mirror of https://github.com/rust-lang/rust.git
37 lines
1.2 KiB
Rust
37 lines
1.2 KiB
Rust
#![feature(precise_capturing_in_traits)]
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trait LifetimeParam<'a> {
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fn test() -> impl Sized;
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}
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// Refining via capturing fewer lifetimes than the trait definition.
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impl<'a> LifetimeParam<'a> for i32 {
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fn test() -> impl Sized + use<> {}
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//~^ WARN impl trait in impl method captures fewer lifetimes than in trait
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}
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// If the lifetime is substituted, then we don't refine anything.
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impl LifetimeParam<'static> for u32 {
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fn test() -> impl Sized + use<> {}
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// Ok
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}
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trait TypeParam<T> {
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fn test() -> impl Sized;
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}
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// Indirectly capturing a lifetime param through a type param substitution.
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impl<'a> TypeParam<&'a ()> for i32 {
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fn test() -> impl Sized + use<> {}
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//~^ WARN impl trait in impl method captures fewer lifetimes than in trait
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}
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// Two of them, but only one is captured...
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impl<'a, 'b> TypeParam<(&'a (), &'b ())> for u32 {
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fn test() -> impl Sized + use<'b> {}
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//~^ WARN impl trait in impl method captures fewer lifetimes than in trait
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}
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// What if we don't capture a type param? That should be an error otherwise.
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impl<T> TypeParam<T> for u64 {
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fn test() -> impl Sized + use<> {}
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//~^ ERROR `impl Trait` must mention all type parameters in scope in `use<...>`
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}
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fn main() {}
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