"expected type parameter but found type parameter"

[catamorphism]

This is a terrible error message. See compile-fail/issue-2611-5.rs, which I'm about to check in, for an example program that triggers it.

[metajack]

Reproduced on 65ed803

[thestinger]

Triage bump, still an issue. This is often caused by a mismatch between lifetimes.

[dradtke]

Confirmed that this is still an issue with Rust 0.9. I ran into it playing around with linked list implementations:

pub enum List<T> {
    Cons(T, ~List<T>),
    Nil,
}

impl<T> List<T> {
    fn prepend<T>(mut self, value: T) {
        self = Cons(value, ~self);
    }
}

This causes the compiler to emit two errors, neither of which is very helpful:

error: mismatched types: expected `~List<T>` but found `~List<T>` (expected type parameter but found type parameter)
error: mismatched types: expected `List<T>` but found `List<T>` (expected type parameter but found type parameter)

[pnkfelix]

accepted for P-low.