v/vlib/v/checker/tests/sum_type_multiple_type_define.out

vlib/v/checker/tests/sum_type_multiple_type_define.vv:3:22: error: sum type FooType cannot hold the type `Foo` more than once
    1 | struct Foo {}
    2 |
    3 | type FooType = Foo | Foo
      |                      ~~~