py: Rework mp_convert_member_lookup to properly handle built-ins.

This commit fixes lookups of class members to make it so that built-in
functions that are used as methods/functions of a class work correctly.

The mp_convert_member_lookup() function is pretty much completely changed
by this commit, but for the most part it's just reorganised and the
indenting changed.  The functional changes are:

- staticmethod and classmethod checks moved to later in the if-logic,
  because they are less common and so should be checked after the more
  common cases.

- The explicit mp_obj_is_type(member, &mp_type_type) check is removed
  because it's now subsumed by other, more general tests in this function.

- MP_TYPE_FLAG_BINDS_SELF and MP_TYPE_FLAG_BUILTIN_FUN type flags added to
  make the checks in this function much simpler (now they just test this
  bit in type->flags).

- An extra check is made for mp_obj_is_instance_type(type) to fix lookup of
  built-in functions.

Fixes #1326 and #6198.

Signed-off-by: Damien George <damien@micropython.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/py/obj.h b/py/obj.h
index 6bec57c35..f621b1dad 100644
--- a/py/obj.h
+++ b/py/obj.h
@@ -473,11 +473,15 @@ typedef mp_obj_t (*mp_fun_kw_t)(size_t n, const mp_obj_t *, mp_map_t *);
 // then the type may check for equality against a different type.
 // If MP_TYPE_FLAG_EQ_HAS_NEQ_TEST is clear then the type only implements the __eq__
 // operator and not the __ne__ operator.  If it's set then __ne__ may be implemented.
+// If MP_TYPE_FLAG_BINDS_SELF is set then the type as a method binds self as the first arg.
+// If MP_TYPE_FLAG_BUILTIN_FUN is set then the type is a built-in function type.
 #define MP_TYPE_FLAG_IS_SUBCLASSED (0x0001)
 #define MP_TYPE_FLAG_HAS_SPECIAL_ACCESSORS (0x0002)
 #define MP_TYPE_FLAG_EQ_NOT_REFLEXIVE (0x0004)
 #define MP_TYPE_FLAG_EQ_CHECKS_OTHER_TYPE (0x0008)
 #define MP_TYPE_FLAG_EQ_HAS_NEQ_TEST (0x0010)
+#define MP_TYPE_FLAG_BINDS_SELF (0x0020)
+#define MP_TYPE_FLAG_BUILTIN_FUN (0x0040)
 
 typedef enum {
     PRINT_STR = 0,