From e3c55f983099d0a614449ec641adfd224fe38ad6 Mon Sep 17 00:00:00 2001
From: sunkaicheng <sunkaicheng@bigo.sg>
Date: Tue, 20 Aug 2019 09:54:09 +0800
Subject: [PATCH] support older version cpp compiler to use
 is_trivially_copyable

---
 parallel_hashmap/phmap_base.h  | 15 ++++++++++++---
 parallel_hashmap/phmap_utils.h | 26 +++-----------------------
 2 files changed, 15 insertions(+), 26 deletions(-)

diff --git a/parallel_hashmap/phmap_base.h b/parallel_hashmap/phmap_base.h
index 82a38b0..b2534bd 100644
--- a/parallel_hashmap/phmap_base.h
+++ b/parallel_hashmap/phmap_base.h
@@ -82,12 +82,21 @@ struct PairTrait<std::pair<T1, T2>>: public std::true_type {
     using second_type = T2;
 };
 
+template<typename T>
+#if defined(__GLIBCXX__) && __GLIBCXX__ < 20150801
+struct IsTriviallyCopyable : public std::integral_constant<bool, __has_trivial_copy(T)> {
+};
+#else
+struct IsTriviallyCopyable : public std::is_trivially_copyable<T> {
+};
+#endif
+
 template<typename V>
 struct IsDumpableType {
-    static constexpr bool value = std::is_trivially_copyable<V>::value
+    static constexpr bool value = IsTriviallyCopyable<V>::value
             || (PairTrait<V>::value
-              && std::is_trivially_copyable<typename PairTrait<V>::first_type>::value
-              && std::is_trivially_copyable<typename PairTrait<V>::second_type>::value);
+              && IsTriviallyCopyable<typename PairTrait<V>::first_type>::value
+              && IsTriviallyCopyable<typename PairTrait<V>::second_type>::value);
 };
 
 template <typename... Ts>
diff --git a/parallel_hashmap/phmap_utils.h b/parallel_hashmap/phmap_utils.h
index e517afd..9146057 100644
--- a/parallel_hashmap/phmap_utils.h
+++ b/parallel_hashmap/phmap_utils.h
@@ -326,7 +326,7 @@ public:
     ~ArchiveGuard() {
         if (ar_) {
             ar_->finish();
-        }        
+        }
     }
 private:
     Archive* ar_;
@@ -351,23 +351,13 @@ public:
     }
 
     template<typename V>
-    typename std::enable_if<std::is_trivially_copyable<V>::value, bool>::type
+    typename std::enable_if<type_traits_internal::IsTriviallyCopyable<V>::value, bool>::type
     dump(const V& v) {
         CHECK_FILE(ofs_);        
         ofs_.write(reinterpret_cast<char*>(const_cast<V*>(&v)), sizeof(V));
         return true;
     }
 
-    template<typename V>
-    typename std::enable_if<type_traits_internal::PairTrait<V>::value
-        && type_traits_internal::IsDumpableType<V>::value, bool>::type
-    dump(const V& v) {
-        using first_type = typename type_traits_internal::PairTrait<V>::first_type;
-        using second_type = typename type_traits_internal::PairTrait<V>::second_type;
-        return dump<first_type>(v.first)
-        && dump<second_type>(v.second);
-    }
-
     void finish() {
         if (ofs_.is_open()) {
             ofs_.close();
@@ -397,23 +387,13 @@ public:
     }
 
     template<typename V>
-    typename std::enable_if<std::is_trivially_copyable<V>::value, bool>::type
+    typename std::enable_if<type_traits_internal::IsTriviallyCopyable<V>::value, bool>::type
     load(V* v) {
         CHECK_FILE(ifs_);
         ifs_.read(reinterpret_cast<char*>(v), sizeof(V));
         return true;
     }
 
-    template<typename V>
-    typename std::enable_if<type_traits_internal::PairTrait<V>::value
-                            && type_traits_internal::IsDumpableType<V>::value, bool>::type
-    load(V* v) {
-        using first_type = typename std::remove_cv<typename type_traits_internal::PairTrait<V>::first_type>::type;
-        using second_type = typename std::remove_cv<typename type_traits_internal::PairTrait<V>::second_type>::type;
-        return load<first_type>(const_cast<first_type*>(&v->first))
-                && load<second_type>(const_cast<second_type*>(&v->second));
-    }
-
     void finish() {
         if (ifs_.is_open()) {
             ifs_.close();