<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/100095>100095</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Crash from Assertion `!Packs.empty() && "Pack expansion without unexpanded packs?"'
        </td>
    </tr>

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

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

    <tr>
      <th>Reporter</th>
      <td>
          ilya-biryukov
      </td>
    </tr>
</table>

<pre>
    The following code crashes Clang with assertion at head, see https://gcc.godbolt.org/z/j6zY4as9h
```cpp
template <class... T>
struct Types {};
template <int& field>
using Forget = int;
template <int&... fields>
using SeqKey = Types<Forget<fields>...>;

template <typename Key, typename Value>
struct HelperBase {
  using ResponseParser = Key();
 HelperBase(ResponseParser response_parser) {}
};
template <int&... fields>
SeqKey<fields...> Parser();

template <int&... fields>
struct Helper : public HelperBase<SeqKey<fields...>, double> {
 using Key = SeqKey<fields...>;
  using Value = double;
  using ParentClass = HelperBase<Key, Value>;
  Helper() : ParentClass(Parser<fields...>) {}
};
void test() { Helper<>(); }
```

This should be relatively recent as it was found by our release testing.
</pre>
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