Is it possible to assign a variable that has a cast prefix? (within a macro)

There are times when its useful to do an assignment in a macro, but this is prevented by casting, eg:

#define SAFE_FREE(v) do { free(v); v = NULL; } while (0)

/* example use */
SAFE_FREE(foo);

however if 'foo' is a 'const int *', a cast is needed.

free((void *)foo);  /* OK */

but this fails because of the cast & assignment

SAFE_FREE((void *)foo);

Gives the warning: error: lvalue required as left operand of assignment

One possible solution is to cast in the macro: eg,

#define SAFE_FREE(v) do { free((void *)v); v = NULL; } while (0)

But I'd prefer not to cast within the macro, since this could end up hiding cases where it should warn.

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Is there a way to assign a variable in a macro that happens to have a cast prefix?