51 lines
1.4 KiB
Rust
51 lines
1.4 KiB
Rust
// 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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// Test that when we pick a trait based on coercion, versus subtyping,
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// we consider all possible coercions equivalent and don't try to pick
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// a best one.
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trait Object { }
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trait foo {
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fn foo(self) -> isize;
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}
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impl foo for Box<Object+'static> {
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fn foo(self) -> isize {1}
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}
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impl foo for Box<Object+Send> {
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fn foo(self) -> isize {2}
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}
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fn test1(x: Box<Object+Send+Sync>) {
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// FIXME(#18737) -- we ought to consider this to be ambiguous,
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// since we could coerce to either impl. However, what actually
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// happens is that we consider both impls applicable because of
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// incorrect subtyping relation. We then decide to call this a
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// call to the `foo` trait, leading to the following error
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// message.
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x.foo(); //~ ERROR `foo` is not implemented
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}
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fn test2(x: Box<Object+Send>) {
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// Not ambiguous because it is a precise match:
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x.foo();
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}
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fn test3(x: Box<Object+'static>) {
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// Not ambiguous because it is a precise match:
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x.foo();
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}
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fn main() { }
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