Re: [PATCH 1/4] Revert "2017-10-04 Petr Ovtchenkov <ptr at void-ptr dot info>"

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

On Thu, 16 Nov 2017 10:56:29 +0000
Jonathan Wakely <jwakely@redhat.com> wrote:

> On 10/10/17 22:55 +0300, Petr Ovtchenkov wrote:
> >This reverts commit 0dfbafdf338cc6899d146add5161e52efb02c067
> >(svn r253417).
> 
> I'm not even going to bother to review patches sent without any
> explanation or rationale for the change.

https://gcc.gnu.org/ml/libstdc++/2017-11/msg00044.html

Along with "violate principles of C++ objects life cycle",
the side-effect is

  - Make istreambuf_iterator::_M_sbuf immutable
  - streambuf_iterator: avoid debug-dependent behaviour

I should underline, that "_M_sbuf = 0" when istreambuf_iterator
see eof, lead to cripple lifecycle of istreambuf_iterator
object and [almost] block usage of istreambuf_iterator
for entities other then immutable files.

All tests from 24_iterators and 25_algorithms passed,
so I expect it conform to Standard.

This is series of patches, not single patch because
I keep in mind technology aspect---easy transfer
to branches other then trunk.

> 
> I will repeat what Paolo said: changing the ABI is not acceptable.

I will repeat special for you:

<snip>
Is we really worry about frozen sizeof of instantiated template?
(Removed private template member).

If yes, than

   int_type __dummy;

is our all.
</snip>

I.e. problem can be easy resolved---i.e. ABI will not suffer, if we will
reach some consensus on the main issue. 

>