bjoernager/rust
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fmt

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DrMeepster 2023-04-16 14:44:09 -07:00
parent 631ea7cc15
commit 2bcb018253
3 changed files with 12 additions and 13 deletions
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14
tests/ui/lint/dead-code/offset-of-correct-param-env.rs
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@ -27,14 +27,16 @@ fn test<T>() -> usize
where
GenericIsEqual<T>: Project<EquateParamTo = MyFieldIsNotDead>,
{
// The first field of the A that we construct here is `<GenericIsEqual<T>> as Project>::EquateParamTo`.
// Typeck normalizes this and figures that the not_dead field is totally fine and accessible.
// But importantly, the normalization ends up with T, which, as we've declared in our param env is MyFieldDead.
// When we're in the param env of the `a` field, the where bound above is not in scope, so we don't know what T is - it's generic.
// We cannot access a field on T. Boom!
// The first field of the A that we construct here is
// `<GenericIsEqual<T>> as Project>::EquateParamTo`.
// Typeck normalizes this and figures that the not_dead field is totally fine and accessible.
// But importantly, the normalization ends up with T, which, as we've declared in our param
// env is MyFieldDead. When we're in the param env of the `a` field, the where bound above
// is not in scope, so we don't know what T is - it's generic.
// We cannot access a field on T. Boom!
std::mem::offset_of!(A<GenericIsEqual<T>>, a.not_dead)
}
fn main() {
test::<MyFieldIsNotDead>();
}
}