check can_dec_provider when transfer allow death (#9411)

substrate/frame/balances/src/lib.rs

@@ -1484,7 +1484,7 @@ where
 						//   may not even be a provider.
 						let allow_death = existence_requirement == ExistenceRequirement::AllowDeath;
 						let allow_death =
-							allow_death && !system::Pallet::<T>::is_provider_required(transactor);
+							allow_death && system::Pallet::<T>::can_dec_provider(transactor);
 						ensure!(
 							allow_death || from_account.total() >= ed,
 							Error::<T, I>::KeepAlive

substrate/frame/balances/src/tests.rs

@@ -76,6 +76,30 @@ macro_rules! decl_tests {
 			});
 		}
 
+		#[test]
+		fn reap_failed_due_to_provider_and_consumer() {
+			<$ext_builder>::default().existential_deposit(1).monied(true).build().execute_with(|| {
+				// SCENARIO: only one provider and there are remaining consumers.
+				assert_ok!(System::inc_consumers(&1));
+				assert!(!System::can_dec_provider(&1));
+				assert_noop!(
+					<Balances as Currency<_>>::transfer(&1, &2, 10, AllowDeath),
+					Error::<$test, _>::KeepAlive
+				);
+				assert!(System::account_exists(&1));
+				assert_eq!(Balances::free_balance(1), 10);
+
+				// SCENARIO: more than one provider, but will not kill account due to other provider.
+				assert_eq!(System::inc_providers(&1), frame_system::IncRefStatus::Existed);
+				assert_eq!(System::providers(&1), 2);
+				assert!(System::can_dec_provider(&1));
+				assert_ok!(<Balances as Currency<_>>::transfer(&1, &2, 10, AllowDeath));
+				assert_eq!(System::providers(&1), 1);
+				assert!(System::account_exists(&1));
+				assert_eq!(Balances::free_balance(1), 0);
+			});
+		}
+
 		#[test]
 		fn partial_locking_should_work() {
 			<$ext_builder>::default().existential_deposit(1).monied(true).build().execute_with(|| {