diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9887657f..1b0bca9f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -23,8 +23,7 @@ option(JSON_MultipleHeaders "Use non-amalgamated version of the library." OFF)
 ## CONFIGURATION
 ##
 set(NLOHMANN_JSON_TARGET_NAME               ${PROJECT_NAME})
-set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}"
-  CACHE INTERNAL "")
+set(NLOHMANN_JSON_CONFIG_INSTALL_DIR        "lib/cmake/${PROJECT_NAME}" CACHE INTERNAL "")
 set(NLOHMANN_JSON_INCLUDE_INSTALL_DIR       "include")
 set(NLOHMANN_JSON_TARGETS_EXPORT_NAME       "${PROJECT_NAME}Targets")
 set(NLOHMANN_JSON_CMAKE_CONFIG_TEMPLATE     "cmake/config.cmake.in")
@@ -47,7 +46,7 @@ endif()
 ##
 add_library(${NLOHMANN_JSON_TARGET_NAME} INTERFACE)
 add_library(${PROJECT_NAME}::${NLOHMANN_JSON_TARGET_NAME} ALIAS ${NLOHMANN_JSON_TARGET_NAME})
-if (${CMAKE_VERSION} VERSION_LESS "3.8.0") 
+if (${CMAKE_VERSION} VERSION_LESS "3.8.0")
     target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_range_for)
 else()
     target_compile_features(${NLOHMANN_JSON_TARGET_NAME} INTERFACE cxx_std_11)
diff --git a/Makefile b/Makefile
index 39f3493f..be2fca4a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,44 +1,31 @@
-.PHONY: pretty clean ChangeLog.md
+.PHONY: pretty clean ChangeLog.md release
 
-SRCS = include/nlohmann/json.hpp \
-       include/nlohmann/json_fwd.hpp \
-       include/nlohmann/adl_serializer.hpp \
-       include/nlohmann/detail/conversions/from_json.hpp \
-       include/nlohmann/detail/conversions/to_chars.hpp \
-       include/nlohmann/detail/conversions/to_json.hpp \
-       include/nlohmann/detail/exceptions.hpp \
-       include/nlohmann/detail/input/binary_reader.hpp \
-       include/nlohmann/detail/input/input_adapters.hpp \
-       include/nlohmann/detail/input/json_sax.hpp \
-       include/nlohmann/detail/input/lexer.hpp \
-       include/nlohmann/detail/input/parser.hpp \
-       include/nlohmann/detail/input/position_t.hpp \
-       include/nlohmann/detail/iterators/internal_iterator.hpp \
-       include/nlohmann/detail/iterators/iter_impl.hpp \
-       include/nlohmann/detail/iterators/iteration_proxy.hpp \
-       include/nlohmann/detail/iterators/json_reverse_iterator.hpp \
-       include/nlohmann/detail/iterators/primitive_iterator.hpp \
-       include/nlohmann/detail/json_pointer.hpp \
-       include/nlohmann/detail/json_ref.hpp \
-       include/nlohmann/detail/macro_scope.hpp \
-       include/nlohmann/detail/macro_unscope.hpp \
-       include/nlohmann/detail/meta/cpp_future.hpp \
-       include/nlohmann/detail/meta/detected.hpp \
-       include/nlohmann/detail/meta/type_traits.hpp \
-       include/nlohmann/detail/meta/void_t.hpp \
-       include/nlohmann/detail/output/binary_writer.hpp \
-       include/nlohmann/detail/output/output_adapters.hpp \
-       include/nlohmann/detail/output/serializer.hpp \
-       include/nlohmann/detail/value_t.hpp
-
-UNAME = $(shell uname)
-CXX=clang++
-
-AMALGAMATED_FILE=single_include/nlohmann/json.hpp
+##########################################################################
+# configuration
+##########################################################################
 
 # directory to recent compiler binaries
 COMPILER_DIR=/Users/niels/Documents/projects/compilers/local/bin
 
+# find GNU sed to use `-i` parameter
+SED:=$(shell command -v gsed || which sed)
+
+
+##########################################################################
+# source files
+##########################################################################
+
+# the list of sources in the include folder
+SRCS=$(shell find include -type f | sort)
+
+# the single header (amalgamated from the source files)
+AMALGAMATED_FILE=single_include/nlohmann/json.hpp
+
+
+##########################################################################
+# documentation of the Makefile's targets
+##########################################################################
+
 # main target
 all:
 	@echo "amalgamate - amalgamate file single_include/nlohmann/json.hpp from the include/nlohmann sources"
@@ -64,6 +51,7 @@ all:
 	@echo "pretty - beautify code with Artistic Style"
 	@echo "run_benchmarks - build and run benchmarks"
 
+
 ##########################################################################
 # unit tests
 ##########################################################################
@@ -76,25 +64,19 @@ json_unit:
 check:
 	$(MAKE) check -C test
 
+# run unit tests and skip expensive tests
 check-fast:
 	$(MAKE) check -C test TEST_PATTERN=""
 
-# clean up
-clean:
-	rm -fr json_unit json_benchmarks fuzz fuzz-testing *.dSYM test/*.dSYM
-	rm -fr benchmarks/files/numbers/*.json
-	rm -fr build_coverage build_benchmarks
-	$(MAKE) clean -Cdoc
-	$(MAKE) clean -Ctest
-
 
 ##########################################################################
 # coverage
 ##########################################################################
 
 coverage:
+	rm -fr build_coverage
 	mkdir build_coverage
-	cd build_coverage ; CXX=g++-7 cmake .. -GNinja -DJSON_Coverage=ON -DJSON_MultipleHeaders=ON
+	cd build_coverage ; CXX=$(COMPILER_DIR)/g++ cmake .. -GNinja -DJSON_Coverage=ON -DJSON_MultipleHeaders=ON
 	cd build_coverage ; ninja
 	cd build_coverage ; ctest -E '.*_default' -j10
 	cd build_coverage ; ninja lcov_html
@@ -115,36 +97,35 @@ doctest:
 ##########################################################################
 
 # calling Clang with all warnings, except:
+# -Wno-c++2a-compat: u8 literals will behave differently in C++20...
+# -Wno-deprecated-declarations: the library deprecated some functions
 # -Wno-documentation-unknown-command: code uses user-defined commands like @complexity
 # -Wno-exit-time-destructors: warning in json code triggered by NLOHMANN_JSON_SERIALIZE_ENUM
-# -Wno-keyword-macro: unit-tests use "#define private public"
-# -Wno-deprecated-declarations: the library deprecated some functions
-# -Wno-weak-vtables: exception class is defined inline, but has virtual method
-# -Wno-range-loop-analysis: items tests "for(const auto i...)"
 # -Wno-float-equal: not all comparisons in the tests can be replaced by Approx
-# -Wno-switch-enum -Wno-covered-switch-default: pedantic/contradicting warnings about switches
-# -Wno-c++2a-compat: u8 literals will behave differently in C++20...
+# -Wno-keyword-macro: unit-tests use "#define private public"
 # -Wno-padded: padding is nothing to warn about
+# -Wno-range-loop-analysis: items tests "for(const auto i...)"
+# -Wno-switch-enum -Wno-covered-switch-default: pedantic/contradicting warnings about switches
+# -Wno-weak-vtables: exception class is defined inline, but has virtual method
 pedantic_clang:
 	$(MAKE) json_unit CXX=$(COMPILER_DIR)/clang++ CXXFLAGS=" \
 		-std=c++11 -Wno-c++98-compat -Wno-c++98-compat-pedantic \
 		-Werror \
 		-Weverything \
+		-Wno-c++2a-compat \
+		-Wno-deprecated-declarations \
 		-Wno-documentation-unknown-command \
 		-Wno-exit-time-destructors \
-		-Wno-keyword-macro \
-		-Wno-deprecated-declarations \
-		-Wno-weak-vtables \
-		-Wno-range-loop-analysis \
 		-Wno-float-equal \
+		-Wno-keyword-macro \
+		-Wno-padded \
+		-Wno-range-loop-analysis \
 		-Wno-switch-enum -Wno-covered-switch-default \
-		-Wno-c++2a-compat \
-		-Wno-c++17-extensions \
-		-Wno-padded"
+		-Wno-weak-vtables"
 
 # calling GCC with most warnings
 pedantic_gcc:
-	$(MAKE) json_unit CXX=$(COMPILER_DIR)/g++ CXXFLAGS=" \
+	$(MAKE) json_unit CXX=$(COMPILER_DIR)/g++ CXXFLAGS="-D_Atomic=volatile \
 		-std=c++11 \
 		-Waddress \
 		-Waddress-of-packed-member \
@@ -372,9 +353,10 @@ pedantic_gcc:
 ##########################################################################
 
 run_benchmarks:
+	rm -fr build_benchmarks
 	mkdir build_benchmarks
-	cd build_benchmarks ; cmake ../benchmarks
-	cd build_benchmarks ; make
+	cd build_benchmarks ; cmake ../benchmarks -GNinja -DCMAKE_BUILD_TYPE=Release
+	cd build_benchmarks ; ninja
 	cd build_benchmarks ; ./json_benchmarks
 
 ##########################################################################
@@ -436,28 +418,39 @@ fuzzing-stop:
 	-killall fuzzer
 	-killall afl-fuzz
 
+
 ##########################################################################
-# static analyzer
+# Static analysis
 ##########################################################################
 
-# call cppcheck on the main header file
+# call cppcheck <http://cppcheck.sourceforge.net>
+# Note: this target is called by Travis
 cppcheck:
 	cppcheck --enable=warning --inline-suppr --inconclusive --force --std=c++11 $(SRCS) --error-exitcode=1
 
