Error code E0367

An attempt was made to implement Drop on a specialization of a generic type.

Erroneous code example:

#![allow(unused)] fn main() { trait Foo {} struct MyStruct<T> { t: T } impl<T: Foo> Drop for MyStruct<T> { fn drop(&mut self) {} } }

This code is not legal: it is not possible to specialize Drop to a subset of implementations of a generic type. In order for this code to work, MyStruct must also require that T implements Foo. Alternatively, another option is to wrap the generic type in another that specializes appropriately:

#![allow(unused)] fn main() { trait Foo{} struct MyStruct<T> { t: T } struct MyStructWrapper<T: Foo> { t: MyStruct<T> } impl <T: Foo> Drop for MyStructWrapper<T> { fn drop(&mut self) {} } }