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py: Raise a ValueError if range() step is zero. 

Following CPython.  Otherwise one gets either an infinite loop (if code is
optimised by the uPy compiler) or possibly a divide-by-zero CPU exception.
This commit is contained in:
Damien George 2017-04-05 10:50:26 +10:00
parent 546ef301a1
commit de9b53695d
2 changed files with 6 additions and 3 deletions
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5
py/compile.c
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@ -1444,8 +1444,9 @@ STATIC void compile_for_stmt(compiler_t *comp, mp_parse_node_struct_t *pns) {
pn_range_start = args[0];
pn_range_end = args[1];
pn_range_step = args[2];
// We need to know sign of step. This is possible only if it's constant
if (!MP_PARSE_NODE_IS_SMALL_INT(pn_range_step)) {
// the step must be a non-zero constant integer to do the optimisation
if (!MP_PARSE_NODE_IS_SMALL_INT(pn_range_step)
|| MP_PARSE_NODE_LEAF_SMALL_INT(pn_range_step) == 0) {
optimize = false;
}
}

4
py/objrange.c
View File

@ -105,8 +105,10 @@ STATIC mp_obj_t range_make_new(const mp_obj_type_t *type, size_t n_args, size_t
o->start = mp_obj_get_int(args[0]);
o->stop = mp_obj_get_int(args[1]);
if (n_args == 3) {
// TODO check step is non-zero
o->step = mp_obj_get_int(args[2]);
if (o->step == 0) {
mp_raise_ValueError("zero step");
}
}
}