Merge pull request #6649 from ethereum/smt_tuple_asgn

[SMTChecker] Support tuple assignment

test/libsolidity/smtCheckerTests/types/tuple_assignment.sol

@@ -0,0 +1,12 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function g() public pure {
+		uint x;
+		uint y;
+		(x, y) = (2, 4);
+		assert(x == 2);
+		assert(y == 4);
+	}
+}

test/libsolidity/smtCheckerTests/types/tuple_assignment_array.sol

@@ -0,0 +1,12 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint[] a;
+	function g(uint x, uint y) public {
+		require(x != y);
+		(a[x], a[y]) = (2, 4);
+		assert(a[x] == 2);
+		assert(a[y] == 4);
+	}
+}

test/libsolidity/smtCheckerTests/types/tuple_assignment_array_empty.sol

@@ -0,0 +1,14 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	uint[] a;
+	function g(uint x, uint y) public {
+		require(x != y);
+		(, a[y]) = (2, 4);
+		assert(a[x] == 2);
+		assert(a[y] == 4);
+	}
+}
+// ----
+// Warning: (136-153): Assertion violation happens here

test/libsolidity/smtCheckerTests/types/tuple_assignment_empty.sol

@@ -0,0 +1,14 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function g() public pure {
+		uint x;
+		uint y;
+		(x, ) = (2, 4);
+		assert(x == 2);
+		assert(y == 4);
+	}
+}
+// ----
+// Warning: (132-146): Assertion violation happens here

test/libsolidity/smtCheckerTests/types/tuple_declarations.sol

@@ -0,0 +1,13 @@
+pragma experimental SMTChecker;
+
+contract C
+{
+	function g() public pure {
+		(uint x, uint y) = (2, 4);
+		assert(x == 2);
+		assert(y == 4);
+	}
+}
+// ----
+// Warning: (76-101): Assertion checker does not yet support such variable declarations.
+// Warning: (105-119): Assertion violation happens here