<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=http://email.email.llvm.org/c/eJy9VlFz4jgM_jXhxUMmdgiUBx7SJLS5QmAIbW_3xWMSA9l1YiZ2yvbfr5wALdvt3c3czQ1BsT7ZkiLLkjcyf53EFhmVKJPloRBFtUNZU9e80mhx4FWazhC24VeiY6H3KBOs2vUzgbBrOzZGNRecKY62tSzRDmY0Gxut94VCjeI50hIdZf3dIgHaNBopzWoN8JZ1lgRTGh05_46Oe16hGDWHnJkJ8_Qp6HQShxD0gkdg7YdRZ4YYGJTIIyzYcY30HuxLIeTR6OR1LWvL9S0ntBzfGjqnp2XP7tv8B0fIItOvhaHTXColKLini8w-5BsD3imnfU1b-mroPDR0QVC_ZHW2t9ywghUv3KCPlC5X0-D-mVLUb_S2f4P609RIYiDEhv-FKapMNDk3UD8EOqNREsZ-cgEWyyiB0NNlHHzAguVjHNLF7R8fJLHvEpqmEfkguU2on87pfJGs_0rmfSa8m5LyIkvvfWzQ9wDxhr9CHiZX0EMUBP4DHjrOFbwKBlf8PPSueD9Kk_gKeVoCdoXc3fvp_RUSBUuaxOn666-O_Uk8D4-voOVi9gW7zrXZUwDCeAW7bHlmGwKTVTDyAkhS1o0aVfdzpfvB6J65JMNjF7sYO4MMFOJuylpKoToNb-4ld3ESpf-ldi8QxaYb8GpXVFz1McW_2D1va_olpc9x4r5JWo7OIh82PAnpPHqXjY9JHCzC6MLTD0CwWtM0Ch5XEU0WNIyWqyjw1-8mgPp0ETy8iUIz8dlfJXFyl37w7zGNqL9czuLk4SJLwuj28c6wqJ-1p1Zm9etBS_hGpirzqYyqYlfZcvPNnLJPpJkJSFsN4gptC8HR6TjmXcX5dJnrw8JzYfn92vPB9oKTFjLlLwcbKoWP8T9eW1Sa1xUTsLrm20w2lW5VkL9Tccqh29DQrAAymz3N-12tvmRIWwThfYHfLCsNySdLKIKty6OLvZPmZS13NSvRFGybrJsXWS2V3Gr0VKiGCZTqJi9M8Ezdhlcgy7KpCv0K46f3-WoqvPFhYLvYNkntfuoIucFQmALI1TF4cSnwyHKv_Y0QtJ1KavQKTUE1h4Nsm03bWt66G1MQplM_0qZRwXOAiFQmiLJGDG0b3dT83NrsUyMhbmv4_7WKLC_6bSPr6IdGC0lR8a5Tty30ffe0UawRE6qbqc4tt2QVbJx4RTlvF4MJStN1GJgD6q8X8zhIKYUyhUFi9_KJm4_dMeuxRu9lPeFlySvBml5Ti8le64MymUKm8JyuAxAEYIR4Ob_6h1p-45kGtlCqgUQiU88d41FvP9nwfIwHA-YOb_Lh0BlvxoRsh-6W8czDW9fpCbbhQk0s79bywt6_N1lMTIwcgm-cG2fkjmxC-HjgjbMcKu4AY2INHF7CfcU2emxZ73r1pFW5aXYKhKJQWr0JmTLVgvOzh7rQgk-mpwvP5fp0vlttmkLk3YZ16cU2sr0onTKsEwm4FMFNqd3S7v7Taz9j0n7DT6QY4fM>53917</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Failing clang-cl OpenSSL build with error about stdatomic with latest MSVC 17.1.0
        </td>
    </tr>

