Error in asset_eq! - binary operation `==` cannot be applied to type

Question

For my pallet I have defined a StorageMap in the storage that stores a tuple.

#[pallet::storage]
pub(super) type NameOf<T: Config> =
    StorageMap<_, Twox64Concat, T::AccountId, (Nickname<T>, BalanceOf<T>)>;

Using a custom struct:

#[derive(Encode, Decode, Default, TypeInfo, MaxEncodedLen, PartialEq, RuntimeDebug)]
#[scale_info(skip_type_params(T))]
#[codec(mel_bound())]
pub struct Nickname<T: Config> {
    pub first: BoundedVec<u8, T::MaxLength>,
    pub last: Option<BoundedVec<u8, T::MaxLength>>,
}

I have found a problem when trying to do one of the unit tests. I want to check if value stored that is suppose to be None is None:

assert_eq!(<NameOf<Test>>::get(2), None);

But I am getting this error:

binary operation `==` cannot be applied to type `std::option::Option<(pallet::Nickname<Test>, u64)>`

If I only get the value of my struct to compare it (even that the unwrap() will panic):

assert_eq!(<NameOf<Test>>::get(2).unwrap().0, None);

I still get the same error, even that I have the PartialEq trait in the struct.

binary operation `==` cannot be applied to type `pallet::Nickname<Test>`

If I just print the value I can see is None:

println!("{:?}", <NameOf<Test>>::get(2));
None

How can I make this assert_eq?

Answer 1

The code will try to apply the PartialEq derive to the config trait T as well, which does not make sense.
You can derive PartialEqNoBound instead.