Allow sub-rent-exempt-minimum transfers to 1nc1nerator (#23382)

* Add failing test

* Allow small burns to incinerator

* Use check_id method

(cherry picked from commit 19448ba)

# Conflicts:
#	runtime/src/account_rent_state.rs

runtime/src/account_rent_state.rs

@@ -55,11 +55,45 @@ pub(crate) fn check_rent_state(
     account: &AccountSharedData,
 ) -> Result<()> {
     if let Some((pre_rent_state, post_rent_state)) = pre_rent_state.zip(post_rent_state) {
+<<<<<<< HEAD
         submit_rent_state_metrics(pre_rent_state, post_rent_state);
         if !post_rent_state.transition_allowed_from(pre_rent_state) {
             debug!("Account {:?} not rent exempt, state {:?}", address, account);
             return Err(TransactionError::InvalidRentPayingAccount);
         }
+=======
+        let expect_msg = "account must exist at TransactionContext index if rent-states are Some";
+        check_rent_state_with_account(
+            pre_rent_state,
+            post_rent_state,
+            transaction_context
+                .get_key_of_account_at_index(index)
+                .expect(expect_msg),
+            &transaction_context
+                .get_account_at_index(index)
+                .expect(expect_msg)
+                .borrow(),
+        )?;
+    }
+    Ok(())
+}
+
+pub(crate) fn check_rent_state_with_account(
+    pre_rent_state: &RentState,
+    post_rent_state: &RentState,
+    address: &Pubkey,
+    account_state: &AccountSharedData,
+) -> Result<()> {
+    submit_rent_state_metrics(pre_rent_state, post_rent_state);
+    if !solana_sdk::incinerator::check_id(address)
+        && !post_rent_state.transition_allowed_from(pre_rent_state)
+    {
+        debug!(
+            "Account {} not rent exempt, state {:?}",
+            address, account_state,
+        );
+        return Err(TransactionError::InvalidRentPayingAccount);
+>>>>>>> 19448ba07 (Allow sub-rent-exempt-minimum transfers to `1nc1nerator` (#23382))
     }
     Ok(())
 }

runtime/src/bank.rs

@@ -17030,6 +17030,28 @@ pub(crate) mod tests {
         ));
     }
 
+    // Ensure System transfers of any size can be made to the incinerator
+    #[test]
+    fn test_rent_state_incinerator() {
+        let GenesisConfigInfo {
+            mut genesis_config,
+            mint_keypair,
+            ..
+        } = create_genesis_config_with_leader(sol_to_lamports(100.), &Pubkey::new_unique(), 42);
+        genesis_config.rent = Rent::default();
+        let rent_exempt_minimum = genesis_config.rent.minimum_balance(0);
+
+        // Activate features, including require_rent_exempt_accounts
+        activate_all_features(&mut genesis_config);
+
+        let bank = Bank::new_for_tests(&genesis_config);
+
+        for amount in [rent_exempt_minimum - 1, rent_exempt_minimum] {
+            bank.transfer(amount, &mint_keypair, &solana_sdk::incinerator::id())
+                .unwrap();
+        }
+    }
+
     #[test]
     fn test_rent_state_list_len() {
         let GenesisConfigInfo {