It's easy to detect in the debugger.

The danger is

signed int x; cin>>x; if(x+1<x){return OVERFLOW;}

will, in modern optimizing compilers, never return OVERFLOW

There were quite a few security holes introduced by the compiler with that.

-----

The only problem is to make a standard, one has to define that MAX_INT+1 = 0 or something. Then, whenever one does

signed int x;

cin>> x;

signed int y = x+1;

really turns into

signed int = 0;

if ( x < MAX_INT)

y= x+1

else

y = 1;