On Tue, Jul 12, 2005 at 09:41:22AM -0500, Nicholas Nethercote wrote: > I've been looking at the gcc.c-torture tests, it seems some of them rely > on undefined behaviour. For example, 920612-1.c looks like this: > > f(j)int j;{return++j>0;} > main(){if(f((~0U)>>1))abort();exit(0);}
Wow. It appears that it would be legal for a C compiler to optimize f() to int f(int j) { return 1;} since the compiler is entitled to assume that overflow does not occur. Just the same, I don't think we necessarily want to take advantage of every degree of freedom the standards give us (at least, not by default). (Oh, crap; I see a massive thread re-emerging).