<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/73449>73449</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `-Wzero-as-null-pointer-constant` not reported with clang-tidy
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang-tidy
      </td>
    </tr>

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

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

<pre>
    ```cpp
#include <cstddef>

void test()
{
        int* p = NULL;
}
```

```
$ clang -Wzero-as-null-pointer-constant test.cpp
test.cpp:5:11: warning: zero as null pointer constant [-Wzero-as-null-pointer-constant]
        int* p = NULL;
 ^~~~
 nullptr
/usr/lib/clang/16/include/stddef.h:84:18: note: expanded from macro 'NULL'
#    define NULL __null
 ^
```

```
$ clang-tidy -checks='*' -extra-arg=-Wzero-as-null-pointer-constant test.cpp
2335 warnings generated.
/home/user/test.cpp:1:1: warning: system include cstddef not allowed [llvmlibc-restrict-system-libc-headers]
#include <cstddef>
^~~~~~~~~~~~~~~~~~
/home/user/test.cpp:3:6: warning: declaration must be declared within the '__llvm_libc' namespace [llvmlibc-implementation-in-namespace]
void test()
 ^
/home/user/test.cpp:5:7: warning: variable name 'p' is too short, expected at least 3 characters [readability-identifier-length]
 int* p = NULL;
             ^
/home/user/test.cpp:5:11: warning: use nullptr [modernize-use-nullptr]
        int* p = NULL;
 ^~~~
                 nullptr
Suppressed 2331 warnings (2331 in non-user code).
```

Strangely in Godbolt the warning is not reported with the compiler: https://godbolt.org/z/hGjG1YM7o

True, `modernize-use-nullptr` and `-Wzero-as-null-pointer-constant` are checking for the same thing but I did not expect that the compiler warning is disabled. I wonder if other warnings are being suppressed as well. I have seen the same "issue" for the same line for other checks in the past.

In our case we have `modernize-use-nullptr` disabled since it duplicates the compiler warning and we use the clang-tidy step in the CI as the step which is supposed to fail on compiler warnings as well.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJycVltv2zgT_TX0y0CGTFq-PPjBqesiQL_vpbtY7FNAiSOLXYoUyFHc9KG_fTGyfElaJNkSiSXxMnPOmQuoU7IHj7gRxZ0odhPdUxPiprYRj_oRJ2UwTxuxyE9_VdeJfCfyrZDK-sr1BkGoD1UiY7AW6uO4Ovw-BmuAMJGQKyHX49Ly7vQC47CehNxCB0Lt4P9_fv4s1N156258Obu_tf5yUs6hctofIPvrO8aQ6ZT53rmsC9YTxqwKPpH2NCCaXohcvtS2EGo7mwm1haOO3voDv7It0AnYFoy24GJLFHdvuBPF7r18QRQff_z4MX6wtY7imd2-T1HIvbOlkPuBqJD72ULI_RgHIfenKEwbobarOZNZMQMfCPmJ3zrtDRqoY2ih1VUMIORygCCXl7AyRoO19Tigg4cHRnJF-BshyciaJ8iqBqt_klA7die3Qi4hw28UdabjQajdfwucVKo4ByrBAT1GTWimF8Ga0OKgG7JwN3Gejf-3YU5PibCFc06PCc3agXYuHNFwrJ17bJ0tqyxiomgryk7nsmGyQW0wpkvE36iRIdjPx9vYlVDbxQvsBiunoyYbPLR9IihxnEMDR0uN9UANcrAfHpjCA8Nl-b1uMXW6wmfkbNs5bNHTYDKzPrvsu3D7ZW3fpMcrFLjMli8oPOpodelwQMRAO4ZnE1AIkJoQScgPnMFYERrQBA51IlBQNTrqijAm5hBRG11aZ-kpswY92dpizBz6AzXXUnylBm_Hu-n81DX6hOcCZlhtMBi9_Y5ZnzA7V_bvdoaX41mn-NJ3XcSU0IBUanatECFXw4T14INnINzHuG-sp6_U9BeK2h_QPfHBT8GUwdGQTaNhDhJXScQuRBoTbthQhbazDiPr0RB1SSgWUsj94WRmGiI3se-s7qevn2Z__28Zbl3_EXvksItF_msBFzlob3j9rSbMOyPC0IEYdB3igDFxunGBHKDsCe7BWDPQOaUaUKPpGZlb2sYmzlkzhXs4Bm8wgq0hUHPdlga3JfKJdI2MTnBE5_hgox8REqK_4hFS2pSYu3wO1HFT5pmTj1M_hbG6O51oeivfvYfQR6h0QjjiydFrUp7pQLK-QrAEpu-crTRh-rUGLP4Rh2Qf1q-9PhF2Z2Af7pnvQIJnj42tGpaP9QisBgWotXUQ_E8u0kWqidkos1ZrPcHNbJnP8rxYzvNJs8FlbpRGLPL1DMtqVRRFsdKrIl_U-RqLemI3MpdqNpOLmVLFPJ_W-UouZL0sV4tqWdVrMc-x1dZNuQNyUk4G-TdLNZ-vJ06X6NJwPZLySlFIydeluOFDWdkfkpjnziZKVzNkyeHmfen5cw1dfU366DYvSshS05fTKrR8KXCP50fWxfAVK-J7AZNIQu4HHv8GAAD___WzIiU">