rust/src/test/ui/variance/variance-use-covariant-struct-2.rs

// Test that a covariant struct permits the lifetime of a reference to
// be shortened.

#![allow(dead_code)]
// compile-pass

struct SomeStruct<T>(T);

fn foo<'min,'max>(v: SomeStruct<&'max ()>)
                  -> SomeStruct<&'min ()>
    where 'max : 'min
{
    v
}

fn main() { }