CReturn/AReturn are no longer needed

Author: jagerman

include/pybind11/detail/init.h

@@ -220,7 +220,7 @@ template <typename... Args> struct alias_constructor {
 };
 
 // Implementation class for py::init(Func) and py::init(Func, AliasFunc)
-template <typename CFunc, typename CReturn, typename AFuncIn, typename AReturn, typename... Args> struct factory {
+template <typename CFunc, typename AFuncIn, typename... Args> struct factory {
 private:
     using CFuncType = typename std::remove_reference<CFunc>::type;
     using AFunc = conditional_t<std::is_void<AFuncIn>::value, void_type, AFuncIn>;
@@ -301,7 +301,7 @@ template <typename Func> using functype =
 
 // Helper definition to infer the detail::initimpl::factory template types from a callable object
 template <typename Func, typename Return, typename... Args>
-factory<functype<Func>, Return, void, void, Args...> func_decltype(Return (*)(Args...));
+factory<functype<Func>, void, Args...> func_decltype(Return (*)(Args...));
 
 // metatemplate that ensures the Class and Alias factories take identical arguments: we need to be
 // able to call either one with the given arguments (depending on the final instance type).
@@ -320,8 +320,7 @@ inline constexpr bool require_matching_arguments(Return1 (*)(Args1...), Return2
 template <typename CFunc, typename AFunc,
           typename CReturn, typename... CArgs, typename AReturn, typename... AArgs,
           bool = require_matching_arguments((CReturn (*)(CArgs...)) nullptr, (AReturn (*)(AArgs...)) nullptr)>
-factory<functype<CFunc>, CReturn, functype<AFunc>, AReturn, CArgs...> func_decltype(
-    CReturn (*)(CArgs...), AReturn (*)(AArgs...));
+factory<functype<CFunc>, functype<AFunc>, CArgs...> func_decltype(CReturn (*)(CArgs...), AReturn (*)(AArgs...));
 
 // Resolves to the appropriate specialization of the `pybind11::detail::initimpl::factory<...>` for a
 // given init function or pair of class/alias init functions.