Merge pull request ethereum#9360 from ethereum/rich-function-type

Improve error message when assigning builtin functions

Author: axic

libsolidity/analysis/TypeChecker.cpp

@@ -2171,7 +2171,8 @@ void TypeChecker::typeCheckFunctionGeneralChecks(
 	for (size_t i = 0; i < paramArgMap.size(); ++i)
 	{
 		solAssert(!!paramArgMap[i], "unmapped parameter");
-		if (!type(*paramArgMap[i])->isImplicitlyConvertibleTo(*parameterTypes[i]))
+		BoolResult result = type(*paramArgMap[i])->isImplicitlyConvertibleTo(*parameterTypes[i]);
+		if (!result)
 		{
 			auto [errorId, description] = [&]() -> tuple<ErrorId, string> {
 				string msg =
@@ -2181,6 +2182,8 @@ void TypeChecker::typeCheckFunctionGeneralChecks(
 					" to " +
 					parameterTypes[i]->toString() +
 					" requested.";
+				if (!result.message().empty())
+					msg += " " + result.message();
 				if (
 					_functionType->kind() == FunctionType::Kind::BareCall ||
 					_functionType->kind() == FunctionType::Kind::BareCallCode ||

libsolidity/ast/Types.cpp

@@ -3111,6 +3111,13 @@ BoolResult FunctionType::isImplicitlyConvertibleTo(Type const& _convertTo) const
 
 	FunctionType const& convertTo = dynamic_cast<FunctionType const&>(_convertTo);
 
+	// These two checks are duplicated in equalExcludingStateMutability, but are added here for error reporting.
+	if (convertTo.bound() != bound())
+		return BoolResult::err("Bound functions can not be converted to non-bound functions.");
+
+	if (convertTo.kind() != kind())
+		return BoolResult::err("Special functions can not be converted to function types.");
+
 	if (!equalExcludingStateMutability(convertTo))
 		return false;
 

test/libsolidity/syntaxTests/abiEncoder/v2_call_to_v2_library_function_pointer_accepting_struct.sol

@@ -22,4 +22,4 @@ contract Test {
     }
 }
 // ----
-// TypeError 9574: (B:269-313): Type function (struct L.Item memory) is not implicitly convertible to expected type function (struct L.Item memory) external.
+// TypeError 9574: (B:269-313): Type function (struct L.Item memory) is not implicitly convertible to expected type function (struct L.Item memory) external. Special functions can not be converted to function types.

test/libsolidity/syntaxTests/events/event_library_function.sol

@@ -30,6 +30,6 @@ contract E {
 	}
 }
 // ----
-// TypeError 9553: (140-143): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested.
-// TypeError 9553: (230-233): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested.
-// TypeError 9553: (345-348): Invalid type for argument in function call. Invalid implicit conversion from function D.f() to function () external requested.
+// TypeError 9553: (140-143): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested. Special functions can not be converted to function types.
+// TypeError 9553: (230-233): Invalid type for argument in function call. Invalid implicit conversion from function () to function () external requested. Special functions can not be converted to function types.
+// TypeError 9553: (345-348): Invalid type for argument in function call. Invalid implicit conversion from function D.f() to function () external requested. Special functions can not be converted to function types.

test/libsolidity/syntaxTests/functionTypes/assign_bound.sol

@@ -0,0 +1,15 @@
+library L {
+    function foo(uint256 a, uint256 b) internal pure returns (uint256) {
+        return a + b;
+    }
+}
+contract C {
+    using L for uint256;
+
+    function bar() public {
+        uint256 x;
+        function (uint256, uint256) internal pure returns (uint256) ptr = x.foo;
+    }
+}
+// ----
+// TypeError 9574: (209-280): Type function (uint256,uint256) pure returns (uint256) is not implicitly convertible to expected type function (uint256,uint256) pure returns (uint256). Bound functions can not be converted to non-bound functions.

