mirror of https://github.com/rust-lang/rust
27 lines
478 B
Rust
27 lines
478 B
Rust
//@ run-pass
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// A basic test of using a higher-ranked trait bound.
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trait FnLike<A,R> {
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fn call(&self, arg: A) -> R;
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}
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type FnObject<'b> = dyn for<'a> FnLike<(&'a i32,), &'a i32> + 'b;
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struct Identity;
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impl<'a, T> FnLike<(&'a T,), &'a T> for Identity {
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fn call(&self, (arg,): (&'a T,)) -> &'a T {
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arg
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}
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}
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fn call_repeatedly(f: &FnObject) {
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let x = 3;
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let y = f.call((&x,));
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assert_eq!(3, *y);
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}
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fn main() {
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call_repeatedly(&Identity);
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}
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