Unable to verify contract on Blockscout (Passet Hub)

[nhussein11]

Description

I'm experiencing issues verifying a smart contract on the Passet Hub Blockscout explorer.

Here are the details

• Contract address: 0xcaC62ec5297dcBCA9f3CF9860Fa089A2c61C7292

• Explorer used: https://blockscout-passet-hub.parity-testnet.parity.io/

• Contract source code:

  // SPDX-License-Identifier: MIT
  pragma solidity ^0.8.0;
  
  contract Counter {
      int256 private count;
  
      function increment() public {
          count += 1;
      }
  
      function decrement() public {
          count -= 1;
      }
  
      function getCount() public view returns (int256) {
          return count;
      }
  }

• Error message shown in the contract verification tab:

  Contract code* - No contract could be verified with provided data
  

[athei]

This doesn't look like it is already making use of resolc in order to compile the EVM code to PVM bytecode. We need to work with blockscout to add custom code to support our stack. cc @pgherveou

@xermicus I guess we need to specify at least the resolc version here in addition to the solc version to make it work. However, there is more parameterization, right?

[xermicus]

Correct, the resolc version needs to match otherwise it might not reproduce the same bytecode. See here for a list of bytecode altering options. These options are all included in the std JSON input. If compilation happened via the std JSON interface the JSON input and the resolc version is all that is required for verification.

[pgherveou]

@nprt did you do anything specific for code verification already on blockscout?

[nprt]

@nprt did you do anything specific for code verification already on blockscout?

Not yet. I was planning on looking into it tomorrow. We're still using defaults, and not running a separate contract verification service: https://docs.blockscout.com/setup/env-variables/backend-envs-integrations#smart-contract-verifier-eth-bytecode-db.

[athei]

So then it is comparing EVM bytecode to PVM bytecode as of right now. You need to call resolc instead of just solc. It will use the solc in your PATH. You can find json descriptions of available versions (including dl links) in the same way as it exists for solc here: https://github.com/paritytech/resolc-bin

[smiasojed]

In this case, it may be useful to use the Revive version manager: https://crates.io/crates/rvm-rs. With it, you can list and install all available versions of resolc.