Update and extend tests for return expressions.

test/libsolidity/syntaxTests/returnExpressions/single_return_mismatching_number.sol

@@ -0,0 +1,14 @@
+contract C
+{
+    function f() public pure returns (uint)
+    {
+        return;
+    }
+    function g() public pure returns (uint)
+    {
+        return (1, 2);
+    }
+}
+// ----
+// TypeError: (71-78): Return arguments required.
+// TypeError: (143-156): Different number of arguments in return statement than in returns declaration.

test/libsolidity/syntaxTests/returnExpressions/single_return_mismatching_number_named.sol

@@ -0,0 +1,14 @@
+contract C
+{
+    function f() public pure returns (uint a)
+    {
+        return;
+    }
+    function g() public pure returns (uint a)
+    {
+        return (1, 2);
+    }
+}
+// ----
+// TypeError: (73-80): Return arguments required.
+// TypeError: (147-160): Different number of arguments in return statement than in returns declaration.

test/libsolidity/syntaxTests/returnExpressions/tuple_return_mismatching_number.sol

@@ -0,0 +1,19 @@
+contract C
+{
+    function f() public pure returns (uint, uint)
+    {
+        return 1;
+    }
+    function g() public pure returns (uint, uint)
+    {
+        return (1, 2, 3);
+    }
+    function h() public pure returns (uint, uint)
+    {
+        return;
+    }
+}
+// ----
+// TypeError: (77-85): Different number of arguments in return statement than in returns declaration.
+// TypeError: (157-173): Different number of arguments in return statement than in returns declaration.
+// TypeError: (245-252): Return arguments required.

test/libsolidity/syntaxTests/returnExpressions/tuple_return_mismatching_number_named.sol

@@ -0,0 +1,19 @@
+contract C
+{
+    function f() public pure returns (uint a, uint b)
+    {
+        return 1;
+    }
+    function g() public pure returns (uint a, uint b)
+    {
+        return (1, 2, 3);
+    }
+    function h() public pure returns (uint a, uint b)
+    {
+        return;
+    }
+}
+// ----
+// TypeError: (81-89): Different number of arguments in return statement than in returns declaration.
+// TypeError: (165-181): Different number of arguments in return statement than in returns declaration.
+// TypeError: (257-264): Return arguments required.

test/libsolidity/syntaxTests/returnExpressions/valid_returns.sol

@@ -0,0 +1,18 @@
+contract C
+{
+    function f() public pure {
+        return;
+    }
+    function g() public pure returns (uint) {
+        return 1;
+    }
+    function h() public pure returns (uint a) {
+        return 1;
+    }
+    function i() public pure returns (uint, uint) {
+        return (1, 2);
+    }
+    function j() public pure returns (uint a, uint b) {
+        return (1, 2);
+    }
+}