ICE with struct-like enum variants

[catamorphism]

I'm not even sure if this should work, but it does pass typechecking.

enum Animal {
    Dog (~str, float),
    Cat { name: ~str, weight: float }
}

fn main() {
    let mut a: Animal = Dog(~"Cocoa", 37.2);
    a = Cat{ name: ~"Spotty", weight: 2.7 };
}

This yields an ICE in trans:

error: internal compiler error: iter_variant: not a function type

The message is from trans::base::iter_structural_ty.

[catamorphism]

It seems like typeck::collect::get_enum_variant_types assigns the wrong type to a struct variant constructor (the enum type itself, rather than an function mapping the struct fields to the enum type). Trying to fix it.

[catamorphism]

Fixed, see #4233