py/parse: Fix handling of empty input so it raises an exception.

1 files changed, 5 insertions, 0 deletions

diff --git a/py/parse.c b/py/parse.c
index ad13a90309..b20fdaacd2 100644
--- a/py/parse.c
+++ b/py/parse.c
@@ -720,6 +720,11 @@ memory_error:
         goto syntax_error;
     }
 
+    // check that parsing resulted in a parse node (can fail on empty input)
+    if (parser.result_stack_top == 0) {
+        goto syntax_error;
+    }
+
     //result_stack_show(parser);
     //printf("rule stack alloc: %d\n", parser.rule_stack_alloc);
     //printf("result stack alloc: %d\n", parser.result_stack_alloc);