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 11:39:30 +0000
Jonathan Wakely <jwakely@redhat.com> wrote:

> On 16/11/17 14:35 +0300, Petr Ovtchenkov wrote:
> >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
> 
> What about other translation units which have inlined the old
> definition of the template, and expect to find a buffered character in
> that member?

I can say that I can write

  int_type _M_c;

but you see, this is a _private_ member of template, so we should (may?) worry only
about size of object.

Just for clarification: Do you made accent on "buffered" or on "character" ("symbol" in ELF)?

> 
> >reach some consensus on the main issue.
> 
> We don't have any consensus, in fact I don't see anybody agreeing with
> you, and I've previously stated I don't want to support your use case:
> https://gcc.gnu.org/ml/libstdc++/2017-09/msg00100.html
>