inside a cpp directive to begin with, although
+it is assumed that point isn't inside a comment or string.
 
 If LIM is provided, it is a limit position at which point is left
 if the end of the macro doesn't occur earlier.
@@ -379,35 +380,32 @@ comment at the start of cc-engine.el for more info."
 	      c-macro-cache-syntactic nil
 	      c-macro-cache-no-comment nil))
       (save-match-data
-	(while
-	    (progn
-	      (while (progn
-		       (end-of-line)
-		       (when (and (eq (char-before) ?\\)
-				  (not (eobp)))
-			 (forward-char)
-			 t)))
-	      (let ((cand-EOM (point)))
-		(if (and c-open-c-comment-on-logical-line-re
-			 (re-search-backward
-			  c-open-c-comment-on-logical-line-re
-			  nil t)
-			 (match-beginning 1)
-			 (progn
-			   (goto-char (match-beginning 1))
-			   (and (c-forward-single-comment)
-				(> (point) cand-EOM))))
-		    t
-		  (goto-char cand-EOM)
-		  nil)))))
-
-      (when (and (car c-macro-cache)
-		 (> (point) (car c-macro-cache)) ; in case we have a
-						 ; zero-sized region.
-		 (bolp)
-		 (not (eq (char-before (1- (point))) ?\\)))
-	(setcdr c-macro-cache (point))
-	(setq c-macro-cache-syntactic nil)))))
+	(let ((safe-pos (point)))	; a point ouside any literal.
+	  ;; Move over stuff followed by a multiline block comment lacking
+	  ;; escaped newlines each time around this loop.
+	  (while
+	      (progn
+		(while (progn
+			 (end-of-line)
+			 (when (and (eq (char-before) ?\\)
+				    (not (eobp)))
+			   (forward-char)
+			   t)))
+		(let ((s (parse-partial-sexp safe-pos (point))))
+		  (when ;; Are we in a block comment?
+		      (and (nth 4 s) (not (nth 7 s)))
+		    (progn
+		      ;; Move to after the block comment.
+		      (parse-partial-sexp
+		       (point) (point-max) nil nil s 'syntax-table)
+		      (setq safe-pos (point)))))))
+
+	  (when (and (car c-macro-cache)
+		     (> (point) (car c-macro-cache)) ; in case we have a
+					; zero-sized region.
+		     (not (eq (char-before (1- (point))) ?\\)))
+	    (setcdr c-macro-cache (point))
+	    (setq c-macro-cache-syntactic nil)))))))
 
 (defun c-syntactic-end-of-macro ()
   ;; Go to the end of a CPP directive, or a "safe" pos just before.
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 667561719cb..e7e7cfd4b09 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -1706,32 +1706,16 @@ ender."
 (c-lang-defvar c-last-c-comment-end-on-line-re
 	       (c-lang-const c-last-c-comment-end-on-line-re))
 
-(c-lang-defconst c-last-open-c-comment-start-on-line-re
-  "Do NOT use this constant any more.  Instead use
-`c-open-c-comment-on-logical-line-re' (2020-02-10).
-
-Regexp which matches the last block comment start on the
-current ine, if any, or nil in those languages without block
-comments.  When a match is found, submatch 1 contains the comment
-starter."
-  t "\\(/\\*\\)\\([^*]\\|\\*+\\([^*/]\\|$\\)\\)*$"
-  awk nil)
-(c-lang-defvar c-last-open-c-comment-start-on-line-re
-	       (c-lang-const c-last-open-c-comment-start-on-line-re))
-(make-obsolete-variable 'c-last-open-c-comment-start-on-line-re
-			'c-open-c-comment-on-logical-line-re
-			"5.35")
-
-(c-lang-defconst c-open-c-comment-on-logical-line-re
-  "Regexp which matches an open block comment on the current logical line.
-It is intended for searching backwards from the end of a line.
-Such a search will stop at the first encountered non-escaped
-newline or open block comment.  If the comment is found, submatch
-1 contains the comment starter."
-t "[^\\\n][\r\n]\\|\\(/\\*\\)\\([^*]\\|\\*+\\([^*/]\\|$\\)\\)*$"
-awk nil)
-(c-lang-defvar c-open-c-comment-on-logical-line-re
-	       (c-lang-const c-open-c-comment-on-logical-line-re))
+;; The following is no longer used (2020-02-16).
+;; (c-lang-defconst c-last-open-c-comment-start-on-line-re
+;;   "Regexp which matches the last block comment start on the
+;; current ine, if any, or nil in those languages without block
+;; comments.  When a match is found, submatch 1 contains the comment
+;; starter."
+;;   t "\\(/\\*\\)\\([^*]\\|\\*+\\([^*/]\\|$\\)\\)*$"
+;;   awk nil)
+;; (c-lang-defvar c-last-open-c-comment-start-on-line-re
+;;   (c-lang-const c-last-open-c-comment-start-on-line-re))
 
 (c-lang-defconst c-literal-start-regexp
   ;; Regexp to match the start of comments and string literals.