CC Mode: Fix a c-backward-token-2 call wrongly jumping back over macros.

This fixes bug #56256.

* lisp/progmodes/cc-fonts.el (c-font-lock-c++-lambda-captures): Replace a
c-backward-token-2, which could jump back too far leading to an infinite
loop, with a save-excursion to remember the point we've got to go back to.

1 files changed, 13 insertions, 10 deletions

diff --git a/lisp/progmodes/cc-fonts.el b/lisp/progmodes/cc-fonts.el
index 63df267b43f..49e8763a28e 100644
--- a/lisp/progmodes/cc-fonts.el
+++ b/lisp/progmodes/cc-fonts.el
@@ -1826,7 +1826,7 @@ casts and declarations are fontified.  Used on level 2 and higher."
   ;; font-lock-keyword-face.  It always returns NIL to inhibit this and
   ;; prevent a repeat invocation.  See elisp/lispref page "Search-based
   ;; Fontification".
-  (let (mode capture-default id-start id-end declaration sub-begin sub-end)
+  (let (mode capture-default id-start id-end declaration sub-begin sub-end tem)
     (while (and (< (point) limit)
                 (search-forward "[" limit t))
       (when (progn (backward-char)
@@ -1838,15 +1838,18 @@ casts and declarations are fontified.  Used on level 2 and higher."
                         (char-after)))
         ;; Is the first element of the list a bare "=" or "&"?
         (when mode
-          (forward-char)
-          (c-forward-syntactic-ws)
-          (if (memq (char-after) '(?, ?\]))
-              (progn
-                (setq capture-default mode)
-                (when (eq (char-after) ?,)
-                  (forward-char)
-                  (c-forward-syntactic-ws)))
-            (c-backward-token-2)))
+          (setq tem nil)
+          (save-excursion
+            (forward-char)
+            (c-forward-syntactic-ws)
+            (if (memq (char-after) '(?, ?\]))
+                (progn
+                  (setq capture-default mode)
+                  (when (eq (char-after) ?,)
+                    (forward-char)
+                    (c-forward-syntactic-ws))
+                  (setq tem (point)))))
+          (if tem (goto-char tem)))
 
         ;; Go round the following loop once per captured item.  We use "\\s)"
         ;; rather than "\\]" here to avoid infinite looping in this situation: