removes TryIntoBoundedSupports trait and impl coversion directly in S…

…upportedBounds

substrate/frame/election-provider-multi-phase/src/lib.rs

@@ -248,7 +248,7 @@ use codec::{Decode, Encode};
 use frame_election_provider_support::{
 	bounds::{CountBound, ElectionBounds, ElectionBoundsBuilder, SizeBound},
 	BoundedSupports, BoundedSupportsOf, DataProviderBounds, ElectionDataProvider, ElectionProvider,
-	InstantElectionProvider, NposSolution, PageIndex, TryIntoBoundedSupports,
+	InstantElectionProvider, NposSolution, PageIndex,
 };
 use frame_support::{
 	dispatch::DispatchClass,
@@ -1007,7 +1007,7 @@ pub mod pallet {
 
 			// bound supports with T::MaxWinners.
 			let supports: BoundedSupportsOf<Pallet<T>> =
-				supports.try_into_bounded_supports().map_err(|_| Error::<T>::TooManyWinners)?;
+				supports.try_into().map_err(|_| Error::<T>::TooManyWinners)?;
 
 			// Note: we don't `rotate_round` at this point; the next call to
 			// `ElectionProvider::elect` will succeed and take care of that.
@@ -2534,7 +2534,7 @@ mod tests {
 				(30, Support { total: 40, voters: vec![(2, 5), (4, 5), (30, 30)] }),
 				(40, Support { total: 60, voters: vec![(2, 5), (3, 10), (4, 5), (40, 40)] }),
 			]
-			.try_into_bounded_supports()
+			.try_into()
 			.unwrap();
 
 			assert_eq!(supports, expected_supports);

substrate/frame/election-provider-multi-phase/src/unsigned.rs

@@ -24,9 +24,7 @@ use crate::{
 };
 use alloc::{boxed::Box, vec::Vec};
 use codec::Encode;
-use frame_election_provider_support::{
-	NposSolution, NposSolver, PerThing128, TryIntoBoundedSupports, VoteWeight,
-};
+use frame_election_provider_support::{NposSolution, NposSolver, PerThing128, VoteWeight};
 use frame_support::{
 	dispatch::DispatchResult,
 	ensure,
@@ -823,7 +821,7 @@ impl<T: MinerConfig> Miner<T> {
 
 		// Size of winners in miner solution is equal to `desired_targets` <= `MaxWinners`.
 		let supports = supports
-			.try_into_bounded_supports()
+			.try_into()
 			.defensive_map_err(|_| FeasibilityError::BoundedConversionFailed)?;
 
 		Ok(ReadySolution { supports, compute, score })

substrate/frame/election-provider-support/src/lib.rs

@@ -849,33 +849,30 @@ impl<AccountId, BOuter: Get<u32>, BInner: Get<u32>> IntoIterator
 	}
 }
 
-/// An extension trait to convert from [`sp_npos_elections::Supports<AccountId>`] into
-/// [`BoundedSupports`].
-pub trait TryIntoBoundedSupports<AccountId, BOuter: Get<u32>, BInner: Get<u32>> {
-	/// Perform the conversion.
-	fn try_into_bounded_supports(self) -> Result<BoundedSupports<AccountId, BOuter, BInner>, ()>;
-}
-
-impl<AccountId, BOuter: Get<u32>, BInner: Get<u32>>
-	TryIntoBoundedSupports<AccountId, BOuter, BInner> for sp_npos_elections::Supports<AccountId>
+impl<AccountId, BOuter: Get<u32>, BInner: Get<u32>> TryFrom<sp_npos_elections::Supports<AccountId>>
+	for BoundedSupports<AccountId, BOuter, BInner>
 {
-	fn try_into_bounded_supports(self) -> Result<BoundedSupports<AccountId, BOuter, BInner>, ()> {
+	type Error = crate::Error;
+
+	fn try_from(supports: sp_npos_elections::Supports<AccountId>) -> Result<Self, Self::Error> {
 		// optimization note: pre-allocate outer bounded vec.
 		let mut outer_bounded_supports = BoundedVec::<
 			(AccountId, BoundedSupport<AccountId, BInner>),
 			BOuter,
 		>::with_bounded_capacity(
-			self.len().min(BOuter::get() as usize)
+			supports.len().min(BOuter::get() as usize)
 		);
 
