Error when re-using the solc settings object

[fvictorio]

Re-using the solc settings object for versions that default to a different EVM version results in a very obscure error:

Invalid EVM version requested.

Reproduction steps

Create a Hardhat config with this content:

const compilerSettings = {}

module.exports = {
  solidity: {
    compilers: [
      { settings: compilerSettings, version: '0.5.17' },
      { settings: compilerSettings, version: '0.8.28' },
    ]
  }
};

And add two Solidity files:

// contracts/Foo.sol
// SPDX-License-Identifier: Unlicense
pragma solidity ^0.5.0;

contract Foo {}

// contracts/Bar.sol
// SPDX-License-Identifier: Unlicense
pragma solidity ^0.8.0;

contract Bar {}

Then run hh compile.

Notice that replacing the config with this makes the issue go away:

module.exports = {
  solidity: {
    compilers: [
      { settings: {}, version: '0.5.17' },
      { settings: {}, version: '0.8.28' },
    ]
  }
};

So it's very likely we are mutating something we shouldn't.

Thanks @shark0der for reporting this!