Why trace_call (stateDiff) not show balance changes from internal txs?

Question

I am using trace_call with stateDiff Tracer, to show balances changes after a transaction. Already tried to use Erigon and core-geth, the results are identical thoughout changes in usage.

For instance, this tx: https://goerli.etherscan.io/tx/0xffa922bc144466247cf1d94db849ae80d36c9d75b300636d6dc68d7ef6c6c114 generate this trace:

[
  {
    "statediff": {
      "0xd44fbeb26c88f0f18f72664e3c446e0c2836908d": {
        "balance": "=",
        "nonce": {
          "*": {
            "from": "0x209",
            "to": "0x20a"
          }
        },
        "code": "=",
        "storage": {}
      }
    }
  }
]

there is no changes in balances, but yes there was, as one can see in etherscan "state" flap. I've noted that this happens always in internal txs, and when there are no internals, the result is expected. Someone can explain why internal tx are not captured by trace? And more important, how to trace Internal Txs and show balance changes?

Answer 1

Hi Developer advocate from Chainstack here

I can't tell if the full trace is working but

[
  {
    "statediff": {
      "0xd44fbeb26c88f0f18f72664e3c446e0c2836908d": {
        "balance": "=",
        "nonce": {
          "*": {
            "from": "0x209",
            "to": "0x20a"
          }
        },
        "code": "=",
        "storage": {}
      }
    }
  }
]

is perfectly correct.

This is a transaction swapping 0.07 WETH for ApeIn, during the tx, the sender 0xd44fbeb26c88f0f18f72664e3c446e0c2836908d doesn't really lose any Eth except for his gas fee, which won't reflect in a trace_call.

A trace_call basically "simulates" a call against a specific "state", the gas fee is undetermined until the tx is finalized in a block. Hence it is not part of this "simulation". If you trace it using trace_transaction, you will probably see the balance reduce due to gas.

Your confusion comes from Etherscan incorrectly using the word "state" here. Maybe it has a different understanding from Geth, but here it certainly mixes Eth(the native currency) and WETH(wrapped Eth, a token) together.

traceCall with stateDiff doesn't trace smart contract data changes, as Nulik pointed out, that should be a storage change. You can use debug_traceCall with disableStorage:false to trace this changes.

I had two blog posts: this is about eth_call, this is about debug_trace API. There are some examples that may help you.

Hope you find it useful, Happy coding!