py/objgenerator: Check stack before resuming a generator

This turns a hard crash in a recursive generator into
a 'maximum recursion depth exceeded' exception.

py/objgenerator.c

@@ -32,6 +32,7 @@
 #include "py/bc.h"
 #include "py/objgenerator.h"
 #include "py/objfun.h"
+#include "py/stackctrl.h"
 
 /******************************************************************************/
 /* generator wrapper                                                          */
@@ -92,6 +93,7 @@ STATIC void gen_instance_print(const mp_print_t *print, mp_obj_t self_in, mp_pri
 }
 
 mp_vm_return_kind_t mp_obj_gen_resume(mp_obj_t self_in, mp_obj_t send_value, mp_obj_t throw_value, mp_obj_t *ret_val) {
+    MP_STACK_CHECK();
     mp_check_self(MP_OBJ_IS_TYPE(self_in, &mp_type_gen_instance));
     mp_obj_gen_instance_t *self = MP_OBJ_TO_PTR(self_in);
     if (self->code_state.ip == 0) {

tests/basics/gen_stack_overflow.py

@@ -0,0 +1,7 @@
+def gen():
+    yield from gen()
+
+try:
+    print(list(gen()))
+except RuntimeError:
+    print("RuntimeError")

tests/run-tests

@@ -345,7 +345,7 @@ def run_tests(pyb, tests, args, base_path=".", num_threads=1):
     # Remove them from the below when they work
     if args.emit == 'native':
         skip_tests.update({'basics/%s.py' % t for t in 'gen_yield_from gen_yield_from_close gen_yield_from_ducktype gen_yield_from_exc gen_yield_from_iter gen_yield_from_send gen_yield_from_stopped gen_yield_from_throw gen_yield_from_throw2 gen_yield_from_throw3 generator1 generator2 generator_args generator_close generator_closure generator_exc generator_return generator_send'.split()}) # require yield
-        skip_tests.update({'basics/%s.py' % t for t in 'bytes_gen class_store_class globals_del string_join'.split()}) # require yield
+        skip_tests.update({'basics/%s.py' % t for t in 'bytes_gen class_store_class globals_del string_join gen_stack_overflow'.split()}) # require yield
         skip_tests.update({'basics/async_%s.py' % t for t in 'def await await2 for for2 with with2'.split()}) # require yield
         skip_tests.update({'basics/%s.py' % t for t in 'try_reraise try_reraise2'.split()}) # require raise_varargs
         skip_tests.update({'basics/%s.py' % t for t in 'with_break with_continue with_return'.split()}) # require complete with support