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# Error code E0275

An evaluation of a trait requirement overflowed.

Erroneous code example:

    #![allow(unused)]
    fn main() {
    trait Foo {}

    struct Bar<T>(T);

    impl<T> Foo for T where Bar<T>: Foo {}
    }

This error occurs when there was a recursive trait requirement that overflowed before it could be evaluated. This often means that there is an unbounded recursion in resolving some type bounds.

To determine if a `T` is `Foo`, we need to check if `Bar<T>` is `Foo`. However, to do this check, we need to determine that `Bar<Bar<T>>` is `Foo`. To determine this, we check if `Bar<Bar<Bar<T>>>` is `Foo`, and so on. This is clearly a recursive requirement that can’t be resolved directly.

Consider changing your trait bounds so that they’re less self-referential.