<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/99744>99744</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Extra implicit 'this' parameter entry when emitting a DW_TAG_subprogram with an explicit object parameter
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          Michael137
      </td>
    </tr>
</table>

<pre>
    ```
struct Foo {                      
 template <class Self>         
    void func(this Self&& self) {}
}; 
                                  
int main() {                      
    Foo{}.func();                 
} 
```
The above will currently produce following DWARF:

```
DW_TAG_structure_type
  DW_AT_name ("Foo")
  DW_TAG_subprogram
    DW_AT_name    ("func<Foo>")
 DW_AT_declaration     (true)
    DW_AT_external        (true)
 DW_TAG_template_type_parameter
      DW_AT_type  (0x0000000000000034 "Foo")
      DW_AT_name  ("Self")
    DW_TAG_formal_parameter
 DW_AT_type  (0x0000000000000051 "Foo *")
      DW_AT_artificial (true)
    DW_TAG_formal_parameter
      DW_AT_type (0x0000000000000056 "Foo &&")
    NULL
 NULL

DW_TAG_subprogram
  DW_AT_specification (0x000000000000003a "_ZNH3Foo4funcIS_EEvOT_")
 DW_TAG_formal_parameter
    DW_AT_location        (DW_OP_fbreg +8)
 DW_AT_name    ("self")
    DW_AT_type    (0x0000000000000056 "Foo &&")
  DW_TAG_template_type_parameter
    DW_AT_type (0x0000000000000034 "Foo")
    DW_AT_name ("Self")
```

Note how the declaration of `func` has 2 `DW_TAG_formal_parameter` entries, one for the explicit object parameter `self` and (erroneously) another for the `implicit` object parameter `this`. The definition only has the explicit object parameter.

Looks like `CGDebugInfo::getOrCreateInstanceMethodType` would need to account for the fact that an explicit object parameter may exist, in which case we don't want to create the implicit artificial `this` parameter.
</pre>
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