From 682606febaf1a00984cf74899b24bc99a0ea8d7c Mon Sep 17 00:00:00 2001
From: aBram <eyalandron@gmail.com>
Date: Tue, 20 Dec 2022 20:17:54 +0200
Subject: [PATCH] improve is_constructible, is_copy_constructible,
 is_move_constructible for type traits with default definitions

---
 include/etl/type_traits.h | 35 +++++++++++++++++++++++------------
 test/test_type_traits.cpp | 15 ---------------
 2 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/include/etl/type_traits.h b/include/etl/type_traits.h
index 03a57c1b8..11f46fa4a 100644
--- a/include/etl/type_traits.h
+++ b/include/etl/type_traits.h
@@ -1980,28 +1980,39 @@ namespace etl
   {
   };
 
+  //***************************************************************************
+  /// is_convertible
+  namespace private_type_traits 
+  {
+    template <class, class T, class... Args>
+    struct is_constructible_ : etl::false_type {};
+
+    template <class T, class... Args>
+    struct is_constructible_<void_t<decltype(T(etl::declval<Args>()...))>, T, Args...> : etl::true_type {};
+  };
+
 #if ETL_USING_CPP11
   //*********************************************
   // is_constructible
-  template <typename T, typename... TArgs>
-  struct is_constructible : public etl::bool_constant<etl::is_arithmetic<T>::value || etl::is_pointer<T>::value>
-  {
-  };
+  template <class T, class... Args>
+  using is_constructible = private_type_traits::is_constructible_<void_t<>, T, Args...>;
 #endif
 
   //*********************************************
   // is_copy_constructible
-  template <typename T>
-  struct is_copy_constructible : public etl::bool_constant<etl::is_arithmetic<T>::value || etl::is_pointer<T>::value>
-  {
-  };
+  template <class T> struct is_copy_constructible : public is_constructible<T,  typename etl::add_lvalue_reference<typename etl::add_const<T>::type>::type>{};
+  template <> struct is_copy_constructible<void> : public false_type{};
+  template <> struct is_copy_constructible<void const> : public false_type{};
+  template <> struct is_copy_constructible<void volatile> : public false_type{};
+  template <> struct is_copy_constructible<void const volatile> : public false_type{};
 
   //*********************************************
   // is_move_constructible
-  template <typename T>
-  struct is_move_constructible : public etl::bool_constant<etl::is_arithmetic<T>::value || etl::is_pointer<T>::value>
-  {
-  };
+  template <typename T> struct is_move_constructible: public is_constructible<T, typename etl::add_rvalue_reference<T>::type>{};
+  template <> struct is_move_constructible<void> : public false_type{};
+  template <> struct is_move_constructible<void const> : public false_type{};
+  template <> struct is_move_constructible<void volatile> : public false_type{};
+  template <> struct is_move_constructible<void const volatile> : public false_type{};
 
   //*********************************************
   // is_trivially_constructible
diff --git a/test/test_type_traits.cpp b/test/test_type_traits.cpp
index 838487572..363d59d98 100644
--- a/test/test_type_traits.cpp
+++ b/test/test_type_traits.cpp
@@ -127,11 +127,6 @@ struct etl::is_assignable<Copyable, Copyable> : public etl::true_type
 {
 };
 
-template <>
-struct etl::is_constructible<Copyable> : public etl::true_type
-{
-};
-
 template <>
 struct etl::is_copy_constructible<Copyable> : public etl::true_type
 {
@@ -148,11 +143,6 @@ struct etl::is_assignable<Moveable, Moveable> : public etl::true_type
 {
 };
 
-template <>
-struct etl::is_constructible<Moveable> : public etl::true_type
-{
-};
-
 template <>
 struct etl::is_copy_constructible<Moveable> : public etl::false_type
 {
@@ -169,11 +159,6 @@ struct etl::is_assignable<MoveableCopyable, MoveableCopyable> : public etl::true
 {
 };
 
-template <>
-struct etl::is_constructible<MoveableCopyable> : public etl::true_type
-{
-};
-
 template <>
 struct etl::is_copy_constructible<MoveableCopyable> : public etl::true_type
 {