[Bug libstdc++/66284] New: std::reference_wrapper is transparent to std::function::target_type

[potswa at mac dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66284

            Bug ID: 66284
           Summary: std::reference_wrapper is transparent to
                    std::function::target_type
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: potswa at mac dot com
  Target Milestone: ---

std::function elides reference_wrappers from the target. This is not
conforming.


#include <functional>
#include <cassert>

struct s { void operator () () {} } g;
std::function< void() > f = std::ref( g );

int main() {
    assert ( f.target< std::reference_wrapper< s > >() );
    assert ( ! f.target< s >() );
}