[Bug c++/31970] New: g++ compiles incorrect c++ code

[Bug c++/31970] New: g++ compiles incorrect c++ code

[asp_ at mail dot ru]

problem with tamplates, an example of incorrect c++ code is here:

http://mx1.ru/super_example.cpp

std::set<int, node_less> b;
std::set<int>::iterator i = b.begin();

the second line should is incorrect, but compiles well.


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           Summary: g++ compiles incorrect c++ code
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: asp_ at mail dot ru


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug c++/31970] g++ compiles incorrect c++ code

[bangerth at dealii dot org]

------- Comment #1 from bangerth at dealii dot org  2007-05-17 15:46 -------
The link you give doesn't work. Can you attach your testcase?
W.


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bangerth at dealii dot org changed:

           What    |Removed                     |Added
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                 CC|                            |bangerth at dealii dot org
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug c++/31970] g++ compiles incorrect c++ code

[asp_ at mail dot ru]

------- Comment #2 from asp_ at mail dot ru  2007-05-18 08:56 -------
Have you received correct link?

http://mx1.ru/~asp/super_example.cpp

Also I've sent email with file attached. Did you receive it?

(In reply to comment #1)
> The link you give doesn't work. Can you attach your testcase?
> W.
> 


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] g++ compiles incorrect c++ code

[pcarlini at suse dot de]

------- Comment #4 from pcarlini at suse dot de  2007-05-18 11:33 -------
Suspending until the next ABI...


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pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] g++ compiles incorrect c++ code

[pcarlini at suse dot de]

------- Comment #3 from pcarlini at suse dot de  2007-05-18 11:33 -------
Yes, that's right, the issue dates back to the original HP / SGI design:
certainly isn't something we can fix without breaking binary compatibility. In
short, it's because _Rb_tree_iterator is templatized only on _Tp.


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pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
          Component|c++                         |libstdc++
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2007-05-18 11:33:02
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] g++ compiles incorrect c++ code

[pcarlini at suse dot de]

------- Comment #5 from pcarlini at suse dot de  2007-05-18 11:45 -------
Note that this is only a Quality of Implementation issue, cannot be considered
a bug, because the type of set::iterator is implementation defined in the
standard, and must only conform to the general requirements in 23.1, must be a
bidirectional iterator.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] set<>::iterator vs type-safety

[pcarlini at suse dot de]

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pcarlini at suse dot de changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |enhancement


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] set<>::iterator vs type-safety

[chris at bubblescope dot net]

------- Comment #6 from chris at bubblescope dot net  2007-06-10 00:10 -------
While fixing this could stop that illegal code, wouldn't it also lead to
increased code size where you have multiple sets of (for example) ints
templated on different comparitors?


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chris at bubblescope dot net changed:

           What    |Removed                     |Added
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                 CC|                            |chris at bubblescope dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] set<>::iterator vs type-safety

[pcarlini at suse dot de]

------- Comment #7 from pcarlini at suse dot de  2007-06-10 00:20 -------
That question occured to me too... Now I'm thinking that probably isn't a real
issue assuming good optimizers, as usual. Do you have a practical example?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] set<>::iterator vs type-safety

[chris at bubblescope dot net]

------- Comment #8 from chris at bubblescope dot net  2007-06-10 08:57 -------
Hmm.. I thought I did have a good example, I had a function that looked like:

template<typename It>
int count_unique(It begin, It end)
{
  set<typename It::value_type> counter(begin, end);
  return counter.size();
}

But, while you might get multiple copies of this function for each iterator
type, the "work parts" (the building of the set and the call to size()) will be
the same regardless of if this is fixed.

The only good example I can come up with would be if someone decided to build
multiple maps of set::iterators, which I've never wanted to do...


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970

[Bug libstdc++/31970] set<>::iterator vs type-safety

[paolo dot carlini at oracle dot com]

------- Comment #9 from paolo dot carlini at oracle dot com  2010-02-13 01:44 -------
Actually, this is a feature, not a bug:

  http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2009/n2913.pdf


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paolo dot carlini at oracle dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31970