| // Copyright 2017 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| // ignore-tidy-linelength |
| |
| // revisions: nll_target |
| |
| // The following revisions are disabled due to missing support from two-phase beyond autorefs |
| //[nll_beyond] compile-flags: -Z borrowck=mir -Z two-phase-borrows -Z two-phase-beyond-autoref |
| |
| //[nll_target] compile-flags: -Z borrowck=mir -Z two-phase-borrows |
| |
| // This is an important corner case pointed out by Niko: one is |
| // allowed to initiate a shared borrow during a reservation, but it |
| // *must end* before the activation occurs. |
| // |
| // FIXME: for clarity, diagnostics for these cases might be better off |
| // if they specifically said "cannot activate mutable borrow of `x`" |
| // |
| // The convention for the listed revisions: "lxl" means lexical |
| // lifetimes (which can be easier to reason about). "nll" means |
| // non-lexical lifetimes. "nll_target" means the initial conservative |
| // two-phase borrows that only applies to autoref-introduced borrows. |
| // "nll_beyond" means the generalization of two-phase borrows to all |
| // `&mut`-borrows (doing so makes it easier to write code for specific |
| // corner cases). |
| |
| #![allow(dead_code)] |
| |
| fn read(_: &i32) { } |
| |
| fn ok() { |
| let mut x = 3; |
| let y = &mut x; |
| { let z = &x; read(z); } |
| //[nll_target]~^ ERROR cannot borrow `x` as immutable because it is also borrowed as mutable |
| *y += 1; |
| } |
| |
| fn not_ok() { |
| let mut x = 3; |
| let y = &mut x; |
| let z = &x; |
| //[nll_target]~^ ERROR cannot borrow `x` as immutable because it is also borrowed as mutable |
| *y += 1; |
| //[lxl_beyond]~^ ERROR cannot borrow `x` as mutable because it is also borrowed as immutable |
| //[nll_beyond]~^^ ERROR cannot borrow `x` as mutable because it is also borrowed as immutable |
| read(z); |
| } |
| |
| fn should_be_ok_with_nll() { |
| let mut x = 3; |
| let y = &mut x; |
| let z = &x; |
| //[nll_target]~^ ERROR cannot borrow `x` as immutable because it is also borrowed as mutable |
| read(z); |
| *y += 1; |
| //[lxl_beyond]~^ ERROR cannot borrow `x` as mutable because it is also borrowed as immutable |
| // (okay with (generalized) nll today) |
| } |
| |
| fn should_also_eventually_be_ok_with_nll() { |
| let mut x = 3; |
| let y = &mut x; |
| let _z = &x; |
| //[nll_target]~^ ERROR cannot borrow `x` as immutable because it is also borrowed as mutable |
| *y += 1; |
| //[lxl_beyond]~^ ERROR cannot borrow `x` as mutable because it is also borrowed as immutable |
| // (okay with (generalized) nll today) |
| } |
| |
| fn main() { } |