[Bug libstdc++/69243] New: std::function summons a non-null pointer out of thin air

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69243

            Bug ID: 69243
           Summary: std::function summons a non-null pointer out of thin
                    air
           Product: gcc
           Version: 5.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org
  Target Milestone: ---

#include <functional>
#include <cassert>

struct X { };

int main()
{
  void (X::*mf)() = nullptr;
  std::function<void(X&)> f = mf;
  auto tgt = f.target<void (X::*)()>();
  assert( tgt == nullptr );
}

a.out: ff.cc:11: int main(): Assertion `tgt == nullptr' failed.
Aborted (core dumped)