Bound Unsigned when signed is not supported. (#6367)

* bound unsigned when necessary

* convert more type to AtLeast32BitUnsigned

* Update primitives/arithmetic/src/traits.rs

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

* doc refactor

* line reorganize

Co-authored-by: Kian Paimani <5588131+kianenigma@users.noreply.github.com>

substrate/frame/staking/src/inflation.rs

@@ -20,7 +20,7 @@
 //! 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::AtLeast32Bit, curve::PiecewiseLinear};
+use sp_runtime::{Perbill, traits::AtLeast32BitUnsigned, curve::PiecewiseLinear};
 
 /// The total payout to all validators (and their nominators) per era and maximum payout.
 ///
@@ -34,7 +34,7 @@ pub fn compute_total_payout<N>(
 	npos_token_staked: N,
 	total_tokens: N,
 	era_duration: u64
-) -> (N, N) where N: AtLeast32Bit + Clone {
+) -> (N, N) where N: AtLeast32BitUnsigned + 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

@@ -306,8 +306,8 @@ use sp_runtime::{
 	Percent, Perbill, PerU16, PerThing, RuntimeDebug, DispatchError,
 	curve::PiecewiseLinear,
 	traits::{
-		Convert, Zero, StaticLookup, CheckedSub, Saturating, SaturatedConversion, AtLeast32Bit,
-		Dispatchable,
+		Convert, Zero, StaticLookup, CheckedSub, Saturating, SaturatedConversion,
+		AtLeast32BitUnsigned, Dispatchable,
 	},
 	transaction_validity::{
 		TransactionValidityError, TransactionValidity, ValidTransaction, InvalidTransaction,
@@ -493,7 +493,7 @@ pub struct StakingLedger<AccountId, Balance: HasCompact> {
 
 impl<
 	AccountId,
-	Balance: HasCompact + Copy + Saturating + AtLeast32Bit,
+	Balance: HasCompact + Copy + Saturating + AtLeast32BitUnsigned,
 > StakingLedger<AccountId, Balance> {
 	/// Remove entries from `unlocking` that are sufficiently old and reduce the
 	/// total by the sum of their balances.
@@ -544,7 +544,7 @@ impl<
 }
 
 impl<AccountId, Balance> StakingLedger<AccountId, Balance> where
-	Balance: AtLeast32Bit + Saturating + Copy,
+	Balance: AtLeast32BitUnsigned + 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`