<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65125>65125</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [libcxx] `error: no member named 'par_unseq' in namespace 'std::execution'`
        </td>
    </tr>

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

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

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

<pre>
    I stumbled upon something strange. If I compile the program
```
$ cat src/foreach_minimal.cpp 
#include <algorithm>
#include <vector>
#include <execution>

void initzero(int& n){n=0;}

int main()
{
 std::vector<int> v(100);
 std::for_each(std::execution::par_unseq,v.begin(), v.end(),initzero);
 return 0;
}
```
with
```
$ clang++ -O1 -Wall -std=c++2a -L/dev/shm/rydahl1/LLVM/install/lib/x86_64-unknown-linux-gnu/ -ltbb src/foreach_minimal.cpp -o bin/foreach_minimal
```
the system version of libc++ on my machine allows me to compile the naive program. If I instead add `-stdlib=libc++`, I get
```
error: no member named 'par_unseq' in namespace 'std::execution'
   10 | std::for_each(std::execution::par_unseq,v.begin(), v.end(),initzero);
```
I used the commit `eb5fe55b810cc186d2ff31b64294b0d666d623da` for the installation.
</pre>
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