add_impl_generic doesn't work with new gen_impl

[RReverser]

For example, modying the current doctest on add_impl_generic to:

s.add_impl_generic(generic)
.gen_impl(quote! {
    gen impl krate::Trait<X> for @Self {
        fn a() {}
    }
})

generates:

#[allow(non_upper_case_globals)]
const _DERIVE_krate_Trait_X_FOR_A: () = {
    impl<T, U> krate::Trait<X> for A<T, U>
    where
        T: krate::Trait<X>,
        Option<U>: krate::Trait<X>,
        U: krate::Trait<X>,
    {
        fn a() {}
    }
};

As you can see, X is completely ignored in impl<...>.

My suggestion would be to either add support for generics produced by this method, or perhaps remove it altogether as part of #29 in favour of allowing gen impl<...> Trait for @Self ... syntax that would automatically merge impl params.

[RReverser]

in favour of allowing gen impl<...> Trait for @self ... syntax that would automatically merge impl params

Actually, it seems this syntax is already allowed and covers my needs. But it still feels confusing that method is completely ignored - it should either be respected, produce an error, or be removed.

[nox]

I have encountered this issue too. At least I have a work-around now :)