47 lines
1.8 KiB
Rust
47 lines
1.8 KiB
Rust
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// 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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// revisions: lxl nll
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//[lxl]compile-flags: -Z borrowck=mir -Z two-phase-borrows
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//[nll]compile-flags: -Z borrowck=mir -Z two-phase-borrows -Z nll
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// This is a corner case that the current implementation is (probably)
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// treating more conservatively than is necessary. But it also does
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// not seem like a terribly important use case to cover.
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//
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// So this test is just making a note of the current behavior, with
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// the caveat that in the future, the rules may be loosened, at which
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// point this test might be thrown out.
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fn main() {
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let mut vec = vec![0, 1];
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let delay: &mut Vec<_>;
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{
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let shared = &vec;
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// we reserve here, which could (on its own) be compatible
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// with the shared borrow. But in the current implementation,
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// its an error.
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delay = &mut vec;
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//[lxl]~^ ERROR cannot borrow `vec` as mutable because it is also borrowed as immutable
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//[nll]~^^ ERROR cannot borrow `vec` as mutable because it is also borrowed as immutable
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shared[0];
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}
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// the &mut-borrow only becomes active way down here.
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//
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// (At least in theory; part of the reason this test fails is that
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// the constructed MIR throws in extra &mut reborrows which
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// flummoxes our attmpt to delay the activation point here.)
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delay.push(2);
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}
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