Extra bytes returned on revert("")

[ZumZoom]

Calling revert(string) in Solidity should return abi-encoded string as if it were a call to Error(string) function (docs).

Therefore when calling revert with empty string revert("") I expect to receive correct abi-encoded Error(""):

0x08c379a0                                                          <- Error(string) selector
0000000000000000000000000000000000000000000000000000000000000020    <- string offset = 32
0000000000000000000000000000000000000000000000000000000000000000    <- string length = 0

However ganache-cli appends extra 32 bytes of zeroes in that case and returned bytes are

0x08c379a0                                                          <- Error(string) selector
0000000000000000000000000000000000000000000000000000000000000020    <- string offset = 32
0000000000000000000000000000000000000000000000000000000000000000    <- string length = 0
0000000000000000000000000000000000000000000000000000000000000000    <- unexpected extra 32 bytes

Those extra zeroes break the code that relies on the size of abi-encoded string.

Expected Behavior

Error("") should be abi-encoded as 68 bytes.

Current Behavior

Error("") is abi-encoded as 100 bytes.

Steps to Reproduce

contract RevertReasonParserTest {
    function emptyStringRevert() external pure  {
        revert("");
    }

    function test() external view {
        try this.emptyStringRevert() {
        } catch (bytes memory reason) {
            require(reason.length == 68, "Incorrect reason length");
        }
    }
}

Your Environment

• Version used: 6.12.1

[axic]

Can you open the same issue on https://github.com/ethereum/solidity? It seems to be belonging there and not here. (Also confirming this is happening.)

[ZumZoom]

Sure. Thanks for suggestion.
ethereum/solidity#10170
I also checked that the behaviour is consistent with mainnet, ropsten and ethereumjs-vm.
It is likely a Solidity bug so I'm closing the issue.