rust/tests/ui/nll/closure-requirements/propagate-from-trait-match.rs

49 lines
1008 B
Rust

// Test that regions which appear only in the closure's generics (in
// this case, `'a`) are properly mapped to the creator's generics. In
// this case, the closure constrains its type parameter `T` to outlive
// the same `'a` for which it implements `Trait`, which can only be the `'a`
// from the function definition.
//@ compile-flags:-Zverbose-internals
#![feature(rustc_attrs)]
#![allow(dead_code)]
trait Trait<'a> {}
fn establish_relationships<T, F>(value: T, closure: F)
where
F: FnOnce(T),
{
closure(value)
}
fn require<'a, T>(t: T)
where
T: Trait<'a> + 'a,
{
}
#[rustc_regions]
fn supply<'a, T>(value: T)
where
T: Trait<'a>,
{
establish_relationships(value, |value| {
// This function call requires that
//
// (a) T: Trait<'a>
//
// and
//
// (b) T: 'a
//
// The latter does not hold.
require(value);
//~^ ERROR the parameter type `T` may not live long enough
});
}
fn main() {}