From ab663358bc7aea9434b5652e07188d944d386eb5 Mon Sep 17 00:00:00 2001
From: greg7mdp <greg7mdp@gmail.com>
Date: Sat, 5 Nov 2022 16:11:40 -0400
Subject: [PATCH] Remove deprecated use of std::aligned_storage. Issue #171

---
 parallel_hashmap/phmap.h      | 10 +++++-----
 parallel_hashmap/phmap_base.h | 25 +++++++++----------------
 2 files changed, 14 insertions(+), 21 deletions(-)

diff --git a/parallel_hashmap/phmap.h b/parallel_hashmap/phmap.h
index 60d2030..a421587 100644
--- a/parallel_hashmap/phmap.h
+++ b/parallel_hashmap/phmap.h
@@ -1450,7 +1450,7 @@ public:
     template <class... Args, typename std::enable_if<
                                  !IsDecomposable<Args...>::value, int>::type = 0>
     std::pair<iterator, bool> emplace(Args&&... args) {
-        typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
+        typename phmap::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
             raw;
         slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
@@ -1461,7 +1461,7 @@ public:
 
     template <class... Args, typename std::enable_if<!IsDecomposable<Args...>::value, int>::type = 0>
     std::pair<iterator, bool> emplace_with_hash(size_t hashval, Args&&... args) {
-        typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
+        typename phmap::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
         slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
         PolicyTraits::construct(&alloc_ref(), slot, std::forward<Args>(args)...);
@@ -2053,7 +2053,7 @@ private:
         //       mark target as FULL
         //       repeat procedure for current slot with moved from element (target)
         ConvertDeletedToEmptyAndFullToDeleted(ctrl_, capacity_);
-        typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
+        typename phmap::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type
             raw;
         slot_type* slot = reinterpret_cast<slot_type*>(&raw);
         for (size_t i = 0; i != capacity_; ++i) {
@@ -3087,7 +3087,7 @@ public:
     template <class... Args, typename std::enable_if<
                                  !IsDecomposable<Args...>::value, int>::type = 0>
     std::pair<iterator, bool> emplace_with_hash(size_t hashval, Args&&... args) {
-        typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
+        typename phmap::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
         slot_type* slot = reinterpret_cast<slot_type*>(&raw);
 
         PolicyTraits::construct(&alloc_ref(), slot, std::forward<Args>(args)...);
@@ -3160,7 +3160,7 @@ public:
     template <class... Args, typename std::enable_if<
                                  !IsDecomposable<Args...>::value, int>::type = 0>
     std::pair<iterator, bool> emplace(Args&&... args) {
-        typename std::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
+        typename phmap::aligned_storage<sizeof(slot_type), alignof(slot_type)>::type raw;
         slot_type* slot = reinterpret_cast<slot_type*>(&raw);
         size_t hashval  = this->hash(PolicyTraits::key(slot));
 
diff --git a/parallel_hashmap/phmap_base.h b/parallel_hashmap/phmap_base.h
index 2a2f380..0cb8931 100644
--- a/parallel_hashmap/phmap_base.h
+++ b/parallel_hashmap/phmap_base.h
@@ -96,19 +96,6 @@ struct VoidTImpl {
   using type = void;
 };
 
-// This trick to retrieve a default alignment is necessary for our
-// implementation of aligned_storage_t to be consistent with any implementation
-// of std::aligned_storage.
-// ---------------------------------------------------------------------------
-template <size_t Len, typename T = std::aligned_storage<Len>>
-struct default_alignment_of_aligned_storage;
-
-template <size_t Len, size_t Align>
-struct default_alignment_of_aligned_storage<Len,
-                                            std::aligned_storage<Len, Align>> {
-  static constexpr size_t value = Align;
-};
-
 // NOTE: The `is_detected` family of templates here differ from the library
 // fundamentals specification in that for library fundamentals, `Op<Args...>` is
 // evaluated as soon as the type `is_detected<Op, Args...>` undergoes
@@ -308,9 +295,15 @@ using remove_extent_t = typename std::remove_extent<T>::type;
 template <typename T>
 using remove_all_extents_t = typename std::remove_all_extents<T>::type;
 
-template <size_t Len, size_t Align = type_traits_internal::
-                          default_alignment_of_aligned_storage<Len>::value>
-using aligned_storage_t = typename std::aligned_storage<Len, Align>::type;
+template<std::size_t Len, std::size_t Align>
+struct aligned_storage {
+    struct type {
+        alignas(Align) unsigned char data[Len];
+    };
+};
+
+template< std::size_t Len, std::size_t Align>
+using aligned_storage_t = typename aligned_storage<Len, Align>::type;
 
 template <typename T>
 using decay_t = typename std::decay<T>::type;