master 7ebdecf: CC Mode: Fix bug in "state cache" invalidation function.

[Alan Mackenzie]

branch: master
commit 7ebdecfcdfc59f34b4751bcd69b4efabec7be48c
Author: Alan Mackenzie <acm@muc.de>
Commit: Alan Mackenzie <acm@muc.de>

    CC Mode: Fix bug in "state cache" invalidation function.
    
    * lisp/progmodes/cc-engine.el (c-invalidate-state-cache-1): Rewrite part of
    it, following the code in c-parse-state-1, to get a proper setting of
    c-state-cache-good-pos.
---
 lisp/progmodes/cc-engine.el | 55 +++++++++++++++++++--------------------------
 1 file changed, 23 insertions(+), 32 deletions(-)

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 9038c7b..4cf7af8 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -4319,38 +4319,29 @@ mhtml-mode."
       (setq c-state-nonlit-pos-cache-limit (1- here)))
   (c-truncate-lit-pos-cache here)
 
-  ;; `c-state-cache':
-  ;; Case 1: if `here' is in a literal containing point-min, everything
-  ;; becomes (or is already) nil.
-  (if (or (null c-state-cache-good-pos)
-         (< here (c-state-get-min-scan-pos)))
-      (setq c-state-cache nil
-           c-state-cache-good-pos nil
-           c-state-min-scan-pos nil)
-
-    ;; Truncate `c-state-cache' and set `c-state-cache-good-pos' to a value
-    ;; below `here'.  To maintain its consistency, we may need to insert a new
-    ;; brace pair.
-    (let ((here-bol (c-point 'bol here))
-         too-high-pa  ; recorded {/(/[ next above or just below here, or nil.
-         dropped-cons)           ; was the last removed element a brace pair?
-      ;; The easy bit - knock over-the-top bits off `c-state-cache'.
-      (while (and c-state-cache
-                 (>= (c-state-cache-top-paren) here))
-       (setq dropped-cons (consp (car c-state-cache))
-             too-high-pa (c-state-cache-top-lparen)
-             c-state-cache (cdr c-state-cache)))
-
-      ;; Do we need to add in an earlier brace pair, having lopped one off?
-      (if (and dropped-cons
-              (<= too-high-pa here))
-         (c-append-lower-brace-pair-to-state-cache too-high-pa here here-bol))
-      (if (and c-state-cache-good-pos (< here c-state-cache-good-pos))
-         (setq c-state-cache-good-pos
-               (or (save-excursion
-                     (goto-char here)
-                     (c-literal-start))
-                   here)))))
+  (cond
+   ;; `c-state-cache':
+   ;; Case 1: if `here' is in a literal containing point-min, everything
+   ;; becomes (or is already) nil.
+   ((or (null c-state-cache-good-pos)
+       (< here (c-state-get-min-scan-pos)))
+    (setq c-state-cache nil
+         c-state-cache-good-pos nil
+         c-state-min-scan-pos nil))
+
+   ;; Case 2: `here' is below `c-state-cache-good-pos', so we need to amend
+   ;; the entire `c-state-cache' data.
+   ((< here c-state-cache-good-pos)
+    (let* ((res (c-remove-stale-state-cache-backwards here))
+          (good-pos (car res))
+          (scan-backward-pos (cadr res))
+          (scan-forward-p (car (cddr res))))
+      (if scan-backward-pos
+         (c-append-lower-brace-pair-to-state-cache scan-backward-pos here))
+      (setq c-state-cache-good-pos
+           (if scan-forward-p
+               (c-append-to-state-cache good-pos here)
+             good-pos)))))
 
   ;; The brace-pair desert marker:
   (when (car c-state-brace-pair-desert)