Missing Benchmark Helper in Implementation

Question

When building the polkadot runtime in https://github.com/polkadot-fellows/runtimes

using

cargo build --profile production --features runtime-benchmarks

i encounter this error every time.

error[E0046]: not all trait items implemented, missing: `BenchmarkHelper`
   --> /Users/user/.cargo/registry/src/index.crates.io-6f17d22bba15001f/penpal-runtime-0.15.1/src/lib.rs:437:1
    |
437 | impl pallet_assets::Config<pallet_assets::Instance1> for Runtime {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `BenchmarkHelper` in implementation
    |
    = help: implement the missing item: `type BenchmarkHelper = /* Type */;`

error[E0046]: not all trait items implemented, missing: `BenchmarkHelper`
   --> /Users/user/.cargo/registry/src/index.crates.io-6f17d22bba15001f/penpal-runtime-0.15.1/src/lib.rs:472:1
    |
472 | impl pallet_assets::Config<ForeignAssetsInstance> for Runtime {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `BenchmarkHelper` in implementation

I have tried downgrading my toolchain several times and using cargo clean, nothing works.

and the thing is when I check the file location for the missing Config, it is there.

pub type ForeignAssetsInstance = pallet_assets::Instance2;
impl pallet_assets::Config<ForeignAssetsInstance> for Runtime {
        type RuntimeEvent = RuntimeEvent;
        type Balance = Balance;
        type AssetId = xcm::v3::Location;
        type AssetIdParameter = xcm::v3::Location;
        type Currency = Balances;
        type CreateOrigin = AsEnsureOriginWithArg<EnsureSigned<AccountId>>;
        type ForceOrigin = EnsureRoot<AccountId>;
        type AssetDeposit = ForeignAssetsAssetDeposit;
        type MetadataDepositBase = ForeignAssetsMetadataDepositBase;
        type MetadataDepositPerByte = ForeignAssetsMetadataDepositPerByte;
        type ApprovalDeposit = ForeignAssetsApprovalDeposit;
        type StringLimit = ForeignAssetsAssetsStringLimit;
        type Freezer = ();
        type Extra = ();
        type WeightInfo = pallet_assets::weights::SubstrateWeight<Runtime>;
        type CallbackHandle = ();
        type AssetAccountDeposit = ForeignAssetsAssetAccountDeposit;
        type RemoveItemsLimit = frame_support::traits::ConstU32<1000>;
        #[cfg(feature = "runtime-benchmarks")]
        type BenchmarkHelper = xcm_config::XcmBenchmarkHelper;
}

I am trying to build weights for pallet instances in the collective-polkadot-runtime.

Answer 1

To build the Polkadot runtime, execute the following command:

cargo b -p polkadot-runtime --profile production --features runtime-benchmarks​

If you run that command on the workspace root, the features won't be configured correctly sometimes.

Use -p to specify the package to avoid that.