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From: "hiraditya at msn dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/109017] ICE on unexpanded pack from C++20
 explicit-template-parameter lambda syntax
Date: Sat, 04 Mar 2023 16:22:45 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D109017

AK <hiraditya at msn dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |hiraditya at msn dot com

--- Comment #1 from AK <hiraditya at msn dot com> ---
Example from twitter: https://twitter.com/seanbax/status/1631689332007337985
which had discussion on similar bug.

```
template<int... Is> struct outer1_t {
  void g() {
    // Compiles for mysterious reasons.
    int array[] { []<int... Is2>(){
      int i =3D Is2;
      return i;
    }.template operator()<Is>() ... };
  }
};

int main() {
  // Compiles OKAY when this is commented out.
  // ICEs when it's compiled.
  outer1_t<1, 5, 10>().g();
}
```

clang issues a compiler error: https://godbolt.org/z/7f6E55svM

```
<source>:6:15: error: initializer contains unexpanded parameter pack 'Is2'
      int i =3D Is2;
```=