parse: Keep track of what files are already open

Fixes #22

1 files changed, 1 insertions, 3 deletions

diff --git a/expr.h b/expr.h
index c0e2b92..0eba0da 100644
--- a/expr.h
+++ b/expr.h
@@ -219,9 +219,7 @@ void dump_expr(CFILE *cfile, const struct expr *expr, bool verbose);
 
 /**
  * Free an expression tree.
- *
- * @return 0 if successful, -1 on error.
  */
-int free_expr(struct expr *expr);
+void free_expr(struct expr *expr);
 
 #endif // EXPR_H