outputSelection with contract name and not * leads to empty compiler output in <=0.5.8

[kuzdogan]

Description

Summary:

Providing a contract name in the contract selection of the outputSelection field of the JSON input is outputting empty JSON fields in versions <=0.5.8.

Doesn't work:

"outputSelection": {
  "*": {
    "Storage": ["*"]
  }
}

Works:

"outputSelection": {
  "*": {
    "*": ["*"]
  }
}

Details

I've encountered multiple issues about the outputSelection.

• Initially Undeclared identifier error when outputSelection is the single target contract but compiles with outputSelection : * #13985 about the file selection in the output selection in v0.6.5.
• Recently I've come across another issue Handle standard JSON transalation with outputSelection for =<0.4.19 solc-js#690 in <=0.4.19
  • I thought it happens because of the introduction of the outputSelection in that version.
  • Shouldn't be related to solc as the field wasn't introduced back then and unfortunately there was no valid field check.
  • Hence issue opened in solc-js to handle the JSON translation for earlier versions

Digging into the issue ethereum/sourcify#1017 in Sourcify, I came across this issue which affects versions <=0.5.8 but not >=0.5.9. I couldn't find any related changes in this version about the outputSelection so I'm opening the issue.

To reproduce, here's the compiler input JSON:

{
  "language": "Solidity",
  "settings": {
    "optimizer": { "enabled": true, "runs": 200 },
    "outputSelection": {
      "*": {
        "Storage": ["evm.bytecode"]
      }
    }
  },
  "sources": {
    "Storage.sol": {
      "content": "pragma solidity >=0.4.0 <0.9.0;\n\ncontract Storage {\n\n    uint256 number;\n\n    function store(uint256 num) public {\n        number = num;\n    }\n\n    function retrieve() public view returns (uint256){\n        return number;\n    }\n}\n"
    }
  }
}

This would generate the following unexpected output:

{
  "contracts": {
    "Storage.sol": {
      "Storage": {
        "evm": {
          "bytecode": {
            "linkReferences": {},
            "object": "",
            "opcodes": "",
            "sourceMap": ""
          }
        }
      }
    }
  },
  "sources": {
    "Storage.sol": {
      "id": 0
    }
  }
}

Changing the "Storage" field in the JSON to "*" will lead to an expected compiler output with bytecode.

The contract is fairly simple and attached here:
Storage.sol.txt

Environment

• Compiler version: affected <=0.5.8
• Target EVM version (as per compiler settings): default
• Framework/IDE (e.g. Truffle or Remix): Both in 0.5.8+commit.23d335f2.Darwin.appleclang downloaded with solc-select. I was able to reproduce in Remix, as well as in Sourcify, which uses solc-js on Mac ARM.
• Operating system: MacOS ARM 64bit

[ekpyron]

Since we won't touch old releases, the fix for this will probably be something similar to ethereum/solc-js#690, although we may want to come up with a nicer cross-platform way to do such input/output translations.

[kuzdogan]

Right. Putting this for the record and if it is indeed a bug, maybe to be listed in bugs.

We just went forward with the workaround of using * on all levels, so all fine if this should be closed.