fix

bin/node/cli/src/chain_spec.rs

@@ -23,8 +23,8 @@ use hex_literal::hex;
 use node_runtime::{
 	constants::currency::*, wasm_binary_unwrap, AuthorityDiscoveryConfig, BabeConfig,
 	BalancesConfig, Block, CouncilConfig, DemocracyConfig, ElectionsConfig, GrandpaConfig,
-	ImOnlineConfig, IndicesConfig, SessionConfig, SessionKeys, SocietyConfig, StakerStatus,
-	StakingConfig, SudoConfig, SystemConfig, TechnicalCommitteeConfig, MAX_NOMINATIONS,
+	ImOnlineConfig, IndicesConfig, MaxNominations, SessionConfig, SessionKeys, SocietyConfig,
+	StakerStatus, StakingConfig, SudoConfig, SystemConfig, TechnicalCommitteeConfig,
 };
 use pallet_im_online::sr25519::AuthorityId as ImOnlineId;
 use sc_chain_spec::ChainSpecExtension;
@@ -278,7 +278,7 @@ pub fn testnet_genesis(
 		.map(|x| (x.0.clone(), x.1.clone(), STASH, StakerStatus::Validator))
 		.chain(initial_nominators.iter().map(|x| {
 			use rand::{seq::SliceRandom, Rng};
-			let limit = (MAX_NOMINATIONS as usize).min(initial_authorities.len());
+			let limit = (MaxNominations::get() as usize).min(initial_authorities.len());
 			let count = rng.gen::<usize>() % limit;
 			let nominations = initial_authorities
 				.as_slice()

bin/node/runtime/src/lib.rs

@@ -541,7 +541,7 @@ impl pallet_staking::BenchmarkingConfig for StakingBenchmarkingConfig {
 }
 
 impl pallet_staking::Config for Runtime {
-	const MAX_NOMINATIONS: u32 = MAX_NOMINATIONS;
+	type MaxNominations = MaxNominations;
 	type Currency = Balances;
 	type UnixTime = Timestamp;
 	type CurrencyToVote = U128CurrencyToVote;
@@ -605,7 +605,9 @@ sp_npos_elections::generate_solution_type!(
 	>(16)
 );
 
-pub const MAX_NOMINATIONS: u32 = <NposSolution16 as sp_npos_elections::NposSolution>::LIMIT as u32;
+parameter_types! {
+	pub MaxNominations: u32 = <NposSolution16 as sp_npos_elections::NposSolution>::LIMIT as u32;
+}
 
 /// The numbers configured here could always be more than the the maximum limits of staking pallet
 /// to ensure election snapshot will not run out of memory. For now, we set them to smaller values
@@ -1792,7 +1794,7 @@ mod tests {
 	#[test]
 	fn perbill_as_onchain_accuracy() {
 		type OnChainAccuracy = <Runtime as onchain::Config>::Accuracy;
-		let maximum_chain_accuracy: Vec<UpperOf<OnChainAccuracy>> = (0..MAX_NOMINATIONS)
+		let maximum_chain_accuracy: Vec<UpperOf<OnChainAccuracy>> = (0..MaxNominations::get())
 			.map(|_| <UpperOf<OnChainAccuracy>>::from(OnChainAccuracy::one().deconstruct()))
 			.collect();
 		let _: UpperOf<OnChainAccuracy> =

frame/babe/src/mock.rs

@@ -178,7 +178,7 @@ impl onchain::Config for Test {
 }
 
 impl pallet_staking::Config for Test {
-	const MAX_NOMINATIONS: u32 = 16;
+	type MaxNominations = ConstU32<16>;
 	type RewardRemainder = ();
 	type CurrencyToVote = frame_support::traits::SaturatingCurrencyToVote;
 	type Event = Event;

frame/balances/src/lib.rs

@@ -488,8 +488,29 @@ pub mod pallet {
 	#[pallet::getter(fn total_issuance)]
 	pub type TotalIssuance<T: Config<I>, I: 'static = ()> = StorageValue<_, T::Balance, ValueQuery>;
 
-	/// The balance of an account.
+	/// The Balances pallet example of storing the balance of an account.
 	///
+	/// # Example
+	///
+	/// ```nocompile
+	///  impl pallet_balances::Config for Runtime {
+	///    type AccountStore = StorageMapShim<Self::Account<Runtime>, frame_system::Provider<Runtime>, AccountId, Self::AccountData<Balance>>
+	///  }
+	/// ```
+	///
+	/// You can also store the balance of an account in the `System` pallet.
+	///
+	/// # Example
+	///
+	/// ```nocompile
+	///  impl pallet_balances::Config for Runtime {
+	///   type AccountStore = System
+	///  }
+	/// ```
+	///
+	/// But this comes with tradeoffs, storing account balances in the system pallet stores
+	/// `frame_system` data alongside the account data contrary to storing account balances in the
+	/// `Balances` pallet, which uses a `StorageMap` to store balances data only.
 	/// NOTE: This is only used in the case that this pallet is used to store balances.
 	#[pallet::storage]
 	pub type Account<T: Config<I>, I: 'static = ()> = StorageMap<