<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/61575>61575</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            std::exclusive_scan narrows to type of initial value
        </td>
    </tr>

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

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

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

<pre>
    ```
#include <vector>
#include <numeric>
#include <iostream>
#include <limits>
#include <cstdint>

int main() {
 std::vector<std::int64_t> vec{1LL << 32, 0};
 std::exclusive_scan(vec.begin(), vec.end(), vec.begin(), 0);
 std::cout << vec[0] << '\n';
        std::cout << vec[1] << '\n';
}
```
I would expect this to output 0 and 1LL<<32, but it outputs 0, 0, because T in std::exclusive_scan is deduced to `int`, which is the computational type that will be used in exclusive_scan. Not sure if this is a library or standard defect, but I think this is pretty bug-prone otherwise. Related to https://github.com/NVIDIA/thrust/issues/1896

https://godbolt.org/z/zMf5M9hGK
</pre>
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