<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJzNV1tv6zYM_jXOixDDlnN9yEPaNDvBekObYcBeDMVWEq2y5CPJSbNfP1J23LQJ0O6cDVhgOLZJkRTJjyJXOj9MFgEdFsSZg1Ab4jRhZSkPxG0NZ3nXMiWc-IsbEtCRg7eAjj2TIg8lV3ePpGSGScklMOXkOqBXcMUxKY3eGFYE9Bp4cyIcsZwXlkjxwsmCbLgjjBiWcWJ4qY0j-63ItqhlOp8ufkU1woK2IfBlrgIVB1zAmaxXaUUKlj08k5jCInqnleOGH-AxDKJZEE3r-3IrLAgilcXdfdMFXxm-J5lk8BonDesgai7_-oFrx40VoC5OwihsWJbMwA6CZEpeR4N00Oui03g3Z2YvFI1D2jJ6N5JC51wie6mteK1JC2Udei6fCYOkgM4ra-AudcYk_OvS4ZvcgRfnK6EuGlvfT7wRxh_8ga6CcC3ggyR3LCOPRqOfaRSPwc3v3HU0mpO1llLv0WnHSL7XnpVl84UmQmWyyjkJkusdz5yG7dxcIgptHbijeCP7u1AOrBcKjcJn8G2GeZNtmSGZBjcBZQpfd0H_KujPwOhm-fCqfiDAkJSGbQpGdFG2OdlS3xgJAa87kTWCrcvB93AdDb8GC8A-iDrYMIrRjh5Fjck7Ec2qTFcOdwYXrggtoACWYfY2X1tWrnJ5IiQYzo6PhrvKKBK11Jb2IdYZ7E1AwpCdYAS_fpoxdO5zuEYl6d5-kmRSrEh3rQHY4MTu-gj-IJnV5YB0_XZmWQtzdHdaEy1b81TAipSZbMtNiCkyiHzhgISCR9BfMrfFjwDJjdhxRawmSJVCvWCyWcchfCJ7AciWntKUGVOprhMFcq4MMwd0MRYWYFFIRJ9cdNrD3WO6fHi4TW8XV0_Tp8XNM2wgGN7Admd6r6QGy70fcNPdGuShNbDFudNaIq3eT-2fZm_5AX2Fsu9_u0uX355upjMUTAFhAJzsnin9h1bouogsn6f36cPjcvFw75VTKjZKG54qrQRkoakKDujMUygTleQWeGIEboi6Q0ixixuT6HOsxe4dXIG9hKRE36DeprxelBA3X8GkH7j82t-nT_eL-1-wftWl7vl4YOCnnLmmyEMSlAJTpx_3oqRFMCFPmFZ6TRA5ZESYI9FrFEVxNB6NxnEyIqvjWUSWMSKpBSFAPnqDV5rGF4BMry9w-ACxd2jHiuRpJwBuKk9yrSopPRMd1dFIpnXVBwhEr3GE5q57-cmmvHExCREcsACSm-fhV0XlefZRFCVp-gKyhNrpF54WIjPaMfvyQSSkJGisc_O95CEb9elHqUlTdb9o1knYjmIeDd8JXVmyN8Lxz8LotdWx_Eog07QOZbpilv9oPN8LaSvzFzZMY7Y6D-m_nW_NajqqlIWiALVdaqzX1wRPQp-CAR38A6sjHp9nz__d6piP--fZ-YPwYWeiev8JfPo_DZ9bdDC2lngaSr2C3hZ7cZDauhneW1jR3hmuojedqMpT4DcCxJ1pWx6rqD-R62JMk1Ec-SYHjlA4iza-8AEfnEYfIAu6z1Fb1rS0XnLuT999pMaFODqk2r6m-UExCMAlL4_X-foccXXoagXpXpsXnEW-GLdBlDP25ohLnfPc6AJmD3DsglQqh17f4dGJboW_LdtBWVtZbnbgEPCFH0Ay6Ob9HAQH79vE0_SV2AEJBuNQG1pWOV0gzQ8x7WC15h54eH6DdpRlK9D0veLYA2cZt5as0TokUd_q-DjYra5kTpR27dGKHKcr_CzFYXA5rmmN4n4UKyo42ZhE0qHe4xYGGI5AZrY2BRMObW-YSiOwQ8F5oZNPknycjFkHNrbVZvK9W3YqIydb50qLOULncG2E21arEHrWk_4S_rowT_wJ9QNehbUVxwarn0SDYWc7geQdjjjNxpSNE94fjfmoxwc0H3AWJQO26ki24tJOcA6gVMGI5kXAM4wFnZ-3QExoRGEuioZxPx7TQTgc5lGfjXuDnA6yHNT0Ig6YkCHKCbXZdMzEi1xVGwtEKayzb0RmfXnkk3pw6TjhJJ_MmbT8fMDG0dBBTwzRg5a2Hlib5hezselBx2QP2zpJu5N8alLQtsNxx-9v4jf3N_w3vVU>53067</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            False thread-sanitizer positive when using OpenMP (archer) with C++11 thread-safe statics on macOS
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          q-p
      </td>
    </tr>
</table>

