rust/tests/ui/regions/regions-variance-invariant-use-covariant.rs
2023-01-11 09:32:08 +00:00

22 lines
620 B
Rust

// Test that a type which is invariant with respect to its region
// parameter used in a covariant way yields an error.
//
// Note: see variance-regions-*.rs for the tests that check that the
// variance inference works in the first place.
struct Invariant<'a> {
f: &'a mut &'a isize
}
fn use_<'b>(c: Invariant<'b>) {
// For this assignment to be legal, Invariant<'b> <: Invariant<'static>.
// Since 'b <= 'static, this would be true if Invariant were covariant
// with respect to its parameter 'a.
let _: Invariant<'static> = c;
//~^ ERROR lifetime may not live long enough
}
fn main() { }