<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/60536>60536</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            libc++ rejects `std::format("{{:{}^1}}", ' ')` 
        </td>
    </tr>

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

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

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

<pre>
    The following valid format strings are rejected by libc++.

```cpp
#include <format>
#include <iostream>

int main() {
  std::cout << std::format("{{:{}^5}}", ' ');
}
```
https://godbolt.org/z/9bsPP7bjq
</pre>
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