How can i resolve this weird error with StorageMap implementation?

Question

I am trying to upgrade pallet-did to substrate v4 but i have an issue am facing with the StorageMap implementation. Below is the code for the storage map functions i am trying to implement:

#[pallet::storage]
#[pallet::getter(fn delegate_of)]
pub type DelegateOf<T: Config> =
StorageMap<_, Blake2_128Concat, (T::AccountId, Vec<u8>, T::AccountId), Option<T::BlockNumber>, OptionQuery>;
    
    
#[pallet::storage]
#[pallet::getter(fn attribute_of)]
pub type AttributeOf<T: Config> =
StorageMap<_, Blake2_128Concat, (T::AccountId, [u8; 32]), Attribute<T::BlockNumber, T::Moment>, OptionQuery>;
    
#[pallet::storage]
#[pallet::getter(fn nonce_of)]
pub type AttributeNonce<T: Config> =
StorageMap<_, Twox64Concat, (T::AccountId, Vec<u8>), u64, ValueQuery>;
    
#[pallet::storage]
#[pallet::getter(fn owner_of)]
pub type OwnerOf<T: Config> =
StorageMap<_, Blake2_128Concat, T::AccountId, Option<T::AccountId>, OptionQuery>;
    
#[pallet::storage]
#[pallet::getter(fn updated_by)]
pub type UpdatedBy<T: Config> =
StorageMap<_, Blake2_128Concat, T::AccountId, (T::AccountId, T::BlockNumber, T::Time), OptionQuery>;

This is the decl_storage! functionality in pallet-did refactored into StorageMap functions. I get the following error:

warning: trait objects without an explicit dyn are deprecated
   --> src/lib.rs:128:5
    |
128 |     StorageMap<_, Blake2_128Concat, (T::AccountId, Vec<u8>, T::AccountId), Option<T::BlockNumber>, OptionQuery>;
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!
    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
    = note: #[warn(bare_trait_objects)] on by default
help: use dyn
    |
128 |     dyn StorageMap<_, Blake2_128Concat, (T::AccountId, Vec<u8>, T::AccountId), Option<T::BlockNumber>, OptionQuery>;
    |     +++

This doesn't make sense to me since StorageMap is a type and not a trait. A solution to this and explanation would be highly appreciated.

Answer 1

I'm not sure about this.

But from your log.

warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021!

What's your rust version? Did you try the latest nightly toolchain?

---

After checking your code.

Because you wrote:

use frame_support::{
    dispatch::DispatchResult, ensure,traits::{Time, IsType}, StorageMap,
    sp_runtime::traits::{Scale, IdentifyAccount, Member, Verify},
};

This StorageMap shadows the same name type from the frame_support::pallet_prelude::*.

Please remove it, or change it to StorageMap as _.