https://gcc.gnu.org/bugzilla/show_bug.cgi?id=46906
Tomasz Kamiński <tkaminsk at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |tkaminsk at gcc dot gnu.org
--- Comment #14 from Tomasz Kamiński <tkaminsk at gcc dot gnu.org> ---
> IMO the example program is broken and cannot be used to proof violation of
> contract of the library. This is so, because istreambuf_iterator is an input
> iterator and any usage of operator++ potentially invalidates copies of the
> iterator (see FDIS, Table 107, expression r++).
I believe that this argument applies for generic code, that accept any istream
iterator. However, any particular iterator may provide a stronger guarantee
that above (I see that as minimum). The wording for operator*
(https://eel.is/c++draft/istreambuf.iterator#ops-1) seem to be clear in this
case:
> Returns: The character obtained via the streambuf member sbuf_->sgetc().
Which for me clearly state that *it on each call obtain character from
sbuf_->getc(), and if the stream is modified, the modification should be
visible. I.e. libstdc++ is one that is conforming here, and no caching is
allowed.
