1 files changed, 13 insertions, 0 deletions

diff --git a/com.c b/com.c
index 695802a..2465777 100644
--- a/com.c
+++ b/com.c
@@ -180,18 +180,30 @@ void if_form(Compiler *C, AstVec l, Op _) {
 	// skip ->B
 	// A: if-false
 	// B:
+
+	int orig_stack_cur = C->stack_cur;
+
 	compile_node(C, l.vals[1]);
 	compile_opcode(C, OP_0BRANCH);
 	size_t ph_a = placeholder(C);
 	compile_node(C, l.vals[2]);
 	compile_opcode(C, OP_SKIP);
+
 	size_t ph_b = placeholder(C);
 	size_t dest_a = BYTECODE(C).len;
+	int stack_cur_a = C->stack_cur;
+	C->stack_cur = orig_stack_cur;
+
 	compile_node(C, l.vals[3]);
 	size_t dest_b = BYTECODE(C).len;
 
+	int stack_cur_b = C->stack_cur;
+
 	patch(C, ph_a, dest_a - ph_a - 2);
 	patch(C, ph_b, dest_b - ph_b - 2);
+
+	CHECK(stack_cur_a == stack_cur_b, "this should never happen");
+	CHECK(stack_cur_a == orig_stack_cur + 1, "this should never happen");
 }
 
 void while_form(Compiler *C, AstVec l, Op _) {
@@ -520,6 +532,7 @@ int main(int argc, char **argv) {
 	}
 
 
+
 	compile_opcode(&com, OP_HALT);
 
 	Thread th = thread_new(S);