Some type parameters have the same name.
Erroneous code example:
```compile_fail,E0403
fn f<T, T>(s: T, u: T) {} // error: the name `T` is already used for a generic
// parameter in this item's generic parameters
```
Please verify that none of the type parameters are misspelled, and rename any
clashing parameters. Example:
```
fn f<T, Y>(s: T, u: Y) {} // ok!
```
Type parameters in an associated item also cannot shadow parameters from the
containing item:
```compile_fail,E0403
trait Foo<T> {
fn do_something(&self) -> T;
fn do_something_else<T: Clone>(&self, bar: T);
}
```