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with the corresponding trait parameter bounds. This is a version of the patch in PR #12611 by Florian Hahn, modified to address Niko's feedback. It does not address the issue of duplicate type parameter bounds, nor does it address the issue of implementation-defined methods that contain *fewer* bounds than the trait, because Niko's review indicates that this should not be necessary (and indeed I believe it is not). A test has been added to ensure that this works. This will break code like: trait Foo { fn bar<T:Baz>(); } impl Foo for Boo { fn bar<T:Baz + Quux>() { ... } // ^~~~ ERROR } This will be rejected because the implementation requires *more* bounds than the trait. It can be fixed by either adding the missing bound to the trait: trait Foo { fn bar<T:Baz + Quux>(); // ^~~~ } impl Foo for Boo { fn bar<T:Baz + Quux>() { ... } // OK } Or by removing the bound from the impl: trait Foo { fn bar<T:Baz>(); } impl Foo for Boo { fn bar<T:Baz>() { ... } // OK // ^ remove Quux } This patch imports the relevant tests from #2687, as well as the test case in #5886, which is fixed as well by this patch. Closes #2687. Closes #5886. [breaking-change]
26 lines
755 B
Rust
26 lines
755 B
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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// Tests that type parameter bounds on an implementation need not match the
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// trait exactly, as long as the implementation doesn't demand *more* bounds
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// than the trait.
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trait A {
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fn foo<T: Eq + Ord>(&self);
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}
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impl A for int {
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fn foo<T: Ord + Ord>(&self) {}
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}
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fn main() {}
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