<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/155054>155054</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Unknown standard attributes should generate an error with -pedantic-errors in C23
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Halalaluyafail3
      </td>
    </tr>
</table>

<pre>
    The following program contains a constraint violation:
```c
[[x]]int main(){}
```
Specifically, it violates the following constraint:
> The identifier in a standard attribute shall be one of:
deprecated
fallthrough
maybe_unused
nodiscard
noreturn
_Noreturn
unsequenced
reproducible

Section 6.7.13.2 Paragraph 2 ISO/IEC 9899:2024

`x` is not one of these identifiers, nor is it one of these identifiers but surrounded on both sides by two underscores. Therefore `-pedantic-errors` should reject this program, which is what GCC currently does. 
</pre>
<img width="1" height="1" alt="" src="http://email.email.llvm.org/o/eJx0k0Fv6zYMxz-NfCEayHLsxAcf0vRle5dtQLfzAy0xljZF8iipefn2g9IW7YY92IBpkH_xpz9ITMktgWgS_aPonxos2UaefkZfn3LDMzrfNXM0t-l3S3CO3serCwusHBfGC-gYMrqQAGuYMqMLGV5c9JhdDKI7CHkQg3x9df2prR6_i_5J9E-1-IIuCLUXahS7R7F7-iwQ8vC8knZnp9H7m1BHcO_HU4L8L6YPgLe23Reo1M5QyO7siMEFQEgZg0E2gDmzm0smSBa9h5kgBoJ4ftUbWpk0ZjJCHs7ofbYcy2KFPFzwNtO3Ekq6J0M0Lmnk15gpFw5CHr798hGXkOjvQkHfBUwrR1O0mz1VUnl4Jl0Ng2Gz27TdRsFvyLgwrhYUfH3-VajT1y9HGPfjKLqDkmr7qhOD_C4GCS5BiPmNvxqTPl88VedC5FrmflwFc8mQCnMswZCBGGCO2UJyhhLMN8jXCDXFSUemtKn-Mp0jE4hBPqxkMGSnH4g5cqpcycbiDTD9STpDti69z05FulqnbYW6Wszw0_EIujBTyP4GJtYGjZk6M3YjNjS1u74fWylb2dhpnGds98OwQ6nPLZm96bFvBySthv24nRs3Kal6uVedlNuhlxs56mFUhlrZz7LbothKuqDzG-9fLpvIS-NSKjS1fS_7beNxJp_uq6FUoCvcs0Kpuik8VdHDXJYkttK7lNPHMdllT9Mf4a8Qr-F_xi29u7JQIMZMgAHulsHVZQv_9bGO7VF1TWE_2ZzXVOdTnYQ6LS7bMm90vAh1qv3fPg8rx2q4UKc7dRLq9Hatl0n9EwAA__-0vlHS">