98 lines
2.9 KiB
Rust
98 lines
2.9 KiB
Rust
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// Copyright 2016 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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// ignore-tidy-linelength
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#![feature(untagged_unions)]
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union U {
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a: u8,
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b: u64,
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}
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impl Clone for U {
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fn clone(&self) -> Self { *self }
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}
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impl Copy for U {}
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fn main() {
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unsafe {
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let mut u = U { b: 0 };
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// Imm borrow, same field
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{
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let ra = &u.a;
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let ra2 = &u.a; // OK
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}
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{
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let ra = &u.a;
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let a = u.a; // OK
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}
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{
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let ra = &u.a;
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let rma = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable because it is also borrowed as immutable
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}
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{
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let ra = &u.a;
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u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
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}
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// Imm borrow, other field
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{
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let ra = &u.a;
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let rb = &u.b; // OK
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}
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{
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let ra = &u.a;
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let b = u.b; // OK
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}
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{
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let ra = &u.a;
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let rmb = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable because `u` is also borrowed as immutable (via `u.a`)
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}
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{
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let ra = &u.a;
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u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
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}
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// Mut borrow, same field
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{
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let rma = &mut u.a;
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let ra = &u.a; //~ ERROR cannot borrow `u.a` as immutable because it is also borrowed as mutable
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}
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{
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let ra = &mut u.a;
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let a = u.a; //~ ERROR cannot use `u.a` because it was mutably borrowed
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}
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{
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let rma = &mut u.a;
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let rma2 = &mut u.a; //~ ERROR cannot borrow `u.a` as mutable more than once at a time
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}
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{
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let rma = &mut u.a;
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u.a = 1; //~ ERROR cannot assign to `u.a` because it is borrowed
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}
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// Mut borrow, other field
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{
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let rma = &mut u.a;
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let rb = &u.b; //~ ERROR cannot borrow `u` (via `u.b`) as immutable because `u` is also borrowed as mutable (via `u.a`)
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}
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{
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let ra = &mut u.a;
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let b = u.b; //~ ERROR cannot use `u.b` because it was mutably borrowed
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}
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{
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let rma = &mut u.a;
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let rmb2 = &mut u.b; //~ ERROR cannot borrow `u` (via `u.b`) as mutable more than once at a time
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}
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{
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let rma = &mut u.a;
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u.b = 1; //~ ERROR cannot assign to `u.b` because it is borrowed
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}
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}
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}
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