<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/95367>95367</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Specifying -ftrapv or -fsanitize=undefined at the same time as -fsanitize=memory does not detect some uninitialized variable references
        </td>
    </tr>

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

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

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

<pre>
    
`test.c`
```c
int main(void)
{
 int a;
    int c = a + 0;
    if(c)
    {
        c++;
 }
    return 0;
}
```
It is expected that a memory access violation will be detected as follows.
```
$ clang -fsanitize=memory -fPIE -pie test.c
$ ./a.out
==1747352==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x5652f3f13413 in main (/tmp/a.out+0xca413) (BuildId: 86494c3488075ddb4a2e0750989d5039f1525021)
 #1 0x7f2f0b8471c9 in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #2 0x7f2f0b84728a in __libc_start_main csu/../csu/libc-start.c:360:3
    #3 0x5652f3e7b2f4 in _start (/tmp/a.out+0x322f4) (BuildId: 86494c3488075ddb4a2e0750989d5039f1525021)

SUMMARY: MemorySanitizer: use-of-uninitialized-value (/tmp/a.out+0xca413) (BuildId: 86494c3488075ddb4a2e0750989d5039f1525021) in main
Exiting
```

However, when I add the -ftrapv or -fsanitize=undefined options, the uninitialized variable access violation is not detected.
```
$ clang -fsanitize=memory -ftrapv -fPIE -pie test.c
$ ./a.out
$ clang -fsanitize=memory -fsanitize=undefined -fPIE -pie test.c
$ ./a.out
```

**Environment Information**
```
$ clang --version
Ubuntu clang version 18.1.3 (1)
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin
$ uname -r
6.8.0-35-generic
$ head -1 /etc/os-release
PRETTY_NAME="Ubuntu 24.04 LTS"
```
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy0VV1v2zYU_TX0CyGButTngx-cOd4CLEXRpBj6ZFDSlc2BIgWScpz--oGS4iSti6LDZgiyeD8O7z26hxLOyYNGXJPshmTblRj90dj1s-hFv6pN-7wmbEvYhuTMo_NxQ3J2scxXM6-l9rQXUhMoT0a2BKolrriZH2iIEIS_LCmdLA0lfEsFJXBD2XtvR6BsLkDB9Aq2_BoCN-G65JFi-xph0Y9Wv4G9eC_Vz8s7T6WjeB6w8dhSfxSeCtpjb-wzFU2DztGTNEp4aTR9kkrRGmmLfo4XjnZGKfPk4qvwBFLaKKEPNOqc0NLLr0j4dsGPuo93tzQaJNKF40tSTGAnYjP6xcS3hG-TIi14BvPir82nD3cffid8Q-8nuIcF3wbT6DAyXTRqGYxCya_YRiehRnzDKXBG2TnLM-h4l_A04VTq6V1SAiWBne-HSx1ww86NSBNOoArum1Gq9q4Nm5V5WqUNT8uSFVnb1qkAZEXGqrJqM8arLskgY5C8vlECPKHsXHTQsbpMi6Spwtb7vZJ1s3deWL9vhFL7qZjGjQR2ceDEPbsWB0dgpwevCOyuJcRHwjdZSfgmyd-1C2_3hFJ8t-e3282PISCaAuKG8A3PWbi_Q-YXIrGooUsn5CnlB1RygC79D6ic7w-f7-83n7788jD8b-_5ZZDm8m7P0kt9uC6R6f6HecITWgK_0acjanpHRRvkiDTqvBXDiRr7XkOjbrGTGltqhiBOF3JDwrs26UlYKWqF34tZOqqNv2j53wl4ru0XhPwTvKsN_gL8NW4JhOtWn6Q1ukft6Z3ujO0nGmbnz3qPTmhdiJ4cn-tR-3HxLR6alHES8zAxr8P5KOwBfRidc5nv8zQamkhJPZ6jgx6XkKNF0dLetKhC4GCcPC9ns3ZeKIXtVk5jTGA3OktgV7_MVahw1KJHGtnZksdlzCKeRQfUaOUbpo5hmygJKOgbAjvjIosKhVuOxI-fbh8fv-w_bO5vwwkLsLQJacxS-ufjAwH4hqdVu-ZtxSuxwnVSJCXkOa_K1XFd1HVVdHWJrEpryBtMWJWnbVeXJZbQ4kqugUHK8oSzMuFJGaMoeN0BZ3nV5WmVkJRhL6SKlTr1sbGHlXRuxHWV8bxYKVGjctO3G0DjE52cocBsu7LrkBPV48GRlCnpvHtF8dIrXD8M2MjuWU5z-DN9CT_pygWevewxfPWuTW9r8K2kqDP9D9VosUOLukG3Gq1aH70fHOEbAjsCu4P0x7GOG9OHw1edXv6iwZq_sfEEdlO_4TMw83Fawz8BAAD__0UGmFU">