[Bug c++/123290] Internal compiler error when lambda is used as template argument

[blubban at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123290

--- Comment #2 from Alfred Agrell <blubban at gmail dot com> ---
Testcase reduction complete, the non-const lvalue reference things disappeared
during reduction (there's probably an accepts-invalid or rejects-valid nearby
as well)

https://godbolt.org/z/v5zM1E8se


template<typename T>
class identity {
public:
        using type = T;
};

  template <auto kLambda>
  class FlatMapHelper {};

template <int=1>
auto Adapter() {
    using OutputType = FlatMapHelper<[]<int>(){}>;
    []<int=0>() {
        using T = identity<OutputType>::type;
    }();
}

int main() {
    Adapter();
}