Internal compiler error casting to trait type twice #3689
Description
I accidentally had something like stdout() as io::Writer and got an ICE, but it also happens with trivial traits/trait impls like this:
trait Foo {}
impl (): Foo {}
fn main() {
let _a = () as Foo as Foo;
}
rustc just errors out with an unexpected failure, and says
rust: task failed at 'get_vtable: expected a static origin', /home/ben/code/repos/rust/src/rustc/middle/trans/meth.rs:507