https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100474
--- Comment #3 from 康桓瑋 <hewillk at gmail dot com> --- (In reply to Enrico Seiler from comment #2) > Here is a version not dependent on range-v3: > > https://godbolt.org/z/PvdhxGo5c > > ``` > template <typename T, typename... Args> > concept foo = __is_constructible(T, Args...); > > class S > { > public: > S() = delete; > S(S const &) = default; > S(S &&) = default; > S & operator=(S const &) = default; > S & operator=(S &&) = default; > ~S() = default; > }; > > int main() > { > // static_assert(!__is_constructible(S)); // OK > // static_assert(!foo<S>); // OK > // static_assert(__is_constructible(S)); // FAILS > static_assert(foo<S>); // ICE > } > ``` > > The parameter pack is not necessary for the ICE to occur, however, it is > what META_IS_CONSTRUCTIBLE is expanded to in range-v3. > > Using `concept foo = static_cast<bool>(__is_constructible(T, Args...));` > will remove the ICE, even though `__is_constructible` should already return > a bool. I can't imagine you can reduce it, thank you very much!
