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Treat loans of 'static data as extending to the end of the enclosing fn. #28321

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Sep 10, 2015
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12 changes: 1 addition & 11 deletions src/librustc_borrowck/borrowck/gather_loans/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -364,17 +364,7 @@ impl<'a, 'tcx> GatherLoanCtxt<'a, 'tcx> {

ty::ReFree(ref fr) => fr.scope,

ty::ReStatic => {
// If we get here, an error must have been
// reported in
// `lifetime::guarantee_lifetime()`, because
// the only legal ways to have a borrow with a
// static lifetime should not require
// restrictions. To avoid reporting derived
// errors, we just return here without adding
// any loans.
return;
}
ty::ReStatic => self.item_ub,

ty::ReEmpty |
ty::ReLateBound(..) |
Expand Down
34 changes: 34 additions & 0 deletions src/test/borrowck-loan-of-static-data-issue-27616.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,34 @@
// Copyright 2015 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.

use std::mem;

fn leak<T>(mut b: Box<T>) -> &'static mut T {
// isn't this supposed to be safe?
let inner = &mut *b as *mut _;
mem::forget(b);
unsafe { &mut *inner }
}

fn evil(mut s: &'static mut String)
{
// create alias
let alias: &'static mut String = s;
let inner: &str = &alias;
// free value
*s = String::new(); //~ ERROR cannot assign
let _spray = "0wned".to_owned();
// ... and then use it
println!("{}", inner);
}

fn main() {
evil(leak(Box::new("hello".to_owned())));
}