[rustc.git] / src / test / ui / impl-trait / multiple-lifetimes / ordinary-bounds-unrelated.rs

// edition:2018

trait Trait<'a, 'b> {}
impl<T> Trait<'_, '_> for T {}

// `Ordinary<'a> <: Ordinary<'b>` if `'a: 'b`, as with most types.
//
// I am purposefully avoiding the terms co- and contra-variant because
// their application to regions depends on how you interpreted Rust
// regions. -nikomatsakis
struct Ordinary<'a>(&'a u8);

// Here we get an error because none of our choices (either `'d` nor `'e`) are outlived
// by both `'a` and `'b`.

fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e>
where
    'a: 'e,
    'b: 'd,
{
    // Hidden type `Ordinary<'0>` with constraints:
    //
    // ```
    // 'a: '0
    // 'b: '0
    // 'a in ['d, 'e]
    // ```
    if condition() { a } else { b }
    //~^ ERROR hidden type for `impl Trait` captures lifetime that does not appear in bounds
}

fn condition() -> bool {
    true
}

fn main() {}
Commit	Line	Data
dc9dc135 XL	1	// edition:2018
dc9dc135 XL	2
dc9dc135 XL	3	trait Trait<'a, 'b> {}
	4	impl<T> Trait<'_, '_> for T {}
	5
	6	// `Ordinary<'a> <: Ordinary<'b>` if `'a: 'b`, as with most types.
	7	//
	8	// I am purposefully avoiding the terms co- and contra-variant because
	9	// their application to regions depends on how you interpreted Rust
	10	// regions. -nikomatsakis
	11	struct Ordinary<'a>(&'a u8);
	12
	13	// Here we get an error because none of our choices (either `'d` nor `'e`) are outlived
	14	// by both `'a` and `'b`.
	15
	16	fn upper_bounds<'a, 'b, 'c, 'd, 'e>(a: Ordinary<'a>, b: Ordinary<'b>) -> impl Trait<'d, 'e>
dc9dc135 XL	17	where
	18	'a: 'e,
	19	'b: 'd,
	20	{
	21	// Hidden type `Ordinary<'0>` with constraints:
	22	//
	23	// ```
	24	// 'a: '0
	25	// 'b: '0
	26	// 'a in ['d, 'e]
	27	// ```
	28	if condition() { a } else { b }
ee023bcb	29	//~^ ERROR hidden type for `impl Trait` captures lifetime that does not appear in bounds
dc9dc135 XL	30	}
	31
	32	fn condition() -> bool {
	33	true
	34	}
	35
	36	fn main() {}