Abstract contract and inheritance

- Checking the linearized base contracts for abstract functions and
  handle their existence appropriately

- If a contract is abstract it can't be created with new

- An abstract contract is not compiled (no backend code is generated)

- Of course tests

libsolidity/AST.cpp

@@ -21,6 +21,7 @@
  */
 
 #include <algorithm>
+#include <boost/range/adaptor/reversed.hpp>
 #include <libsolidity/Utils.h>
 #include <libsolidity/AST.h>
 #include <libsolidity/ASTVisitor.h>
@@ -52,6 +53,7 @@ void ContractDefinition::checkTypeRequirements()
 		baseSpecifier->checkTypeRequirements();
 
 	checkIllegalOverrides();
+	checkAbstractFunctions();
 
 	FunctionDefinition const* constructor = getConstructor();
 	if (constructor && !constructor->getReturnParameters().empty())
@@ -128,6 +130,42 @@ FunctionDefinition const* ContractDefinition::getFallbackFunction() const
 	return nullptr;
 }
 
+void ContractDefinition::checkAbstractFunctions()
+{
+	map<string, bool> functions;
+
+	// Search from base to derived
+	for (ContractDefinition const* contract: boost::adaptors::reverse(getLinearizedBaseContracts()))
+	{
+		for (ASTPointer<FunctionDefinition> const& function: contract->getDefinedFunctions())
+		{
+			string const& name = function->getName();
+			if (!function->isFullyImplemented() && functions.count(name) && functions[name])
+				BOOST_THROW_EXCEPTION(function->createTypeError("Redeclaring an already implemented function as abstract"));
+			// if (functions.count(name) && !functions[name] && function->isFullyImplemented())
+			// 	functions.insert(make_pair(name, true);
+
+			// if (functions.count(name) && !functions[name] && function->isFullyImplemented)
+			// 	functions.insert(make_pair(name, true));
+			
+			// functions.insert(make_pair(name, function->isFullyImplemented()));
+			functions[name] = function->isFullyImplemented();
+			
+			// if (function->isFullyImplemented())
+			// 	full_functions.insert(make_pair(name, function.get()));
+			// else
+			// 	abs_functions.insert(make_pair(name, function.get()));
+		}
+	}
+	for (auto const& it: functions)
+		if (!it.second)
+		{
+			setFullyImplemented(false);
+			break;
+		}
+
+}
+
 void ContractDefinition::checkIllegalOverrides() const
 {
 	// TODO unify this at a later point. for this we need to put the constness and the access specifier
@@ -643,6 +681,8 @@ void NewExpression::checkTypeRequirements()
 	m_contract = dynamic_cast<ContractDefinition const*>(m_contractName->getReferencedDeclaration());
 	if (!m_contract)
 		BOOST_THROW_EXCEPTION(createTypeError("Identifier is not a contract."));
+	if (!m_contract->isFullyImplemented())
+		BOOST_THROW_EXCEPTION(m_contract->createTypeError("Trying to create an object of an abstract contract."));
 	shared_ptr<ContractType const> contractType = make_shared<ContractType>(*m_contract);
 	TypePointers const& parameterTypes = contractType->getConstructorType()->getParameterTypes();
 	m_type = make_shared<FunctionType>(parameterTypes, TypePointers{contractType},

libsolidity/AST.h

@@ -283,6 +283,7 @@ public:
 
 private:
 	void checkIllegalOverrides() const;
+	void checkAbstractFunctions();
 
 	std::vector<std::pair<FixedHash<4>, FunctionTypePointer>> const& getInterfaceFunctionList() const;
 

libsolidity/CompilerStack.cpp

@@ -138,6 +138,8 @@ void CompilerStack::compile(bool _optimize)
 		for (ASTPointer<ASTNode> const& node: source->ast->getNodes())
 			if (ContractDefinition* contract = dynamic_cast<ContractDefinition*>(node.get()))
 			{
+				if (!contract->isFullyImplemented())
+					continue;
 				shared_ptr<Compiler> compiler = make_shared<Compiler>(_optimize);
 				compiler->compileContract(*contract, contractBytecode);
 				Contract& compiledContract = m_contracts[contract->getName()];

