src/test/ui/resolve/resolve-unknown-trait.rs

trait NewTrait : SomeNonExistentTrait {}
//~^ ERROR cannot find trait `SomeNonExistentTrait` in this scope

impl SomeNonExistentTrait for isize {}
//~^ ERROR cannot find trait `SomeNonExistentTrait` in this scope

fn f<T:SomeNonExistentTrait>() {}
//~^ ERROR cannot find trait `SomeNonExistentTrait` in this scope

fn main() {}