<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - contexpr return type from a member function is allowed where it should not"
   href="https://bugs.llvm.org/show_bug.cgi?id=32904">32904</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>contexpr return type from a member function is allowed where it should not
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>clang
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>4.0
          </td>
        </tr>

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

        <tr>
          <th>OS</th>
          <td>Linux
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>C++14
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>mikhail.katliar@tuebingen.mpg.de
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvm-bugs@lists.llvm.org
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Minimal example:

#include <iostream>

int f()
{
    static int n = 42;
    return n++;
}

struct A
{
    A()
    :   f_(&f)
    {

    }

    int constexpr n() const
    {
        return f_();
    }

    int (*f_)();
};

int main(int, char **)
{
    std::cout << A().n() << std::endl;
    std::cout << A().n() << std::endl;

    return 0;
}

Build with clang:
$ clang++ -std=c++14 example.cpp

Run:
$ ./a.out
42
43

Try building with gcc:
$ g++ -std=c++14 example.cpp
example.cpp:17:19: error: enclosing class of constexpr non-static member
function ‘int A::n() const’ is not a literal type
     int constexpr n() const
                   ^
example.cpp:9:8: note: ‘A’ is not literal because:
 struct A
        ^
example.cpp:9:8: note:   ‘A’ is not an aggregate, does not have a trivial
default constructor, and has no constexpr constructor that is not a copy or
move constructor</pre>
        </div>
      </p>


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