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    <head>
      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - INVOKEing pointer to const&-qualified member function with rvalue results in an error"
   href="https://bugs.llvm.org/show_bug.cgi?id=40524">40524</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>INVOKEing pointer to const&-qualified member function with rvalue results in an error
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libc++
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>unspecified
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>MacOS X
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>All Bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedclangbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>lunow@math.hu-berlin.de
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Following code is rejected:

#include <functional>

struct S
{
    void foo() const&;
};

void bar()
{
    (S{}.*&S::foo)(); // OK
    std::mem_fn(&S::foo)(S{}); // Error
}

Bullet point 1.1 of [func.require] reads (citing N4296)
Define INVOKE (f, t1, t2, ..., tN) as follows:
(t1.*f)(t2, ..., tN) when f is a pointer to a member function of a class T and
t1  is an object of
type T or a reference to an object of type T or a reference to an object of a
type derived from T; 

I assume the problem is that T is substituted with S const& when applicability
of that bullet point is checked, but S const& is not a class, so T must be
substituted with S.</pre>
        </div>
      </p>


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