Per-things trait. (#4904)

* Give perthigns the trait it always deserved.

* Make staking and phragmen work with the new generic per_thing

* Make everything work together 🔨

* a bit of cleanup

* Clean usage

* Bump.

* Fix name

* fix grumbles

* hopefully fix the ui test

* Some grumbles

* revamp traits again

* Better naming again.

substrate/frame/staking/src/inflation.rs

@@ -19,7 +19,7 @@
 //! The staking rate in NPoS is the total amount of tokens staked by nominators and validators,
 //! divided by the total token supply.
 
-use sp_runtime::{Perbill, traits::SimpleArithmetic, curve::PiecewiseLinear};
+use sp_runtime::{Perbill, PerThing, traits::AtLeast32Bit, curve::PiecewiseLinear};
 
 /// The total payout to all validators (and their nominators) per era.
 ///
@@ -32,7 +32,7 @@ pub fn compute_total_payout<N>(
 	npos_token_staked: N,
 	total_tokens: N,
 	era_duration: u64
-) -> (N, N) where N: SimpleArithmetic + Clone {
+) -> (N, N) where N: AtLeast32Bit + Clone {
 	// Milliseconds per year for the Julian year (365.25 days).
 	const MILLISECONDS_PER_YEAR: u64 = 1000 * 3600 * 24 * 36525 / 100;
 

substrate/frame/staking/src/lib.rs

@@ -267,12 +267,11 @@ use frame_support::{
 };
 use pallet_session::historical::SessionManager;
 use sp_runtime::{
-	Perbill,
-	RuntimeDebug,
+	Perbill, PerThing, RuntimeDebug,
 	curve::PiecewiseLinear,
 	traits::{
 		Convert, Zero, One, StaticLookup, CheckedSub, Saturating, Bounded, SaturatedConversion,
-		SimpleArithmetic, EnsureOrigin,
+		AtLeast32Bit, EnsureOrigin,
 	}
 };
 use sp_staking::{
@@ -396,7 +395,7 @@ pub struct StakingLedger<AccountId, Balance: HasCompact> {
 
 impl<
 	AccountId,
-	Balance: HasCompact + Copy + Saturating + SimpleArithmetic,
+	Balance: HasCompact + Copy + Saturating + AtLeast32Bit,
 > StakingLedger<AccountId, Balance> {
 	/// Remove entries from `unlocking` that are sufficiently old and reduce the
 	/// total by the sum of their balances.
@@ -440,7 +439,7 @@ impl<
 }
 
 impl<AccountId, Balance> StakingLedger<AccountId, Balance> where
-	Balance: SimpleArithmetic + Saturating + Copy,
+	Balance: AtLeast32Bit + Saturating + Copy,
 {
 	/// Slash the validator for a given amount of balance. This can grow the value
 	/// of the slash in the case that the validator has less than `minimum_balance`
@@ -1503,7 +1502,7 @@ impl<T: Trait> Module<T> {
 		});
 		all_nominators.extend(nominator_votes);
 
-		let maybe_phragmen_result = sp_phragmen::elect::<_, _, _, T::CurrencyToVote>(
+		let maybe_phragmen_result = sp_phragmen::elect::<_, _, _, T::CurrencyToVote, Perbill>(
 			Self::validator_count() as usize,
 			Self::minimum_validator_count().max(1) as usize,
 			all_validators,
@@ -1520,7 +1519,7 @@ impl<T: Trait> Module<T> {
 			let to_balance = |e: ExtendedBalance|
 				<T::CurrencyToVote as Convert<ExtendedBalance, BalanceOf<T>>>::convert(e);
 
-			let supports = sp_phragmen::build_support_map::<_, _, _, T::CurrencyToVote>(
+			let supports = sp_phragmen::build_support_map::<_, _, _, T::CurrencyToVote, Perbill>(
 				&elected_stashes,
 				&assignments,
 				Self::slashable_balance_of,

substrate/frame/staking/src/slashing.rs

@@ -52,7 +52,7 @@ use super::{
 	EraIndex, Trait, Module, Store, BalanceOf, Exposure, Perbill, SessionInterface,
 	NegativeImbalanceOf, UnappliedSlash,
 };
-use sp_runtime::traits::{Zero, Saturating};
+use sp_runtime::{traits::{Zero, Saturating}, PerThing};
 use frame_support::{
 	StorageMap, StorageDoubleMap,
 	traits::{Currency, OnUnbalanced, Imbalance},