v/vlib/v/checker/tests/sum_type_mutable_cast_err.vv

type Abc = int | string

struct Bar {
mut:
	a Abc
}

struct Foo {
	b Bar
}

fn main() {
	mut x := Abc(0)
	if x is int {
		_ := x + 5
	}
	mut f := Foo{Bar{Abc(0)}}
	if f.b.a is int {
		_ := f.b.a + 5
	}
}