chore(lint): add exception to `mixed-case-function` rule when referring to constant functions in interface

[smol-ninja]

Component

Forge

Describe the feature you would like

Problem

Take the below example,

interface ICounter {
    function MAX_NUMBER() external view returns (uint256);
}

contract Counter is ICounter {
    uint256 public constant override MAX_NUMBER = 100;
}

forge lint would throw mixed-case-function: function names should use mixedCase whereas this is a valid function name since its referring to a constant (SNAKE_CASE) in the contract.

Solution

An exception could be added when the following rules are met:

• Be declared in an interface.
• Have external view visibility and mutability.
• Have zero parameters.
• Have exactly one return value.
• The return type must be one of the following:
• An elementary type (uint*, int*, bool, address, string, bytes, bytesN).
• An enum.
• A user-defined value type (UDVT) based on an elementary type (e.g. UD60x18).
• A contract/interface type (e.g. IERC20).
• Not allowed: arrays, tuples, structs, or any return type with a storageLocation (memory/calldata).

Also see protofire/solhint#699 where I raised a similar issue.

Note: this behaviour is a result of the latest foundry upgrade.

Additional context

No response