<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/109311>109311</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang should not warn about =delete("reason") in C++17 mode while claiming to support it
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

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

<pre>
    Clang 19 seems to define `__cpp_deleted_function` even in pre-C++26 modes. However using it results in a warning:

```
void f() = delete
#if __cpp_deleted_function >= 202403L
 ("reason")
#endif
;
```

```
<source>:3:6: warning: '= delete' with a message is a C++2c extension [-Wc++26-extensions]
    3 | ("reason")
      |      ^~~~~~~~
1 warning generated.
Compiler returned: 0
```

https://godbolt.org/z/Esqh5aPfb

It sounds a bit strange to claim support for a given language feature (by setting the corresponding feature-define macro), but then warn if that feature is used? Would it be possible, in pre-C++26 modes, to support the syntax and warn but _not_ set the macro?
</pre>
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