 		// optimization note: avoid intermediate allocations.
-		self.into_iter()
+		supports
+			.into_iter()
 			.map(|(account, support)| (account, support.try_into().map_err(|_| ())))
 			.try_for_each(|(account, maybe_bounded_supports)| {
 				outer_bounded_supports
 					.try_push((account, maybe_bounded_supports?))
 					.map_err(|_| ())
-			})?;
+			})
+			.map_err(|_| crate::Error::BoundsExceeded)?;
 
 		Ok(outer_bounded_supports.into())
 	}

substrate/frame/election-provider-support/src/onchain.rs

@@ -22,7 +22,7 @@
 use crate::{
 	bounds::{DataProviderBounds, ElectionBounds, ElectionBoundsBuilder},
 	BoundedSupportsOf, Debug, ElectionDataProvider, ElectionProvider, InstantElectionProvider,
-	NposSolver, PageIndex, TryIntoBoundedSupports, WeightInfo, Zero,
+	NposSolver, PageIndex, WeightInfo, Zero,
 };
 use alloc::collections::btree_map::BTreeMap;
 use core::marker::PhantomData;
@@ -147,9 +147,8 @@ impl<T: Config> OnChainExecution<T> {
 
 		// defensive: Since npos solver returns a result always bounded by `desired_targets`, this
 		// is never expected to happen as long as npos solver does what is expected for it to do.
-		let supports: BoundedSupportsOf<Self> = to_supports(&staked)
-			.try_into_bounded_supports()
-			.map_err(|_| Error::TooManyWinners)?;
+		let supports: BoundedSupportsOf<Self> =
+			to_supports(&staked).try_into().map_err(|_| Error::TooManyWinners)?;
 
 		Ok(supports)
 	}
@@ -321,7 +320,7 @@ mod tests {
 				),
 				(30, Support { total: 35, voters: vec![(2, 20), (3, 15)] }),
 			]
-			.try_into_bounded_supports()
+			.try_into()
 			.unwrap();
 
 			assert_eq!(
@@ -357,7 +356,7 @@ mod tests {
 					),
 					(30, Support { total: 35, voters: vec![(2, 20), (3, 15)] })
 				]
-				.try_into_bounded_supports()
+				.try_into()
 				.unwrap()
 			);
 		})

substrate/frame/staking/src/mock.rs

@@ -21,7 +21,7 @@ use crate::{self as pallet_staking, *};
 use frame_election_provider_support::{
 	bounds::{ElectionBounds, ElectionBoundsBuilder},
 	onchain, BoundedSupports, BoundedSupportsOf, ElectionProvider, PageIndex, SequentialPhragmen,
-	Support, TryIntoBoundedSupports, VoteWeight,
+	Support, VoteWeight,
 };
 use frame_support::{
 	assert_ok, derive_impl, ord_parameter_types, parameter_types,
@@ -1023,5 +1023,5 @@ pub(crate) fn to_bounded_supports(
 	<<Test as Config>::ElectionProvider as ElectionProvider>::MaxWinnersPerPage,
 	<<Test as Config>::ElectionProvider as ElectionProvider>::MaxBackersPerWinner,
 > {
-	supports.try_into_bounded_supports().unwrap()
+	supports.try_into().unwrap()
 }

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

@@ -127,6 +127,8 @@ pub enum Error {
 	InvalidSupportEdge,
 	/// The number of voters is bigger than the `MaxVoters` bound.
 	TooManyVoters,
+	/// Some bounds were exceeded when converting election types.
+	BoundsExceeded,
 }
 
 /// A type which is used in the API of this crate as a numeric weight of a vote, most often the