46846496ed
(since I made this mistake at first but the tests didn't catch it): we should not suggest adding `mut` to a reassigned `ref` or `ref mut` binding. (The Rust language, since at least 1.0, does not have `mut ref mut` or `ref mut mut` etc.)
27 lines
1.1 KiB
Rust
27 lines
1.1 KiB
Rust
// Copyright 2017 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 how we behave when the user attempts to mutate an immutable
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// binding that was introduced by either `ref` or `ref mut`
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// patterns.
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//
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// Such bindings cannot be made mutable via the mere addition of the
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// `mut` keyword, and thus we want to check that the compiler does not
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// suggest doing so.
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fn main() {
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let (mut one_two, mut three_four) = ((1, 2), (3, 4));
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let &mut (ref a, ref mut b) = &mut one_two;
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a = &three_four.0;
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//~^ ERROR cannot assign twice to immutable variable `a` [E0384]
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b = &mut three_four.1;
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//~^ ERROR cannot assign twice to immutable variable `b` [E0384]
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}
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