[Bug libstdc++/45628] std::fstream::tellg invalidates I/O buffer

["potswa at mac dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #54 from potswa at mac dot com  2010-09-17 21:51 -------
Well, for my part, a few years ago I played around with fstream a little,
noticed the tellg requirement was weird (I only discovered it by throwing the
kitchen sink at the problem), wasn't able to interpret the standard well enough
to confirm that GCC was wrong, and decided never to use that part of fstream.
It's not really a common use case anyway.

I think that a minority of people actually consider submitting bugs.

Companies are often very conservative with compilers and qualification, and are
less motivated to report something the further behind they fall. Under what
conditions does a manager actually decide to upgrade? If you're still using
2.95 and considering upgrading to 3.4, why bother reporting a bug against a
compiler which is already obsolete?

> but I do not accept comments
> implying that the current design is just wrong and should be changed to
> something else without a careful analysis, benchmarks, a discussion on the
> mailing list with all the experts involved, etc.

Changes should never occur without analysis one way or another. It's easy to
see that there is a bug? just look at the Standard's requirements on underflow.
As for whether this bug is a symptom of a "wrong design," I don't think so. I'm
getting the impression that you guys got tired after a long redesign process
and oversimplified the state machine.

While fixing bugs in the overambitious design with simultaneous get and put
areas (they might as well be overlapping as synchronized, both are impractical
and not the intent of the Standard), the decision was made to cut back
features, and non-explicit mode switches got lost.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45628