<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/144280>144280</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang rejects templated consteval lambda within template
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

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

<pre>
    Consider this piece of code:

```cpp
template <int...>
consteval void foo()
{
 constexpr auto bar = []<int...>() consteval {
    return [](int* p) { *p = 42; };
  };
  (void) bar();
}
```

This compiles with Clang 18 and earlier, as well as with GCC. Later versions of Clang give this error:

```
<source>:5:26: error: variable 'p' cannot be implicitly captured in a lambda with no capture-default specified
    5 |     return [](int* p) { *p = 42; };
```

https://godbolt.org/z/dzqj9Pq9c

Removing `consteval` from the lambda gets the code to compile, as does converting either `foo()` or the lambda into a non-template.

I managed to bisect this down to commit 5e767bd7d16dcdfc1ad8b32ba399f969dd940f57.
</pre>
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