Re: Defect Report: istreambuf_iterator should have an operator->()

From:
"James Kanze" <james.kanze@gmail.com>
Newsgroups:
comp.std.c++
Date:
Mon, 26 Mar 2007 08:40:32 CST
Message-ID:
<1174900910.996128.148860@y80g2000hsf.googlegroups.com>
On Mar 26, 1:40 am, nore...@this.is.invalid (Niels Dekker - no return
address) wrote:

Okay, okay, I'm converted! Greg Herlihy has clearly demonstrated that a
user defined input iterator should have an operator->(), even if its
value type is a built-in type. And as Howard Hinnant remarked that the
input iterator istreambuf_iterator doesn't have one, this must be a
defect!

Based on Greg's example, the following code demonstrates the issue:

  #include <iostream>
  #include <fstream>
  #include <streambuf>

  typedef char C;
  int main ()
  {
    std::ifstream s("filename", std::ios::in);
    std::istreambuf_iterator<char> i(s);

    (*i).~C(); // This is well-formed...


Well formed, perhaps, but it looks like undefined behavior at
execution. (Maybe not in the case of char; char's rather
special in this regard. But definitily in the case of other
types.)

    i->~C(); // ... so this should be supported!
  }


I'm not convinced, at least not for istreambuf_iterator (which
is a bit special).

--
James Kanze (GABI Software) email:james.kanze@gmail.com
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