36 lines
915 B
Rust
36 lines
915 B
Rust
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// check-pass
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struct Foo<'a>(&'a ())
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where
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(): Trait<'a>;
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trait Trait<'a> {
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fn id<T>(value: &'a T) -> &'static T;
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}
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impl Trait<'static> for () {
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fn id<T>(value: &'static T) -> &'static T {
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value
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}
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}
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fn could_use_implied_bounds<'a, T>(_: Foo<'a>, x: &'a T) -> &'static T
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where
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(): Trait<'a>, // This could be an implied bound
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{
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<()>::id(x)
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}
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fn main() {
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let bar: for<'a, 'b> fn(Foo<'a>, &'b ()) = |_, _| {};
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// If `could_use_implied_bounds` were to use implied bounds,
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// keeping 'a late-bound, then we could assign that function
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// to this variable.
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let bar: for<'a> fn(Foo<'a>, &'a ()) = bar;
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// In this case, the subtyping relation here would be unsound,
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// allowing us to transmute lifetimes. This currently compiles
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// because we incorrectly deal with implied bounds inside of binders.
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let _bar: for<'a, 'b> fn(Foo<'a>, &'b ()) = bar;
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}
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