From 1c3e8a6ff8d8b6c054141503c7318d69319d8d41 Mon Sep 17 00:00:00 2001
From: PJ Reiniger <pj.reiniger@gmail.com>
Date: Sun, 8 May 2022 16:42:09 -0400
Subject: [PATCH 18/28] Use std::is_trivially_copy_constructible

---
 llvm/include/llvm/ADT/PointerIntPair.h  | 12 ----
 llvm/include/llvm/Support/type_traits.h | 91 +------------------------
 2 files changed, 2 insertions(+), 101 deletions(-)

diff --git a/llvm/include/llvm/ADT/PointerIntPair.h b/llvm/include/llvm/ADT/PointerIntPair.h
index b7ddf8855..a48fb904b 100644
--- a/llvm/include/llvm/ADT/PointerIntPair.h
+++ b/llvm/include/llvm/ADT/PointerIntPair.h
@@ -128,18 +128,6 @@ public:
   }
 };
 
-// Specialize is_trivially_copyable to avoid limitation of llvm::is_trivially_copyable
-// when compiled with gcc 4.9.
-template <typename PointerTy, unsigned IntBits, typename IntType,
-          typename PtrTraits,
-          typename Info>
-struct is_trivially_copyable<PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>> : std::true_type {
-#ifdef HAVE_STD_IS_TRIVIALLY_COPYABLE
-  static_assert(std::is_trivially_copyable<PointerIntPair<PointerTy, IntBits, IntType, PtrTraits, Info>>::value,
-                "inconsistent behavior between llvm:: and std:: implementation of is_trivially_copyable");
-#endif
-};
-
 
 template <typename PointerT, unsigned IntBits, typename PtrTraits>
 struct PointerIntPairInfo {
diff --git a/llvm/include/llvm/Support/type_traits.h b/llvm/include/llvm/Support/type_traits.h
index 7b7d5d991..72a2e84ad 100644
--- a/llvm/include/llvm/Support/type_traits.h
+++ b/llvm/include/llvm/Support/type_traits.h
@@ -92,98 +92,11 @@ union trivial_helper {
 
 } // end namespace detail
 
-/// An implementation of `std::is_trivially_copy_constructible` since we have
-/// users with STLs that don't yet include it.
 template <typename T>
-struct is_trivially_copy_constructible
-    : std::is_copy_constructible<
-          ::llvm::detail::copy_construction_triviality_helper<T>> {};
-template <typename T>
-struct is_trivially_copy_constructible<T &> : std::true_type {};
-template <typename T>
-struct is_trivially_copy_constructible<T &&> : std::false_type {};
+using is_trivially_move_constructible = std::is_trivially_move_constructible<T>;
 
-/// An implementation of `std::is_trivially_move_constructible` since we have
-/// users with STLs that don't yet include it.
-template <typename T>
-struct is_trivially_move_constructible
-    : std::is_move_constructible<
-          ::llvm::detail::move_construction_triviality_helper<T>> {};
 template <typename T>
-struct is_trivially_move_constructible<T &> : std::true_type {};
-template <typename T>
-struct is_trivially_move_constructible<T &&> : std::true_type {};
-
-
-template <typename T>
-struct is_copy_assignable {
-  template<class F>
-    static auto get(F*) -> decltype(std::declval<F &>() = std::declval<const F &>(), std::true_type{});
-    static std::false_type get(...);
-    static constexpr bool value = decltype(get((T*)nullptr))::value;
-};
-
-template <typename T>
-struct is_move_assignable {
-  template<class F>
-    static auto get(F*) -> decltype(std::declval<F &>() = std::declval<F &&>(), std::true_type{});
-    static std::false_type get(...);
-    static constexpr bool value = decltype(get((T*)nullptr))::value;
-};
-
-
-// An implementation of `std::is_trivially_copyable` since STL version
-// is not equally supported by all compilers, especially GCC 4.9.
-// Uniform implementation of this trait is important for ABI compatibility
-// as it has an impact on SmallVector's ABI (among others).
-template <typename T>
-class is_trivially_copyable {
-
-  // copy constructors
-  static constexpr bool has_trivial_copy_constructor =
-      std::is_copy_constructible<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_copy_constructor =
-      !std::is_copy_constructible<T>::value;
-
-  // move constructors
-  static constexpr bool has_trivial_move_constructor =
-      std::is_move_constructible<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_move_constructor =
-      !std::is_move_constructible<T>::value;
-
-  // copy assign
-  static constexpr bool has_trivial_copy_assign =
-      is_copy_assignable<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_copy_assign =
-      !is_copy_assignable<T>::value;
-
-  // move assign
-  static constexpr bool has_trivial_move_assign =
-      is_move_assignable<detail::trivial_helper<T>>::value;
-  static constexpr bool has_deleted_move_assign =
-      !is_move_assignable<T>::value;
-
-  // destructor
-  static constexpr bool has_trivial_destructor =
-      std::is_destructible<detail::trivial_helper<T>>::value;
-
-  public:
-
-  static constexpr bool value =
-      has_trivial_destructor &&
-      (has_deleted_move_assign || has_trivial_move_assign) &&
-      (has_deleted_move_constructor || has_trivial_move_constructor) &&
-      (has_deleted_copy_assign || has_trivial_copy_assign) &&
-      (has_deleted_copy_constructor || has_trivial_copy_constructor);
-
-#ifdef HAVE_STD_IS_TRIVIALLY_COPYABLE
-  static_assert(value == std::is_trivially_copyable<T>::value,
-                "inconsistent behavior between llvm:: and std:: implementation of is_trivially_copyable");
-#endif
-};
-template <typename T>
-class is_trivially_copyable<T*> : public std::true_type {
-};
+using is_trivially_copy_constructible = std::is_trivially_copy_constructible<T>;
 
 
 } // end namespace llvm