I can't make sense of what you're saying. See the page I linked in my previous post for an example of what we're talking about: https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html

    #define maxint(a,b) \
      ({int _a = (a), _b = (b); _a > _b ? _a : _b; })

>Note that introducing variable declarations (as we do in maxint) can cause variable shadowing [...] this example using maxint will not [produce correct results]:

    int _a = 1, _b = 2, c;
    c = maxint (_a, _b);