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py: Add parenthesis to default impl of MP_OBJ_TO_PTR, MP_OBJ_FROM_PTR.

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Unless MICROPY_OBJ_REPR == MICROPY_OBJ_REPR_D, these macros only work with
values and "->"/"." expressions as their sole argument.  In other words,
the macros are broken with expressions which contain operations of lower
precedence than the cast operator.

Depending on situation, the old code either results in compiler error:

 MP_OBJ_TO_PTR(flag ? o1 : o2) expands into "(void *)flag ? o1 : o2",
 which some compiler configurations will reject (e.g. GCC -Wint-conversion
 -Wint-to-pointer-cast -Werror)

Or in an incorrect address calculation:

 For ptr declared as "uint8_t *" the MP_OBJ_FROM_PTR(ptr + off)
 expands into ((mp_obj_t)ptr) + off, resulting in an obviously
 wrong address.

Signed-off-by: Alex Riesen <alexander.riesen@cetitec.com>
This commit is contained in:
Alex Riesen 2023-01-19 12:09:39 +01:00 committed by Damien George
parent 94ee1b629a
commit abaa4abd2d
1 changed files with 2 additions and 2 deletions
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py/obj.h
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@ -313,12 +313,12 @@ typedef union _mp_rom_obj_t {
// Cast mp_obj_t to object pointer
#ifndef MP_OBJ_TO_PTR
#define MP_OBJ_TO_PTR(o) ((void *)o)
#define MP_OBJ_TO_PTR(o) ((void *)(o))
#endif
// Cast object pointer to mp_obj_t
#ifndef MP_OBJ_FROM_PTR
#define MP_OBJ_FROM_PTR(p) ((mp_obj_t)p)
#define MP_OBJ_FROM_PTR(p) ((mp_obj_t)(p))
#endif
// Macros to create objects that are stored in ROM.