"pointer being freed was not allocated" when triggering out-of-stack-space compiler bug

[jruderman]

tag clam[T] { a(T); }
fn main() { let c = a(c); alt c { a[int](_) { } } }

Compiling it gives "Out of stack space, sorry" (which is probably the same problem as #768).

Compiling it ALSO triggers "rustc(21383,0xb0509000) malloc: *** error for object 0x2900450: pointer being freed was not allocated" about 10% of the time. Yikes!

[catamorphism]

As of the current revision, the typechecker rightly rejects this program (the fix was the same as for #768 - so I'm closing).

The "pointer being freed was not allocated" problem is, I think, a known bug; a lot of things that fail don't fail cleanly.