pragma experimental ABIEncoderV2; library L { struct S { uint256 a; } function f(S storage s) external returns (uint) { return s.a; } function g(S memory m) public returns (uint) { return m.a; } } contract C { L.S s; constructor() public { s.a = 42; } function f() public returns (bool, bool, uint256) { uint256 s_ptr; assembly { s_ptr := s_slot } (bool success, bytes memory data) = address(L).delegatecall(abi.encodeWithSelector(L.f.selector, s_ptr)); return (L.f.selector == bytes4(keccak256("f(L.S storage)")), success, abi.decode(data, (uint256))); } function g() public returns (bool, bool, uint256) { (bool success, bytes memory data) = address(L).delegatecall(abi.encodeWithSelector(L.g.selector, L.S(23))); return (L.g.selector == bytes4(keccak256("g(L.S)")), success, abi.decode(data, (uint256))); } } // ==== // EVMVersion: >homestead // ---- // library: L // f() -> true, true, 42 // g() -> true, true, 23