Multi-variable declarations.

libsolidity/AST.cpp

@@ -325,6 +325,13 @@ ReturnAnnotation& Return::annotation() const
 	return static_cast<ReturnAnnotation&>(*m_annotation);
 }
 
+VariableDeclarationStatementAnnotation& VariableDeclarationStatement::annotation() const
+{
+	if (!m_annotation)
+		m_annotation = new VariableDeclarationStatementAnnotation();
+	return static_cast<VariableDeclarationStatementAnnotation&>(*m_annotation);
+}
+
 ExpressionAnnotation& Expression::annotation() const
 {
 	if (!m_annotation)

libsolidity/AST.h

@@ -982,6 +982,8 @@ public:
 	virtual void accept(ASTVisitor& _visitor) override;
 	virtual void accept(ASTConstVisitor& _visitor) const override;
 
+	VariableDeclarationStatementAnnotation& annotation() const override;
+
 	std::vector<ASTPointer<VariableDeclaration>> const& declarations() const { return m_variables; }
 	Expression const* initialValue() const { return m_initialValue.get(); }
 

libsolidity/ASTAnnotations.h

@@ -84,6 +84,13 @@ struct UserDefinedTypeNameAnnotation: TypeNameAnnotation
 	Declaration const* referencedDeclaration = nullptr;
 };
 
+struct VariableDeclarationStatementAnnotation: ASTAnnotation
+{
+	/// Information about which component of the vaule is assigned to which variable.
+	/// The pointer can be null to signify that the component is discarded.
+	std::vector<VariableDeclaration const*> assignments;
+};
+
 struct ExpressionAnnotation: ASTAnnotation
 {
 	/// Inferred type of the expression.

libsolidity/Compiler.cpp

@@ -623,13 +623,29 @@ bool Compiler::visit(VariableDeclarationStatement const& _variableDeclarationSta
 {
 	StackHeightChecker checker(m_context);
 	CompilerContext::LocationSetter locationSetter(m_context, _variableDeclarationStatement);
-	solAssert(_variableDeclarationStatement.declarations().size() == 1, "To be implemented.");
-	solAssert(!!_variableDeclarationStatement.declarations().front(), "");
-	VariableDeclaration const& varDecl = *_variableDeclarationStatement.declarations().front();
 	if (Expression const* expression = _variableDeclarationStatement.initialValue())
 	{
-		compileExpression(*expression, varDecl.annotation().type);
-		CompilerUtils(m_context).moveToStackVariable(varDecl);
+		CompilerUtils utils(m_context);
+		compileExpression(*expression);
+		TypePointers valueTypes;
+		if (auto tupleType = dynamic_cast<TupleType const*>(expression->annotation().type.get()))
+			valueTypes = tupleType->components();
+		else
+			valueTypes = TypePointers{expression->annotation().type};
+		auto const& assignments = _variableDeclarationStatement.annotation().assignments;
+		solAssert(assignments.size() == valueTypes.size(), "");
+		for (size_t i = 0; i < assignments.size(); ++i)
+		{
+			size_t j = assignments.size() - i - 1;
+			VariableDeclaration const* varDecl = assignments[j];
+			if (!varDecl)
+				utils.popStackElement(*valueTypes[j]);
+			else
+			{
+				utils.convertType(*valueTypes[j], *varDecl->annotation().type);
+				utils.moveToStackVariable(*varDecl);
+			}
+		}
 	}
 	checker.check();
 	return false;

libsolidity/ExpressionCompiler.cpp

@@ -427,11 +427,6 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall)
 			unsigned returnParametersSize = CompilerUtils::sizeOnStack(function.returnParameterTypes());
 			// callee adds return parameters, but removes arguments and return label
 			m_context.adjustStackOffset(returnParametersSize - CompilerUtils::sizeOnStack(function.parameterTypes()) - 1);
-
-			// @todo for now, the return value of a function is its first return value, so remove
-			// all others
-			for (unsigned i = 1; i < function.returnParameterTypes().size(); ++i)
-				utils().popStackElement(*function.returnParameterTypes()[i]);
 			break;
 		}
 		case Location::External:
@@ -1123,19 +1118,15 @@ void ExpressionCompiler::appendExternalFunctionCall(
 	bool returnSuccessCondition = funKind == FunctionKind::Bare || funKind == FunctionKind::BareCallCode;
 	bool isCallCode = funKind == FunctionKind::BareCallCode || funKind == FunctionKind::CallCode;
 
-	//@todo only return the first return value for now
-	Type const* firstReturnType =
-		_functionType.returnParameterTypes().empty() ?
-		nullptr :
-		_functionType.returnParameterTypes().front().get();
 	unsigned retSize = 0;
 	if (returnSuccessCondition)
 		retSize = 0; // return value actually is success condition
-	else if (firstReturnType)
-	{
-		retSize = firstReturnType->calldataEncodedSize();
-		solAssert(retSize > 0, "Unable to return dynamic type from external call.");
-	}
+	else
+		for (auto const& retType: _functionType.returnParameterTypes())
+		{
+			solAssert(retType->calldataEncodedSize() > 0, "Unable to return dynamic type from external call.");
+			retSize += retType->calldataEncodedSize();
+		}
 
