What size is an enum member inside of a struct

Question

Let's consider the following code:

pragma solidity ^0.4.18;

contract Test {
  enum EnumTest {
    Test0,
    Test1
  }

  struct StructTest {
    EnumTest Foo;
    uint256 Bar;
  }
}

Not taking into account struct tight packing, what is the size of the member Foo inside StructTest? Does it depend on the number of members in the enum EnumTest?

Answer 1

Yes, it depends on the number of members in the enum.

See the official documentation:

pragma solidity >=0.4.16 <0.6.0;

contract test {
    enum ActionChoices { GoLeft, GoRight, GoStraight, SitStill }
    ActionChoices choice;
    ActionChoices constant defaultChoice = ActionChoices.GoStraight;

    function setGoStraight() public {
        choice = ActionChoices.GoStraight;
    }

    // Since enum types are not part of the ABI, the signature of "getChoice"
    // will automatically be changed to "getChoice() returns (uint8)"
    // for all matters external to Solidity. The integer type used is just
    // large enough to hold all enum values, i.e. if you have more than 256 values,
    // `uint16` will be used and so on.
    function getChoice() public view returns (ActionChoices) {
        return choice;
    }

    function getDefaultChoice() public pure returns (uint) {
        return uint(defaultChoice);
    }
}