Attempt to remove the where bounds in arithmetic. (#7933)

* Attempt to remove the where bounds.

* Fix further and further.

* Format better.

* Update primitives/npos-elections/src/lib.rs

* fix build

* remove unused

substrate/primitives/npos-elections/benches/phragmen.rs

@@ -65,7 +65,6 @@ mod bench_closure_and_slice {
 	) -> Vec<StakedAssignment<A>>
 	where
 		T: sp_std::ops::Mul<ExtendedBalance, Output = ExtendedBalance>,
-		ExtendedBalance: From<<T as PerThing>::Inner>,
 	{
 		ratio
 			.into_iter()

substrate/primitives/npos-elections/src/helpers.rs

@@ -17,11 +17,8 @@
 
 //! Helper methods for npos-elections.
 
-use crate::{
-	Assignment, Error, ExtendedBalance, IdentifierT, PerThing128, StakedAssignment, VoteWeight,
-	WithApprovalOf,
-};
-use sp_arithmetic::{InnerOf, PerThing};
+use crate::{Assignment, Error, IdentifierT, PerThing128, StakedAssignment, VoteWeight, WithApprovalOf};
+use sp_arithmetic::PerThing;
 use sp_std::prelude::*;
 
 /// Converts a vector of ratio assignments into ones with absolute budget value.
@@ -33,7 +30,6 @@ pub fn assignment_ratio_to_staked<A: IdentifierT, P: PerThing128, FS>(
 ) -> Vec<StakedAssignment<A>>
 where
 	for<'r> FS: Fn(&'r A) -> VoteWeight,
-	ExtendedBalance: From<InnerOf<P>>,
 {
 	ratios
 		.into_iter()
@@ -51,7 +47,6 @@ pub fn assignment_ratio_to_staked_normalized<A: IdentifierT, P: PerThing128, FS>
 ) -> Result<Vec<StakedAssignment<A>>, Error>
 where
 	for<'r> FS: Fn(&'r A) -> VoteWeight,
-	ExtendedBalance: From<InnerOf<P>>,
 {
 	let mut staked = assignment_ratio_to_staked(ratio, &stake_of);
 	staked
@@ -68,24 +63,19 @@ where
 /// Note that this will NOT attempt at normalizing the result.
 pub fn assignment_staked_to_ratio<A: IdentifierT, P: PerThing>(
 	staked: Vec<StakedAssignment<A>>,
-) -> Vec<Assignment<A, P>>
-where
-	ExtendedBalance: From<InnerOf<P>>,
-{
+) -> Vec<Assignment<A, P>> {
 	staked.into_iter().map(|a| a.into_assignment()).collect()
 }
 
 /// Same as [`assignment_staked_to_ratio`] and try and do normalization.
 pub fn assignment_staked_to_ratio_normalized<A: IdentifierT, P: PerThing128>(
 	staked: Vec<StakedAssignment<A>>,
-) -> Result<Vec<Assignment<A, P>>, Error>
-where
-	ExtendedBalance: From<InnerOf<P>>,
-{
+) -> Result<Vec<Assignment<A, P>>, Error> {
 	let mut ratio = staked.into_iter().map(|a| a.into_assignment()).collect::<Vec<_>>();
-	ratio.iter_mut().map(|a|
-		a.try_normalize().map_err(|err| Error::ArithmeticError(err))
-	).collect::<Result<_, _>>()?;
+	ratio
+		.iter_mut()
+		.map(|a| a.try_normalize().map_err(|err| Error::ArithmeticError(err)))
+		.collect::<Result<_, _>>()?;
 	Ok(ratio)
 }
 

substrate/primitives/npos-elections/src/lib.rs

@@ -75,7 +75,7 @@
 
 use sp_arithmetic::{
 	traits::{Bounded, UniqueSaturatedInto, Zero},
-	InnerOf, Normalizable, PerThing, Rational128, ThresholdOrd,
+	Normalizable, PerThing, Rational128, ThresholdOrd,
 };
 use sp_std::{
 	cell::RefCell,
@@ -209,7 +209,6 @@ pub trait CompactSolution: Sized {
 	where
 		for<'r> FS: Fn(&'r A) -> VoteWeight,
 		A: IdentifierT,
-		ExtendedBalance: From<InnerOf<Self::Accuracy>>,
 	{
 		let ratio = self.into_assignment(voter_at, target_at)?;
 		let staked = helpers::assignment_ratio_to_staked_normalized(ratio, stake_of)?;
@@ -332,14 +331,14 @@ impl<AccountId: IdentifierT> Voter<AccountId> {
 	/// Note that this might create _un-normalized_ assignments, due to accuracy loss of `P`. Call
 	/// site might compensate by calling `normalize()` on the returned `Assignment` as a
 	/// post-precessing.
-	pub fn into_assignment<P: PerThing>(self) -> Option<Assignment<AccountId, P>>
-	where
-		ExtendedBalance: From<InnerOf<P>>,
-	{
+	pub fn into_assignment<P: PerThing>(self) -> Option<Assignment<AccountId, P>> {
 		let who = self.who;
 		let budget = self.budget;
-		let distribution = self.edges.into_iter().filter_map(|e| {
-			let per_thing = P::from_rational_approximation(e.weight, budget);
+		let distribution = self
+			.edges
+			.into_iter()
+			.filter_map(|e| {
+				let per_thing = P::from_rational_approximation(e.weight, budget);
 			// trim zero edges.
 			if per_thing.is_zero() { None } else { Some((e.who, per_thing)) }
 		}).collect::<Vec<_>>();
@@ -507,7 +506,6 @@ impl<AccountId> StakedAssignment<AccountId> {
 	/// can never be re-created and does not mean anything useful anymore.
 	pub fn into_assignment<P: PerThing>(self) -> Assignment<AccountId, P>
 	where
-		ExtendedBalance: From<InnerOf<P>>,
 		AccountId: IdentifierT,
 	{
 		let stake = self.total();
@@ -706,10 +704,7 @@ where
 /// greater or less than `that`.
 ///
 /// Note that the third component should be minimized.
-pub fn is_score_better<P: PerThing>(this: ElectionScore, that: ElectionScore, epsilon: P) -> bool
-where
-	ExtendedBalance: From<InnerOf<P>>,
-{
+pub fn is_score_better<P: PerThing>(this: ElectionScore, that: ElectionScore, epsilon: P) -> bool {
 	match this
 		.iter()
 		.zip(that.iter())

