[Bug c++/61512] New: libstd++ postfix operator hangs

[Bug c++/61512] New: libstd++ postfix operator hangs

[srohit.pda at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

            Bug ID: 61512
           Summary: libstd++ postfix operator hangs
           Product: gcc
           Version: 4.4.7
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: srohit.pda at gmail dot com

Created attachment 32942
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=32942&action=edit
testcase files- source code, pre-processed code, assembly code, object code and
executable

Following code hangs forever in postfix operator.


#include <iostream>
#include <set>

int main()
{
  std::set<int> empty;
  std::set<int>::iterator iter = empty.begin() ;
  while (iter++ != empty.end())
  {
        std::cout << *iter << "\n";
  }
  return 0;
}

[Bug c++/61512] libstd++ postfix operator hangs

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #1 from Marc Glisse <glisse at gcc dot gnu.org> ---
You are not allowed to call ++ on an iterator if calling * on it would be
illegal.

[Bug c++/61512] libstd++ postfix operator hangs

[srohit.pda at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #2 from Rohit Sharma <srohit.pda at gmail dot com> ---
(In reply to Marc Glisse from comment #1)
> You are not allowed to call ++ on an iterator if calling * on it would be
> illegal.

I may agree to your comment Marc. 

Hanging code is manifestation is a sure bug - either in libstdc++ or gcc. Do
you agree?

[Bug c++/61512] libstd++ postfix operator hangs

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #3 from Marc Glisse <glisse at gcc dot gnu.org> ---
No, the bug is in your code. Try compiling with -D_GLIBCXX_DEBUG for a more
meaningful output.

[Bug c++/61512] libstd++ postfix operator hangs

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

Jonathan Wakely <redi at gcc dot gnu.org> changed:

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

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Invalid, do not increment a non-incrementable iterator.

[Bug c++/61512] libstd++ postfix operator hangs

[srohit.pda at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #5 from Rohit Sharma <srohit.pda at gmail dot com> ---
Thank you Marc for the flag.

Compiling with that flag and running it, code "abort (core dumped)" - which I
take is reasonable behavior on a bad code.

bests.
-Rohit

[Bug c++/61512] libstd++ postfix operator hangs

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #6 from Marc Glisse <glisse at gcc dot gnu.org> ---
Really? With _GLIBCXX_DEBUG, your program is supposed to print the following
message (even with the old gcc-4.4 you reported this against):

/usr/include/c++/4.8/debug/safe_iterator.h:307:error: attempt to increment 
    a past-the-end iterator.

Objects involved in the operation:
iterator "this" @ 0x0x7fff4a666fb0 {
type =
N11__gnu_debug14_Safe_iteratorISt23_Rb_tree_const_iteratorIiENSt7__debug3setIiSt4lessIiESaIiEEEEE
(mutable iterator);
  state = past-the-end;
  references sequence with type `NSt7__debug3setIiSt4lessIiESaIiEEE' @
0x0x7fff4a666fe0
}

[Bug c++/61512] libstd++ postfix operator hangs

[srohit.pda at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61512

--- Comment #7 from Rohit Sharma <srohit.pda at gmail dot com> ---
Yes, it did print that message clearly before core-dump.

thank you much.
-Rohit