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

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

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

<pre>
    I'm compiling current OpenSSL 1.1.1m with clang-cl 13.0.1 release from github. This used to work, but started failing last week when I updated MSVC from 2022 v17.0.x to v17.1.0. Now I get the following error:
```
clang-cl.exe  /Zi /Fdossl_static.pdb /Gs0 /GF /Gy /MD /O2 -march=native /U__PRFCHW__ -utf-8 -FS /I "." /I "include" -D"L_ENDIAN" -D"OPENSSL_PIC" -D"OPENSSL_CPUID_OBJ" -D"OPENSSL_IA32_SSE2" -D"OPENSSL_BN_ASM_MONT" -D"OPENSSL_BN_ASM_MONT5" -D"OPENSSL_BN_ASM_GF2m" -D"SHA1_ASM" -D"SHA256_ASM" -D"SHA512_ASM" -D"KECCAK1600_ASM" -D"RC4_ASM" -D"MD5_ASM" -D"AESNI_ASM" -D"VPAES_ASM" -D"GHASH_ASM" -D"ECP_NISTZ256_ASM" -D"X25519_ASM" -D"POLY1305_ASM" -D"OPENSSLDIR=\"C:\\data\\usr-dst-C7Ha32c193131104c1301\\Tools\"" -D"ENGINESDIR=\"C:\\data\\usr-dst-C7Ha32c193131104c1301\\Tools\\lib\\engines-1_1\"" -D"OPENSSL_SYS_WIN32" -D"WIN32_LEAN_AND_MEAN" -D"UNICODE" -D"_UNICODE" -D"_CRT_SECURE_NO_DEPRECATE" -D"_WINSOCK_DEPRECATED_NO_WARNINGS" -D"OPENSSL_USE_APPLINK" -D"NDEBUG"  -c /Focrypto\asn1\a_sign.obj "crypto\asn1\a_sign.c"
In file included from crypto\asn1\a_sign.c:22:
In file included from include\crypto/evp.h:11:
In file included from include\internal/refcount.h:21:
In file included from C:\BDA\ci\LLVM-13.0.1\lib\clang\13.0.1\include\stdatomic.h:17:
C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Tools\MSVC\14.31.31103\include\stdatomic.h(15,2): error: <stdatomic.h> is not yet supported when compiling as C, but this is planned for a future release.
#error <stdatomic.h> is not yet supported when compiling as C, but this is planned for a future release.
 ^
```

This used to work fine with MSVC 2022 v17.0.x. It also works when I manually define `__STDC_NO_ATOMICS__=1`.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy9Vl9zozgM_zTkxRMGm5A_D3mgQFquCcmEtL3dF48DTsKuwRls2u23PxmStGm3d_dwcxMirJ9sSciy5K3MX6exRUYlymR5LERR7VHW1DWvNFoeeZWmc4Rt-JXopdAHlAlW7fuZQNi1HRujmgvOFEe7WpZoDzOarY02h0KhRvEcaYleZP3TIgHaNhopzWoN8I51lgRTGr1w_hO9HHiFYtQcc2YmLNLHoNNJHELQMx6BtV9GnRliYFAiX2DBnmukD2BfCiFfjE5e17K2XN9yQsvxraFzelr27L7Nf3GELDL7Xhg6y6VSgoJ7usjsY7414K1y2tespa-GLkJDlwT1S1ZnB8sNK1jxzA36QOlqPQvunihF_Ubv-mPUn6VGEgMhNvwvTFFlosm5gfoh0DmNkjD2kwuwXEUJhJ6u4uATFqwe4pAub_74JIl9l9A0jcgnyU1C_XRBF8tk83cy7yvh7YyUF1l652ODvgeIN_wIeZhcQfdREPj3eOg4V_A6GFzxi9C74v0oTeIr5HEF2BVye-end1dIFKxoEqeb7x8d-5N4Hp5cQavl_Bt2nWuzpwCE8Rp22fLMNgQmq2DkBZCkrBs1qu7nSveD0R1zSYYnLnYxdgYZKMTdlI2UQnUa3txLbuMkSv9L7V4gim034NW-qLjqY4o_2D1va_otpU9x4r5JWo7OIx82PAnpInqXjQ9JHCzD6MLTT0Cw3tA0Ch7WEU2WNIxW6yjwN-8mgPp0Gdy_iUIz8clfJ3Fym37y7yGNqL9azePk_iJLwujm4dawqJ-1p1Zm9etRS_hGpirzqYyqYl_ZcvvDnLIvpJkJSFsN4grtCsHR6TjmXcX5cpnrw8JzYfn92vPB9oKTFjLjz0cbKoWP8b9eW1Sa1xUTsLrmu0w2lW5VkH9Sccqhm9DQrAAynz8u-l2tvmRIWwThfYHfLCsNySdLKIKty6OLvZPmVS33NSvRDGybrFsUWS2V3Gn0WKiGCZTqJi9M8Ezdhlcgy7KpCv0K48f3-WoqvPFhYLvYNkntfukIGWMoTAHk6gS8uBR4ZLnX_kYI2k4lNXqFpqCa41G2zaZtLW_djSkI06kfadOo4DlCRCoTRFkjhnaNbmp-bm32qZEQtzX8_1pFlhf9tpF19FOjhaSoeNep2xb6vnvaKNaICdXNVOeWW7IKNk68opy3i8EEpekmDMwB9TfLRRyklEKZwiCxe_nUzSfuhPV0oQWfzk6d_HIvOF8atk0h8s6TLm5sK9sbwCl0nUhAt4crQOtr19h7TS2mB62PymQcmcFzulZAMIER4vn86h9r-YNnGthCqQYSksw8d4JHvcOUuINsOHTwmPPdcIx3g5wQ7DGWT9g2H-NhT7AtF2pqeTeWF_aKqYmUQ_DYGTsjd2QTwicDb5LlUHcHGBNr4PASvtU2hm1Z73v1tPVh2-wVCEWhtHoTMmVqBudn_azRB1lPeVnySrCm1_o7bZ39Cy9_zHQ">