Optimisations and undefined behaviour

[Andrew Haley]

On 11/09/2015 02:56 PM, Richard Earnshaw wrote:
> On 09/11/15 14:29, Andrew Haley wrote:

>> Here it is again:
>>
>> int foo(int x) {
>> 	if (x > 1290) {
>> 		printf("X is wrong here %d, but we don't care\n", x);
>> 	}
>> 	return x*x*x;
>>
>> Here, the printf writes to a stream then the UB happens.  
> 
> Not if setvbuf has been used to make the stream unbuffered.

It hasn't.  And I know it hasn't because it's my example.

And besides, the UB might cause the computer to crash before the data
has been written to stdout by the kernel; the same reasoning applies.

Andrew.