<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/66448>66448</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            `-Wuninitialized` does not take `malloc` function attribute into account
        </td>
    </tr>

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

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

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

<pre>
    The `malloc` function attribute indicates that the newly allocated memory is uninitialized. This doesn't appear to be informing the `-Wuninitialized` diagnostics, though:

```
#include <stdio.h>
#include <stdlib.h>

void foo(void)
{
        int *p = malloc(sizeof(*p));
        printf("%d\n", *p);
}
```

Building with `-Wall`, Clang produces no warnings, but GCC does:

https://godbolt.org/z/K8Ga18KoM

It looks like the IR does know that `malloc` is `allockind("alloc,uninitialized")`, so I imagine something isn't fully wired up:

```
; Function Attrs: mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0)
memory(inaccessiblemem: readwrite)
declare noalias noundef ptr @malloc(i64 noundef) local_unnamed_addr #3
...
attributes #3 = { mustprogress nofree nounwind willreturn allockind("alloc,uninitialized") allocsize(0)
memory(inaccessiblemem: readwrite) "alloc-family"="malloc" "no-trapping-math"="true" "stack-protector-buffer-size"="8"
"target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
```

@nickdesaulniers @isanbard 
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzMVV-v2rgT_TTmZQQKTgjhgYcCP6qq-r2sKu1j5cSTZBbHjuxxubeffuUksL1X290-LkLhmPnjmZPjsQqBOot4FLuT2F1WKnLv_PGGGFa106_HLz2CKLNBGeMaUWbQRtswOQuK2VMdGYGspkYxBuBeMXCPYPFuXmEKUowaBhycfwUKEC1ZYlKGvqPewJeeAmiHwQq5Z1DjiMoDO6hT3tb5gWw3pRRltv79TXQqR5PqrAtMTRDyDNy72PUi_yCyi8gezzJbvvNS5mQbEzWCyM-BNblNL_L__cRqqP7RPD2_OdLQOidklaCQh8W6P80Alg9ZBiE_jCDyCywkyirQd3StkFUypWB5EPm7yNGT5dlHCrnTYne2EzzDI-oRIvaXv290ep4iGZ1IvBP3M4vKmOQkz3A2ynYweqdjgwGsg7vylmw3sVlHho_n8_R-3nHaM4_Tf_Iq5LVzunaGN853Ql6_C3n9XH1U2-qz-_-PQZ8YjHO3AIZuOL3UT79NyeFm3X1WzxuxUUjraXkjq2c2FhbPb7WQqDksXQUHn4AG1ZFFCG5A7hMBtIisjca8wp08aojjv4glP8H1IfkPzD41DUMMPHrXeQyJtNYjgnXR3slquJMxHjl6C79e-eyahCFklT0FNZ8bISuyqmkwBKoNDjikIjwqfffE-PTW2BjlUynKkApTSRpbGNmDKLKn_qgsHra0dTqk5mu0Vg2ovyqtPQiZ53POzWYzg-d5D5N1UrTYn_57XMAj-7pVA5nXlDS_CCkf_cvkYd2avRpHst16UNw_vdhHXHwCq-a2Hr1jbNj5dR3bFv16rmxxn87nMjkkK98hr5sxPu0vVbkuiyXhYm9RcfQYnk5CnprBfRPynNBLNYP2JfgZDcPLDELAJ5Azeqn2j-zR4pu9O7Toae74H2eEKDJLzU1jUNFYQh-SXigoWyuvYaWPuT7kB7XC47Y8FPu8LLJq1R-zMqukRF3umryucrndllpVpa7z7a7Yy2pFR5nJPDtsd1mWlUW1kTu5y3RZynxXFrqSoshwUGQ2xnwb0vxYUQgRj2VZFNXKqBpNmC4nKS3eYTKm_naXlT-mmHUduyCKzFDg8FcWJjZ4_Mmd4aZRx8Dq9iu3GztQTeOi5VX05vhu9BH3sd40bhDymrZffpJs_sCGhbxORQchr1NTfwYAAP__XulMKw">