mirror of https://github.com/rust-lang/rust
52 lines
1017 B
Rust
52 lines
1017 B
Rust
// In this fn, the type `F` is a function that takes a reference to a
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// struct and returns another reference with the same lifetime.
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//
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// Meanwhile, the bare fn `foo` takes a reference to a struct with
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// *ANY* lifetime and returns a reference with the 'static lifetime.
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// This can safely be considered to be an instance of `F` because all
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// lifetimes are sublifetimes of 'static.
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#![allow(dead_code)]
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#![allow(unused_variables)]
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struct S;
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// Given 'cx, return 'cx
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type F = for<'cx> fn(&'cx S) -> &'cx S;
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fn want_F(f: F) {}
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// Given anything, return 'static
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type G = for<'cx> fn(&'cx S) -> &'static S;
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fn want_G(f: G) {}
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// Should meet both.
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fn foo(x: &S) -> &'static S {
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panic!()
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}
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// Should meet both.
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fn bar<'a, 'b>(x: &'a S) -> &'b S {
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panic!()
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}
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// Meets F, but not G.
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fn baz(x: &S) -> &S {
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panic!()
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}
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fn supply_F() {
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want_F(foo);
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want_F(bar);
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want_F(baz);
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}
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fn supply_G() {
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want_G(foo);
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want_G(bar);
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want_G(baz); //~ ERROR mismatched types
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}
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pub fn main() {}
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