diff -rup a/expr.c b/expr.c

--- a/expr.c	2013-10-10 08:43:55.000000000 -0400

+++ b/expr.c	2020-02-06 17:05:40.658679755 -0500

@@ -189,10 +189,10 @@ int

 expr_clone(struct expr_node *retp, const struct expr_node *node)

 {

 	*retp = *node;

+	struct expr_node *nlhs;

+	struct expr_node *nrhs = NULL;

 	switch (node->kind) {

-		struct expr_node *nlhs;

-		struct expr_node *nrhs;

 	case EXPR_OP_ARGNO:

 	case EXPR_OP_SELF: