diff --git a/CMakeLists.txt b/CMakeLists.txt
index fa77a5aed2..44ede3e799 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -6,6 +6,15 @@ cmake_minimum_required(VERSION 3.1)
 ##
 project(nlohmann_json VERSION 3.9.1 LANGUAGES CXX)
 
+##
+## MAIN_PROJECT CHECK
+## determine if nlohmann_json is built as a subproject (using add_subdirectory) or if it is the main project
+##
+set(MAIN_PROJECT OFF)
+if (CMAKE_CURRENT_SOURCE_DIR STREQUAL CMAKE_SOURCE_DIR)
+  set(MAIN_PROJECT ON)
+endif()
+
 ##
 ## INCLUDE
 ##
@@ -21,8 +30,8 @@ if (POLICY CMP0077)
     cmake_policy(SET CMP0077 NEW)
 endif ()
 
-option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ON)
-option(JSON_Install "Install CMake targets during install step." ON)
+option(JSON_BuildTests "Build the unit tests when BUILD_TESTING is enabled." ${MAIN_PROJECT})
+option(JSON_Install "Install CMake targets during install step." ${MAIN_PROJECT})
 option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)
 option(JSON_ImplicitConversions "Enable implicit conversions." ON)
 
@@ -101,9 +110,8 @@ CONFIGURE_FILE(
 ## TESTS
 ## create and configure the unit test target
 ##
-include(CTest) #adds option BUILD_TESTING (default ON)
-
-if(BUILD_TESTING AND JSON_BuildTests)
+if (JSON_BuildTests)
+    include(CTest)
     enable_testing()
     add_subdirectory(test)
 endif()
diff --git a/include/nlohmann/detail/json_ref.hpp b/include/nlohmann/detail/json_ref.hpp
index 18e09f0519..26a4903828 100644
--- a/include/nlohmann/detail/json_ref.hpp
+++ b/include/nlohmann/detail/json_ref.hpp
@@ -57,7 +57,7 @@ class json_ref
 
     value_type const* operator->() const
     {
-        return &**this;
+        return &** this;
     }
 
   private:
diff --git a/include/nlohmann/detail/meta/cpp_future.hpp b/include/nlohmann/detail/meta/cpp_future.hpp
index dd929ee142..4ba1a55714 100644
--- a/include/nlohmann/detail/meta/cpp_future.hpp
+++ b/include/nlohmann/detail/meta/cpp_future.hpp
@@ -2,19 +2,32 @@
 
 #include <cstddef> // size_t
 #include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
+#include <utility> // index_sequence, make_index_sequence, index_sequence_for
+
+#include <nlohmann/detail/macro_scope.hpp>
 
 namespace nlohmann
 {
 namespace detail
 {
-// alias templates to reduce boilerplate
-template<bool B, typename T = void>
-using enable_if_t = typename std::enable_if<B, T>::type;
 
 template<typename T>
 using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
 
-// implementation of C++14 index_sequence and affiliates
+#ifdef JSON_HAS_CPP_14
+
+// the following utilities are natively available in C++14
+using std::enable_if_t;
+using std::index_sequence;
+using std::make_index_sequence;
+using std::index_sequence_for;
+
+#else
+
+// alias templates to reduce boilerplate
+template<bool B, typename T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
 // source: https://stackoverflow.com/a/32223343
 template<std::size_t... Ints>
 struct index_sequence
@@ -45,6 +58,8 @@ template<> struct make_index_sequence<1> : index_sequence<0> {};
 template<typename... Ts>
 using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
 
+#endif
+
 // dispatch utility (taken from ranges-v3)
 template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
 template<> struct priority_tag<0> {};
@@ -58,5 +73,6 @@ struct static_const
 
 template<typename T>
 constexpr T static_const<T>::value;
+
 }  // namespace detail
 }  // namespace nlohmann
diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index ac143becf5..56c15a3f66 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -168,7 +168,9 @@ struct is_iterator_traits<iterator_traits<T>>
         is_detected<reference_t, traits>::value;
 };
 
-// source: https://stackoverflow.com/a/37193089/4116453
+// The following implementation of is_complete_type is taken from
+// https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
+// and is written by Xiang Fan who agreed to using it in this library.
 
 template<typename T, typename = void>
 struct is_complete_type : std::false_type {};
@@ -186,7 +188,6 @@ struct is_compatible_object_type_impl <
     enable_if_t < is_detected<mapped_type_t, CompatibleObjectType>::value&&
     is_detected<key_type_t, CompatibleObjectType>::value >>
 {
-
     using object_t = typename BasicJsonType::object_t;
 
     // macOS's is_constructible does not play well with nonesuch...
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index cd56dafdc4..a726d1adf3 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -923,14 +923,14 @@ class basic_json
         AllocatorType<T> alloc;
         using AllocatorTraits = std::allocator_traits<AllocatorType<T>>;
 
-        auto deleter = [&](T * object)
+        auto deleter = [&](T * obj)
         {
-            AllocatorTraits::deallocate(alloc, object, 1);
+            AllocatorTraits::deallocate(alloc, obj, 1);
         };
-        std::unique_ptr<T, decltype(deleter)> object(AllocatorTraits::allocate(alloc, 1), deleter);
-        AllocatorTraits::construct(alloc, object.get(), std::forward<Args>(args)...);
-        JSON_ASSERT(object != nullptr);
-        return object.release();
+        std::unique_ptr<T, decltype(deleter)> obj(AllocatorTraits::allocate(alloc, 1), deleter);
+        AllocatorTraits::construct(alloc, obj.get(), std::forward<Args>(args)...);
+        JSON_ASSERT(obj != nullptr);
+        return obj.release();
     }
 
     ////////////////////////
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 835140b3dc..88c8fa74d9 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -2736,19 +2736,33 @@ class other_error : public exception
 
 #include <cstddef> // size_t
 #include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
+#include <utility> // index_sequence, make_index_sequence, index_sequence_for
+
+// #include <nlohmann/detail/macro_scope.hpp>
+
 
 namespace nlohmann
 {
 namespace detail
 {
-// alias templates to reduce boilerplate
-template<bool B, typename T = void>
-using enable_if_t = typename std::enable_if<B, T>::type;
 
 template<typename T>
 using uncvref_t = typename std::remove_cv<typename std::remove_reference<T>::type>::type;
 
-// implementation of C++14 index_sequence and affiliates
+#ifdef JSON_HAS_CPP_14
+
+// the following utilities are natively available in C++14
+using std::enable_if_t;
+using std::index_sequence;
+using std::make_index_sequence;
+using std::index_sequence_for;
+
+#else
+
+// alias templates to reduce boilerplate
+template<bool B, typename T = void>
+using enable_if_t = typename std::enable_if<B, T>::type;
+
 // source: https://stackoverflow.com/a/32223343
 template<std::size_t... Ints>
 struct index_sequence
@@ -2779,6 +2793,8 @@ template<> struct make_index_sequence<1> : index_sequence<0> {};
 template<typename... Ts>
 using index_sequence_for = make_index_sequence<sizeof...(Ts)>;
 
+#endif
+
 // dispatch utility (taken from ranges-v3)
 template<unsigned N> struct priority_tag : priority_tag < N - 1 > {};
 template<> struct priority_tag<0> {};
@@ -2792,6 +2808,7 @@ struct static_const
 
 template<typename T>
 constexpr T static_const<T>::value;
+
 }  // namespace detail
 }  // namespace nlohmann
 
@@ -3174,7 +3191,9 @@ struct is_iterator_traits<iterator_traits<T>>
         is_detected<reference_t, traits>::value;
 };
 
-// source: https://stackoverflow.com/a/37193089/4116453
+// The following implementation of is_complete_type is taken from
+// https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
+// and is written by Xiang Fan who agreed to using it in this library.
 
 template<typename T, typename = void>
 struct is_complete_type : std::false_type {};
@@ -3192,7 +3211,6 @@ struct is_compatible_object_type_impl <
     enable_if_t < is_detected<mapped_type_t, CompatibleObjectType>::value&&
     is_detected<key_type_t, CompatibleObjectType>::value >>
 {
-
     using object_t = typename BasicJsonType::object_t;
 
     // macOS's is_constructible does not play well with nonesuch...
@@ -4515,15 +4533,15 @@ class byte_container_with_subtype : public BinaryType
         : container_type(std::move(b))
     {}
 
-    byte_container_with_subtype(const container_type& b, std::uint8_t subtype) noexcept(noexcept(container_type(b)))
+    byte_container_with_subtype(const container_type& b, std::uint8_t subtype_) noexcept(noexcept(container_type(b)))
         : container_type(b)
-        , m_subtype(subtype)
+        , m_subtype(subtype_)
         , m_has_subtype(true)
     {}
 
-    byte_container_with_subtype(container_type&& b, std::uint8_t subtype) noexcept(noexcept(container_type(std::move(b))))
+    byte_container_with_subtype(container_type&& b, std::uint8_t subtype_) noexcept(noexcept(container_type(std::move(b))))
         : container_type(std::move(b))
-        , m_subtype(subtype)
+        , m_subtype(subtype_)
         , m_has_subtype(true)
     {}
 
@@ -4556,9 +4574,9 @@ class byte_container_with_subtype : public BinaryType
 
     @since version 3.8.0
     */
-    void set_subtype(std::uint8_t subtype) noexcept
+    void set_subtype(std::uint8_t subtype_) noexcept
     {
-        m_subtype = subtype;
+        m_subtype = subtype_;
         m_has_subtype = true;
     }
 
@@ -12645,7 +12663,7 @@ class json_ref
 
     value_type const* operator->() const
     {
-        return &**this;
+        return &** this;
     }
 
   private:
@@ -17495,14 +17513,14 @@ class basic_json
         AllocatorType<T> alloc;
         using AllocatorTraits = std::allocator_traits<AllocatorType<T>>;
 
-        auto deleter = [&](T * object)
+        auto deleter = [&](T * obj)
         {
-            AllocatorTraits::deallocate(alloc, object, 1);
+            AllocatorTraits::deallocate(alloc, obj, 1);
         };
-        std::unique_ptr<T, decltype(deleter)> object(AllocatorTraits::allocate(alloc, 1), deleter);
-        AllocatorTraits::construct(alloc, object.get(), std::forward<Args>(args)...);
-        JSON_ASSERT(object != nullptr);
-        return object.release();
+        std::unique_ptr<T, decltype(deleter)> obj(AllocatorTraits::allocate(alloc, 1), deleter);
+        AllocatorTraits::construct(alloc, obj.get(), std::forward<Args>(args)...);
+        JSON_ASSERT(obj != nullptr);
+        return obj.release();
     }
 
     ////////////////////////