pragma abicoder v2; contract C { struct S { function() external f; } function ggg(function() external x) external pure returns (uint256 r) { assembly { r := calldataload(4) } } function h(S calldata x) external pure returns (uint256 r) { x.f; // validation only happens here assembly { r := calldataload(4) } } function dummy() external {} function ffff(uint256 a) external view returns (uint256, uint256) { S memory s = S(this.dummy); assembly { mstore(s, a) } return (this.ggg(s.f), this.h(s)); } } // ==== // compileViaYul: also // ---- // ffff(uint256): 0 -> 0, 0 // ggg(function): 0 -> 0 // ffff(uint256): "01234567890123456789abcd" -> "01234567890123456789abcd", "01234567890123456789abcd" // ggg(function): "01234567890123456789abcd" -> "01234567890123456789abcd" // h((function)): "01234567890123456789abcd" -> "01234567890123456789abcd" // h((function)): 0 -> 0 // ffff(uint256): "01234567890123456789abcdX" -> "01234567890123456789abcd", "01234567890123456789abcd" // ggg(function): "01234567890123456789abcdX" -> FAILURE // h((function)): "01234567890123456789abcdX" -> FAILURE