9330bae4bd
impls. This is a [breaking-change] (for gated code) in that when you implement `Fn` (`FnMut`) you must also implement `FnOnce`. This commit demonstrates how to fix it.
90 lines
2.1 KiB
Rust
90 lines
2.1 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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#![feature(unboxed_closures)]
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use std::ops::{Fn, FnMut, FnOnce};
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struct SFn {
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x: isize,
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y: isize,
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}
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impl Fn<(isize,)> for SFn {
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extern "rust-call" fn call(&self, (z,): (isize,)) -> isize {
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self.x * self.y * z
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}
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}
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impl FnMut<(isize,)> for SFn {
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extern "rust-call" fn call_mut(&mut self, args: (isize,)) -> isize { self.call(args) }
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}
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impl FnOnce<(isize,)> for SFn {
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type Output = isize;
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extern "rust-call" fn call_once(self, args: (isize,)) -> isize { self.call(args) }
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}
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struct SFnMut {
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x: isize,
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y: isize,
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}
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impl FnMut<(isize,)> for SFnMut {
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extern "rust-call" fn call_mut(&mut self, (z,): (isize,)) -> isize {
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self.x * self.y * z
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}
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}
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impl FnOnce<(isize,)> for SFnMut {
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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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struct SFnOnce {
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x: String,
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}
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impl FnOnce<(String,)> for SFnOnce {
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type Output = usize;
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extern "rust-call" fn call_once(self, (z,): (String,)) -> usize {
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self.x.len() + z.len()
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}
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}
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fn f() {
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let mut s = SFn {
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x: 1,
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y: 2,
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};
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let sp = &mut s;
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s(3); //~ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
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//~^ ERROR cannot borrow `s` as immutable because it is also borrowed as mutable
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}
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fn g() {
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let s = SFnMut {
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x: 1,
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y: 2,
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};
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s(3); //~ ERROR cannot borrow immutable local variable `s` as mutable
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}
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fn h() {
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let s = SFnOnce {
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x: "hello".to_string(),
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};
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s(" world".to_string());
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s(" world".to_string()); //~ ERROR use of moved value: `s`
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}
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fn main() {}
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