@value
struct S[T: CollectionElement]:
    var data: T

    fn __eq__[
        T: ComparableCollectionElement, //,
    ](self: S[T], other: S[T]) -> Bool:
        return self.data == other.data

fn main():
    var a = S(1)
    var b = S(2)
    a == b       # invalid call to '__eq__': could not deduce parameter 'T' of parent struct 'S'
    a.__eq__(b)  # runs fine