Safer way to free a variable in C

destroy.h

#include <stdlib.h>

/*! Frees the pointer pointed to by the parameter and then sets it to NULL */
#define destroy(pptr) do { \
	__typeof__(*(pptr)) volatile* _pptr = (pptr); \
	if(!_pptr) { \
		break; \
	} \
	free(*_pptr); \
	*_pptr = NULL; \
} while(0)

/*
This is a safer alternative to calling free() directly, and is no more difficult to use.
Instead of calling free(myVar), just call destroy(&myVar). This will call free() on myVar
and then set myVar to NULL in a type safe and optimization safe manner. As with free(),
destroy(NULL) is safe and is a no-op. Works on any compiler that supports __typeof__, which
include gcc and clang but not MSVC unfortunately. If you're using MSVC (Visual Studio), instead
do the following (which I believe is fully type safe due to the ErrorIfNotAtLeastDoublePointer()
macro, but I'm not 100% sure of that).
*/

/*! Frees the pointer pointed to by the parameter and then sets it to NULL */
#define ErrorIfNotAtLeastDoublePointer(pptr) sizeof(&**(pptr))
#define destroy(pptr) (ErrorIfNotAtLeastDoublePointer(pptr), _destroy((volatile void**)(pptr)))
static inline void _destroy(volatile void** pptr) {
	if(!pptr) {
		return;
	}
	
	free((void*)*pptr);
	*pptr = NULL;
}