The TIP 481 machinery compels all callers to add typecasting to their NULL

arguments, which is quite unwelcome.  This branch is a first attempt to
work around this problem.  So far not a working solution because of the
insistence if the sizeof(.) operator that it have an argument of known,
non-void type.  Finding the magic bridge to satisfy that for all three
inputs -- a (size_t *), a (int *), and a NULL -- is still elusive.

generic/tclDecls.h

@@ -4201,30 +4201,42 @@ extern const TclStubs *tclStubsPtr;
 #define Tcl_GetUnicode(objPtr) \
 	Tcl_GetUnicodeFromObj(objPtr, (int *)NULL)
 #undef Tcl_GetBytesFromObj
+#define Tcl_GetBytesFromObj(interp, objPtr, x) \
+	TclGetBytesFromObjInner(interp, objPtr, ((x) ? (x) : (int *)NULL))
 #ifdef TCL_NO_DEPRECATED
 #undef Tcl_GetStringFromObj
 #undef Tcl_GetUnicodeFromObj
 #undef Tcl_GetByteArrayFromObj
+#define Tcl_GetByteArrayFromObj(objPtr, x) \
+	TclGetByteArrayFromObjInner(objPtr, ((x) ? (x) : (int *)NULL))
 #endif
 #if defined(USE_TCL_STUBS)
-#define Tcl_GetBytesFromObj(interp, objPtr, sizePtr) \
-	(sizeof(*sizePtr) <= sizeof(int) ? tclStubsPtr->tclGetBytesFromObj(interp, objPtr, (int *)sizePtr) : tclStubsPtr->tcl_GetBytesFromObj(interp, objPtr, (size_t *)sizePtr))
+#define TclGetBytesFromObjInner(interp, objPtr, sizePtr) \
+	(sizeof(*sizePtr) <= sizeof(int) ? \
+	tclStubsPtr->tclGetBytesFromObj(interp, objPtr, (int *)sizePtr) : \
+	tclStubsPtr->tcl_GetBytesFromObj(interp, objPtr, (size_t *)sizePtr))
 #ifdef TCL_NO_DEPRECATED
 #define Tcl_GetStringFromObj(objPtr, sizePtr) \
 	(sizeof(*sizePtr) <= sizeof(int) ? tclStubsPtr->tcl_GetStringFromObj(objPtr, (int *)sizePtr) : tclStubsPtr->tclGetStringFromObj(objPtr, (size_t *)sizePtr))
-#define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
-	(sizeof(*sizePtr) <= sizeof(int) ? tclStubsPtr->tcl_GetByteArrayFromObj(objPtr, (int *)sizePtr) : tclStubsPtr->tclGetByteArrayFromObj(objPtr, (size_t *)sizePtr))
+#define TclGetByteArrayFromObjInner(objPtr, sizePtr) \
+	(sizeof(*sizePtr) <= sizeof(int) ? \
+	tclStubsPtr->tcl_GetByteArrayFromObj(objPtr, (int *)sizePtr) : \
+	tclStubsPtr->tclGetByteArrayFromObj(objPtr, (size_t *)sizePtr))
 #define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
 	(sizeof(*sizePtr) <= sizeof(int) ? tclStubsPtr->tcl_GetUnicodeFromObj(objPtr, (int *)sizePtr) : tclStubsPtr->tclGetUnicodeFromObj(objPtr, (size_t *)sizePtr))
 #endif
 #else
-#define Tcl_GetBytesFromObj(interp, objPtr, sizePtr) \
-	(sizeof(*sizePtr) <= sizeof(int) ? (TclGetBytesFromObj)(interp, objPtr, (int *)sizePtr) : (Tcl_GetBytesFromObj)(interp, objPtr, (size_t *)sizePtr))
+#define TclGetBytesFromObjInner(interp, objPtr, sizePtr) \
+	(sizeof(*sizePtr) <= sizeof(int) ? \
+	(TclGetBytesFromObj)(interp, objPtr, (int *)sizePtr) : \
+	(Tcl_GetBytesFromObj)(interp, objPtr, (size_t *)sizePtr))
 #ifdef TCL_NO_DEPRECATED
 #define Tcl_GetStringFromObj(objPtr, sizePtr) \
 	(sizeof(*sizePtr) <= sizeof(int) ? (Tcl_GetStringFromObj)(objPtr, (int *)sizePtr) : (TclGetStringFromObj)(objPtr, (size_t *)sizePtr))
-#define Tcl_GetByteArrayFromObj(objPtr, sizePtr) \
-	(sizeof(*sizePtr) <= sizeof(int) ? (Tcl_GetByteArrayFromObj)(objPtr, (int *)sizePtr) : TclGetByteArrayFromObj(objPtr, (size_t *)sizePtr))
+#define TclGetByteArrayFromObjInner(objPtr, sizePtr) \
+	(sizeof(*sizePtr) <= sizeof(int) ? \
+	(Tcl_GetByteArrayFromObj)(objPtr, (int *)sizePtr) : \
+	(TclGetByteArrayFromObj)(objPtr, (size_t *)sizePtr))
 #define Tcl_GetUnicodeFromObj(objPtr, sizePtr) \
 	(sizeof(*sizePtr) <= sizeof(int) ? (Tcl_GetUnicodeFromObj)(objPtr, (int *)sizePtr) : TclGetUnicodeFromObj(objPtr, (size_t *)sizePtr))
 #endif