CC Mode: Fix error in macro cache. This fixes bug #36802

* lisp/progmodes/cc-engine.el (c-invalidate-macro-cache): Add in a cond arm
to handle the change position being less than the recorded CPP contruct end.

1 files changed, 5 insertions, 0 deletions

diff --git a/lisp/progmodes/cc-engine.el b/lisp/progmodes/cc-engine.el
index 37d4591fc96..a095277989a 100644
--- a/lisp/progmodes/cc-engine.el
+++ b/lisp/progmodes/cc-engine.el
@@ -271,6 +271,11 @@
     (setcdr c-macro-cache nil)
     (setq c-macro-cache-start-pos beg
           c-macro-cache-syntactic nil
+          c-macro-cache-no-comment nil))
+   ((and c-macro-cache-start-pos
+         (< beg c-macro-cache-start-pos))
+    (setq c-macro-cache-start-pos beg
+          c-macro-cache-syntactic nil
           c-macro-cache-no-comment nil))))
 
 (defun c-macro-is-genuine-p ()