fixed assigning negative number to unsigned

libsolidity/Types.cpp

@@ -371,7 +371,7 @@ bool IntegerConstantType::isImplicitlyConvertibleTo(Type const& _convertTo) cons
 			if (m_value <= (u256(-1) >> (256 - targetType->getNumBits() + forSignBit)))
 				return true;
 		}
-		else if (-m_value <= (u256(1) << (targetType->getNumBits() - forSignBit)))
+		else if (targetType->isSigned() && -m_value <= (u256(1) << (targetType->getNumBits() - forSignBit)))
 			return true;
 		return false;
 	}

test/libsolidity/SolidityNameAndTypeResolution.cpp

@@ -1866,6 +1866,16 @@ BOOST_AUTO_TEST_CASE(negative_integers_to_unsigned)
 	BOOST_CHECK_THROW(parseTextAndResolveNames(sourceCode), TypeError);
 }
 
+BOOST_AUTO_TEST_CASE(positive_integers_to_unsigned_out_of_bound)
+{
+	char const* sourceCode = R"(
+		contract test {
+			uint8 public x = 700;
+		}
+	)";
+	BOOST_CHECK_THROW(parseTextAndResolveNames(sourceCode), TypeError);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }