error: Invalid generic declaration, trait is defined with instance but generic use none

Question

I want to make a storage for the pallet but I'm getting this error

    /// The target parachains to ping.
#[pallet::storage]
pub type Targets<T:Config> = StorageValue<
    _,
    BoundedVec<(ParaId, BoundedVec<u8, MaxPayloadSize>), MaxParachains>,
    ValueQuery,
>;

And the Error

  error: Invalid generic declaration, trait is defined with instance but generic use none
  --> pallets/xnft/src/lib.rs:50:11
   |
50 |     pub type Targets<T:Config> = StorageValue<
   |              ^^^^^^^

Answer 1

It looks like your pallet supports multi-instances.

You need to add I to your storage items as well.

/// The target parachains to ping.
#[pallet::storage]
pub type Targets<T: Config, I: 'static = ()> = StorageValue<
    _,
    BoundedVec<(ParaId, BoundedVec<u8, MaxPayloadSize>), MaxParachains>,
    ValueQuery,
>;

---

Real world example:

https://github.com/paritytech/substrate/blob/4b6e735f0fab0c50f13e5b7f656512c101cacdeb/frame/balances/src/lib.rs#L372-L376.

/// The total units issued in the system.
#[pallet::storage]
#[pallet::getter(fn total_issuance)]
#[pallet::whitelist_storage]
pub type TotalIssuance<T: Config<I>, I: 'static = ()> = StorageValue<_, T::Balance, ValueQuery>;