bf6c007760
This implements RFC 179 by making the pattern `&<pat>` require matching
against a variable of type `&T`, and introducing the pattern `&mut
<pat>` which only works with variables of type `&mut T`.
The pattern `&mut x` currently parses as `&(mut x)` i.e. a pattern match
through a `&T` or a `&mut T` that binds the variable `x` to have type
`T` and to be mutable. This should be rewritten as follows, for example,
for &mut x in slice.iter() {
becomes
for &x in slice.iter() {
let mut x = x;
Due to this, this is a
[breaking-change]
Closes #20496.
24 lines
807 B
Rust
24 lines
807 B
Rust
// Copyright 2015 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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fn main() {
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let foo = &mut 1i;
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let &mut x = foo;
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x += 1; //~ ERROR re-assignment of immutable variable
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// explicitly mut-ify internals
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let &mut mut x = foo;
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x += 1;
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// check borrowing is detected successfully
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let &mut ref x = foo;
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*foo += 1; //~ ERROR cannot assign to `*foo` because it is borrowed
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}
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