From: Alan Mackenzie <acm@muc.de>
Date: Fri, 11 Oct 2019 19:10:11 +0000 (+0000)
Subject: C++ Mode: Correctly handle <:, <::, <::>, etc, according to the C++ standard
X-Git-Tag: emacs-27.0.90~1147
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=255c892b486eeb507b4533141fec9218b7a67b2f;p=emacs.git

C++ Mode: Correctly handle <:, <::, <::>, etc, according to the C++ standard

* lisp/progmodes/cc-engine.el (c-before-change-check-<>-operators): Perform
checking now on an insertion, should point be inside a critical token.
(c-forward-<>-arglist-recur, c-guess-continued-construct): Check for <::, etc.

* lisp/progmodes/cc-langs.el (c-<-pseudo-digraph-cont-regexp)
(c-<-pseudo-digraph-cont-len): New lang variables/constants.
---

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 4ca440fd84b..9ed4fe3d88c 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -6922,7 +6922,15 @@ comment at the start of cc-engine.el for more info."
   ;;
   ;; FIXME!!!  This routine ignores the possibility of macros entirely.
   ;; 2010-01-29.
-  (when (and (> end beg)
+  (when (and (or (> end beg)
+		 (and (> c-<-pseudo-digraph-cont-len 0)
+		      (goto-char beg)
+		      (progn
+			(skip-chars-backward
+			 "^<" (max (- (point) c-<-pseudo-digraph-cont-len)
+				   (point-min)))
+			(eq (char-before) ?<))
+		      (looking-at c-<-pseudo-digraph-cont-regexp)))
 	     (or
 	      (progn
 		(goto-char beg)
@@ -7948,7 +7956,8 @@ comment at the start of cc-engine.el for more info."
 
       (forward-char) ; Forward over the opening '<'.
 
-      (unless (looking-at c-<-op-cont-regexp)
+      (unless (and (looking-at c-<-op-cont-regexp)
+		   (not (looking-at c-<-pseudo-digraph-cont-regexp)))
 	;; go forward one non-alphanumeric character (group) per iteration of
 	;; this loop.
 	(while (and
@@ -8026,7 +8035,8 @@ comment at the start of cc-engine.el for more info."
 		  (let (id-start id-end subres keyword-match)
 		    (cond
 		     ;; The '<' begins a multi-char operator.
-		     ((looking-at c-<-op-cont-regexp)
+		     ((and (looking-at c-<-op-cont-regexp)
+			   (not (looking-at c-<-pseudo-digraph-cont-regexp)))
 		      (goto-char (match-end 0)))
 		     ;; We're at a nested <.....>
 		     ((progn
@@ -12552,7 +12562,8 @@ comment at the start of cc-engine.el for more info."
 		  (/= (char-before placeholder) ?<)
 		  (progn
 		    (goto-char (1+ placeholder))
-		    (not (looking-at c-<-op-cont-regexp))))))
+		    (or (not (looking-at c-<-op-cont-regexp))
+			(looking-at c-<-pseudo-digraph-cont-regexp))))))
       (goto-char placeholder)
       (c-beginning-of-statement-1 containing-sexp t)
       (if (save-excursion
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index d092094817c..a6fdc3ec798 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -1406,6 +1406,23 @@ operators."
 		    (lambda (op) (substring op 1)))))
 (c-lang-defvar c-<-op-cont-regexp (c-lang-const c-<-op-cont-regexp))
 
+(c-lang-defconst c-<-pseudo-digraph-cont-regexp
+  "Regexp matching the continuation of a pseudo digraph starting \"<\".
+This is used only in C++ Mode, where \"<::\" is handled as a
+template opener followed by the \"::\" operator - usually."
+  t regexp-unmatchable
+  c++ "::\\([^:>]\\|$\\)")
+(c-lang-defvar c-<-pseudo-digraph-cont-regexp
+	       (c-lang-const c-<-pseudo-digraph-cont-regexp))
+
+(c-lang-defconst c-<-pseudo-digraph-cont-len
+  "The maximum length of the main bit of a `c-<pseudp-digraph-cont-regexp' match.
+This doesn't count the merely contextual bits of the regexp match."
+  t 0
+  c++ 2)
+(c-lang-defvar c-<-pseudo-digraph-cont-len
+	       (c-lang-const c-<-pseudo-digraph-cont-len))
+
 (c-lang-defconst c->-op-cont-tokens
   ;; A list of second and subsequent characters of all multicharacter tokens
   ;; that begin with ">".