Fix syntax scanning bug causing fontification crashes.

* src/syntax.c (find_defun_start): Update all cache variables if
exiting early.

Fixes: debbugs:9401

1 files changed, 5 insertions, 0 deletions

diff --git a/src/syntax.c b/src/syntax.c
index bfdf0e5ee6d..ba3810227eb 100644
--- a/src/syntax.c
+++ b/src/syntax.c
@@ -364,7 +364,12 @@ find_defun_start (pos, pos_byte)
 
   if (!open_paren_in_column_0_is_defun_start)
     {
+      find_start_value = BEGV;
       find_start_value_byte = BEGV_BYTE;
+      find_start_buffer = current_buffer;
+      find_start_modiff = MODIFF;
+      find_start_begv = BEGV;
+      find_start_pos = pos;
       return BEGV;
     }