py/objstr: Fix eager optimisation of str/bytes addition.

The RHS can only be returned if it is the same type as the LHS.
8 years ago · d279bcff8a
1 changed files with 1 additions and 1 deletions
--- a/py/objstr.c
+++ b/py/objstr.c
@ -354,7 +354,7 @@ mp_obj_t mp_obj_str_binary_op(mp_uint_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
    switch (op) {
        case MP_BINARY_OP_ADD:
        case MP_BINARY_OP_INPLACE_ADD: {
-            if (lhs_len == 0) {
+            if (lhs_len == 0 && mp_obj_get_type(rhs_in) == lhs_type) {
                return rhs_in;
            }
            if (rhs_len == 0) {