ICE with C generic enum

[pravic]

http://is.gd/DOkUCJ Playground with backtrace

#[repr(C)]
pub enum CPOption<T> {
    PSome(T),
}

fn main() {
  println!("sizeof CPOption<i32> {}", std::mem::size_of::<CPOption<i32>>());
}

Versions affected: stable, beta, nightly.

[MagaTailor]

Here's a debug trace from rustc 1.9.0-dev (470ca1c3f 2016-04-07)

[luqmana]

This is not limited to generic enums. Just an oversight in typeck that we allow it to get to trans at all.