Fontify C++ for loop variable as variable, even when followed by parentheses

In the following: "for (auto *Friend : Class->friends()) {", "Friend" was
getting fontified as a function, due to insufficient checking of the tokens
between it and "()".

* lisp/progmodes/cc-langs.el (c-:-op-cont-tokens, c-:-op-cont-regexp): New
lang-consts/vars.

* lisp/progmodes/cc-engine.el (c-forward-declarator): After finding a putative
declarator's identifier, check for a ":" token inside a for's parentheses, and
abort the search for "(" if this is found.

2 files changed, 38 insertions, 2 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 6d7bab7a65c..9773b1ca85b 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -8092,8 +8092,29 @@ comment at the start of cc-engine.el for more info."
          ;; initializing brace lists.
          (let (found)
            (while
-               (and (setq found (c-syntactic-re-search-forward
-                                 "[;,]\\|\\s)\\|\\'\\|\\(=\\|\\s(\\)" limit t t))
+               (and (progn
+                      ;; In the next loop, we keep searching forward whilst
+                      ;; we find ":"s which aren't single colons inside C++
+                      ;; "for" statements.
+                      (while
+                          (and
+                           (setq found
+                                 (c-syntactic-re-search-forward
+                                  "[;:,]\\|\\s)\\|\\'\\|\\(=\\|\\s(\\)"
+                                  limit t t))
+                           (eq (char-before) ?:)
+                           (if (looking-at c-:-op-cont-regexp)
+                               (progn (goto-char (match-end 0)) t)
+                             (not
+                              (and (c-major-mode-is 'c++-mode)
+                                   (save-excursion
+                                     (and
+                                      (c-go-up-list-backward)
+                                      (eq (char-after) ?\()
+                                      (progn (c-backward-syntactic-ws)
+                                             (c-simple-skip-symbol-backward))
+                                      (looking-at c-paren-stmt-key))))))))
+                      found)
                     (eq (char-before) ?\[)
                     (c-go-up-list-forward))
              (setq brackets-after-id t))
diff --git a/lisp/progmodes/cc-langs.el b/lisp/progmodes/cc-langs.el
index 3b455fc0908..84d4eab75af 100644
--- a/lisp/progmodes/cc-langs.el
+++ b/lisp/progmodes/cc-langs.el
@@ -1334,6 +1334,21 @@ operators."
 (c-lang-defvar c-multichar->-op-not->>-regexp
   (c-lang-const c-multichar->-op-not->>-regexp))
 
+(c-lang-defconst c-:-op-cont-tokens
+  ;; A list of second and subsequent characters of all multicharacter tokens
+  ;; that begin with ":".
+  t (c-filter-ops (c-lang-const c-all-op-syntax-tokens)
+                  t
+                  "\\`:."
+                  (lambda (op) (substring op 1))))
+
+(c-lang-defconst c-:-op-cont-regexp
+  ;; Regexp matching the second and subsequent characters of all
+  ;; multicharacter tokens that begin with ":".
+  t (c-make-keywords-re nil (c-lang-const c-:-op-cont-tokens)))
+(c-lang-defvar c-:-op-cont-regexp
+  (c-lang-const c-:-op-cont-regexp))
+
 (c-lang-defconst c-stmt-delim-chars
   ;; The characters that should be considered to bound statements.  To
   ;; optimize `c-crosses-statement-barrier-p' somewhat, it's assumed to