<pre>
    I'm trying to apply thread-sanitizer (tsan) to an OpenMP parallelized C++11 program, and it seems like I get a race report which (AFAIK) isn't actually a real race on macOS 12 "Monterey".

This is using Homebrew clang 13
```
Homebrew clang version 13.0.0
Target: x86_64-apple-darwin21.2.0
Thread model: posix
InstalledDir: /usr/local/opt/llvm/bin
```

on macOS 12.1 "Monterey" on an Intel Mac Pro (2019).


The following program
```cpp
#include <vector>
#include <iostream>

int main (int argc, char const *argv[])
{
  #pragma omp parallel
  {
    static const std::vector<int> vec(1, 42);
    std::cout << vec.size() << std::endl;
  }
  return 0;
}
```
compiled via `/usr/local/opt/llvm/bin/clang++ -L /usr/local/opt/llvm/lib -fopenmp -fsanitize=thread -std=c++11  omp_threadsafe_init_archer.cpp` (the `-L path` is given so the linking step picks up the OpenMP run-time library) and then run via
```
OMP_TOOL_LIBRARIES=~/Downloads/openmp-13.0.0.src/tools/archer/libarcher.dylib OMP_NUM_THREADS=2 MallocNanoZone=0 TSAN_OPTIONS="ignore_noninstrumented_modules=1" ./a.out
```
leads to the following output and TSAN report
```
1
==================
WARNING: ThreadSanitizer: data race (pid=51403)
  Read of size 8 at 0x000109889138 by thread T1:
    #0 std::__1::vector<int, std::__1::allocator<int> >::size() const <null> (a.out:x86_64+0x100001f4d)
    #1 .omp_outlined. <null> (a.out:x86_64+0x100001ddc)
    #2 __kmp_invoke_microtask <null> (libomp.dylib:x86_64+0x7a852)
    #3 main <null> (a.out:x86_64+0x100001d03)

  Previous write of size 8 at 0x000109889138 by main thread:
    #0 std::__1::__vector_base<int, std::__1::allocator<int> >::__vector_base() <null> (a.out:x86_64+0x1000021ab)
    #1 std::__1::vector<int, std::__1::allocator<int> >::vector(unsigned long, int const&) <null> (a.out:x86_64+0x1000020e1)
    #2 std::__1::vector<int, std::__1::allocator<int> >::vector(unsigned long, int const&) <null> (a.out:x86_64+0x100001e95)
    #3 .omp_outlined. <null> (a.out:x86_64+0x100001da5)
    #4 __kmp_invoke_microtask <null> (libomp.dylib:x86_64+0x7a852)
    #5 main <null> (a.out:x86_64+0x100001d03)

  Location is global 'main::vec' of size 24 at 0x000109889130 (a.out+0x000100008138)

  Thread T1 (tid=5238101, running) created by main thread at:
    #0 pthread_create <null> (libclang_rt.tsan_osx_dynamic.dylib:x86_64+0x9fdf)
    #1 __kmp_create_worker <null> (libomp.dylib:x86_64+0x60daa)
```

