Add more cases to test.

tests/test-mcore.c

@@ -180,6 +180,12 @@ static void test_let(void)
     M_LET((zz,42), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
       assert( testobj_cmp_ui(zz, 42) == 0);
     }
+    M_LET((zz,z), z2, M_CLASSIC_OPLIST(testobj)) {
+      assert( testobj_cmp_ui(zz, 12) == 0);
+    }
+    M_LET(z3, (zz,42), M_OPEXTEND(M_CLASSIC_OPLIST(testobj), INIT_WITH(testobj_init_set_ui))) {
+      assert( testobj_cmp_ui(zz, 42) == 0);
+    }
     b = true;
     break;
     assert(0);