fix: handle type for unary expression (#108)

interp/interp_eval_test.go

@@ -218,6 +218,14 @@ func TestEvalCompositeArray0(t *testing.T) {
 	}
 }
 
+func TestEvalUnary0(t *testing.T) {
+	i := interp.New(interp.Opt{})
+	v := evalCheck(t, i, `a := -1`)
+	if expected := "-1"; fmt.Sprintf("%v", v) != expected {
+		t.Fatalf("Expected %v, got %v", expected, v)
+	}
+}
+
 func evalCheck(t *testing.T, i *interp.Interpreter, src string) reflect.Value {
 	t.Helper()
 

interp/type.go

@@ -193,6 +193,9 @@ func nodeType(interp *Interpreter, scope *Scope, n *Node) (*Type, error) {
 			err = n.cfgError("missign support for type %T", n.val)
 		}
 
+	case UnaryExpr:
+		t, err = nodeType(interp, scope, n.child[0])
+
 	case BinaryExpr:
 		t, err = nodeType(interp, scope, n.child[0])
 		if err != nil {