>From what I understand (and have observed in real code) the C++11 static initialization is automatically thread-safe, so that the subsequent access from the 2nd thread should not race (the access from whichever thread initialized it must already have happened as the size is already printed).
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzNV1uP6jYQ_jXhxSJKHK4PPLDL0oO6N-1SVepL5CQG3DV2ajuw9Nd3xgmBXZDO9rSViqKQZMYz428unsl0cZgsAjrcEmcOQq2J04SVpTwQtzGcFV3LlHDiT25IQEcO3gI69kyKPJVcPTyTkhkmJZfAVJDbgN7AFcekNHpt2Dagt8BbEOGI5XxriRRvnCzImjvCiGE5J4aX2jiy34h8g1qm8-niZ1QjLGgbAl_uKlBxwAWcyXqVVmTL8qdXElNYRB-0ctzwAzyGQTQLoml9X26EBUGksri7b3rLM8P3JJcMXuOkYR1EzeVfP3HtuLEC1MVJGIUNy5IZ2EGQTMn7aJAOel0EjXcLZvZC0TikLaOHkWx1wSWyl9qK95q0UNYhcsVMGCQFdF5ZA3epcybhX5cO3-QOUJxnQl01tr6foRHGn_BAqMBdC_ggyQPLybPRiDON4jHA_AGuo9GcrLSUeo-gHT35UXtels0XmgiVy6rgJEhudzx3GrZzd40otHUAx_ZE9nehHFgvFBqFz4BtjnGTb5ghuQaYgDKFr7ugfxP0Z2B0s3x4Uz8QYEhKw9ZbRvS2bGOypZ4YCQHUncgbwdYVgD1cR8NvwQKwD7wONoxitKNHUWPyQUSzKteVw53BhStCC1kAyzB6m68tK1eFPBMSDGfHR8NdZRSJWmpL--TrHPYmIGDITjCCX78bMXTuY7jOStK9_06QSZGR7kpDYgOI3dUx-YNkVpcD0vXbmeVtmiPcaU20bMVTAStSZvINNyGGyCDyhQMCCh5Bf8ncBj9CSq7FjitiNUGqFOoNg806Du4T-RukbOkpTZkxleo6sUXOzDBzQIixsACLQiJichW0p4fndPn0dJ_eL25epi-Lu1fYQDC8g-3O9F5JDZZ7HHDT3TrJQ2tgi3OntURavZ8an2ZvxQGxQtmPvzyky28vd9MZCqaQYZA4-SNT-jetELqILF-nj-nT83Lx9OiVUyrWShueKq0ERKGpthyys0ihTFSSW-CJMXFD1B1CiF3dmETMsRa7D-kK7CUEJWKDepvyelVC3HwFk37g8mt_nb48Lh5_wvpVl7rX44GBnwrmmiIPQVAKDJ1-3IuSNoMJecGw0iuCmUNGhDkSvUdRFEfj0WgcJyOSHc8isowxk9okhJSPTumVpvGVRKa3Vzi8g9iHbMeK5GlnCdxUnuRWVVJ6JjqqvZFM66oPKRC9xxGau-oVZ5vyxsUkxOSABRDcvAi_Kqoo8s-iKEnTN5Al1E6_8XQrcqMds2-fREJIgsY6Nj9KHrJRn36WmjRV94tmnbntKObZ8J3QlSV7Ixz_nhu9ttqXX3FkmtauTDNm-Y_686OQtjJ_YcM0ZtmlS__teGtW01GlLBQFqO1SY72-JXgS-hAM6OBvWB3x-DJ6_u9Wx3zcv4zOH0wfdiGq95-kT_8fp889AoytJZ6GUmfQ22IvDlJbmOG9TSvau8ir6KQTVXkK_EaQcRfalscq6k_kuhjTZBRHvsmBIxTOorUvfMAHp9GnlAXdl1lb1rS0XnKJp-8-UuNCHB1Sbd_T4qAYOOAayuNVsbrMuNp1tYJ0r80bziJf9NsgKhg7AXGtc54bvYXZA4BdkEoV0Os7PDoRVvjbsB2UtcxyswNAAAs_gOTQzfs5CA7e08TT9JXYAQkG41DrWlY5vUWaH2LawWrFfeLh-Q3aUZatQNMfFcceOM-5tWSF1iGJ-lbH-8FudCULorRrj1bkOF_hZykOg8txTWsU96PYtoKTjUkkHeo9bmCA4ZjIzNamYMCh7Q1TaQR2KDgvdIpJUoyTMes44SSfzJm0_HJexEnHQYsHxkCHVs9fTS-H4DYt1ZjshducoXgGT4OobWe9TmXkZONcaTES6RyuNayushA647MuFv66MLX8DlUKXoW1Fcc2rp9Eg2FnM8l7jK-yjDLeH47Gg2SYFTQaDlg-ZmwMpagjWcalneC0QamCQdCLgGcYPjpiQiMKs1M0jPvxmA7C4bCI-mzcGxR0kBfA1Is45I0M0Y5Qm3XHTLxJWbW2QJTCOnsiMutLKJ_Uw00HomWjzeSPbtnxaife7L8AQ_qoog">