substrate/primitives/npos-elections/src/mock.rs

@@ -22,7 +22,7 @@
 use crate::*;
 use sp_arithmetic::{
 	traits::{One, SaturatedConversion, Zero},
-	InnerOf, PerThing,
+	PerThing,
 };
 use sp_runtime::assert_eq_error_rate;
 use sp_std::collections::btree_map::BTreeMap;
@@ -321,9 +321,7 @@ pub(crate) fn run_and_compare<Output: PerThing128>(
 	voters: Vec<(AccountId, Vec<AccountId>)>,
 	stake_of: &Box<dyn Fn(&AccountId) -> VoteWeight>,
 	to_elect: usize,
-) where
-	ExtendedBalance: From<InnerOf<Output>>,
-{
+) {
 	// run fixed point code.
 	let ElectionResult { winners, assignments } = seq_phragmen::<_, Output>(
 		to_elect,

substrate/primitives/npos-elections/src/phragmen.rs

@@ -27,7 +27,7 @@ use crate::{
 use sp_arithmetic::{
 	helpers_128bit::multiply_by_rational,
 	traits::{Bounded, Zero},
-	InnerOf, Rational128,
+	Rational128,
 };
 use sp_std::prelude::*;
 
@@ -68,10 +68,7 @@ pub fn seq_phragmen<AccountId: IdentifierT, P: PerThing128>(
 	initial_candidates: Vec<AccountId>,
 	initial_voters: Vec<(AccountId, VoteWeight, Vec<AccountId>)>,
 	balance: Option<(usize, ExtendedBalance)>,
-) -> Result<ElectionResult<AccountId, P>, crate::Error>
-where
-	ExtendedBalance: From<InnerOf<P>>,
-{
+) -> Result<ElectionResult<AccountId, P>, crate::Error> {
 	let (candidates, voters) = setup_inputs(initial_candidates, initial_voters);
 
 	let (candidates, mut voters) = seq_phragmen_core::<AccountId>(

substrate/primitives/npos-elections/src/phragmms.rs

@@ -25,7 +25,7 @@ use crate::{
 	IdentifierT, ElectionResult, ExtendedBalance, setup_inputs, VoteWeight, Voter, CandidatePtr,
 	balance, PerThing128,
 };
-use sp_arithmetic::{PerThing, InnerOf, Rational128, traits::Bounded};
+use sp_arithmetic::{PerThing, Rational128, traits::Bounded};
 use sp_std::{prelude::*, rc::Rc};
 
 /// Execute the phragmms method.
@@ -46,10 +46,7 @@ pub fn phragmms<AccountId: IdentifierT, P: PerThing128>(
 	initial_candidates: Vec<AccountId>,
 	initial_voters: Vec<(AccountId, VoteWeight, Vec<AccountId>)>,
 	balancing_config: Option<(usize, ExtendedBalance)>,
-) -> Result<ElectionResult<AccountId, P>, &'static str>
-where
-	ExtendedBalance: From<InnerOf<P>>,
-{
+) -> Result<ElectionResult<AccountId, P>, &'static str> {
 	let (candidates, mut voters) = setup_inputs(initial_candidates, initial_voters);
 
 	let mut winners = vec![];
@@ -89,7 +86,7 @@ where
 pub(crate) fn calculate_max_score<AccountId: IdentifierT, P: PerThing>(
 	candidates: &[CandidatePtr<AccountId>],
 	voters: &[Voter<AccountId>],
-) -> Option<CandidatePtr<AccountId>> where ExtendedBalance: From<InnerOf<P>> {
+) -> Option<CandidatePtr<AccountId>> {
 	for c_ptr in candidates.iter() {
 		let mut candidate = c_ptr.borrow_mut();
 		if !candidate.elected {