py/objmodule: Add a table of built-in modules with delegation.

This replaces the previous QSTR_null entry in the globals dict which could
leak out to Python (e.g. via iteration of mod.__dict__) and could lead to
crashes.

It results in smaller code size at the expense of turning a lookup into a
loop, but the list it is looping over likely only contains one or two
elements.

To allow a module to register its custom attr function it can use the new
`MP_REGISTER_MODULE_DELEGATION` macro.

This work was funded through GitHub Sponsors.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

1 files changed, 1 insertions, 6 deletions

diff --git a/py/builtinhelp.c b/py/builtinhelp.c
index c60ed44e9c..9bd56cca09 100644
--- a/py/builtinhelp.c
+++ b/py/builtinhelp.c
@@ -151,12 +151,7 @@ STATIC void mp_help_print_obj(const mp_obj_t obj) {
     if (map != NULL) {
         for (uint i = 0; i < map->alloc; i++) {
             mp_obj_t key = map->table[i].key;
-            if (key != MP_OBJ_NULL
-                #if MICROPY_MODULE_ATTR_DELEGATION
-                // MP_MODULE_ATTR_DELEGATION_ENTRY entries have MP_QSTRnull as qstr key.
-                && key != MP_OBJ_NEW_QSTR(MP_QSTRnull)
-                #endif
-                ) {
+            if (key != MP_OBJ_NULL) {
                 mp_help_print_info_about_object(key, map->table[i].value);
             }
         }