-# compile and check with Clang Static Analyzer
+# call Clang Static Analyzer <https://clang-analyzer.llvm.org>
 clang_analyze:
 	rm -fr clang_analyze_build
 	mkdir clang_analyze_build
 	cd clang_analyze_build ; CCC_CXX=$(COMPILER_DIR)/clang++ CXX=$(COMPILER_DIR)/clang++ $(COMPILER_DIR)/scan-build cmake .. -GNinja
-	cd clang_analyze_build ; $(COMPILER_DIR)/scan-build -enable-checker alpha.core.BoolAssignment,alpha.core.CallAndMessageUnInitRefArg,alpha.core.CastSize,alpha.core.CastToStruct,alpha.core.Conversion,alpha.core.DynamicTypeChecker,alpha.core.FixedAddr,alpha.core.PointerArithm,alpha.core.PointerSub,alpha.core.SizeofPtr,alpha.core.StackAddressAsyncEscape,alpha.core.TestAfterDivZero,alpha.deadcode.UnreachableCode,core.builtin.BuiltinFunctions,core.builtin.NoReturnFunctions,core.CallAndMessage,core.DivideZero,core.DynamicTypePropagation,core.NonnilStringConstants,core.NonNullParamChecker,core.NullDereference,core.StackAddressEscape,core.UndefinedBinaryOperatorResult,core.uninitialized.ArraySubscript,core.uninitialized.Assign,core.uninitialized.Branch,core.uninitialized.CapturedBlockVariable,core.uninitialized.UndefReturn,core.VLASize,cplusplus.InnerPointer,cplusplus.Move,cplusplus.NewDelete,cplusplus.NewDeleteLeaks,cplusplus.SelfAssignment,deadcode.DeadStores,nullability.NullableDereferenced,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull --use-c++=$(COMPILER_DIR)/clang++ --view -analyze-headers -o clang_analyze_build/report.html ninja
+	cd clang_analyze_build ; \
+		$(COMPILER_DIR)/scan-build \
+			-enable-checker alpha.core.BoolAssignment,alpha.core.CallAndMessageUnInitRefArg,alpha.core.CastSize,alpha.core.CastToStruct,alpha.core.Conversion,alpha.core.DynamicTypeChecker,alpha.core.FixedAddr,alpha.core.PointerArithm,alpha.core.PointerSub,alpha.core.SizeofPtr,alpha.core.StackAddressAsyncEscape,alpha.core.TestAfterDivZero,alpha.deadcode.UnreachableCode,core.builtin.BuiltinFunctions,core.builtin.NoReturnFunctions,core.CallAndMessage,core.DivideZero,core.DynamicTypePropagation,core.NonnilStringConstants,core.NonNullParamChecker,core.NullDereference,core.StackAddressEscape,core.UndefinedBinaryOperatorResult,core.uninitialized.ArraySubscript,core.uninitialized.Assign,core.uninitialized.Branch,core.uninitialized.CapturedBlockVariable,core.uninitialized.UndefReturn,core.VLASize,cplusplus.InnerPointer,cplusplus.Move,cplusplus.NewDelete,cplusplus.NewDeleteLeaks,cplusplus.SelfAssignment,deadcode.DeadStores,nullability.NullableDereferenced,nullability.NullablePassedToNonnull,nullability.NullableReturnedFromNonnull,nullability.NullPassedToNonnull,nullability.NullReturnedFromNonnull \
+			--use-c++=$(COMPILER_DIR)/clang++ -analyze-headers -o report ninja
+	open clang_analyze_build/report/*/index.html
 
-# call cpplint (some errors expected due to false positives)
+# call cpplint <https://github.com/cpplint/cpplint>
+# Note: some errors expected due to false positives
 cpplint:
-	third_party/cpplint/cpplint.py --filter=-whitespace,-legal,-readability/alt_tokens,-runtime/references,-runtime/explicit --quiet --recursive include
+	third_party/cpplint/cpplint.py \
+		--filter=-whitespace,-legal,-readability/alt_tokens,-runtime/references,-runtime/explicit \
+		--quiet --recursive $(SRCS)
 
+# call Clang-Tidy <https://clang.llvm.org/extra/clang-tidy/>
 clang_tidy:
 	$(COMPILER_DIR)/clang-tidy $(SRCS) -- -Iinclude -std=c++11
 
+# call PVS-Studio Analyzer <https://www.viva64.com/en/pvs-studio/>
 pvs_studio:
 	rm -fr pvs_studio_build
 	mkdir pvs_studio_build
@@ -466,45 +459,70 @@ pvs_studio:
 	cd pvs_studio_build ; plog-converter -a'GA:1,2;64:1;CS' -t fullhtml PVS-Studio.log -o pvs
 	open pvs_studio_build/pvs/index.html
 
+# call Infer <https://fbinfer.com> static analyzer
 infer:
 	rm -fr infer_build
 	mkdir infer_build
 	cd infer_build ; infer compile -- cmake .. ; infer run -- make -j 4
 
+# call OCLint <http://oclint.org> static analyzer
 oclint:
 	oclint $(SRCS) -report-type html -enable-global-analysis -o oclint_report.html -max-priority-1=10000 -max-priority-2=10000 -max-priority-3=10000 -- -std=c++11 -Iinclude
 	open oclint_report.html
 
+# execute the test suite with Clang sanitizers (address and undefined behavior)
+clang_sanitize:
+	rm -fr clang_sanitize_build
+	mkdir clang_sanitize_build
+	cd clang_sanitize_build ; CXX=$(COMPILER_DIR)/clang++ cmake .. -DJSON_Sanitizer=On -DJSON_MultipleHeaders=ON -GNinja
+	cd clang_sanitize_build ; ninja
+	cd clang_sanitize_build ; ctest -E '.*_default' -j10
+
+
 ##########################################################################
-# maintainer targets
+# Code format and source amalgamation
 ##########################################################################
 
-# pretty printer
+# call the Artistic Style pretty printer on all source files
 pretty:
-	astyle --style=allman --indent=spaces=4 --indent-modifiers \
-	   --indent-switches --indent-preproc-block --indent-preproc-define \
-	   --indent-col1-comments --pad-oper --pad-header --align-pointer=type \
-	   --align-reference=type --add-brackets --convert-tabs --close-templates \
-	   --lineend=linux --preserve-date --suffix=none --formatted \
-	   $(SRCS) $(AMALGAMATED_FILE) test/src/*.cpp \
-	   benchmarks/src/benchmarks.cpp doc/examples/*.cpp
+	astyle \
+		--style=allman \
+		--indent=spaces=4 \
+		--indent-modifiers \
+	    --indent-switches \
+	    --indent-preproc-block \
+	    --indent-preproc-define \
+	    --indent-col1-comments \
+	    --pad-oper \
+	    --pad-header \
+	    --align-pointer=type \
+	    --align-reference=type \
+	    --add-brackets \
+	    --convert-tabs \
+	    --close-templates \
+	    --lineend=linux \
+	    --preserve-date \
+	    --suffix=none \
+	    --formatted \
+	   $(SRCS) $(AMALGAMATED_FILE) test/src/*.cpp benchmarks/src/benchmarks.cpp doc/examples/*.cpp
 
 # create single header file
 amalgamate: $(AMALGAMATED_FILE)
 
+# call the amalgamation tool and pretty print
 $(AMALGAMATED_FILE): $(SRCS)
 	third_party/amalgamate/amalgamate.py -c third_party/amalgamate/config.json -s . --verbose=yes
 	$(MAKE) pretty
 
-# check if single_include/nlohmann/json.hpp has been amalgamated from the nlohmann sources
+# check if file single_include/nlohmann/json.hpp has been amalgamated from the nlohmann sources
+# Note: this target is called by Travis
 check-amalgamation:
 	@mv $(AMALGAMATED_FILE) $(AMALGAMATED_FILE)~
 	@$(MAKE) amalgamate
 	@diff $(AMALGAMATED_FILE) $(AMALGAMATED_FILE)~ || (echo "===================================================================\n  Amalgamation required! Please read the contribution guidelines\n  in file .github/CONTRIBUTING.md.\n===================================================================" ; mv $(AMALGAMATED_FILE)~ $(AMALGAMATED_FILE) ; false)
 	@mv $(AMALGAMATED_FILE)~ $(AMALGAMATED_FILE)
 
-# check if every header in nlohmann includes sufficient headers to be compiled
-# individually
+# check if every header in nlohmann includes sufficient headers to be compiled individually
 check-single-includes:
 	@for x in $(SRCS); do \
 	  echo "Checking self-sufficiency of $$x..." ; \
@@ -513,29 +531,79 @@ check-single-includes:
 	  rm -f single_include_test.cpp single_include_test; \
 	done
 
+
 ##########################################################################
-# changelog
+# CMake
 ##########################################################################
 
+# grep "^option" CMakeLists.txt test/CMakeLists.txt | sed 's/(/ /' | awk '{print $2}' | xargs
+
+# check if all flags of our CMake files work
+check_cmake_flags_do:
+	$(CMAKE_BINARY) --version
+	for flag in '' JSON_BuildTests JSON_Install JSON_MultipleHeaders JSON_Sanitizer JSON_Valgrind JSON_NoExceptions JSON_Coverage; do \
+		rm -fr cmake_build; \
+		mkdir cmake_build; \
+		echo "$(CMAKE_BINARY) .. -D$$flag=On" ; \
+		cd cmake_build ; \
+		CXX=g++-8 $(CMAKE_BINARY) .. -D$$flag=On -DCMAKE_CXX_COMPILE_FEATURES="cxx_std_11;cxx_range_for" -DCMAKE_CXX_FLAGS="-std=gnu++11" ; \
+		test -f Makefile || exit 1 ; \
+		cd .. ; \
+	done;
+
+# call target `check_cmake_flags_do` twice: once for minimal required CMake version 3.1.0 and once for the installed version
+check_cmake_flags:
+	wget https://github.com/Kitware/CMake/releases/download/v3.1.0/cmake-3.1.0-Darwin64.tar.gz
+	tar xfz cmake-3.1.0-Darwin64.tar.gz
+	CMAKE_BINARY=$(abspath cmake-3.1.0-Darwin64/CMake.app/Contents/bin/cmake) $(MAKE) check_cmake_flags_do
+	CMAKE_BINARY=$(shell which cmake) $(MAKE) check_cmake_flags_do
+
+
+##########################################################################
+# ChangeLog
+##########################################################################
+
+# Create a ChangeLog based on the git log using the GitHub Changelog Generator
+# (<https://github.com/github-changelog-generator/github-changelog-generator>).
+
+# variable to control the diffs between the last released version and the current repository state
 NEXT_VERSION ?= "unreleased"
 
 ChangeLog.md:
 	github_changelog_generator -o ChangeLog.md --simple-list --release-url https://github.com/nlohmann/json/releases/tag/%s --future-release $(NEXT_VERSION)
-	gsed -i 's|https://github.com/nlohmann/json/releases/tag/HEAD|https://github.com/nlohmann/json/tree/HEAD|' ChangeLog.md
-	gsed -i '2i All notable changes to this project will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org/).' ChangeLog.md
+	$(SED) -i 's|https://github.com/nlohmann/json/releases/tag/HEAD|https://github.com/nlohmann/json/tree/HEAD|' ChangeLog.md
+	$(SED) -i '2i All notable changes to this project will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org/).' ChangeLog.md
 
 
 ##########################################################################
-# release
+# Release files
 ##########################################################################
 
+# Create the files for a release and add signatures and hashes. We use `--no-extra` to make the resulting ZIP file
+# reproducible, see <https://content.pivotal.io/blog/barriers-to-deterministic-reproducible-zip-files>.
+
 release:
+	rm -fr release_files
 	mkdir release_files
-	zip -9 -r include.zip include/*
+	zip -9 --recurse-paths --no-extra include.zip $(SRCS)
 	gpg --armor --detach-sig include.zip
 	mv include.zip include.zip.asc release_files
-	gpg --armor --detach-sig single_include/nlohmann/json.hpp
-	cp single_include/nlohmann/json.hpp release_files
-	mv single_include/nlohmann/json.hpp.asc release_files
+	gpg --armor --detach-sig $(AMALGAMATED_FILE)
+	cp $(AMALGAMATED_FILE) release_files
+	mv $(AMALGAMATED_FILE).asc release_files
 	cd release_files ; shasum -a 256 json.hpp > hashes.txt
 	cd release_files ; shasum -a 256 include.zip >> hashes.txt
+
+
+##########################################################################
+# Maintenance
+##########################################################################
+
+# clean up
+clean:
+	rm -fr json_unit json_benchmarks fuzz fuzz-testing *.dSYM test/*.dSYM oclint_report.html
+	rm -fr benchmarks/files/numbers/*.json
+	rm -fr cmake-3.1.0-Darwin64.tar.gz cmake-3.1.0-Darwin64
+	rm -fr build_coverage build_benchmarks fuzz-testing clang_analyze_build pvs_studio_build infer_build clang_sanitize_build cmake_build
+	$(MAKE) clean -Cdoc
+	$(MAKE) clean -Ctest
diff --git a/include/nlohmann/detail/iterators/iterator_traits.hpp b/include/nlohmann/detail/iterators/iterator_traits.hpp
index 9806be8c..4cced80c 100644
--- a/include/nlohmann/detail/iterators/iterator_traits.hpp
+++ b/include/nlohmann/detail/iterators/iterator_traits.hpp
@@ -13,15 +13,16 @@ template <typename It, typename = void>
 struct iterator_types {};
 
 template <typename It>
-struct iterator_types<
+struct iterator_types <
     It,
     void_t<typename It::difference_type, typename It::value_type, typename It::pointer,
-           typename It::reference, typename It::iterator_category>> {
-  using difference_type = typename It::difference_type;
-  using value_type = typename It::value_type;
-  using pointer = typename It::pointer;
-  using reference = typename It::reference;
-  using iterator_category = typename It::iterator_category;
+    typename It::reference, typename It::iterator_category >>
+{
+    using difference_type = typename It::difference_type;
+    using value_type = typename It::value_type;
+    using pointer = typename It::pointer;
+    using reference = typename It::reference;
+    using iterator_category = typename It::iterator_category;
 };
 
 // This is required as some compilers implement std::iterator_traits in a way that
@@ -32,18 +33,19 @@ struct iterator_traits
 };
 
 template <typename T>
-struct iterator_traits<T, enable_if_t<!std::is_pointer<T>::value>>
-  : iterator_types<T>
+struct iterator_traits < T, enable_if_t < !std::is_pointer<T>::value >>
+            : iterator_types<T>
 {
 };
 
 template <typename T>
-struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>> {
-  using iterator_category = std::random_access_iterator_tag;
-  using value_type = T;
-  using difference_type = ptrdiff_t;
-  using pointer = T*;
-  using reference = T&;
+struct iterator_traits<T*, enable_if_t<std::is_object<T>::value>>
+{
+    using iterator_category = std::random_access_iterator_tag;
+    using value_type = T;
+    using difference_type = ptrdiff_t;
+    using pointer = T*;
+    using reference = T&;
 };
 } // namespace detail
 } // namespace nlohmann
diff --git a/include/nlohmann/detail/macro_scope.hpp b/include/nlohmann/detail/macro_scope.hpp
index ef138100..e41180a9 100644
--- a/include/nlohmann/detail/macro_scope.hpp
+++ b/include/nlohmann/detail/macro_scope.hpp
@@ -18,6 +18,14 @@
     #endif
 #endif
 
+// C++ language standard detection
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
+    #define JSON_HAS_CPP_17
+    #define JSON_HAS_CPP_14
+#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
+    #define JSON_HAS_CPP_14
+#endif
+
 // disable float-equal warnings on GCC/clang
 #if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
     #pragma GCC diagnostic push
@@ -42,7 +50,11 @@
 // allow for portable nodiscard warnings
 #if defined(__has_cpp_attribute)
     #if __has_cpp_attribute(nodiscard)
-        #define JSON_NODISCARD [[nodiscard]]
+        #if defined(__clang__) && !defined(JSON_HAS_CPP_17) // issue #1535
+            #define JSON_NODISCARD
+        #else
+            #define JSON_NODISCARD [[nodiscard]]
+        #endif
     #elif __has_cpp_attribute(gnu::warn_unused_result)
         #define JSON_NODISCARD [[gnu::warn_unused_result]]
     #else
@@ -95,14 +107,6 @@
     #define JSON_UNLIKELY(x)    x
 #endif
 
-// C++ language standard detection
-#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
-    #define JSON_HAS_CPP_17
-    #define JSON_HAS_CPP_14
-#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
-    #define JSON_HAS_CPP_14
-#endif
-
 /*!
 @brief macro to briefly define a mapping between an enum and JSON
 @def NLOHMANN_JSON_SERIALIZE_ENUM
diff --git a/include/nlohmann/detail/meta/is_sax.hpp b/include/nlohmann/detail/meta/is_sax.hpp
index 4a4f5bbd..88295bec 100644
--- a/include/nlohmann/detail/meta/is_sax.hpp
+++ b/include/nlohmann/detail/meta/is_sax.hpp
@@ -24,119 +24,119 @@ using number_integer_function_t =
 
 template <typename T, typename Unsigned>
 using number_unsigned_function_t =
-    decltype(std::declval<T &>().number_unsigned(std::declval<Unsigned>()));
+    decltype(std::declval<T&>().number_unsigned(std::declval<Unsigned>()));
 
 template <typename T, typename Float, typename String>
-using number_float_function_t = decltype(std::declval<T &>().number_float(
-    std::declval<Float>(), std::declval<const String &>()));
+using number_float_function_t = decltype(std::declval<T&>().number_float(
+                                    std::declval<Float>(), std::declval<const String&>()));
 
 template <typename T, typename String>
 using string_function_t =
-    decltype(std::declval<T &>().string(std::declval<String &>()));
+    decltype(std::declval<T&>().string(std::declval<String&>()));
 
 template <typename T>
 using start_object_function_t =
-    decltype(std::declval<T &>().start_object(std::declval<std::size_t>()));
+    decltype(std::declval<T&>().start_object(std::declval<std::size_t>()));
 
 template <typename T, typename String>
 using key_function_t =
-    decltype(std::declval<T &>().key(std::declval<String &>()));
+    decltype(std::declval<T&>().key(std::declval<String&>()));
 
 template <typename T>
-using end_object_function_t = decltype(std::declval<T &>().end_object());
+using end_object_function_t = decltype(std::declval<T&>().end_object());
 
 template <typename T>
 using start_array_function_t =
-    decltype(std::declval<T &>().start_array(std::declval<std::size_t>()));
+    decltype(std::declval<T&>().start_array(std::declval<std::size_t>()));
 
 template <typename T>
-using end_array_function_t = decltype(std::declval<T &>().end_array());
+using end_array_function_t = decltype(std::declval<T&>().end_array());
 
 template <typename T, typename Exception>
-using parse_error_function_t = decltype(std::declval<T &>().parse_error(
-    std::declval<std::size_t>(), std::declval<const std::string &>(),
-    std::declval<const Exception &>()));
+using parse_error_function_t = decltype(std::declval<T&>().parse_error(
+        std::declval<std::size_t>(), std::declval<const std::string&>(),
+        std::declval<const Exception&>()));
 
 template <typename SAX, typename BasicJsonType>
 struct is_sax
 {
-private:
-  static_assert(is_basic_json<BasicJsonType>::value,
-                "BasicJsonType must be of type basic_json<...>");
+  private:
+    static_assert(is_basic_json<BasicJsonType>::value,
+                  "BasicJsonType must be of type basic_json<...>");
 
-  using number_integer_t = typename BasicJsonType::number_integer_t;
-  using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-  using number_float_t = typename BasicJsonType::number_float_t;
-  using string_t = typename BasicJsonType::string_t;
-  using exception_t = typename BasicJsonType::exception;
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using exception_t = typename BasicJsonType::exception;
 
-public:
-  static constexpr bool value =
-      is_detected_exact<bool, null_function_t, SAX>::value &&
-      is_detected_exact<bool, boolean_function_t, SAX>::value &&
-      is_detected_exact<bool, number_integer_function_t, SAX,
-                        number_integer_t>::value &&
-      is_detected_exact<bool, number_unsigned_function_t, SAX,
-                        number_unsigned_t>::value &&
-      is_detected_exact<bool, number_float_function_t, SAX, number_float_t,
-                        string_t>::value &&
-      is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
-      is_detected_exact<bool, start_object_function_t, SAX>::value &&
-      is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
-      is_detected_exact<bool, end_object_function_t, SAX>::value &&
-      is_detected_exact<bool, start_array_function_t, SAX>::value &&
-      is_detected_exact<bool, end_array_function_t, SAX>::value &&
-      is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
+  public:
+    static constexpr bool value =
+        is_detected_exact<bool, null_function_t, SAX>::value &&
+        is_detected_exact<bool, boolean_function_t, SAX>::value &&
+        is_detected_exact<bool, number_integer_function_t, SAX,
+        number_integer_t>::value &&
+        is_detected_exact<bool, number_unsigned_function_t, SAX,
+        number_unsigned_t>::value &&
+        is_detected_exact<bool, number_float_function_t, SAX, number_float_t,
+        string_t>::value &&
+        is_detected_exact<bool, string_function_t, SAX, string_t>::value &&
+        is_detected_exact<bool, start_object_function_t, SAX>::value &&
+        is_detected_exact<bool, key_function_t, SAX, string_t>::value &&
+        is_detected_exact<bool, end_object_function_t, SAX>::value &&
+        is_detected_exact<bool, start_array_function_t, SAX>::value &&
+        is_detected_exact<bool, end_array_function_t, SAX>::value &&
+        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value;
 };
 
 template <typename SAX, typename BasicJsonType>
 struct is_sax_static_asserts
 {
-private:
-  static_assert(is_basic_json<BasicJsonType>::value,
-                "BasicJsonType must be of type basic_json<...>");
+  private:
+    static_assert(is_basic_json<BasicJsonType>::value,
+                  "BasicJsonType must be of type basic_json<...>");
 
-  using number_integer_t = typename BasicJsonType::number_integer_t;
-  using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
-  using number_float_t = typename BasicJsonType::number_float_t;
-  using string_t = typename BasicJsonType::string_t;
-  using exception_t = typename BasicJsonType::exception;
+    using number_integer_t = typename BasicJsonType::number_integer_t;
+    using number_unsigned_t = typename BasicJsonType::number_unsigned_t;
+    using number_float_t = typename BasicJsonType::number_float_t;
+    using string_t = typename BasicJsonType::string_t;
+    using exception_t = typename BasicJsonType::exception;
 
-public:
-  static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
-                "Missing/invalid function: bool null()");
-  static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                "Missing/invalid function: bool boolean(bool)");
-  static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
-                "Missing/invalid function: bool boolean(bool)");
-  static_assert(
-      is_detected_exact<bool, number_integer_function_t, SAX,
-                        number_integer_t>::value,
-      "Missing/invalid function: bool number_integer(number_integer_t)");
-  static_assert(
-      is_detected_exact<bool, number_unsigned_function_t, SAX,
-                        number_unsigned_t>::value,
-      "Missing/invalid function: bool number_unsigned(number_unsigned_t)");
-  static_assert(is_detected_exact<bool, number_float_function_t, SAX,
-                                  number_float_t, string_t>::value,
-                "Missing/invalid function: bool number_float(number_float_t, const string_t&)");
-  static_assert(
-      is_detected_exact<bool, string_function_t, SAX, string_t>::value,
-      "Missing/invalid function: bool string(string_t&)");
-  static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
-                "Missing/invalid function: bool start_object(std::size_t)");
-  static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
-                "Missing/invalid function: bool key(string_t&)");
-  static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
-                "Missing/invalid function: bool end_object()");
-  static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
-                "Missing/invalid function: bool start_array(std::size_t)");
-  static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
-                "Missing/invalid function: bool end_array()");
-  static_assert(
-      is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
-      "Missing/invalid function: bool parse_error(std::size_t, const "
-      "std::string&, const exception&)");
+  public:
+    static_assert(is_detected_exact<bool, null_function_t, SAX>::value,
+                  "Missing/invalid function: bool null()");
+    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
+                  "Missing/invalid function: bool boolean(bool)");
+    static_assert(is_detected_exact<bool, boolean_function_t, SAX>::value,
+                  "Missing/invalid function: bool boolean(bool)");
+    static_assert(
+        is_detected_exact<bool, number_integer_function_t, SAX,
+        number_integer_t>::value,
+        "Missing/invalid function: bool number_integer(number_integer_t)");
+    static_assert(
+        is_detected_exact<bool, number_unsigned_function_t, SAX,
+        number_unsigned_t>::value,
+        "Missing/invalid function: bool number_unsigned(number_unsigned_t)");
+    static_assert(is_detected_exact<bool, number_float_function_t, SAX,
+                  number_float_t, string_t>::value,
+                  "Missing/invalid function: bool number_float(number_float_t, const string_t&)");
+    static_assert(
+        is_detected_exact<bool, string_function_t, SAX, string_t>::value,
+        "Missing/invalid function: bool string(string_t&)");
+    static_assert(is_detected_exact<bool, start_object_function_t, SAX>::value,
+                  "Missing/invalid function: bool start_object(std::size_t)");
+    static_assert(is_detected_exact<bool, key_function_t, SAX, string_t>::value,
+                  "Missing/invalid function: bool key(string_t&)");
+    static_assert(is_detected_exact<bool, end_object_function_t, SAX>::value,
+                  "Missing/invalid function: bool end_object()");
+    static_assert(is_detected_exact<bool, start_array_function_t, SAX>::value,
+                  "Missing/invalid function: bool start_array(std::size_t)");
+    static_assert(is_detected_exact<bool, end_array_function_t, SAX>::value,
+                  "Missing/invalid function: bool end_array()");
+    static_assert(
+        is_detected_exact<bool, parse_error_function_t, SAX, exception_t>::value,
+        "Missing/invalid function: bool parse_error(std::size_t, const "
+        "std::string&, const exception&)");
 };
 }  // namespace detail
 }  // namespace nlohmann
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 5003a4fa..1f11538c 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -469,6 +469,14 @@ class other_error : public exception
     #endif
 #endif
 
