<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/137472>137472</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [macOS] openmp fails to find pthread even though it's found by llvm
        </td>
    </tr>

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

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

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

<pre>
    When compiling llvm from source with openmp:
```
(…) 
-- Looking for pthread_create in pthread 
-- Looking for pthread_create in pthread - found 
-- Looking for pthread_rwlock_init in pthread 
-- Looking for pthread_rwlock_init in pthread - found 
-- Looking for pthread_mutex_lock in pthread 
-- Looking for pthread_mutex_lock in pthread - found 
(…) 
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD 
-- Performing Test CMAKE_HAVE_LIBC_PTHREAD - Success 
-- Found Threads: TRUE 
(…) 
-- Looking for pthread_getname_np 
-- Looking for pthread_getname_np - found 
-- Looking for pthread_setname_np 
-- Looking for pthread_setname_np - found 
(…)
-- Check if compiler accepts -pthread 
-- Check if compiler accepts -pthread - no 
CMake Error at /Applications/CMake.app/Contents/share/cmake-4.0/Modules/FindPackageHandleStandardArgs.cmake:227 (message): Could NOT find Threads (missing: Threads_FOUND) Call Stack (most recent call first): /Applications/CMake.app/Contents/share/cmake-4.0/Modules/FindPackageHandleStandardArgs.cmake:591 (_FPHSA_FAILURE_MESSAGE) /Applications/CMake.app/Contents/share/cmake-4.0/Modules/FindThreads.cmake:226 (find_package_handle_standard_args) /Users/holsthein/llvm-project/openmp/runtime/cmake/config-ix.cmake:162 (find_package) /Users/holsthein/llvm-project/openmp/runtime/CMakeLists.txt:283 (include)
```

I then edited the FindThreads in Cmake to return true on apple without the flag and... I got this instead:

```
-- Looking for pthread_create in pthreads
-- Looking for pthread_create in pthreads - not found
-- Looking for pthread_create in pthread
-- Looking for pthread_create in pthread - not found
-- Found Threads: TRUE
CMake Error at /Users/holsthein/llvm-project/openmp/runtime/cmake/LibompUtils.cmake:26 (message):
  LIBOMP: Need pthread interface on Unix-like systems.
Call Stack (most recent call first):
  /Users/holsthein/llvm-project/openmp/runtime/cmake/config-ix.cmake:169 (libomp_error_say)
  /Users/holsthein/llvm-project/openmp/runtime/CMakeLists.txt:283 (include)
```

The way openmp is set up to look for and utilize threads on mac seems to be faulty?
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJy8Vl2P4jYX_jXm5ogoOHxecJFlyDujl9lBC7SXkXFOEhfHjmxnZ-ivr2yY6ewu7cJuWwmJyD7nPM_5NrNWVApxTkYfyOiuxzpXazNf18xx5np7XRznv9aogOumFVKoCqT83EBpdANWd4YjPAtXg25RNS1JUhKnZByff3FK6JQsKZnGJB0TOiMLSlJ_3u_DSuuDN1hqA62rDbIi5waZQxDq9eRmBehDqTv1XUXzLDU_5EIJdwPcZa1rMZvO4UvuLdwAeVHpG8S_ifMaTalN4-1u0TpYPKb_X-b36S_LfPXwYZGvt_eflundD6hAHzYd52jte-XME4Nt4GlJksL20255DdFL3lfoFGswV-31ktemw15t2_617a_9CTYWNfp0lee2QQOMc2ydhf6FrH9fGvqg9JvK4pEdEJbGaAPMAaFZ2rZScOaEVpbQLAhErG39t1YOlfPHtmYGCc14ww7YH0YxodmjLjqJ_jYTqlgzfmAV3jNVSNw4pgpmitRUNgo6JEkpnQCh0watZRV6h5MUFrqTBXx82kIp_kx9kBPWClWFKjid5tnT7uMdoTNYMClh4xg_BEltHRjkqBxwf1MKY90Z4D91cTQbeEJ5tr7fpHmWPqx2n5b543KzSf-39MT_QTbnoLwL79hj-zDm7YlpXgequT1zzZmp7JnGzqLxpmotratRKEIzP5_7rdG_IXeEZufBTDPTKSeaNzr-X6tSVH3x8gY_GNOv4X8KKcRlJayzkXtx3r9p4gGE4rIr8NQvX6yLOH0A5xcOFsJh4b_hXaD8CFx4suA0GHSdUeBMh6AVsLaVp22kOxcUS8kqYKqIoggeoNL-VHgb1vkWPC2rLwlcu2bsLbKhfd15cNyw-27ael8hXJ7Cl4bHzxXRSux10-6ckO-qePzNjCBxCrB6-PD0uPZkPiIWb9yFcmhKxkMWd0q89KU4INijddjYyJO-elQEnH-lM3wbTGXwNkcfvtyy46mCfwLxRzpkWyM8s-P5zQXCgkUHXet7Qmp9CKXCVAGdE1L8jvBahlpBwzhYxMZ64T1CyTrpjiTJesU8KWbJjPVwPpgMR-PZLJ5MevV8MKExnc2KhI1xMJok48Go2M8G09EsmezL8b4n5jSmo3hIxzSmw2QSMcbomI-KeMA5o2xAhjE2TMjIhyPSpuoJazucD5LJcEJ7ku1R2vACpVThM4RbQql_kJp5iOG-qywZxjIE6s2ME06Gp2vD-NOGjO5eQ1IyIYOHYR-91hl-RgV-OlQ1CEfoxJ4aBvbH8KrtdUbOa-da3y-EZoRmlXB1t4-4bs7Z_Dapga1P_Nmdz3P6RwAAAP__lLOyQg">