rust/src/test/ui/traits/negative-impls/negative-specializes-positive.rs

#![feature(specialization)]
#![feature(optin_builtin_traits)]

// Negative impl for u32 cannot "specialize" the base impl.
trait MyTrait {}
impl<T> MyTrait for T {}
impl !MyTrait for u32 {} //~ ERROR E0748

// The second impl specializes the first, no error.
trait MyTrait2 {}
impl<T> MyTrait2 for T {}
impl MyTrait2 for u32 {}

fn main() {}