Segfault with let _x = "test" as &Any

[lilyball]

The following program segfaults when run (it compiles just fine):

fn main() {
    let _x = "test" as &::std::any::Any;
}

Reproduced with rustc 0.11.0-pre (22e2204 2014-05-21 23:31:27 -0700).

[lilyball]

LLDB says EXC_BAD_ACCESS (code=1, address=0xffffffffffffff9b).

[jfager]

This works for me today, are you still seeing the problem?

[nathantypanski]

@jfager

scratch$ rustc segf.rs 
scratch$ ./segf
zsh: segmentation fault  ./segf
scratch$ rustc -v
rustc 0.12.0-pre (b3a732a3e 2014-07-23 19:56:15 +0000)

[jfager]

Hmm.

scratch$ rustc r14366.rs 
scratch$ ./r14366 
scratch$ rustc -v
rustc 0.12.0-pre-nightly (217f1fbfc 2014-07-22 23:11:12 +0000)

Maybe platform-specific? I'm on a mac, 10.9.

[lilyball]

On May 22nd I was obviously seeing it (on a Mac), as I authored this, but I too cannot reproduce today.

rustc 0.12.0-pre (9cc39a054d485e46f7b8292cea690407932232ce 2014-07-21 16:51:37 +0000)

[nathantypanski]

I'm on Linux:

$ uname -a
Linux dionysus 3.15.5-2-ARCH #1 SMP PREEMPT Fri Jul 11 07:56:02 CEST 2014 x86_64 GNU/Linux

Interesting bit: compiling this with debug symbols -> no crash:

scratch$ rustc 14366.rs
scratch$ ./14366
zsh: segmentation fault  ./14366
scratch$ rustc -g 14366.rs
scratch$ ./14366

The best I can convince lldb to tell me is this:

* thread #1: tid = 23259, 0x00007ff4c1e90dc0, name = '14366', stop reason = trace
    frame #0: 0x00007ff4c1e90dc0
-> 0x7ff4c1e90dc0:  movq   %rsp, %rdi
   0x7ff4c1e90dc3:  callq  0x7ff4c1e94ab0
   0x7ff4c1e90dc8:  movq   %rax, %r12
   0x7ff4c1e90dcb:  movl   0x21ffa7(%rip), %eax
Process 23259 stopped
* thread #1: tid = 23259, 0x0000000000000004, name = '14366', stop reason = invalid address (fault address: 0x4)
    frame #0: 0x0000000000000004
error: Input/output error

[ghost]

This correctly fails to compile now:

<anon>:2:14: 2:40 error: the trait `core::kinds::Sized` is not implemented for the type `str`
<anon>:2     let _x = "test" as &::std::any::Any;
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
<anon>:2:14: 2:40 note: the trait `core::kinds::Sized` must be implemented for the cast to the object type `core::any::Any`
<anon>:2     let _x = "test" as &::std::any::Any;
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
<anon>:2:14: 2:40 error: the trait `core::kinds::Sized` is not implemented for the type `str`
<anon>:2     let _x = "test" as &::std::any::Any;
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
<anon>:2:14: 2:40 note: the trait `core::kinds::Sized` must be implemented for the cast to the object type `core::any::Any`
<anon>:2     let _x = "test" as &::std::any::Any;
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~

(though the repeated diagnostic is undesirable)

And the correct version works:

fn main() {
    let _x = "test" as &::std::any::Any;
}