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Re: libstdc++/4150: catastrophic performance decrease in C++ code
On Thu, Apr 18, 2002 at 03:18:17AM +0100, Jason Merrill wrote:
> >>>>> "Jason" == Jason Merrill <jason@redhat.com> writes:
>
> ... how often do people
> really read a few characters, write a few characters, and then read a few
> more characters without an intervening seek?
>
> A problem with the current implementation of this is that if we do a read
> on an input/output filebuf, we end up writing the contents of the buffer
> back out to the file, even if we've never requested a write. Oops.
Not only that, it's undefined behavior to switch between reading
and writing without a seek between. We don't have to make it do
anything "reasonable" in that case, but might just as well set
badbit if that were convenient, as a favor to users who might not
otherwise have known they were corrupting their stream state.
Nathan Myers
ncm at cantrip dot org