rpc: fix cumulative gas (#662)

* rpc: fix cumulative gas

* changelog

rpc/namespaces/eth/api.go

@@ -677,6 +677,11 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 		return nil, err
 	}
 
+	cumulativeGasUsed := uint64(tx.TxResult.GasUsed)
+	if tx.Index != 0 {
+		cumulativeGasUsed += rpctypes.GetBlockCumulativeGas(api.clientCtx.Codec, block.Block, int(tx.Index))
+	}
+
 	// Set status codes based on tx result
 	var status hexutil.Uint
 	if tx.TxResult.IsOK() {
@@ -699,7 +704,7 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 	receipt := map[string]interface{}{
 		// Consensus fields: These fields are defined by the Yellow Paper
 		"status":            status,
-		"cumulativeGasUsed": nil, // ignore until needed
+		"cumulativeGasUsed": hexutil.Uint64(cumulativeGasUsed),
 		"logsBloom":         data.Bloom,
 		"logs":              data.Logs,
 
@@ -715,7 +720,7 @@ func (api *PublicEthereumAPI) GetTransactionReceipt(hash common.Hash) (map[strin
 		"blockNumber":      hexutil.Uint64(tx.Height),
 		"transactionIndex": hexutil.Uint64(tx.Index),
 
-		// sender and receiver (contract or EOA) addreses
+		// sender and receiver (contract or EOA) addresses
 		"from": from,
 		"to":   ethTx.To(),
 	}