ICE: Drop does not check trait bounds

[mahkoh]

#![feature(optin_builtin_traits, unsafe_destructor)]

trait Print {
    fn print(&self);
}

struct X<T> {
    x: T,
}

#[unsafe_destructor]
impl<T: Print> Drop for X<T> {
    fn drop(&mut self) {
        self.x.print();
    }
}

fn main() {
    X { x: 1 };
}

test4.rs:14:9: 14:23 error: internal compiler error: Encountered error `Unimplemented` selecting `Binder(Print)` during trans
test4.rs:14         self.x.print();
                    ^~~~~~~~~~~~~~

[mahkoh]

Note that

#[unsafe_destructor]
impl<T: Send> Drop for X<T> {
    fn drop(&mut self) {
    }
}

compiles without an error even if T is not Send.

[oli-obk]

trait bounds on impl Drop are forbidden anyway, the compiler just doesn't check them yet. See #8142

[huonw]

To be clear, only trait bounds more specific than those on the type declaration is forbidden, e.g. this is fine:

struct Foo<T: Trait>;
impl<T: Trait> Drop for Foo { ... }