[RFC] err |= ios_base::failbit or err = ios_base::failbit?!?

[Nathan Myers]

On Mon, Jan 05, 2004 at 03:42:05PM +0100, Paolo Carlini wrote:
> 
> the standard, in 22.2.2.1.2, p11-12, always talks about:
> 
>    "... ios_base::failbit is assigned to err."
> 
> On the other hand, we have been always doing:
> 
>    err |= ios_base::failbit.
> ... 
> Again, I'm not at all sure that the standard prescribes this.

If, in every case where it prescribes assigning failbit, that point 
could not be reached unless the error state was already clear, then 
they are equivalent.  I suspect that was the reasoning in committee.  
Have you found a case where the code can set failbit but the error 
state was not zero?  (I.e., maybe our use of operator|= is merely 
defensive coding.)

Nathan Myers
ncm-nospam@cantrip.org