1. I want this too.
2. Here is my proposal: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n2366.pdf
3. Yes, variadic functions should be improved.
I think the authors of C89 most likely thought that principle was sufficiently obvious that there was no need to expressly state it. Were it not for the Standard's rule forbidding it, an implementation might plausibly have ignored the possibility of an `int` being accessed via an `unsigned`, but I don't think the authors of the Standard imagined that a non-obtuse compiler writer wouldn't allow for the possibility that something like:
void inc_float_bits(float *f)
{
((unsigned*)f)+=1;
}
The present rules, as written, have absurd corner cases. Given something like:
union U { float f[2]; unsigned ui[2]; } uu;
float test1(int i, int j)
{
uu.f[i] = 1.0f;
uu.ui[j] += 1;
return uu.f[i];
}
float test2(int i, int j)
{
*(uu.f+i) = 1.0f;
*(uu.ui+j) += 1;
return *(uu.f+i);
}
float evil(unsigned *ui, float *f)
{ *f = 1.0f; *ui += 1; return *f; }
int test2(int i, int j)
{
evil(uu.f+i, uu.ui+j);
}
BTW, I think any quality compiler should recognize the possiblity of type punning in the first two, though the Standard doesn't actually require either. Neither clang or gcc, however, recognizes the possibility of type punning in the second even though the behavior of the [] operators in the first are
defined* as equivalent to the second.