[Bug c++/103428] New: Parameter packs not expanded with local struct in lambda

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103428

            Bug ID: 103428
           Summary: Parameter packs not expanded with local struct in
                    lambda
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

gcc-10 rejects this well-formed code. 
Fortunately, gcc-11.1 accepts it, however, gcc-11.2 rejected it again.

template<class... Ts>
auto f(Ts... args) {
  ([]() { struct B : decltype(args) { }; }, ...);
};

int main() {
  f([]{});
}

https://godbolt.org/z/rYhnKee7M