Re: [PATCH] streambuf_iterator: avoid debug-dependent behaviour

[Petr Ovtchenkov <ptr at void-ptr dot info>]

On Thu, 21 Sep 2017 21:23:13 +0300
Petr Ovtchenkov <ptr@void-ptr.info> wrote:

> On Fri, 1 Sep 2017 10:10:37 +0100
> Jonathan Wakely <jwakely@redhat.com> wrote:
> 
> > On 24/08/17 12:57 +0300, Petr Ovtchenkov wrote:
> > >Explicit do sgetc from associated streambuf. Avoid debug-dependent
> > >sgetc (within _M_at_eof()):
> > >
> > >       __glibcxx_requires_cond(!_M_at_eof(),
> > >                               _M_message(__gnu_debug::__msg_inc_istreambuf)
> > >                               ._M_iterator(*this));
> > >
> > >Increment operators not require not-eof precoditions.
> > >
> > >Don't unlink associated streambuf if eof detected (in _M_get).
> > >
> > >Clean logic in postfix increment operator.
> > 
> > I find it very hard to understand the reasons for this patch. What
> > you've written above is too terse for me.
> > 
> > Are you fixing a bug? If so, do you have a testcase that demonstrates
> > the problem, and is fixed by these changes?
> 
> Yes, I think I see a bug and I have testcase (at least I think
> that I have it). Looks, that François see this issue too
> and suggest patch. But I'm not satisfied with it.
> 
> My previous suggestion has side effect, that is not acceptable.
> I'm trying to find better solution.

https://gcc.gnu.org/ml/libstdc++/2017-09/msg00088.html