<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 - Accepts-invalid with parameter pack expansion in lambda capture"
   href="https://bugs.llvm.org/show_bug.cgi?id=47852">47852</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Accepts-invalid with parameter pack expansion in lambda capture
          </td>
        </tr>

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

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </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++17
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>sgiesecke@mozilla.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Referring to this gcc bug report
(<a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97358#c2">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97358#c2</a>), clang accepts this
seemingly invalid code:
```
template <typename... T> void foo (T... x)
{
}

template <typename... T> void bar (T... x)
{
  foo ([x...] { static_cast<void> (x); }...);
}

void
test ()
{
  bar ();
  bar (1);
  bar (2.0, 3LL, 4);
}
```

gcc trunk produces these errors now:
```
<source>: In lambda function:

<source>:7:17: error: parameter packs not expanded with '...':

    7 |   foo ([x...] { static_cast<void> (x); }...);

      |                 ^~~~~~~~~~~~~~~~~~~~~

<source>:7:17: note:         'x'

<source>: In function 'void bar(T ...)':

<source>:7:41: error: expansion pattern '<lambda>' contains no parameter packs

    7 |   foo ([x...] { static_cast<void> (x); }...);

      |                                         ^~~

ASM generation compiler returned: 1

<source>: In lambda function:

<source>:7:17: error: parameter packs not expanded with '...':

    7 |   foo ([x...] { static_cast<void> (x); }...);

      |                 ^~~~~~~~~~~~~~~~~~~~~

<source>:7:17: note:         'x'

<source>: In function 'void bar(T ...)':

<source>:7:41: error: expansion pattern '<lambda>' contains no parameter packs

    7 |   foo ([x...] { static_cast<void> (x); }...);

      |                                         ^~~

Execution build compiler returned: 1
```

Earlier gcc versions produced an ICE, which the mentioned bug was about.</pre>
        </div>
      </p>


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