| // Copyright 2018 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. |
| |
| // This is testing an attempt to corrupt the discriminant of the match |
| // arm in a guard, followed by an attempt to continue matching on that |
| // corrupted discriminant in the remaining match arms. |
| // |
| // Basically this is testing that our new NLL feature of emitting a |
| // fake read on each match arm is catching cases like this. |
| // |
| // This case is interesting because it includes a guard that |
| // diverges, and therefore a single final fake-read at the very end |
| // after the final match arm would not suffice. |
| // |
| // It is also interesting because the access to the corrupted data |
| // occurs in the pattern-match itself, and not in the guard |
| // expression. |
| |
| #![feature(nll)] |
| |
| struct ForceFnOnce; |
| |
| fn main() { |
| let mut x = &mut Some(&2); |
| let force_fn_once = ForceFnOnce; |
| match x { |
| &mut None => panic!("unreachable"), |
| &mut Some(&_) |
| if { |
| // ForceFnOnce needed to exploit #27282 |
| (|| { *x = None; drop(force_fn_once); })(); |
| //~^ ERROR closure requires unique access to `x` but it is already borrowed [E0500] |
| false |
| } => {} |
| |
| // this segfaults if we corrupted the discriminant, because |
| // the compiler gets to *assume* that it cannot be the `None` |
| // case, even though that was the effect of the guard. |
| &mut Some(&2) |
| if { |
| panic!() |
| } => {} |
| _ => panic!("unreachable"), |
| } |
| } |
