Returning a struct that holds an owned trait object results in a segfault

[zargony]

Using rustc 0.6, the compiled executable of the following code results in a segfault. I'm not exactly sure why, but I suppose this shouldn't happen ;).

Btw, using @Animal instead of ~Animal works fine. Using @Cage or ~Cage doesn't matter (both crash). Building ~Cage directly in main() also works fine.

pub trait Animal { }

struct Cage {
  animal: ~Animal,
}

fn capture (animal: ~Animal) -> ~Cage {
  let cage = ~Cage { animal: animal };
  debug!("still alive");
  cage
}

struct Duck { foo: int }

impl Animal for Duck { }

fn main () {
  let duck = ~Duck { foo: 123 };
  let _ = capture(duck as ~Animal);
  debug!("never reached");
}


zargony@lina:~$ uname -a
Darwin lina.fritz.box 12.3.0 Darwin Kernel Version 12.3.0: Sun Jan  6 22:37:10 PST 2013; root:xnu-2050.22.13~1/RELEASE_X86_64 x86_64
zargony@lina:~$ rustc --version
rustc 0.6
host: x86_64-apple-darwin

[zargony]

Same with rustc from master branch (rev 2d28d64)

[zargony]

Latest rustc from incoming branch (rev 9355330) fails to compile this example:

Assertion failed: (Ty && "Invalid GetElementPtrInst indices for type!"), function checkGEPType, file /private/tmp/rust-Fx9w/src/llvm/include/llvm/IR/Instructions.h, line 704.
Abort trap: 6

[thestinger]

Fixed by #7214.