Re: [PATCH 3/4] libstdc++: avoid character accumulation in istreambuf_iterator

[Paolo Carlini <paolo dot carlini at oracle dot com>]

Hi,

On 16/11/2017 12:03, Petr Ovtchenkov wrote:
> On Thu, 16 Nov 2017 10:39:02 +0100
> Paolo Carlini <paolo.carlini@oracle.com> wrote:
>
> > Hi,
> >
> > On 16/11/2017 06:31, Petr Ovtchenkov wrote:
> > > Is we really worry about frozen sizeof of instantiated template?
> > Yes we do. See https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html
> > under "Prohibited Changes", point 8.
> >
> > Of course removing the buffering has performance implications too -
> > that's why it's there in the first place!
> "buffering" here is a secondary buffering (after streambuf).
> No relation to performance, but place for incoherence with
> state of attached streambuf.
It depends, we may be dealing with an unbuffered stream. For sure at the 
time we measured a performance impact in some cases, likewise whoever 
implemented it in the first place (not me) otherwise, again, why bothering?

Paolo.