41 lines
1.1 KiB
Rust
41 lines
1.1 KiB
Rust
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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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// Illustrates the "projection gap": in this test, even though we know
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// that `T::Foo: 'x`, that does not tell us that `T: 'x`, because
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// there might be other ways for the caller of `func` to show that
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// `T::Foo: 'x` holds (e.g., where-clause).
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trait Trait1<'x> {
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type Foo;
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}
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// calling this fn should trigger a check that the type argument
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// supplied is well-formed.
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fn wf<T>() { }
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fn func<'x, T:Trait1<'x>>(t: &'x T::Foo)
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{
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wf::<&'x T>();
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//~^ ERROR the parameter type `T` may not live long enough
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}
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fn caller2<'x, T:Trait1<'x>>(t: &'x T)
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{
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wf::<&'x T::Foo>(); // OK
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}
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fn caller3<'x, T:Trait1<'x>>(t: &'x T::Foo)
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{
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wf::<&'x T::Foo>(); // OK
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}
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fn main() { }
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