The only reason I can imagine for this behaviour is that the compiler/standard writers did not want it. Maybe C just shouldn't include generics. Especially not as part of the macro layer.
The macros in tgmath and more recently stdbit show why those could be necessary. If you have a set of functions for addition with overflow detection, say add_overflow{i,l,ll}, and you have a pair of ptrdiff_t’s or int32_t’s or whatnot that you know are standard integer types, and you want to use the appropriate add_overflow* function, can you do it? With _Generic you can. Without it I think you’re stuck providing sep…
You make it sound alot more complicated. Ignoring the library functions or stuff you can include from safe coding standard headers. You just do something like.
BOOL AddOverflowUnsigned(BYTE* a, BYTE* b, INT32 sizea, INT32 sizeb)
{
BOOL IsMsb = PlatformIsMSB();
BOOL IsLsb = PlatformIsLSB();
//log error
if(!IsMsb && !IsLsb)
return FALSE;
//Early out for overflow. Assuming
if(sizea == sizeb && PlatformIsMSB())
{
BOOL AMsb = (a >> ((sizea * PlatformByteSize()) - 1)) & 1;
BOOL BMsb = (b >> ((sizeb * PlatformByteSize()) - 1)) & 1;
if(AMSB && BMsb)
{
//We overflow, early out.
return FALSE;
}
else if(sizea == sizeb && PlatformIsLSB())
//Code here.
//We add using bitwise operators so we can do it on any size.
//SUM = A XOR B XOR CARRY, return in A
//Impliment algo here.
return TRUE;
}
int main()
{
UINT64 a = 69;
UINT64 b = 420;
if(sizeof(a) !
return AddOverflowUnsinged(&a, &b, sizeof(a), sizeof(b));
}
You also only have a few you can hardcode if you don't do it generic, since all will go back to the primitives of uint8, uint16 ....