From ef5f3d5ee7211430e5af4952042a0bebdcbc27ff Mon Sep 17 00:00:00 2001
From: Alan Mackenzie <acm@muc.de>
Date: Sun, 27 Jun 2021 12:59:18 +0000
Subject: [PATCH] C++ Mode: Handle new keywords static_cast, etc., wrt angle
 brackets

* lisp/progmodes/cc-langs.el (c-<>-arglist-kwds): Add const_cast,
dynamic_cast, reinterpret_cast and static_cast into this lang const.

* lisp/progmodes/cc-engine.el (c-clear-<-pair-props, c-clear->-pair-props)
(c-clear-<-pair-props-if-match-after, c-clear->-pair-props-if-match-before)
(c-forward-<>-arglist-recur):
Invalidate caches with c-trunctate-lit-pos-cache.
(c-forward-<>-arglist-recur): If in a matching <...> expression, the < has a
syntax-table property, but the > not, remove that property.
---
 lisp/progmodes/cc-engine.el | 33 ++++++++++++++++++++++++++-------
 lisp/progmodes/cc-langs.el  |  3 ++-
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 5a0f9350755..9cba87f4d91 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -6868,8 +6868,10 @@ comment at the start of cc-engine.el for more info."
 	(c-go-list-forward))
       (when (equal (c-get-char-property (1- (point)) 'syntax-table)
 		   c->-as-paren-syntax) ; should always be true.
-	(c-unmark-<->-as-paren (1- (point))))
-      (c-unmark-<->-as-paren pos))))
+	(c-unmark-<->-as-paren (1- (point)))
+	(c-truncate-lit-pos-cache (1- (point))))
+      (c-unmark-<->-as-paren pos)
+      (c-truncate-lit-pos-cache pos))))
 
 (defun c-clear->-pair-props (&optional pos)
   ;; POS (default point) is at a > character.  If it is marked with
@@ -6885,8 +6887,10 @@ comment at the start of cc-engine.el for more info."
 	(c-go-up-list-backward))
       (when (equal (c-get-char-property (point) 'syntax-table)
 			c-<-as-paren-syntax) ; should always be true.
-	(c-unmark-<->-as-paren (point)))
-      (c-unmark-<->-as-paren pos))))
+	(c-unmark-<->-as-paren (point))
+	(c-truncate-lit-pos-cache (point)))
+      (c-unmark-<->-as-paren pos)
+      (c-truncate-lit-pos-cache pos))))
 
 (defun c-clear-<>-pair-props (&optional pos)
   ;; POS (default point) is at a < or > character.  If it has an
@@ -6919,7 +6923,8 @@ comment at the start of cc-engine.el for more info."
 		 (equal (c-get-char-property (1- (point)) 'syntax-table)
 			c->-as-paren-syntax)) ; should always be true.
 	(c-unmark-<->-as-paren (1- (point)))
-	(c-unmark-<->-as-paren pos))
+	(c-unmark-<->-as-paren pos)
+	(c-truncate-lit-pos-cache pos))
       t)))
 
 (defun c-clear->-pair-props-if-match-before (lim &optional pos)
@@ -6940,6 +6945,7 @@ comment at the start of cc-engine.el for more info."
 		 (equal (c-get-char-property (point) 'syntax-table)
 			c-<-as-paren-syntax)) ; should always be true.
 	(c-unmark-<->-as-paren (point))
+	(c-truncate-lit-pos-cache (point))
 	(c-unmark-<->-as-paren pos))
       t)))
 
@@ -7980,13 +7986,14 @@ comment at the start of cc-engine.el for more info."
 	;; bracket arglist.  It's propagated through the return value
 	;; on successful completion.
 	(c-record-found-types c-record-found-types)
+	(syntax-table-prop-on-< (c-get-char-property (point) 'syntax-table))
 	;; List that collects the positions after the argument
 	;; separating ',' in the arglist.
 	arg-start-pos)
     ;; If the '<' has paren open syntax then we've marked it as an angle
     ;; bracket arglist before, so skip to the end.
     (if (and (not c-parse-and-markup-<>-arglists)
-	     (c-get-char-property (point) 'syntax-table))
+	     syntax-table-prop-on-<)
 
 	(progn
 	  (forward-char)
@@ -8071,8 +8078,20 @@ comment at the start of cc-engine.el for more info."
 			(c-put-c-type-property (1- (car arg-start-pos))
 					       'c-<>-arg-sep)
 			(setq arg-start-pos (cdr arg-start-pos)))
+		      (when (and (not syntax-table-prop-on-<)
+				 (c-get-char-property (1- (point))
+						      'syntax-table))
+			;; Clear the now spuriously matching < of its
+			;; syntax-table property.  This could happen on
+			;; inserting "_cast" into "static <" with C-y.
+			(save-excursion
+			  (and (c-go-list-backward)
+			       (eq (char-after) ?<)
+			       (c-truncate-lit-pos-cache (point))
+			       (c-unmark-<->-as-paren (point)))))
 		      (c-mark-<-as-paren start)
-		      (c-mark->-as-paren (1- (point))))
+		      (c-mark->-as-paren (1- (point)))
+		      (c-truncate-lit-pos-cache start))
 		    (setq res t)
 		    nil))		; Exit the loop.
 
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index acdb72fb7b7..86627d9502b 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -2719,7 +2719,8 @@ if this isn't nil."
 `c-recognize-<>-arglists' for details.  That language constant is
 assumed to be set if this isn't nil."
   t    nil
-  c++  '("template")
+  c++  '("template" "const_cast" "dynamic_cast" "reinterpret_cast"
+	 "static_cast")
   idl  '("fixed" "string" "wstring"))
 
 (c-lang-defconst c-<>-sexp-kwds
-- 
2.39.2