<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/144829>144829</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libc++] `std::locale(named, unnamed, std::locale::none)` should obtain its name from `named`
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            libc++
      </td>
    </tr>

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

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

<pre>
    Reduced from [`libcxx/test/std/localization/locales/locale/locale.cons/name_construction.pass.cpp`](https://github.com/llvm/llvm-project/blob/351303c28e8feb85c93d8e9480f534653b032735/libcxx/test/std/localization/locales/locale/locale.cons/name_construction.pass.cpp):

```c++
#include <iostream>
#include <locale>

constexpr auto LOCALE_en_US_UTF_8 = "en_US.UTF-8";
int main(int, char**) {
    std::locale en(LOCALE_en_US_UTF_8);
    std::locale unnamed(std::locale(), new std::ctype<char>);

    {
        std::locale loc(en, unnamed, std::locale::none);
        std::cout << loc.name() << '\n';
    }
 return 0;
}
```

Both libstdc++ and MSVC's STL print "en_US.UTF-8" for `loc.name()`, but libc++ prints "*".

I think this can be fixed by swapping the two conditions in `build_name`.

https://github.com/llvm/llvm-project/blob/351303c28e8feb85c93d8e9480f534653b032735/libcxx/src/locale.cpp#L101-L110
</pre>
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