library D {
    struct s { uint a; }
    function mul(s storage self, uint x) public returns (uint) { return self.a *= x; }
    function mul(s storage self, bytes32 x) public returns (bytes32) { }
}
contract C {
    using D for D.s;
    D.s public x;
    function f(uint a) public returns (uint) {
        x.a = 6;
        return x.mul(a);
    }
}
// ====
// compileToEwasm: false
// ----
// library: D
// f(uint256): 7 -> 0x2a
// x() -> 0x2a