Stack Closure Owned Pointer Reference Crash

[simonjlewis]

Creating a stack closure which references an owned pointer and then transferring ownership of the owned box before invoking the stack closure results in a crash.

For example, in Rust 0.6, this will compile

fn twice(x: ~uint) -> uint
{
     *x * 2
}

fn invoke(f : &fn() -> uint)
{
     f();
}

fn main()
{
      let x  : ~uint         = ~9;
      let sq : &fn() -> uint = || { *x * *x };

      twice(x);
      invoke(sq);
}

and the resulting program will then crash with a SEGV

[jdm]

Does it still crash on the incoming branch?

[lkuper]

It dumps core for me, on incoming:

lkuper@lenny:~/repos/rust$ x86_64-unknown-linux-gnu/stage2/bin/rustc /home/lkuper/repos/rust/src/test/compile-fail/issue-6762.rs -o x86_64-unknown-linux-gnu/test/compile-fail/issue-6762.stage2-x86_64-unknown-linux-gnu -L x86_64-unknown-linux-gnu/test/compile-fail -L x86_64-unknown-linux-gnu/test/compile-fail/issue-6762.libaux --target=x86_64-unknown-linux-gnu
lkuper@lenny:~/repos/rust$ x86_64-unknown-linux-gnu/test/compile-fail/issue-6762.stage2-x86_64-unknown-linux-gnu 
Segmentation fault (core dumped)
lkuper@lenny:~/repos/rust$ 

Adding an xfailed test. We want this to fail compilation, I guess.

[bblum]

This bug could be fixed by the proposed solution in this post: http://smallcultfollowing.com/babysteps/blog/2013/04/30/the-case-of-the-recurring-closure/ (namely, bullet 1, not 2)

[nikomatsakis]

Dup of #2202 and more specifically #6801.