<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/92300>92300</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Wrong formatting of labels in preprocessor lines
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Julien-Elie
      </td>
    </tr>
</table>

<pre>
    Contrary to previous versions, clang-format 18 reformats:

```
#    define TXN_START(label, tid) \
    label: \
        TXN_START_NORETRY(label, tid)

# define failure_response           \
    failure: \
        simple_response(client, code); \
 break;
```

as:

```
#    define TXN_START(label, tid) label : TXN_START_NORETRY(label, tid)

#    define failure_response \
        failure : simple_response(client, code); \
 break;
```

I don't think it is the expected output. Previous versions of clang-format kept it unchanged.  It looks like `:` is now interpreted as a colon in a ternary operation instead of a colon following a label name.
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJy0VE1v2zgQ_TXUZWBDIi3JPuiQLwPZQ3aRNdD2FFDSSGJNcwRylDT_vqDs1HWTU9ESAiWSM-89Pg2pQzC9Q6xEfi3y20RPPJCv_pmsQbe4swaTmtrX6oYce-1fgQlGj8-GpgDP6IMhF4S8gcZq1y868gfNkK3B4_E7CHUl0luRvvVFenqOQ6kAAFrsjEPYfX54-n939bgTcm11jTYis2mF3IDIb44pMf64qK4uZ2P7AfH08O_j3e7xy3uoCzlSvZF32tjJ45PHMJILCOd2wXKK-5A9mMNozxBCrptoJM8OUYuRXV3_lFd71Huhrj82Z-71H7NwHkMU_hsunSneGfXOhlPETPU3LLmHlpyQJQMPxu3BMJgAPCDgtxEbxhZo4nHiJfz3a7ECdZfFuseRI8LkmkG7HtslwD2DJdoHsGaPENlVVBJZHL2AcYx-9BiJdAANDVlyYBxoYPQuHhQa0Ws283Rg1G0kfovsyFp6Ma4HfforTh9wmbSVajdqoxOssjLLy02ZlmUyVEXa5FJp2cl0jYXs8nq12pR5k6lca1moxFQylas0z_JsnZV5udR1VxRpWeC6yNWq7sQqxYM2dmnt82FJvk9MCBNWG6nSNJk1hPkSkNLhC8yLQsp4J_gq5izqqQ9ilVoTOJxR2LDF6pMn18PRUI7bou64rxBNGT2OnhoMgTxY4zAkk7fVwDzOtS23Qm57w8NULxs6CLmN8KfXYvT0FRsWcjuLCkJuZ9HfAwAA__-qr24Q">