 	// Evaluate arguments.
 	TypePointers argumentTypes;
@@ -1255,16 +1246,20 @@ void ExpressionCompiler::appendExternalFunctionCall(
 		utils().loadFromMemoryDynamic(IntegerType(160), false, true, false);
 		utils().convertType(IntegerType(160), FixedBytesType(20));
 	}
-	else if (firstReturnType)
+	else if (!_functionType.returnParameterTypes().empty())
 	{
 		utils().fetchFreeMemoryPointer();
-		if (dynamic_cast<ReferenceType const*>(firstReturnType))
+		bool memoryNeeded = false;
+		for (auto const& retType: _functionType.returnParameterTypes())
 		{
-			utils().loadFromMemoryDynamic(*firstReturnType, false, true, true);
-			utils().storeFreeMemoryPointer();
+			utils().loadFromMemoryDynamic(*retType, false, true, true);
+			if (dynamic_cast<ReferenceType const*>(retType.get()))
+				memoryNeeded = true;
 		}
+		if (memoryNeeded)
+			utils().storeFreeMemoryPointer();
 		else
-			utils().loadFromMemoryDynamic(*firstReturnType, false, true, false);
+			m_context << eth::Instruction::POP;
 	}
 }
 

libsolidity/Parser.cpp

@@ -785,12 +785,13 @@ ASTPointer<VariableDeclarationStatement> Parser::parseVariableDeclarationStateme
 		// Parse `var (a, b, ,, c) = ...` into a single VariableDeclarationStatement with multiple variables.
 		m_scanner->next();
 		m_scanner->next();
-		do
+		while (true)
 		{
 			ASTPointer<VariableDeclaration> var;
-			if (m_scanner->currentToken() == Token::Comma)
-				m_scanner->next();
-			else
+			if (
+				m_scanner->currentToken() != Token::Comma &&
+				m_scanner->currentToken() != Token::RParen
+			)
 			{
 				ASTNodeFactory varDeclNodeFactory(*this);
 				ASTPointer<ASTString> name = expectIdentifierToken();
@@ -802,7 +803,11 @@ ASTPointer<VariableDeclarationStatement> Parser::parseVariableDeclarationStateme
 				);
 			}
 			variables.push_back(var);
-		} while (m_scanner->currentToken() != Token::RParen);
+			if (m_scanner->currentToken() == Token::RParen)
+				break;
+			else
+				expectToken(Token::Comma);
+		}
 		nodeFactory.markEndPosition();
 		m_scanner->next();
 	}

libsolidity/TypeChecker.cpp

@@ -617,47 +617,57 @@ bool TypeChecker::visit(VariableDeclarationStatement const& _statement)
 	// the variable declaration(s).
 
 	_statement.initialValue()->accept(*this);
-	shared_ptr<TupleType const> valueType = dynamic_pointer_cast<TupleType const>(_statement.initialValue()->annotation().type);
-	if (!valueType)
-		valueType = make_shared<TupleType const>(TypePointers{_statement.initialValue()->annotation().type});
+	TypePointers valueTypes;
+	if (auto tupleType = dynamic_cast<TupleType const*>(_statement.initialValue()->annotation().type.get()))
+		valueTypes = tupleType->components();
+	else
+		valueTypes = TypePointers{_statement.initialValue()->annotation().type};
 