test/libsolidity/syntaxTests/functionTypes/assign_builtin.sol

@@ -0,0 +1,7 @@
+contract C {
+  function f() public {
+     function (uint) view returns (bytes32) _blockhash = blockhash;
+  }
+}
+// ----
+// TypeError 9574: (42-103): Type function (uint256) view returns (bytes32) is not implicitly convertible to expected type function (uint256) view returns (bytes32). Special functions can not be converted to function types.

test/libsolidity/syntaxTests/functionTypes/external_library_function_to_external_function_type.sol

@@ -10,5 +10,5 @@ contract C {
     }
 }
 // ----
-// TypeError 9553: (230-233): Invalid type for argument in function call. Invalid implicit conversion from function (uint256) returns (uint256) to function (uint256) external returns (uint256) requested.
-// TypeError 9574: (244-305): Type function (uint256) returns (uint256) is not implicitly convertible to expected type function (uint256) external returns (uint256).
+// TypeError 9553: (230-233): Invalid type for argument in function call. Invalid implicit conversion from function (uint256) returns (uint256) to function (uint256) external returns (uint256) requested. Special functions can not be converted to function types.
+// TypeError 9574: (244-305): Type function (uint256) returns (uint256) is not implicitly convertible to expected type function (uint256) external returns (uint256). Special functions can not be converted to function types.

test/libsolidity/syntaxTests/functionTypes/function_type_variable_external_internal.sol

@@ -3,4 +3,4 @@ contract test {
     function(bytes memory) external internal a = fa;
 }
 // ----
-// TypeError 7407: (106-108): Type function (bytes memory) is not implicitly convertible to expected type function (bytes memory) external.
+// TypeError 7407: (106-108): Type function (bytes memory) is not implicitly convertible to expected type function (bytes memory) external. Special functions can not be converted to function types.

test/libsolidity/syntaxTests/nameAndTypeResolution/262_bound_function_in_var.sol

@@ -9,5 +9,5 @@ contract C {
     }
 }
 // ----
-// TypeError 9574: (218-271): Type function (struct D.s storage pointer,uint256) returns (uint256) is not implicitly convertible to expected type function (struct D.s storage pointer,uint256) returns (uint256).
+// TypeError 9574: (218-271): Type function (struct D.s storage pointer,uint256) returns (uint256) is not implicitly convertible to expected type function (struct D.s storage pointer,uint256) returns (uint256). Bound functions can not be converted to non-bound functions.
 // TypeError 6160: (298-302): Wrong argument count for function call: 1 arguments given but expected 2.

test/libsolidity/syntaxTests/types/contractTypeType/members/assign_function_via_base_name_to_var.sol

@@ -10,5 +10,5 @@ contract B is A {
     }
 }
 // ----
-// TypeError 9574: (133-160): Type function A.f() is not implicitly convertible to expected type function () external.
-// TypeError 9574: (170-202): Type function A.g() pure is not implicitly convertible to expected type function () pure external.
+// TypeError 9574: (133-160): Type function A.f() is not implicitly convertible to expected type function () external. Special functions can not be converted to function types.
+// TypeError 9574: (170-202): Type function A.g() pure is not implicitly convertible to expected type function () pure external. Special functions can not be converted to function types.

test/libsolidity/syntaxTests/types/contractTypeType/members/assign_function_via_contract_name_to_var.sol

@@ -10,5 +10,5 @@ contract B {
     }
 }
 // ----
-// TypeError 9574: (128-155): Type function A.f() is not implicitly convertible to expected type function () external.
-// TypeError 9574: (165-197): Type function A.g() pure is not implicitly convertible to expected type function () pure external.
+// TypeError 9574: (128-155): Type function A.f() is not implicitly convertible to expected type function () external. Special functions can not be converted to function types.
+// TypeError 9574: (165-197): Type function A.g() pure is not implicitly convertible to expected type function () pure external. Special functions can not be converted to function types.