Hedera Hashgraph

[stefan-stefanooov]

Version of Hardhat

^2.17.3

What happened?

Hello everyone,

I am working on the Hedera Hashgraph project.
We are trying to integrate with your wonderful project for obvious reasons :)

In Hedera we have a thing called system contracts that allow the network to expose native service implementations on top of the EVM through smart contracts.

They are called from a predefined address. ("0x167" for example)
If we create a smart contract, that uses this address and write a test for it with your tool, we get the following error:

A little something from the "--show-stack-traces" flag ...

Can you please have a look?
We would really like for you to support our project.

Please let me know if I can do anything else to help US solve this.

Best of wishes,
Stefan

Minimal reproduction steps

• Create a normal out of the box hardhat project.
  npm install --save-dev hardhat
npx hardhat init --- use TypeScript
• add the 4 contracts and test file in the GitHub gist
• run the tests
• we also use this tool for our code-caverage

Search terms

hedera hashgraph hardhat precompile address code-coverage

[ChristopherDedominici]

Hi @stefan-stefanooov, I'm checking the issue and I have a question: is the GitHub gist that you shared correct? I see a lot of code that I cannot understand, see screenshot:

[stefan-stefanooov]

Apologies Sir @ChristopherDedominici ,
I just edited my link ...hopefully to the correct gist.
Please confirm that you can open it. And that it's something meaningful.

I'll also add it here.
https://gist.github.com/stefan-stefanooov/08191e704db60aacda6e6c7d0332969c

Thank you for checking this out :)
I am here for you if you need me for more clarifications.

[fvictorio]

Hey @stefan-stefanooov, I can confirm that your transaction is reverting, but that doesn't necessarily mean there's a bug in Hardhat.

If you think this is happening because the code assumes that some precompile exist, then the problem is that the Hardhat network only has Ethereum's standard precompiles. If you want to simulate those, then you need to have some bytecode in those addresses with the same functionality (you can use hardhat_setCode for that).

I'm tentatively closing this, but I can re-open it if there's indeed a problem on our side.

[fvictorio]

I think what's going on here. This code:

        (bool success, bytes memory result) = precompileAddress.call(
            abi.encodeWithSelector(IHederaTokenService.cryptoTransfer.selector, tokenTransfers));
        responseCode = success ? abi.decode(result, (int32)) : HederaResponseCodes.UNKNOWN;

is making a call to an address (0x167) that doesn't have bytecode. But low-level calls (done with address.call) to addresses without bytecode always succeed, with an empty result. You can confirm this by adding some logs:

        (bool success, bytes memory result) = precompileAddress.call(
            abi.encodeWithSelector(IHederaTokenService.cryptoTransfer.selector, tokenTransfers));
        console.log(success);
        console.logBytes(result);
        responseCode = success ? abi.decode(result, (int32)) : HederaResponseCodes.UNKNOWN;

So you are doing abi.decode(result, (int32)) with an empty result, and that fails.