Merge pull request #1749 from ethereum/compoundForTuples

Disallow compound assignment for tuples.

3 files changed, 18 insertions, 0 deletions

diff --git a/Changelog.md b/Changelog.md
index 178bd39f..8900eab7 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -12,6 +12,7 @@ Bugfixes:
  * Commandline interface: Do not try creating paths ``.`` and ``..``.
  * Parser: Disallow octal literals.
  * Type system: Fix a crash caused by continuing on fatal errors in the code.
+ * Type system: Disallow compound assignment for tuples.
  * Type system: Detect cyclic dependencies between constants.
  * Type system: Disallow arrays with negative length.
  * Type system: Fix a crash related to invalid binary operators.
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 93b183a2..acceffda 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -947,6 +947,11 @@ bool TypeChecker::visit(Assignment const& _assignment)
 	_assignment.annotation().type = t;
 	if (TupleType const* tupleType = dynamic_cast<TupleType const*>(t.get()))
 	{
+		if (_assignment.assignmentOperator() != Token::Assign)
+			typeError(
+				_assignment.location(),
+				"Compound assignment is not allowed for tuple types."
+			);
 		// Sequenced assignments of tuples is not valid, make the result a "void" type.
 		_assignment.annotation().type = make_shared<TupleType>();
 		expectType(_assignment.rightHandSide(), *tupleType);
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 3d82fc70..da3e81ed 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -2992,6 +2992,18 @@ BOOST_AUTO_TEST_CASE(tuple_assignment_from_void_function)
 	CHECK_ERROR(text, TypeError, "Cannot declare variable with void (empty tuple) type.");
 }
 
+BOOST_AUTO_TEST_CASE(tuple_compound_assignment)
+{
+	char const* text = R"(
+		contract C {
+			function f() returns (uint a, uint b) {
+				(a, b) += (1, 1);
+			}
+		}
+	)";
+	CHECK_ERROR(text, TypeError, "Compound assignment is not allowed for tuple types.");
+}
+
 BOOST_AUTO_TEST_CASE(member_access_parser_ambiguity)
 {
 	char const* text = R"(