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From: "ai.azuma at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug libstdc++/55861] New: [C++11] `std::shared_future::get' is not const-qualified
Date: Thu, 03 Jan 2013 14:12:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55861

             Bug #: 55861
           Summary: [C++11] `std::shared_future::get' is not
                    const-qualified
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: ai.azuma@gmail.com


`std::shared_future<R>::get' member function is specified as const-qualified in
[futures.shared_future]. However, libstdc++'s implementation is not. A testcase
would be as follows;

//--------------------------------------------------
#include <future>

int f()
{
  return 42;
}

int main()
{
  std::shared_future<int> const ftr(std::async(&f));
  ftr.get(); // Line 11
}
//--------------------------------------------------

For the above testcase, GCC 4.8.0 20121230 complains as follows;

main.cpp: In function 'int main()':
main.cpp:11:11: error: passing 'const std::shared_future<int>' as 'this'
argument of 'const _Res& std::shared_future<_Res>::get() [with _Res = int]'
discards qualifiers [-fpermissive]
   ftr.get();
           ^