Remove implicit approval chilling upon slash.

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

@@ -2174,6 +2174,8 @@ mod tests {
 			assert_eq!(MultiPhase::elect().unwrap_err(), ElectionError::Fallback("NoFallback."));
 			// phase is now emergency.
 			assert_eq!(MultiPhase::current_phase(), Phase::Emergency);
+			// snapshot is still there until election finalizes.
+			assert!(MultiPhase::snapshot().is_some());
 		})
 	}
 
@@ -2190,6 +2192,7 @@ mod tests {
 			// phase is now emergency.
 			assert_eq!(MultiPhase::current_phase(), Phase::Emergency);
 			assert!(MultiPhase::queued_solution().is_none());
+			assert!(MultiPhase::snapshot().is_some());
 
 			// no single account can trigger this
 			assert_noop!(

frame/staking/src/benchmarking.rs

@@ -791,12 +791,10 @@ benchmarks! {
 	}
 
 	get_npos_voters {
-		// number of validator intention.
-		let v in (MaxValidators::<T>::get() / 2) .. MaxValidators::<T>::get();
-		// number of nominator intention.
-		let n in (MaxNominators::<T>::get() / 2) .. MaxNominators::<T>::get();
-		// total number of slashing spans. Assigned to validators randomly.
-		let s in 1 .. 20;
+		// number of validator intention. we will iterate all of them.
+		let v in (MaxValidators::<T>::get() / 4) .. MaxValidators::<T>::get();
+		// number of nominator intention. we will iterate all of them.
+		let n in (MaxNominators::<T>::get() / 4) .. MaxNominators::<T>::get();
 
 		let validators = create_validators_with_nominators_for_era::<T>(
 			v, n, T::MaxNominations::get() as usize, false, None
@@ -805,9 +803,8 @@ benchmarks! {
 		.map(|v| T::Lookup::lookup(v).unwrap())
 		.collect::<Vec<_>>();
 
-		(0..s).for_each(|index| {
-			add_slashing_spans::<T>(&validators[index as usize], 10);
-		});
+		assert_eq!(Validators::<T>::count(), v);
+		assert_eq!(Nominators::<T>::count(), n);
 
 		let num_voters = (v + n) as usize;
 	}: {

frame/staking/src/pallet/impls.rs

@@ -40,7 +40,7 @@ use sp_staking::{
 	offence::{DisableStrategy, OffenceDetails, OnOffenceHandler},
 	EraIndex, SessionIndex, StakingInterface,
 };
-use sp_std::{collections::btree_map::BTreeMap, prelude::*};
+use sp_std::prelude::*;
 
 use crate::{
 	log, slashing, weights::WeightInfo, ActiveEraInfo, BalanceOf, EraPayout, Exposure, ExposureOf,
@@ -348,6 +348,7 @@ impl<T: Config> Pallet<T> {
 		}
 	}
 
+	/// Start a new era. It does:
 	///
 	/// * Increment `active_era.index`,
 	/// * reset `active_era.start`,
@@ -696,7 +697,6 @@ impl<T: Config> Pallet<T> {
 
 		// cache a few things.
 		let weight_of = Self::weight_of_fn();
-		let slashing_spans = <SlashingSpans<T>>::iter().collect::<BTreeMap<_, _>>();
 
 		let mut voters_seen = 0u32;
 		let mut validators_taken = 0u32;
@@ -714,18 +714,12 @@ impl<T: Config> Pallet<T> {
 				None => break,
 			};
 
-			if let Some(Nominations { submitted_in, mut targets, suppressed: _ }) =
-				<Nominators<T>>::get(&voter)
-			{
-				// if this voter is a nominator:
-				targets.retain(|stash| {
-					slashing_spans
-						.get(stash)
-						.map_or(true, |spans| submitted_in >= spans.last_nonzero_slash())
-				});
-				if !targets.len().is_zero() {
+			if let Some(Nominations { targets, .. }) = <Nominators<T>>::get(&voter) {
+				if !targets.is_empty() {
 					all_voters.push((voter.clone(), weight_of(&voter), targets));
 					nominators_taken.saturating_inc();
+				} else {
+					// A nominator's nominations might become empty due to slashing.
 				}
 			} else if Validators::<T>::contains_key(&voter) {
 				// if this voter is a validator:
@@ -748,7 +742,7 @@ impl<T: Config> Pallet<T> {
 					warn,
 					"DEFENSIVE: invalid item in `VoterList`: {:?}, this nominator probably has too many nominations now",
 					voter
-				)
+				);
 			}
 		}
 
@@ -758,7 +752,7 @@ impl<T: Config> Pallet<T> {
 		Self::register_weight(T::WeightInfo::get_npos_voters(
 			validators_taken,
 			nominators_taken,
-			slashing_spans.len() as u32,
+			0,
 		));
 
 		log!(
@@ -1262,6 +1256,12 @@ where
 				disable_strategy,
 			});
 
+			Self::deposit_event(Event::<T>::SlashReported {
+				validator: stash.clone(),
+				fraction: slash_fraction.clone(),
+				slash_era,
+			});
+
 			if let Some(mut unapplied) = unapplied {
 				let nominators_len = unapplied.others.len() as u64;
 				let reporters_len = details.reporters.len() as u64;

frame/staking/src/pallet/mod.rs

@@ -515,7 +515,7 @@ pub mod pallet {
 	#[pallet::storage]
 	#[pallet::getter(fn slashing_spans)]
 	#[pallet::unbounded]
-	pub(crate) type SlashingSpans<T: Config> =
+	pub type SlashingSpans<T: Config> =
 		StorageMap<_, Twox64Concat, T::AccountId, slashing::SlashingSpans>;
 
 	/// Records information about the maximum slash of a stash within a slashing span,
@@ -545,6 +545,7 @@ pub mod pallet {
 	/// `OffendingValidatorsThreshold` is reached. The vec is always kept sorted so that we can find
 	/// whether a given validator has previously offended using binary search. It gets cleared when
 	/// the era ends.
+	// TODO: invariant test for the above.
 	#[pallet::storage]
 	#[pallet::unbounded]
 	#[pallet::getter(fn offending_validators)]
@@ -665,8 +666,11 @@ pub mod pallet {
 		EraPaid { era_index: EraIndex, validator_payout: BalanceOf<T>, remainder: BalanceOf<T> },
 		/// The nominator has been rewarded by this amount.
 		Rewarded { stash: T::AccountId, amount: BalanceOf<T> },
-		/// One staker (and potentially its nominators) has been slashed by the given amount.
+		/// A staker (validator or nominator) has been slashed by the given amount.
 		Slashed { staker: T::AccountId, amount: BalanceOf<T> },
+		/// A slash for the given validator, for the given percentage of their stake, at the given
+		/// era as been reporter
+		SlashReported { validator: T::AccountId, fraction: Perbill, slash_era: EraIndex },
 		/// An old slashing report from a prior era was discarded because it could
 		/// not be processed.
 		OldSlashingReportDiscarded { session_index: SessionIndex },