Error code E0366

An attempt was made to implement Drop on a concrete specialization of a generic type. An example is shown below:

#![allow(unused)] fn main() { struct Foo<T> { t: T } impl Drop for Foo<u32> { 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. One workaround for this is to wrap the generic type, as shown below:

#![allow(unused)] fn main() { struct Foo<T> { t: T } struct Bar { t: Foo<u32> } impl Drop for Bar { fn drop(&mut self) {} } }