<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/140057>140057</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Unexpected error when passing a type to an unidentified preprocessor definition
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Anthony-Nicholls
      </td>
    </tr>
</table>

<pre>
    Given the following code...

```cpp
class T{};

void f()
{
    UNDEFINED_MACRO (T);
}
```
https://godbolt.org/z/5WjGM4KE6

we might expect an error regarding the undeclared identifier `UNDEFINED_MACRO` however, in this specific case we get `'T' does not refer to a value`. 

If we change the code to so that it passes a variable instead of a type, for example...

```cpp
void f()
{
    int i;
    UNDEFINED_MACRO (i);
}
```
https://godbolt.org/z/YT1GGPG4Y

then the error is the more expected `use of undeclared identifier 'UNDEFINED_MACRO'`.

gcc and MSVC both appear to error as we might expect in this scenario.

I've tested this using trunk on CompilerExplorer as linked above.
</pre>
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