<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/105462>105462</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Clang fails to match the out-of-line member function specialization's noexcept specifier containing packs
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          zyn0217
      </td>
    </tr>
</table>

<pre>
    I stumbled upon this case when I was trying to [clean up](https://github.com/llvm/llvm-project/pull/104911) the uses of `getTemplateInstantiationArgs()`, which is in preparation for my CWG 2369 implementation.

https://clang.godbolt.org/z/MnYbGKoqP

```cpp
template <typename T> struct S {
  template <typename... U>
  constexpr int UseAlignOf(int param = 1) noexcept(sizeof...(U) == 4);
};

template <>
template <typename... U>
constexpr int S<int>::UseAlignOf(int param) noexcept(sizeof...(U) == 4) {
  return param;
}

static_assert(S<int>().UseAlignOf<char>(), "");
```

Tested with @jcsxky's https://github.com/llvm/llvm-project/pull/102267 but everything persists.
</pre>
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