type annotations needed in substrate frotier rpc pallet

I’m using susbtrate 2.0.1 and trying to integrate frontier implementation into the runtime, this implementation was working fine with substrate 2.0.0 but now having some syntax errors.

Frontier Dependencies
frontier-consensus = {  default-features = false,git = 'https://github.com/PureStake/frontier.git', branch = 'substrate-v2' }
frontier-rpc = {  default-features = false, git = 'https://github.com/PureStake/frontier.git', branch = 'substrate-v2' }
frontier-rpc-primitives = { default-features = false, git = 'https://github.com/PureStake/frontier.git', branch = 'substrate-v2' }

Below is the error :

    error[E0283]: type annotations needed
   --> /Users/dev/Applications/.cargo/git/checkouts/frontier-6f1ff17f29a883b0/c5fe2a6/rpc/src/eth.rs:299:56
    |
299 |         Ok(U256::from(self.client.info().best_number.clone().unique_saturated_into()))
    |                                                              ^^^^^^^^^^^^^^^^^^^^^
    |
    = note: multiple `impl`s satisfying `U256: From<_>` found in the following crates: `core`, `primitive_types`:
            - impl From<&'static str> for U256;
            - impl From<U128> for U256;
            - impl From<[u8; _]> for U256;
            - impl From<i128> for U256;
            and 15 more
help: try using a fully qualified path to specify the expected types
    |
299 |         Ok(U256::from(<<<B as BlockT>::Header as HeaderT>::Number as UniqueSaturatedInto<T>>::unique_saturated_into(self.client.info().best_number.clone())))


type annotations needed
  --> /Users/dev/Applications/.cargo/git/checkouts/frontier-6f1ff17f29a883b0/c5fe2a6/rpc/src/eth_pubsub.rs:88:46
   |
88 |                         self.client.info().best_number.clone().unique_saturated_into() as u32
   |                                                                ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: type must be known at this point
help: try using a fully qualified path to specify the expected types
   |
88 |                         <<<B as BlockT>::Header as HeaderT>::Number as UniqueSaturatedInto<T>>::unique_saturated_into(self.client.info().best_number.clone()) as u32

On this line of code having this error :

fn block_number(&self) -> Result<U256> {
        
        Ok(U256::from(self.client.info().best_number.clone().unique_saturated_into()))
        
    }

native_number = Some(
                        self.client.info().best_number.clone().unique_saturated_into() as u32
);

>Solution :

The compiler can not deduce U256 from which type (u32?u64?…?) within this context.

You need to write it explicitly.

BTW, you could use saturated_into instead unique_saturated_into, which supports turbo fish style.

Example:

U256::from(self.client.info().best_number.clone().saturated_into::<u32>());

If you want unique_saturated_into anyway:

let bn: u32 = self.client.info().best_number.clone().unique_saturated_into();
U256::from(bn);