<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/113654>113654</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            chrono::time_zone::to_sys() on 'nonexistent time' deviates
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          chrisse74
      </td>
    </tr>
</table>

<pre>
    When calling the (experimental-library feature) std::chrono::time_zone::to_sys() with a 'nonexistent time' (daylight saving) the hour is corrected, but the minute part remains.

According to https://en.cppreference.com/w/cpp/chrono/time_zone/to_sys the correct behaviour would be: "If tp represents a nonexistent time between two UTC time_points, those two time_points will be the same, and that time_point will be returned."

### Example
```
int main()
{
    using namespace std::literals;
    const std::chrono::time_zone* specificTimeZone = std::chrono::get_tzdb().locate_zone("Europe/Vienna");
    {
 const std::chrono::local_seconds inpTime{ std::chrono::local_days{ 2024y / std::chrono::March / 31d } + 2h + 0min };
        const std::chrono::sys_seconds experimentalSystemTimestamp = specificTimeZone->to_sys(inpTime, std::chrono::choose::earliest);
 std::cout << "UTC Timestamp: " << experimentalSystemTimestamp << std::endl;
    }

    {
        const std::chrono::local_seconds inpTime{ std::chrono::local_days{ 2024y / std::chrono::March / 31d } + 2h + 30min };
        const std::chrono::sys_seconds experimentalSystemTimestamp = specificTimeZone->to_sys(inpTime, std::chrono::choose::earliest);
        std::cout << "UTC Timestamp: " << experimentalSystemTimestamp << std::endl;
    }

    {
 const std::chrono::local_seconds inpTime{ std::chrono::local_days{ 2024y / std::chrono::March / 31d } + 3h + 0min };
        const std::chrono::sys_seconds experimentalSystemTimestamp = specificTimeZone->to_sys(inpTime, std::chrono::choose::earliest);
 std::cout << "UTC Timestamp: " << experimentalSystemTimestamp << std::endl;
    }
```

### Output
```
UTC Timestamp: 2024-03-31 01:00:00
UTC Timestamp: 2024-03-31 01:30:00
UTC Timestamp: 2024-03-31 01:00:00
```

### Expected output
I would expect all the local timestamps between 31.03.2024 02:00 and 3:00 being converted to the same UTC timestamp (2024-03-31 01:00:00).


### Environment
* clang version 19.1.2
* compiled using -fexperimental-library
* RHEL 9.4



</pre>
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