-	vector<ASTPointer<VariableDeclaration>> variables = _statement.declarations();
+	// Determine which component is assigned to which variable.
 	// If numbers do not match, fill up if variables begin or end empty (not both).
-	if (valueType->components().size() != variables.size())
-	{
-		if (!variables.front() && !variables.back())
-			fatalTypeError(
-				_statement,
-				"Wildcard both at beginning and end of variable declaration list is only allowed "
-				"if the number of components is equal."
-			);
-		while (valueType->components().size() > variables.size())
-			if (!variables.front())
-				variables.insert(variables.begin(), shared_ptr<VariableDeclaration>());
-			else
-				variables.push_back(shared_ptr<VariableDeclaration>());
-		while (valueType->components().size() < variables.size())
-			if (!variables.empty() && !variables.front())
-				variables.erase(variables.begin());
-			else if (!variables.empty() && !variables.back())
-				variables.pop_back();
-			else
-				break;
-		if (valueType->components().size() != variables.size())
-			fatalTypeError(
-				_statement,
-				"Unable to match the number of variables to the number of values."
-			);
-	}
-	solAssert(variables.size() == valueType->components().size(), "");
+	vector<VariableDeclaration const*>& assignments = _statement.annotation().assignments;
+	assignments.resize(valueTypes.size(), nullptr);
+	vector<ASTPointer<VariableDeclaration>> const& variables = _statement.declarations();
+	if (valueTypes.size() != variables.size() && !variables.front() && !variables.back())
+		fatalTypeError(
+			_statement,
+			"Wildcard both at beginning and end of variable declaration list is only allowed "
+			"if the number of components is equal."
+		);
+	size_t minNumValues = variables.size();
+	if (!variables.back() || !variables.front())
+		--minNumValues;
+	if (valueTypes.size() < minNumValues)
+		fatalTypeError(
+			_statement,
+			"Not enough components (" +
+			toString(valueTypes.size()) +
+			") in value to assign all variables (" +
+			toString(minNumValues) + ")."
+		);
+	if (valueTypes.size() > variables.size() && variables.front() && variables.back())
+		fatalTypeError(
+			_statement,
+			"Too many components (" +
+			toString(valueTypes.size()) +
+			") in value for variable assignment (" +
+			toString(minNumValues) +
+			" needed)."
+		);
+	bool fillRight = (!variables.back() || variables.front());
+	for (size_t i = 0; i < min(variables.size(), valueTypes.size()); ++i)
+		if (fillRight)
+			assignments[i] = variables[i].get();
+		else
+			assignments[assignments.size() - i - 1] = variables[variables.size() - i - 1].get();
 
-	for (size_t i = 0; i < variables.size(); ++i)
+	for (size_t i = 0; i < assignments.size(); ++i)
 	{
-		if (!variables[i])
+		if (!assignments[i])
 			continue;
-		VariableDeclaration const& var = *variables[i];
+		VariableDeclaration const& var = *assignments[i];
 		solAssert(!var.value(), "Value has to be tied to statement.");
-		TypePointer const& valueComponentType = valueType->components()[i];
+		TypePointer const& valueComponentType = valueTypes[i];
 		solAssert(!!valueComponentType, "");
 		if (!var.annotation().type)
 		{

test/libsolidity/SolidityNameAndTypeResolution.cpp

@@ -2405,6 +2405,65 @@ BOOST_AUTO_TEST_CASE(multi_variable_declaration_fail)
 	SOLIDITY_CHECK_ERROR_TYPE(parseAndAnalyseReturnError(text), TypeError);
 }
 
+BOOST_AUTO_TEST_CASE(multi_variable_declaration_wildcards_fine)
+{
+	char const* text = R"(
+		contract C {
+			function three() returns (uint, uint, uint);
+			function two() returns (uint, uint);
+			function f() {
+				var (a,) = three();
+				var (b,c,) = two();
+				var (,d) = three();
+				var (,e,g) = two();
+		}
+	)";
+	BOOST_CHECK_NO_THROW(parseAndAnalyseReturnError(text));
+}
+
+BOOST_AUTO_TEST_CASE(multi_variable_declaration_wildcards_fail_1)
+{
+	char const* text = R"(
+		contract C {
+			function one() returns (uint);
+			function f() { var (a, b, ) = one(); }
+		}
+	)";
+	SOLIDITY_CHECK_ERROR_TYPE(parseAndAnalyseReturnError(text), TypeError);
+}
+BOOST_AUTO_TEST_CASE(multi_variable_declaration_wildcards_fail_2)
+{
+	char const* text = R"(
+		contract C {
+			function one() returns (uint);
+			function f() { var (a, , ) = one(); }
+		}
+	)";
+	SOLIDITY_CHECK_ERROR_TYPE(parseAndAnalyseReturnError(text), TypeError);
+}
+
+BOOST_AUTO_TEST_CASE(multi_variable_declaration_wildcards_fail_3)
+{
+	char const* text = R"(
+		contract C {
+			function one() returns (uint);
+			function f() { var (, , a) = one(); }
+		}
+	)";
+	SOLIDITY_CHECK_ERROR_TYPE(parseAndAnalyseReturnError(text), TypeError);
+}
+
+BOOST_AUTO_TEST_CASE(multi_variable_declaration_wildcards_fail_4)
+{
+	char const* text = R"(
+		contract C {
+			function one() returns (uint);
+			function f() { var (, a, b) = one(); }
+		}
+	)";
+	SOLIDITY_CHECK_ERROR_TYPE(parseAndAnalyseReturnError(text), TypeError);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 }

test/libsolidity/SolidityParser.cpp

@@ -952,18 +952,6 @@ BOOST_AUTO_TEST_CASE(multi_variable_declaration)
 	BOOST_CHECK_NO_THROW(parseText(text));
 }
 
-BOOST_AUTO_TEST_CASE(multi_variable_declaration_invalid)
-{
-	char const* text = R"(
-		library Lib {
-			function f() {
-				var () = g();
-			}
-		}
-	)";
-	BOOST_CHECK_THROW(parseText(text), ParserError);
-}
-
 BOOST_AUTO_TEST_SUITE_END()
 
 }