* parser.l (end_of_regex): Fix start condition stack underflow

during regex_parse.

2 files changed, 10 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 885366af..729fcc4e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
 2013-12-06  Kaz Kylheku  <kaz@kylheku.com>
 
+	* parser.l (end_of_regex): Fix start condition stack underflow
+	during regex_parse.
+
+2013-12-06  Kaz Kylheku  <kaz@kylheku.com>
+
 	* parser.l (regex_parse): Match the simplified grammar now
 	expected in the parser, with no slashes around the regex.
 	Change prefix for diagnostic message. 
diff --git a/parser.l b/parser.l
index 0370bd2d..7c5a4d84 100644
--- a/parser.l
+++ b/parser.l
@@ -778,9 +778,11 @@ void end_of_regex(void)
     internal_error("end_of_regex called in wrong scanner state");
 
   yy_pop_state();
-  if (yy_top_state() == INITIAL
-      || yy_top_state() == QSILIT)
-    yy_pop_state();
+
+  if (YYSTATE != INITIAL) {
+    if (yy_top_state() == INITIAL || yy_top_state() == QSILIT)
+      yy_pop_state();
+  }
 }
 
 void end_of_char(void)