UnimplementedFeatureError: Only byte arrays can be encoded from calldata currently

Question

I received the error message UnimplementedFeatureError: Only byte arrays can be encoded from calldata currently from the compiler, but without any reference to a file or line. In a big project, and with a lot of changes, this made the source difficult to find.

The code that caused it ultimately was of this form:

pragma solidity >0.5.0;
pragma experimental ABIEncoderV2;

contract Foo {
    constructor(address[] memory _addrs) public {}
}

contract FooFactory {
    function createInstance(address[] calldata _addrs) external {
        new Foo(_addrs);
    }
}

Answer 1

Ultimately, the fix was to implement FooFactory as public:

contract FooFactory {
    function createInstance(address[] memory _addrs) public {
        new Foo(_addrs);
    }
}

but another fix would be to remove the pragma experimental ABIEncoderV2; line if you don't need it.

• Compiler line throwing this error