[stable2512] Backport #11154 (#11280)

Backport #11154 into `stable2512` from laurogripa.

See the
[documentation](https://github.com/paritytech/polkadot-sdk/blob/master/docs/BACKPORT.md)
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---------

Co-authored-by: Lauro Gripa <laurogripa@gmail.com>
Co-authored-by: cmd[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Bastian Köcher <git@kchr.de>
Co-authored-by: Paolo La Camera <paolo@parity.io>

Author: 5 people

prdoc/pr_11154.prdoc

@@ -0,0 +1,9 @@
+title: Add kick_member to Society pallet
+doc:
+- audience: Runtime Dev
+  description: Adds a kick_member extrinsic to pallet-society, callable by the Founder,
+    that removes a member, slashes its payouts and returns them to the society pot.
+crates:
+- name: pallet-society
+  bump: minor
+  validate: false

substrate/frame/society/src/benchmarking.rs

@@ -558,6 +558,43 @@ mod benchmarks {
 		Ok(())
 	}
 
+	#[benchmark]
+	fn kick_member() -> Result<(), BenchmarkError> {
+		// Add member
+		let founder = setup_funded_society::<T, I>()?;
+		let member: T::AccountId = account("member", 0, 0);
+		let member_lookup: <T::Lookup as StaticLookup>::Source =
+			T::Lookup::unlookup(member.clone());
+
+		let _ = Society::<T, I>::insert_member(&member, 0u32.into());
+		let mut record = Members::<T, I>::get(&member).ok_or("Member not found")?;
+		record.vouching = Some(VouchingStatus::Vouching);
+		Members::<T, I>::insert(&member, &record);
+
+		// Populate payouts to max to cover worst-case slashing scenario
+		for i in 0..T::MaxPayouts::get() {
+			Society::<T, I>::bump_payout(&member, i.into(), 1u32.into());
+		}
+
+		// Add vouch to cover worst-case scenario
+		let vouched: T::AccountId = account("vouched", 0, 0);
+		let mut bids = Bids::<T, I>::get();
+		Society::<T, I>::insert_bid(
+			&mut bids,
+			&vouched,
+			10u32.into(),
+			BidKind::Vouch(member.clone(), 0u32.into()),
+		);
+		Bids::<T, I>::put(bids);
+
+		#[extrinsic_call]
+		_(RawOrigin::Signed(founder), member_lookup);
+
+		assert!(!Members::<T, I>::contains_key(&member));
+		assert!(!SuspendedMembers::<T, I>::contains_key(&member));
+		Ok(())
+	}
+
 	impl_benchmark_test_suite!(
 		Society,
 		sp_io::TestExternalities::from(

substrate/frame/society/src/lib.rs

@@ -671,6 +671,8 @@ pub mod pallet {
 			old_deposit: BalanceOf<T, I>,
 			new_deposit: BalanceOf<T, I>,
 		},
+		/// A member was kicked by the founder.
+		MemberKicked { member: T::AccountId },
 	}
 
 	/// Old name generated by `decl_event`.
@@ -1461,6 +1463,35 @@ pub mod pallet {
 
 			Ok(Pays::No.into())
 		}
+
+		/// Kick a member from the society. Callable only by the Signed origin of the Founder.
+		///
+		/// The member is fully removed (not suspended). All unclaimed payouts are slashed and
+		/// returned to the society pot.
+		///
+		/// Parameters:
+		/// - `who`: The member to be removed.
+		#[pallet::call_index(21)]
+		#[pallet::weight(T::WeightInfo::kick_member())]
+		pub fn kick_member(origin: OriginFor<T>, who: AccountIdLookupOf<T>) -> DispatchResult {
+			ensure!(
+				Some(ensure_signed(origin)?) == Founder::<T, I>::get(),
+				Error::<T, I>::NotFounder
+			);
+			let who = T::Lookup::lookup(who)?;
+
+			let _ = Self::remove_member(&who)?;
+
+			let payout_record = Payouts::<T, I>::take(&who);
+			let total = payout_record
+				.payouts
+				.into_iter()
+				.fold(Zero::zero(), |acc: BalanceOf<T, I>, x| acc.saturating_add(x.1));
+			Self::unreserve_payout(total);
+
+			Self::deposit_event(Event::<T, I>::MemberKicked { member: who });
+			Ok(())
+		}
 	}
 }
 

substrate/frame/society/src/tests.rs

@@ -1660,3 +1660,70 @@ fn intake_idempotency() {
 		assert_eq!(Balances::free_balance(20), 50);
 	});
 }
+
+#[test]
+fn kick_member_works() {
+	EnvBuilder::new().execute(|| {
+		// Given: 20 is a regular member.
+		place_members([20]);
+		assert!(Members::<Test>::contains_key(20));
+
+		// When: a non-founder tries to kick → fails.
+		assert_noop!(Society::kick_member(Origin::signed(20), 20), Error::<Test>::NotFounder);
+
+		// When: founder kicks member 20.
+		assert_ok!(Society::kick_member(Origin::signed(10), 20));
+
+		// Then: member is fully removed, not suspended.
+		assert!(!Members::<Test>::contains_key(20));
+		assert!(!SuspendedMembers::<Test>::contains_key(20));
+
+		// Then: event is emitted.
+		System::assert_has_event(Event::<Test>::MemberKicked { member: 20 }.into());
+
+		// Then: kicking again fails — not a member anymore.
+		assert_noop!(Society::kick_member(Origin::signed(10), 20), Error::<Test>::NotMember);
+	});
+}
+
+#[test]
+fn kicked_member_cannot_claim_payout() {
+	EnvBuilder::new().execute(|| {
+		// Given: members 20 and 30 exist, and 30 has a pending payout of 100.
+		place_members([20, 30]);
+		// Simulate a reserved payout for member 30.
+		Society::bump_payout(&30, 1, 100);
+		let pot_after_reserve = Pot::<Test>::get();
+
+		// When: founder kicks member 30.
+		assert_ok!(Society::kick_member(Origin::signed(10), 30));
+
+		// Then: member is fully removed, not suspended.
+		assert!(!Members::<Test>::contains_key(30));
+		assert!(!SuspendedMembers::<Test>::contains_key(30));
+
+		// Then: payouts are cleared.
+		assert_eq!(
+			Payouts::<Test>::get(30),
+			PayoutRecord { paid: 0, payouts: vec![].try_into().unwrap() }
+		);
+
+		// Then: slashed amount (100) is returned to the pot.
+		assert_eq!(Pot::<Test>::get(), pot_after_reserve + 100);
+
+		// Then: kicked member cannot claim payout.
+		assert_noop!(Society::payout(Origin::signed(30)), Error::<Test>::NotMember);
+	});
+}
+
+#[test]
+fn founder_cannot_kick_head() {
+	EnvBuilder::new().execute(|| {
+		// Given: member 20 is the current Head.
+		place_members([20]);
+		Head::<Test>::put(20);
+
+		// When: founder tries to kick Head → fails.
+		assert_noop!(Society::kick_member(Origin::signed(10), 20), Error::<Test>::Head);
+	});
+}