<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/147324>147324</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang: Missing line and file in message error when ‘auto’ is used in a not permitted context (and bad diagnostic)
        </td>
    </tr>

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

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

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

<pre>
    With this code:

```cpp
int main()
{ 
  struct A
  { 
    void foo(auto x) {} // auto not permitted
  };
} 
```

And clang-18,19,20 or trunk and `-std=c++20` or `-std=c++23`:

> error: templates cannot be declared inside of a local class

No line number, no filename and refer to `template`.

With `-std=c++17`:

```
test.cpp:5:14: error: 'auto' not allowed in function prototype
    5 |     void foo(auto x) {}
      |              ^~~~
```

With gcc (same message for C++17 or C++20):

```
test.cpp: In function ‘int main()’:
test.cpp:5:14: error: ‘auto’ parameter not permitted in this context
    5 |     void foo(auto x) {}
      |              ^~~~
```

https://gcc.godbolt.org/z/5YGdh6Pnb
</pre>
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