+// C++ language standard detection
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
+    #define JSON_HAS_CPP_17
+    #define JSON_HAS_CPP_14
+#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
+    #define JSON_HAS_CPP_14
+#endif
+
 // disable float-equal warnings on GCC/clang
 #if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
     #pragma GCC diagnostic push
@@ -493,7 +501,11 @@ class other_error : public exception
 // allow for portable nodiscard warnings
 #if defined(__has_cpp_attribute)
     #if __has_cpp_attribute(nodiscard)
-        #define JSON_NODISCARD [[nodiscard]]
+        #if defined(__clang__) && !defined(JSON_HAS_CPP_17) // issue #1535
+            #define JSON_NODISCARD
+        #else
+            #define JSON_NODISCARD [[nodiscard]]
+        #endif
     #elif __has_cpp_attribute(gnu::warn_unused_result)
         #define JSON_NODISCARD [[gnu::warn_unused_result]]
     #else
@@ -546,14 +558,6 @@ class other_error : public exception
     #define JSON_UNLIKELY(x)    x
 #endif
 
-// C++ language standard detection
-#if (defined(__cplusplus) && __cplusplus >= 201703L) || (defined(_HAS_CXX17) && _HAS_CXX17 == 1) // fix for issue #464
-    #define JSON_HAS_CPP_17
-    #define JSON_HAS_CPP_14
-#elif (defined(__cplusplus) && __cplusplus >= 201402L) || (defined(_HAS_CXX14) && _HAS_CXX14 == 1)
-    #define JSON_HAS_CPP_14
-#endif
-
 /*!
 @brief macro to briefly define a mapping between an enum and JSON
 @def NLOHMANN_JSON_SERIALIZE_ENUM
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 53fd3ae6..f6c8829b 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -6,7 +6,7 @@ option(JSON_Coverage "Build test suite with coverage information" OFF)
 if(JSON_Sanitizer)
     message(STATUS "Building test suite with Clang sanitizer")
     if(NOT MSVC)
-        set(CMAKE_CXX_FLAGS "-g -O2 -fsanitize=address -fsanitize=undefined -fno-omit-frame-pointer")
+        set(CMAKE_CXX_FLAGS "-g -O2 -fsanitize=address -fsanitize=undefined -fsanitize=integer -fsanitize=nullability -fno-omit-frame-pointer")
     endif()
 endif()
 
@@ -64,7 +64,6 @@ set_target_properties(doctest_main PROPERTIES
     COMPILE_DEFINITIONS "$<$<CXX_COMPILER_ID:MSVC>:_SCL_SECURE_NO_WARNINGS>"
     COMPILE_OPTIONS "$<$<CXX_COMPILER_ID:MSVC>:/EHsc;$<$<CONFIG:Release>:/Od>>"
 )
-
 if (${CMAKE_VERSION} VERSION_LESS "3.8.0") 
     target_compile_features(doctest_main PUBLIC cxx_range_for)
 else()
diff --git a/third_party/cpplint/LICENSE b/third_party/cpplint/LICENSE
old mode 100755
new mode 100644
diff --git a/third_party/cpplint/README.rst b/third_party/cpplint/README.rst
old mode 100755
new mode 100644
diff --git a/third_party/cpplint/update.sh b/third_party/cpplint/update.sh
new file mode 100755
index 00000000..03b6785b
--- /dev/null
+++ b/third_party/cpplint/update.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+
+wget -N https://raw.githubusercontent.com/cpplint/cpplint/master/cpplint.py
+wget -N https://raw.githubusercontent.com/cpplint/cpplint/master/LICENSE
+wget -N https://raw.githubusercontent.com/cpplint/cpplint/master/README.rst