8a461d940c
suggest adding a where-clause when there is an unmet trait-bound that can be satisfied if some type can implement it.
59 lines
1.3 KiB
Rust
59 lines
1.3 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 a trait (`Bar`) with a higher-ranked supertrait.
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trait Foo<'tcx>
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{
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fn foo(&'tcx self) -> &'tcx isize;
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}
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trait Bar<'ccx>
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: for<'tcx> Foo<'tcx>
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{
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fn bar(&'ccx self) -> &'ccx isize;
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}
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fn want_foo_for_some_tcx<'x,F>(f: &'x F)
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where F : Foo<'x>
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{
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want_foo_for_some_tcx(f);
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want_foo_for_any_tcx(f); //~ ERROR E0277
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}
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fn want_foo_for_any_tcx<F>(f: &F)
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where F : for<'tcx> Foo<'tcx>
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{
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want_foo_for_some_tcx(f);
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want_foo_for_any_tcx(f);
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}
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fn want_bar_for_some_ccx<'x,B>(b: &B)
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where B : Bar<'x>
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{
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want_foo_for_some_tcx(b);
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want_foo_for_any_tcx(b);
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want_bar_for_some_ccx(b);
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want_bar_for_any_ccx(b); //~ ERROR E0277
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}
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fn want_bar_for_any_ccx<B>(b: &B)
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where B : for<'ccx> Bar<'ccx>
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{
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want_foo_for_some_tcx(b);
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want_foo_for_any_tcx(b);
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want_bar_for_some_ccx(b);
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want_bar_for_any_ccx(b);
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}
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fn main() {}
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