Warn on using literals in tight packing

3 files changed, 67 insertions, 0 deletions

diff --git a/Changelog.md b/Changelog.md
index c3482c4b..670182af 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -2,6 +2,7 @@
 
 Features:
  * Optimizer: Add new optimization step to remove unused ``JUMPDEST``s.
+ * Type Checker: Warn on using literals as tight packing parameters in ``keccak256``, ``sha3``, ``sha256`` and ``ripemd160``.
 
 Bugfixes:
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 99f3c64c..d594a060 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -1446,6 +1446,28 @@ bool TypeChecker::visit(FunctionCall const& _functionCall)
 		_functionCall.annotation().type = make_shared<TupleType>(functionType->returnParameterTypes());
 
 	TypePointers parameterTypes = functionType->parameterTypes();
+
+	if (!functionType->padArguments())
+	{
+		for (size_t i = 0; i < arguments.size(); ++i)
+		{
+			auto const& argType = type(*arguments[i]);
+			if (auto literal = dynamic_cast<RationalNumberType const*>(argType.get()))
+			{
+				/* If no mobile type is available an error will be raised elsewhere. */
+				if (literal->mobileType())
+					m_errorReporter.warning(
+						_functionCall.location(),
+						"The type of \"" +
+						argType->toString() +
+						"\" was inferred as " +
+						literal->mobileType()->toString() +
+						". This is probably not desired. Use an explicit type to silence this warning."
+					);
+			}
+		}
+	}
+
 	if (!functionType->takesArbitraryParameters() && parameterTypes.size() != arguments.size())
 	{
 		string msg =
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 380978e8..15b06125 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -6744,6 +6744,50 @@ BOOST_AUTO_TEST_CASE(reject_interface_constructors)
 	CHECK_ERROR(text, TypeError, "Wrong argument count for constructor call: 1 arguments given but expected 0.");
 }
 
+BOOST_AUTO_TEST_CASE(tight_packing_literals)
+{
+	char const* text = R"(
+		contract C {
+			function f() returns (bytes32) {
+				return keccak256(1);
+			}
+		}
+	)";
+	CHECK_WARNING(text, "The type of \"int_const 1\" was inferred as uint8.");
+	text = R"(
+		contract C {
+			function f() returns (bytes32) {
+				return keccak256(uint8(1));
+			}
+		}
+	)";
+	CHECK_SUCCESS_NO_WARNINGS(text);
+	text = R"(
+		contract C {
+			function f() returns (bytes32) {
+				return sha3(1);
+			}
+		}
+	)";
+	CHECK_WARNING(text, "The type of \"int_const 1\" was inferred as uint8.");
+	text = R"(
+		contract C {
+			function f() returns (bytes32) {
+				return sha256(1);
+			}
+		}
+	)";
+	CHECK_WARNING(text, "The type of \"int_const 1\" was inferred as uint8.");
+	text = R"(
+		contract C {
+			function f() returns (bytes32) {
+				return ripemd160(1);
+			}
+		}
+	)";
+	CHECK_WARNING(text, "The type of \"int_const 1\" was inferred as uint8.");
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }