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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// Checks that the Fn trait hierarchy rules do not permit
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// Fn to be used where FnMut is implemented.
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#![feature(unboxed_closures)]
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#![feature(overloaded_calls)]
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use std::ops::{Fn,FnMut,FnOnce};
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struct S;
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impl FnMut<(isize,)> for S {
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extern "rust-call" fn call_mut(&mut self, (x,): (isize,)) -> isize {
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x * x
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}
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}
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impl FnOnce<(isize,)> for S {
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type Output = isize;
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extern "rust-call" fn call_once(mut self, args: (isize,)) -> isize { self.call_mut(args) }
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}
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fn call_it<F:Fn(isize)->isize>(f: &F, x: isize) -> isize {
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f.call((x,))
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}
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fn main() {
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let x = call_it(&S, 22);
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//~^ ERROR E0277
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}
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