Merge pull request #2244 from ethereum/inlineasm-let-multi

Support tuple assignment in inline assembly

libsolidity/inlineasm/AsmAnalysis.cpp

@@ -181,10 +181,21 @@ bool AsmAnalyzer::operator()(FunctionalAssignment const& _assignment)
 
 bool AsmAnalyzer::operator()(assembly::VariableDeclaration const& _varDecl)
 {
+	int const expectedItems = _varDecl.variables.size();
 	int const stackHeight = m_stackHeight;
 	bool success = boost::apply_visitor(*this, *_varDecl.value);
-	solAssert(m_stackHeight - stackHeight == 1, "Invalid value size.");
-	boost::get<Scope::Variable>(m_currentScope->identifiers.at(_varDecl.variable.name)).active = true;
+	if ((m_stackHeight - stackHeight) != expectedItems)
+	{
+		m_errors.push_back(make_shared<Error>(
+			Error::Type::DeclarationError,
+			"Variable count mismatch.",
+			_varDecl.location
+		));
+		return false;
+	}
+
+	for (auto const& variable: _varDecl.variables)
+		boost::get<Scope::Variable>(m_currentScope->identifiers.at(variable.name)).active = true;
 	m_info.stackHeightInfo[&_varDecl] = m_stackHeight;
 	return success;
 }

libsolidity/inlineasm/AsmCodeGen.cpp

@@ -251,11 +251,15 @@ public:
 	void operator()(assembly::VariableDeclaration const& _varDecl)
 	{
 		int height = m_assembly.stackHeight();
+		int expectedItems = _varDecl.variables.size();
 		boost::apply_visitor(*this, *_varDecl.value);
-		expectDeposit(1, height);
-		auto& var = boost::get<Scope::Variable>(m_scope.identifiers.at(_varDecl.variable.name));
-		var.stackHeight = height;
-		var.active = true;
+		expectDeposit(expectedItems, height);
+		for (auto const& variable: _varDecl.variables)
+		{
+			auto& var = boost::get<Scope::Variable>(m_scope.identifiers.at(variable.name));
+			var.stackHeight = height++;
+			var.active = true;
+		}
 	}
 	void operator()(assembly::Block const& _block)
 	{

libsolidity/inlineasm/AsmData.h

@@ -65,7 +65,7 @@ struct FunctionalAssignment { SourceLocation location; Identifier variableName;
 struct FunctionalInstruction { SourceLocation location; Instruction instruction; std::vector<Statement> arguments; };
 struct FunctionCall { SourceLocation location; Identifier functionName; std::vector<Statement> arguments; };
 /// Block-scope variable declaration ("let x:u256 := mload(20:u256)"), non-hoisted
-struct VariableDeclaration { SourceLocation location; TypedName variable; std::shared_ptr<Statement> value; };
+struct VariableDeclaration { SourceLocation location; TypedNameList variables; std::shared_ptr<Statement> value; };
 /// Block that creates a scope (frees declared stack variables)
 struct Block { SourceLocation location; std::vector<Statement> statements; };
 /// Function definition ("function f(a, b) -> (d, e) { ... }")

libsolidity/inlineasm/AsmParser.cpp

@@ -258,7 +258,14 @@ assembly::VariableDeclaration Parser::parseVariableDeclaration()
 {
 	VariableDeclaration varDecl = createWithLocation<VariableDeclaration>();
 	expectToken(Token::Let);
-	varDecl.variable = parseTypedName();
+	while (true)
+	{
+		varDecl.variables.push_back(parseTypedName());
+		if (m_scanner->currentToken() == Token::Comma)
+			expectToken(Token::Comma);
+		else
+			break;
+	}
 	expectToken(Token::Colon);
 	expectToken(Token::Assign);
 	varDecl.value.reset(new Statement(parseExpression()));

libsolidity/inlineasm/AsmPrinter.cpp

@@ -121,7 +121,16 @@ string AsmPrinter::operator()(assembly::FunctionalAssignment const& _functionalA
 
