[Bug libstdc++/59768] New: [4.8 Regression] std::thread constructor not handling reference_wrapper correctly

["Casey at Carter dot net" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59768

            Bug ID: 59768
           Summary: [4.8 Regression] std::thread constructor not handling
                    reference_wrapper correctly
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Casey at Carter dot net

Created attachment 31809
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31809&action=edit
Minimal test case.

Originally reported in Stackoverflow question
http://stackoverflow.com/questions/21059115/c11-thread-class-how-to-use-a-class-member-function

Construction of a std::thread with a pointer-to-member-function and
reference_wrapper as in this simple program:

#include <functional>
#include <iostream>
#include <thread>

class A {
public:
    void foo(int n) { std::cout << n << std::endl; }
};

int main()
{
    A a;

    std::thread t1(&A::foo, std::ref(a), 100);
    t1.join();
}

incorrectly results in a compilation error:

In file included from /usr/local/include/c++/4.8.2/thread:39:0,
                  from check.cc:2:
/usr/local/include/c++/4.8.2/functional: In instantiation of âstruct
std::_Bind_simple<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>,
int)>â:
/usr/local/include/c++/4.8.2/thread:137:47:   required from
âstd::thread::thread(_Callable&&, _Args&& ...) [with _Callable = void
(A::*)(int); _Args = {std::reference_wrapper<A>, int}]â
check.cc:13:42:   required from here
/usr/local/include/c++/4.8.2/functional:1697:61: errorïno type named âtypeâ in
âclass std::result_of<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>,
int)>â
        typedef typename result_of<_Callable(_Args...)>::type result_type;
                                                              ^
/usr/local/include/c++/4.8.2/functional:1727:9: errorïno type named âtypeâ in
âclass std::result_of<std::_Mem_fn<void (A::*)(int)>(std::reference_wrapper<A>,
int)>â
          _M_invoke(_Index_tuple<_Indices...>)
          ^

I reduced the original program to:

#include <functional>
#include <thread>

int main() {
  struct A { void foo(int) {} } a;
  std::thread(&A::foo, std::ref(a), 100).join();
}

which still displays the erroneous behavior. Note that std::bind(&A::foo,
std::ref(a), 100) *does* compile correctly, as does a similar program in which
the member function foo has no parameter.

Program is incorrectly compiled by g++ 4.8.2 and 4.8.1, correctly compiles with
4.6.4 and 4.7.3.