<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/122517>122517</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [TySan] False positive related to structs in structs?
        </td>
    </tr>

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

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

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

<pre>
    Maybe I'm just not using it right, or not understanding something, but OTOH TySan is new, and thus probably a bit buggy... I used creduce to create a C test case showing, I think, a false positive.

```C
typedef struct {
        int len;
        char *list;
} str_list;

typedef struct {
        str_list infiles;
        char command;
} nt_opts;

int add_string(str_list *slist) {
        (void)(slist->list);
}

int process_opts(nt_opts *opts) {
        add_string(&opts->infiles);
}

void free_opts_mem(nt_opts *nopt) {
        (void)(nopt->infiles.list); // •••TySan warns here•••
}

void main(int argc, char *argv[]) {
        nt_opts opts;
        int rv = process_opts(&opts);
        free_opts_mem(&opts);
}
```

then I run:

`(xcrun /Users/sean/llvm/llvm-install/bin/clang -w -g -fsanitize=type test.c && ./a.out)`

and I get:

```
==4848==ERROR: TypeSanitizer: type-aliasing-violation on address 0x00016cfc71f0 (pc 0x000102e3b690 bp 0x00016cfc6ea0 sp 0x00016cfc6620 tid 24776816)
READ of size 8 at 0x00016cfc71f0 with type p1 omnipotent char (in <anonymous type> at offset 8) accesses an existing object of type p1 omnipotent char (in <anonymous type> at offset 8)
    #0 0x000102e3b68c in free_opts_mem test.c:20
```

Aside:

- what is an "omnipotent char"?
- what is "type p1" referring to?
</pre>
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