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      <base href="https://bugs.llvm.org/">
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    <body><span class="vcard"><a class="email" href="mailto:david@doublewise.net" title="David Stone <david@doublewise.net>"> <span class="fn">David Stone</span></a>
</span> changed
          <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED - -Wunneeded-member-function incorrect for default constructor"
   href="https://bugs.llvm.org/show_bug.cgi?id=25084">bug 25084</a>
          <br>
             <table border="1" cellspacing="0" cellpadding="8">
          <tr>
            <th>What</th>
            <th>Removed</th>
            <th>Added</th>
          </tr>

         <tr>
           <td style="text-align:right;">Status</td>
           <td>RESOLVED
           </td>
           <td>REOPENED
           </td>
         </tr>

         <tr>
           <td style="text-align:right;">Resolution</td>
           <td>INVALID
           </td>
           <td>---
           </td>
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            <b><a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED - -Wunneeded-member-function incorrect for default constructor"
   href="https://bugs.llvm.org/show_bug.cgi?id=25084#c2">Comment # 2</a>
              on <a class="bz_bug_link 
          bz_status_REOPENED "
   title="REOPENED - -Wunneeded-member-function incorrect for default constructor"
   href="https://bugs.llvm.org/show_bug.cgi?id=25084">bug 25084</a>
              from <span class="vcard"><a class="email" href="mailto:david@doublewise.net" title="David Stone <david@doublewise.net>"> <span class="fn">David Stone</span></a>
</span></b>
        <pre>Sorry, I had incorrectly reduced this bug when I initially posted this. Here is
the correct test case:

#include <type_traits>

namespace {

struct default_constructible {
        default_constructible() = default;
        default_constructible(default_constructible const &) = delete;
        default_constructible(default_constructible &&) = delete;
};

} // namespace

static_assert(std::is_default_constructible_v<default_constructible>);




<a href="https://godbolt.org/z/kieneu">https://godbolt.org/z/kieneu</a>



We need to explicitly default the default constructor because we delete another
special member function. The code does not compile without the `= default`
line. However, it is used only at compile time, and thus the function does not
need to be emitted for use at link-time, which is presumably why this warning
is being triggered.</pre>
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