disallow declaration of void type

https://www.pivotaltracker.com/n/projects/1189488/stories/86318578

libsolidity/AST.cpp

@@ -383,6 +383,8 @@ void VariableDefinition::checkTypeRequirements()
 					BOOST_THROW_EXCEPTION(m_value->createTypeError("Invalid integer constant " + type->toString()));
 				type = intType;
 			}
+			else if (type->getCategory() == Type::Category::VOID)
+				BOOST_THROW_EXCEPTION(m_variable->createTypeError("var cannot be void type"));
 			m_variable->setType(type);
 		}
 	}

test/SolidityNameAndTypeResolution.cpp

@@ -904,6 +904,12 @@ BOOST_AUTO_TEST_CASE(invalid_parameter_names_in_named_args)
 	BOOST_CHECK_THROW(parseTextAndResolveNames(sourceCode), TypeError);
 }
 
+BOOST_AUTO_TEST_CASE(disallow_declaration_of_void_type)
+{
+	char const* sourceCode = "contract c { function f() { var x = f(); } }";
+	BOOST_CHECK_THROW(parseTextAndResolveNames(sourceCode), TypeError);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }