Correct c-parse-state-get-strategy for moving HERE backward into a macro.

* list/progmodes/c-engine.el (c-parse-state-get-strategy): When HERE is below
its previous value, we chose strategy 'forward, and the new HERE is in a
(different) macro, ensure the returned START-POINT is not above the start of
the macro.

1 files changed, 20 insertions, 6 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 3077e0085d3..e84c4cebf69 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -2931,11 +2931,23 @@ comment at the start of cc-engine.el for more info."
   ;; o - ('BOD START-POINT) - scan forwards from START-POINT, which is at the
   ;;   top level.
   ;; o - ('IN-LIT nil) - point is inside the literal containing point-min.
-  (let ((cache-pos (c-get-cache-scan-pos here)) ; highest position below HERE in cache (or 1)
-        BOD-pos             ; position of 2nd BOD before HERE.
-        strategy            ; 'forward, 'backward, 'BOD, or 'IN-LIT.
-        start-point
-        how-far)                        ; putative scanning distance.
+  (let* ((in-macro-start              ; start of macro containing HERE or nil.
+          (save-excursion
+            (goto-char here)
+            (and (c-beginning-of-macro)
+                 (point))))
+         (changed-macro-start
+          (and in-macro-start
+               (not (and c-state-old-cpp-beg
+                         (= in-macro-start c-state-old-cpp-beg)))
+               in-macro-start))
+         (cache-pos (c-get-cache-scan-pos (if changed-macro-start
+                                              (min changed-macro-start here)
+                                            here))) ; highest suitable position in cache (or 1)
+         BOD-pos                      ; position of 2nd BOD before HERE.
+         strategy                     ; 'forward, 'backward, 'BOD, or 'IN-LIT.
+         start-point
+         how-far)                       ; putative scanning distance.
     (setq good-pos (or good-pos (c-state-get-min-scan-pos)))
     (cond
      ((< here (c-state-get-min-scan-pos))
@@ -2945,7 +2957,9 @@ comment at the start of cc-engine.el for more info."
             how-far 0))
      ((<= good-pos here)
       (setq strategy 'forward
-            start-point (max good-pos cache-pos)
+            start-point (if changed-macro-start
+                            cache-pos
+                          (max good-pos cache-pos))
             how-far (- here start-point)))
      ((< (- good-pos here) (- here cache-pos)) ; FIXME!!! ; apply some sort of weighting.
       (setq strategy 'backward