 string AsmPrinter::operator()(assembly::VariableDeclaration const& _variableDeclaration)
 {
-	return "let " + _variableDeclaration.variable.name + appendTypeName(_variableDeclaration.variable.type) + " := " + boost::apply_visitor(*this, *_variableDeclaration.value);
+	string out = "let ";
+	out += boost::algorithm::join(
+		_variableDeclaration.variables | boost::adaptors::transformed(
+			[this](TypedName variable) { return variable.name + appendTypeName(variable.type); }
+		),
+		", "
+	);
+	out += " := ";
+	out += boost::apply_visitor(*this, *_variableDeclaration.value);
+	return out;
 }
 
 string AsmPrinter::operator()(assembly::FunctionDefinition const& _functionDefinition)

libsolidity/inlineasm/AsmScopeFiller.cpp

@@ -59,7 +59,10 @@ bool ScopeFiller::operator()(Label const& _item)
 
 bool ScopeFiller::operator()(assembly::VariableDeclaration const& _varDecl)
 {
-	return registerVariable(_varDecl.variable, _varDecl.location, *m_currentScope);
+	for (auto const& variable: _varDecl.variables)
+		if (!registerVariable(variable, _varDecl.location, *m_currentScope))
+			return false;
+	return true;
 }
 
 bool ScopeFiller::operator()(assembly::FunctionDefinition const& _funDef)

test/libjulia/Parser.cpp

@@ -161,6 +161,11 @@ BOOST_AUTO_TEST_CASE(function_calls)
 	BOOST_CHECK(successParse("{ function f(a:u256) -> b:u256 {} function g(a:u256, b:u256, c:u256) {} function x() { g(1:u256, 2:u256, f(mul(2:u256, 3:u256))) x() } }"));
 }
 
+BOOST_AUTO_TEST_CASE(tuple_assignment)
+{
+	BOOST_CHECK(successParse("{ function f() -> a:u256, b:u256, c:u256 {} let x:u256, y:u256, z:u256 := f() }"));
+}
+
 BOOST_AUTO_TEST_CASE(label)
 {
 	CHECK_ERROR("{ label: }", ParserError, "Labels are not supported.");

test/libsolidity/InlineAssembly.cpp

@@ -161,6 +161,21 @@ BOOST_AUTO_TEST_CASE(vardecl)
 	BOOST_CHECK(successParse("{ let x := 7 }"));
 }
 
+BOOST_AUTO_TEST_CASE(vardecl_name_clashes)
+{
+	CHECK_PARSE_ERROR("{ let x := 1 let x := 2 }", DeclarationError, "Variable name x already taken in this scope.");
+}
+
+BOOST_AUTO_TEST_CASE(vardecl_multi)
+{
+	BOOST_CHECK(successParse("{ function f() -> x, y {} let x, y := f() }"));
+}
+
+BOOST_AUTO_TEST_CASE(vardecl_multi_conflict)
+{
+	CHECK_PARSE_ERROR("{ function f() -> x, y {} let x, x := f() }", DeclarationError, "Variable name x already taken in this scope.");
+}
+
 BOOST_AUTO_TEST_CASE(vardecl_bool)
 {
 	CHECK_PARSE_ERROR("{ let x := true }", ParserError, "True and false are not valid literals.");
@@ -249,6 +264,12 @@ BOOST_AUTO_TEST_CASE(variable_access_cross_functions)
 	CHECK_PARSE_ERROR("{ let x := 2 function g() { x pop } }", DeclarationError, "Identifier not found.");
 }
 
+BOOST_AUTO_TEST_CASE(invalid_tuple_assignment)
+{
+	/// The push(42) is added here to silence the unbalanced stack error, so that there's only one error reported.
+	CHECK_PARSE_ERROR("{ 42 let x, y := 1 }", DeclarationError, "Variable count mismatch.");
+}
+
 BOOST_AUTO_TEST_SUITE_END()
 
 BOOST_AUTO_TEST_SUITE(Printing)
@@ -283,6 +304,11 @@ BOOST_AUTO_TEST_CASE(print_assignments)
 	parsePrintCompare("{\n    let x := mul(2, 3)\n    7\n    =: x\n    x := add(1, 2)\n}");
 }
 
+BOOST_AUTO_TEST_CASE(print_multi_assignments)
+{
+	parsePrintCompare("{\n    function f() -> x, y\n    {\n    }\n    let x, y := f()\n}");
+}
+
 BOOST_AUTO_TEST_CASE(print_string_literals)
 {
 	parsePrintCompare("{\n    \"\\n'\\xab\\x95\\\"\"\n    pop\n}");