ICE when using type parameters of an impl.

[paulstansifer]

The error is in kind checking. It looks like the impl cannot use the type parameter T.

import dvec::dvec;

class c1<T: copy> {
    new() {}

    fn f1(x: T) {} // OK
}

impl i1<T: copy> for c1<T> {
    fn f2(x: T) {} // can't be used
}


fn main() {
    c1::<int>().f1(4);
    c1::<int>().f2(4); //comment out this line, and the ICE disappears
}

The error is

rust: upcall fail 'Internal error: in kind::check_expr, length mismatch between actual and declared bounds: actual 
= int (1 tys), declared = [@[bound_copy], @[bound_copy]] (2 tys)', /home/rustbuild/src/rustbot/workspace-snap-stage
3-x86_64-unknown-linux-gnu/src/src/rustc/middle/kind.rs:269  

[paulstansifer]

It turns out that you can get the same issue, even if the type parameters aren't used:

class c1<T: copy> {
    new() {}

    fn f1(x: int) {
    }
}

impl i1<T: copy> for c1<T> {
    fn f2(x: int) {
    }
}


fn main() {
    c1::<int>().f1(4);
    c1::<int>().f2(4); //comment out to prevent ICE
}

[catamorphism]

I'll take this.

[catamorphism]

I looked at it... I'm going to say that #2364 blocks this. It looks like another bug resulting from concatenating the iface ty params with method ty params in one place but not the other.

[catamorphism]

Happily, this seems to have been accidentally fixed at some point. I added the test cases.