Add control flow tests for "and" and "or" operators

test/libsolidity/syntaxTests/controlFlow/localStorageVariables/and_operator_err.sol

@@ -0,0 +1,11 @@
+struct S { bool f; }
+
+contract C {
+    function f() public view {
+        S storage s;
+        s.f && true;
+    }
+}
+
+// ----
+// TypeError 3464: (95-96): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/localStorageVariables/or_operator_err.sol

@@ -0,0 +1,11 @@
+struct S { bool f; }
+
+contract C {
+    function f() public view {
+        S storage s;
+        s.f || true;
+    }
+}
+
+// ----
+// TypeError 3464: (95-96): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/userDefinedTypeOperators/binary_operator.sol

@@ -2,16 +2,25 @@ struct S { bool f; }
 
 using {add as +} for S;
 
-function add(S storage x, S storage) pure returns (S storage) { return x; }
+function add(S storage _s, S storage) pure returns (S storage) {
+    return _s;
+    _s.f = true;
+}
 
 contract C {
-    S s;
-    function f() public {
-        S storage x = s;
-        S storage y;
-        x + y;
+    function get() private returns (S storage) {
+	S storage s;
+        return s;
     }
+
+    function f() public {
+        S storage s;
+        get() + s;
+    }
+
 }
 
 // ----
-// TypeError 3464: (230-231): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.
+// Warning 5740: (131-142): Unreachable code.
+// TypeError 3464: (238-239): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.
+// TypeError 3464: (311-312): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.