<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/144232>144232</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            __builtin_is_replaceable issues
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          jakubjelinek
      </td>
    </tr>
</table>

<pre>
    ```c
struct E trivially_relocatable_if_eligible replaceable_if_eligible {
  E (E &&);
  E &operator= (E &&) = default;
};

static_assert (__builtin_is_replaceable (E), "");

E &&foo ();

void
bar (E &y)
{
  E x = foo ();
  y = foo ();
}
```

This and also
```c
struct F trivially_relocatable_if_eligible replaceable_if_eligible {
  F (F &&) = default;
  F &operator= (F &&);
};

struct G replaceable_if_eligible { G (G const &) = default; };

struct I replaceable_if_eligible { I &operator= (const I &) = default; };

static_assert (__builtin_is_replaceable (F), "");
static_assert (__builtin_is_replaceable (G), "");
static_assert (__builtin_is_replaceable (I), "");
```

is where my current GCC implementation disagrees with clang trunk.
Sure, none of the classes here are default-movable, but all are replaceable_if_eligible, so that is irrelevant.
I believe all of them are eligible for replacement though.  None of these have any non-static data members nor bases, so the first two bullets of https://eel.is/c++draft/class.prop#6 don't apply, none of these has deleted dtor.
For the first class I've tried to show in bar function that it can be successfully direct initialized from an xvalue of type E and it can be also assigned from an xvalue of type E.
</pre>
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