8a461d940c
suggest adding a where-clause when there is an unmet trait-bound that can be satisfied if some type can implement it.
41 lines
1.1 KiB
Rust
41 lines
1.1 KiB
Rust
// Copyright 2014 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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// Test that an impl with only one bound region `'a` cannot be used to
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// satisfy a constraint where there are two bound regions.
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trait Foo<X> {
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fn foo(&self, x: X) { }
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}
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fn want_foo2<T>()
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where T : for<'a,'b> Foo<(&'a isize, &'b isize)>
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{
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}
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fn want_foo1<T>()
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where T : for<'z> Foo<(&'z isize, &'z isize)>
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{
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}
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///////////////////////////////////////////////////////////////////////////
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// Expressed as a where clause
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struct SomeStruct;
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impl<'a> Foo<(&'a isize, &'a isize)> for SomeStruct
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{
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}
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fn a() { want_foo1::<SomeStruct>(); } // OK -- foo wants just one region
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fn b() { want_foo2::<SomeStruct>(); } //~ ERROR E0277
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fn main() { }
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