Offences report system rework (#13425)

* Experiments with common equivocation trait

* Improved equivocation trait

* Fix grandpa equivocation implementation

* Remove some cruft

* Remove some more cruft

* More generic naming

* Simplification of offences manipilation

* More refactory

* Some prograss with the encapsulation of offence report system

* Finally unit type works as a universal null report system

* Align substrate node code

* Further simplification

* Fix test utils

* Remove not required associated type

* Fix benches

* Rollback to prev field name

* Box big params

* Fix typo

* Remove new tag computation

* Remove default implementations

* Better docs

* Return 'Result' instead of bool

* Change offence report system return types

* Some renaming and documentation

* Improve documentation

* More abstract offence report system

* Rename 'consume_evidence' to 'process_evidence'

* Further docs refinements

* Doc for dummy offence report

* Fix rustdoc

* Fix after master merge

* Apply code review suggestions

* Improve docs

substrate/frame/offences/src/lib.rs

@@ -112,10 +112,10 @@ pub mod pallet {
 	}
 }
 
-impl<T: Config, O: Offence<T::IdentificationTuple>>
-	ReportOffence<T::AccountId, T::IdentificationTuple, O> for Pallet<T>
+impl<T, O> ReportOffence<T::AccountId, T::IdentificationTuple, O> for Pallet<T>
 where
-	T::IdentificationTuple: Clone,
+	T: Config,
+	O: Offence<T::IdentificationTuple>,
 {
 	fn report_offence(reporters: Vec<T::AccountId>, offence: O) -> Result<(), OffenceError> {
 		let offenders = offence.offenders();

substrate/frame/offences/src/mock.rs

@@ -134,17 +134,17 @@ pub fn offence_reports(kind: Kind, time_slot: u128) -> Vec<OffenceDetails<u64, u
 }
 
 #[derive(Clone)]
-pub struct Offence<T> {
+pub struct Offence {
 	pub validator_set_count: u32,
-	pub offenders: Vec<T>,
+	pub offenders: Vec<u64>,
 	pub time_slot: u128,
 }
 
-impl<T: Clone> offence::Offence<T> for Offence<T> {
+impl offence::Offence<u64> for Offence {
 	const ID: offence::Kind = KIND;
 	type TimeSlot = u128;
 
-	fn offenders(&self) -> Vec<T> {
+	fn offenders(&self) -> Vec<u64> {
 		self.offenders.clone()
 	}
 
@@ -167,5 +167,5 @@ impl<T: Clone> offence::Offence<T> for Offence<T> {
 
 /// Create the report id for the given `offender` and `time_slot` combination.
 pub fn report_id(time_slot: u128, offender: u64) -> H256 {
-	Offences::report_id::<Offence<u64>>(&time_slot, &offender)
+	Offences::report_id::<Offence>(&time_slot, &offender)
 }

substrate/frame/offences/src/tests.rs

@@ -160,20 +160,18 @@ fn doesnt_deposit_event_for_dups() {
 
 #[test]
 fn reports_if_an_offence_is_dup() {
-	type TestOffence = Offence<u64>;
-
 	new_test_ext().execute_with(|| {
 		let time_slot = 42;
 		assert_eq!(offence_reports(KIND, time_slot), vec![]);
 
 		let offence =
-			|time_slot, offenders| TestOffence { validator_set_count: 5, time_slot, offenders };
+			|time_slot, offenders| Offence { validator_set_count: 5, time_slot, offenders };
 
 		let mut test_offence = offence(time_slot, vec![0]);
 
 		// the report for authority 0 at time slot 42 should not be a known
 		// offence
-		assert!(!<Offences as ReportOffence<_, _, TestOffence>>::is_known_offence(
+		assert!(!<Offences as ReportOffence<_, _, Offence>>::is_known_offence(
 			&test_offence.offenders,
 			&test_offence.time_slot
 		));
@@ -182,7 +180,7 @@ fn reports_if_an_offence_is_dup() {
 		Offences::report_offence(vec![], test_offence.clone()).unwrap();
 
 		// the same report should be a known offence now
-		assert!(<Offences as ReportOffence<_, _, TestOffence>>::is_known_offence(
+		assert!(<Offences as ReportOffence<_, _, Offence>>::is_known_offence(
 			&test_offence.offenders,
 			&test_offence.time_slot
 		));
@@ -197,7 +195,7 @@ fn reports_if_an_offence_is_dup() {
 		test_offence.offenders.push(1);
 
 		// it should not be a known offence anymore
-		assert!(!<Offences as ReportOffence<_, _, TestOffence>>::is_known_offence(
+		assert!(!<Offences as ReportOffence<_, _, Offence>>::is_known_offence(
 			&test_offence.offenders,
 			&test_offence.time_slot
 		));
@@ -208,7 +206,7 @@ fn reports_if_an_offence_is_dup() {
 		// creating a new offence for the same authorities on the next slot
 		// should be considered a new offence and thefore not known
 		let test_offence_next_slot = offence(time_slot + 1, vec![0, 1]);
-		assert!(!<Offences as ReportOffence<_, _, TestOffence>>::is_known_offence(
+		assert!(!<Offences as ReportOffence<_, _, Offence>>::is_known_offence(
 			&test_offence_next_slot.offenders,
 			&test_offence_next_slot.time_slot
 		));