py/obj.h: When constructing a small-int cast to mp_uint_t for bit-shift.

dpgeorge · dpgeorge · commit 2bddfd492255 · 2016-04-26T09:51:37.000+01:00
The C standard says that left-shifting a signed value (on the LHS of the
operator) is undefined.  So we cast to an unsigned integer before the
shift.  gcc does not issue a warning about this, but clang does.
diff --git a/py/obj.h b/py/obj.h
@@ -83,7 +83,7 @@ typedef struct _mp_obj_base_t mp_obj_base_t;
 static inline bool MP_OBJ_IS_SMALL_INT(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 1) != 0); }
 #define MP_OBJ_SMALL_INT_VALUE(o) (((mp_int_t)(o)) >> 1)
-#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_int_t)(small_int)) << 1) | 1))
+#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 1) | 1))
 
 static inline bool MP_OBJ_IS_QSTR(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 3) == 2); }
@@ -109,7 +109,7 @@ static inline bool MP_OBJ_IS_OBJ(mp_const_obj_t o)
 static inline bool MP_OBJ_IS_SMALL_INT(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 3) == 1); }
 #define MP_OBJ_SMALL_INT_VALUE(o) (((mp_int_t)(o)) >> 2)
-#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_int_t)(small_int)) << 2) | 1))
+#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 2) | 1))
 
 static inline bool MP_OBJ_IS_QSTR(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 3) == 3); }
@@ -135,7 +135,7 @@ static inline bool MP_OBJ_IS_OBJ(mp_const_obj_t o)
 static inline bool MP_OBJ_IS_SMALL_INT(mp_const_obj_t o)
     { return ((((mp_int_t)(o)) & 1) != 0); }
 #define MP_OBJ_SMALL_INT_VALUE(o) (((mp_int_t)(o)) >> 1)
-#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_int_t)(small_int)) << 1) | 1))
+#define MP_OBJ_NEW_SMALL_INT(small_int) ((mp_obj_t)((((mp_uint_t)(small_int)) << 1) | 1))
 
 #define mp_const_float_e MP_ROM_PTR((mp_obj_t)(((0x402df854 & ~3) | 2) + 0x80800000))
 #define mp_const_float_pi MP_ROM_PTR((mp_obj_t)(((0x40490fdb & ~3) | 2) + 0x80800000))