libsolidity/Parser.cpp

@@ -141,10 +141,7 @@ ASTPointer<ContractDefinition> Parser::parseContractDefinition()
 		if (currentToken == Token::RBrace)
 			break;
 		else if (currentToken == Token::Function)
-		{
-			ASTPointer<FunctionDefinition> func = parseFunctionDefinition(name.get());
-			functions.push_back(func);
-		}
+			functions.push_back(parseFunctionDefinition(name.get()));
 		else if (currentToken == Token::Struct)
 			structs.push_back(parseStructDefinition());
 		else if (currentToken == Token::Enum)

test/SolidityNameAndTypeResolution.cpp

@@ -353,14 +353,56 @@ BOOST_AUTO_TEST_CASE(function_no_implementation)
 		"  function functionName(bytes32 input) returns (bytes32 out);\n"
 		"}\n";
 	ETH_TEST_REQUIRE_NO_THROW(sourceUnit = parseTextAndResolveNames(text), "Parsing and name Resolving failed");
-	ContractDefinition* contract;
-	for (ASTPointer<ASTNode> const& node: sourceUnit->getNodes())
-		contract = dynamic_cast<ContractDefinition*>(node.get());
+	std::vector<ASTPointer<ASTNode>> nodes = sourceUnit->getNodes();
+	ContractDefinition* contract = dynamic_cast<ContractDefinition*>(nodes[0].get());
 	BOOST_CHECK(contract);
 	BOOST_CHECK(!contract->isFullyImplemented());
 	BOOST_CHECK(!contract->getDefinedFunctions()[0]->isFullyImplemented());
 }
 
+BOOST_AUTO_TEST_CASE(abstract_contract)
+{
+	ASTPointer<SourceUnit> sourceUnit;
+	char const* text = R"(
+		contract base { function foo(); }
+		contract derived is base { function foo() {} }
+		)";
+	ETH_TEST_REQUIRE_NO_THROW(sourceUnit = parseTextAndResolveNames(text), "Parsing and name Resolving failed");
+	std::vector<ASTPointer<ASTNode>> nodes = sourceUnit->getNodes();
+	ContractDefinition* base = dynamic_cast<ContractDefinition*>(nodes[0].get());
+	ContractDefinition* derived = dynamic_cast<ContractDefinition*>(nodes[1].get());
+	BOOST_CHECK(base);
+	BOOST_CHECK(!base->isFullyImplemented());
+	BOOST_CHECK(!base->getDefinedFunctions()[0]->isFullyImplemented());
+	BOOST_CHECK(derived);
+	BOOST_CHECK(derived->isFullyImplemented());
+	BOOST_CHECK(derived->getDefinedFunctions()[0]->isFullyImplemented());
+}
+
+BOOST_AUTO_TEST_CASE(create_abstract_contract)
+{
+	ASTPointer<SourceUnit> sourceUnit;
+	char const* text = R"(
+		contract base { function foo(); }
+		contract derived { 
+			base b;
+            function foo() { b = new base();}
+        }
+		)";
+	BOOST_CHECK_THROW(parseTextAndResolveNames(text), TypeError);
+}
+
+BOOST_AUTO_TEST_CASE(redeclare_implemented_abstract_function_as_abstract)
+{
+	ASTPointer<SourceUnit> sourceUnit;
+	char const* text = R"(
+		contract base { function foo(); }
+		contract derived is base { function foo() {} }
+		contract wrong is derived { function foo(); }
+		)";
+	BOOST_CHECK_THROW(parseTextAndResolveNames(text), TypeError);
+}
+
 BOOST_AUTO_TEST_CASE(function_canonical_signature)
 {
 	ASTPointer<SourceUnit> sourceUnit;