This is some code to assert the behaviour of variance over T for some generic types using PhantomData.
Specifically, the following should hold true for a type Type<T> for variance over T where Type<T> contains the specified PhantomData:
Type |
Variance Over T |
|---|---|
PhantomData<fn() -> T> |
covariant |
PhantomData<fn(T)> |
contravariant |
PhantomData<fn(T) -> T> |
invariant |
To use: cargo doc --open