for vs2015 error C3256

Author: mutouyun

src/libipc/utility/pimpl.h

@@ -3,6 +3,7 @@
 #include <new>
 #include <utility>
 
+#include "libipc/platform/detail.h"
 #include "libipc/utility/concept.h"
 #include "libipc/pool_alloc.h"
 
@@ -17,49 +18,45 @@ template <typename T, typename R = T*>
 using IsImplUncomfortable = ipc::require<(sizeof(T) > sizeof(T*)), R>;
 
 template <typename T, typename... P>
-constexpr auto make_impl(P&&... params) -> IsImplComfortable<T> {
+IPC_CONSTEXPR_ auto make_impl(P&&... params) -> IsImplComfortable<T> {
     T* buf {};
     ::new (&buf) T { std::forward<P>(params)... };
     return buf;
 }
 
 template <typename T>
-constexpr auto impl(T* const (& p)) -> IsImplComfortable<T> {
+IPC_CONSTEXPR_ auto impl(T* const (& p)) -> IsImplComfortable<T> {
     return reinterpret_cast<T*>(&const_cast<char &>(reinterpret_cast<char const &>(p)));
 }
 
 template <typename T>
-constexpr auto clear_impl(T* p) -> IsImplComfortable<T, void> {
+IPC_CONSTEXPR_ auto clear_impl(T* p) -> IsImplComfortable<T, void> {
     if (p != nullptr) impl(p)->~T();
 }
 
 template <typename T, typename... P>
-constexpr auto make_impl(P&&... params) -> IsImplUncomfortable<T> {
+IPC_CONSTEXPR_ auto make_impl(P&&... params) -> IsImplUncomfortable<T> {
     return mem::alloc<T>(std::forward<P>(params)...);
 }
 
 template <typename T>
-constexpr auto clear_impl(T* p) -> IsImplUncomfortable<T, void> {
+IPC_CONSTEXPR_ auto clear_impl(T* p) -> IsImplUncomfortable<T, void> {
     mem::free(p);
 }
 
 template <typename T>
-constexpr auto impl(T* const (& p)) -> IsImplUncomfortable<T> {
+IPC_CONSTEXPR_ auto impl(T* const (& p)) -> IsImplUncomfortable<T> {
     return p;
 }
 
 template <typename T>
 struct pimpl {
     template <typename... P>
-    constexpr static T* make(P&&... params) {
+    IPC_CONSTEXPR_ static T* make(P&&... params) {
         return make_impl<T>(std::forward<P>(params)...);
     }
 
-#if __cplusplus >= 201703L
-    constexpr void clear() {
-#else /*__cplusplus < 201703L*/
-    void clear() {
-#endif/*__cplusplus < 201703L*/
+    IPC_CONSTEXPR_ void clear() {
         clear_impl(static_cast<T*>(const_cast<pimpl*>(this)));
     }
 };