better coinbase diff calc (#836)

* better coinbase diff calc

* lint

crates/evm/src/evm/handler.rs

@@ -381,6 +381,7 @@ fn calc_diff_size<EXT, DB: Database>(
     let InnerEvmContext {
         db,
         journaled_state,
+        env,
         ..
     } = &mut context.evm.inner;
 
@@ -449,6 +450,13 @@ fn calc_diff_size<EXT, DB: Database>(
     let slot_size = 2 * size_of::<U256>(); // key + value;
     let mut diff_size = 0usize;
 
+    // no matter the type of transaction or its fee rates, a tx must pay at least base fee and L1 fee
+    // thus we increment the diff size by 20 (coinbase address) + 32 (coinbase balance change)
+    // notice, we don't add to diff size when an address explicitly sends funds to coinbase
+    if !account_changes.contains_key(&env.block.coinbase) {
+        diff_size += size_of::<Address>() + size_of::<U256>();
+    }
+
     for (addr, account) in account_changes {
         // Apply size of address of changed account
         diff_size += size_of::<Address>();
@@ -500,27 +508,6 @@ fn calc_diff_size<EXT, DB: Database>(
         }
     }
 
-    // The diff size of balance change originating from priority fee is not included if priority fee is zero or None
-    // However l1 fee will be applied in any case thus balance change diff size must be applied
-    match context.evm.env.tx.gas_priority_fee {
-        Some(U256::ZERO) => {
-            // EIP 1559 enabled transaction, priority fee is zero, include the diff size of balance change for l1 fee
-            diff_size += size_of::<U256>();
-            // Include the diff size of coinbase address for l1 fee
-            diff_size += size_of::<Address>();
-        }
-        None => {
-            // If priority fee is None, meaning it is a legacy transaction
-            // Check if effective gas price is zero, if so include the diff size of balance change for l1 fee
-            if context.evm.env.effective_gas_price() == U256::ZERO {
-                diff_size += size_of::<U256>();
-                // Include the diff size of coinbase address for l1 fee
-                diff_size += size_of::<Address>();
-            }
-        }
-        _ => {}
-    }
-
     Ok(diff_size)
 }
 

crates/evm/src/tests/queries/estimate_gas_tests.rs

@@ -93,7 +93,7 @@ fn test_tx_request_fields_gas() {
     );
     assert_eq!(
         contract_diff_size.unwrap(),
-        serde_json::from_value::<EstimatedDiffSize>(json![{"gas":"0x6601","diffSize":"0xa8"}])
+        serde_json::from_value::<EstimatedDiffSize>(json![{"gas":"0x6601","diffSize":"0xdc"}])
             .unwrap()
     );