30 lines
903 B
Rust
30 lines
903 B
Rust
// Test that a type which is covariant with respect to its region
|
|
// parameter yields an error when used in a contravariant way.
|
|
//
|
|
// Note: see variance-regions-*.rs for the tests that check that the
|
|
// variance inference works in the first place.
|
|
|
|
// `S` is contravariant with respect to both parameters.
|
|
struct S<'a, 'b> {
|
|
f: &'a isize,
|
|
g: &'b isize,
|
|
}
|
|
|
|
fn use_<'short,'long>(c: S<'long, 'short>,
|
|
s: &'short isize,
|
|
l: &'long isize,
|
|
_where:Option<&'short &'long ()>) {
|
|
|
|
let _: S<'long, 'short> = c; // OK
|
|
let _: S<'short, 'short> = c; // OK
|
|
|
|
// Test whether S<_,'short> <: S<_,'long>. Since
|
|
// 'short <= 'long, this would be true if the Contravariant type were
|
|
// covariant with respect to its parameter 'a.
|
|
|
|
let _: S<'long, 'long> = c;
|
|
//~^ ERROR lifetime may not live long enough
|
|
}
|
|
|
|
fn main() {}
|