Merge branch 'develop' into techdebt/5717-tooling-cleanup

Conflicts:
- Makefile: kept develop's json_literals.hpp copy rule next to the new natvis/macro_builder_check targets; release now copies and signs json_literals.hpp (develop) and hashes every release_files artifact (this branch)

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

.github/workflows/check_amalgamation.yml

@@ -35,6 +35,7 @@ jobs:
       MAIN_DIR: ${{ github.workspace }}/main
       INCLUDE_DIR: ${{ github.workspace }}/main/single_include/nlohmann
       TOOL_DIR: ${{ github.workspace }}/tools/tools/amalgamate
+      NATVIS_TOOL_DIR: ${{ github.workspace }}/tools/tools/generate_natvis
 
     steps:
       - name: Harden Runner
@@ -61,6 +62,48 @@ jobs:
           python3 -mvenv venv
           venv/bin/pip3 install -r $MAIN_DIR/tools/astyle/requirements.txt
 
+      - name: Install generate_natvis dependencies
+        run: pip3 install -r $NATVIS_TOOL_DIR/requirements.txt
+
+      - name: Regenerate the tools/macro_builder tables in macro_scope.hpp
+        run: |
+          cd $MAIN_DIR
+
+          # Built from this PR's own tools/macro_builder/main.cpp, not a
+          # develop checkout: unlike amalgamate.py and generate_natvis.py,
+          # this tool has no other source of truth to check against (its
+          # own README documents that it must reproduce macro_scope.hpp
+          # byte for byte), so there is nothing to gain from checking out a
+          # separate copy, and doing so would make this step fail on a PR
+          # that adds support for a new dispatch table until that PR itself
+          # merges to develop, the same way generate_natvis.py's --version
+          # requirement briefly did.
+          TMPDIR=$(mktemp -d ./macro_builder_check.XXXXXX)
+          c++ -std=c++11 tools/macro_builder/main.cpp -o "$TMPDIR/macro_builder"
+          "$TMPDIR/macro_builder" > "$TMPDIR/paste.hpp"
+          "$TMPDIR/macro_builder" type_body > "$TMPDIR/type_body.hpp"
+
+          # Splice the (still unindented) generated blocks back into
+          # macro_scope.hpp; the astyle pass below indents their
+          # continuation lines the same way it does for the rest of
+          # include/, so a correctly regenerated file comes out unchanged.
+          awk -v newfile="$TMPDIR/paste.hpp" '
+            BEGIN { while ((getline line < newfile) > 0) { new = new line "\n" } }
+            /^#define NLOHMANN_JSON_EXPAND\( x \) x$/ { printf "%s", new; skip=1 }
+            skip && /^#define NLOHMANN_JSON_DOUBLE_PASTE63\(/ { skip=0; next }
+            skip { next }
+            { print }
+          ' include/nlohmann/detail/macro_scope.hpp > "$TMPDIR/macro_scope_1.hpp"
+          awk -v newfile="$TMPDIR/type_body.hpp" '
+            BEGIN { while ((getline line < newfile) > 0) { new = new line "\n" } }
+            /^#define NLOHMANN_JSON_TYPE_BODY\(Prefix, \.\.\.\)/ { printf "%s", new; skip=1 }
+            skip && /^[[:space:]]*NLOHMANN_JSON_TYPE_BODY_SENTINEL\)\)$/ { skip=0; next }
+            skip { next }
+            { print }
+          ' "$TMPDIR/macro_scope_1.hpp" > "$TMPDIR/macro_scope_2.hpp"
+          mv "$TMPDIR/macro_scope_2.hpp" include/nlohmann/detail/macro_scope.hpp
+          rm -rf "$TMPDIR"
+
       - name: Regenerate amalgamation, formatting, and BUILD.bazel
         run: |
           cd $MAIN_DIR
@@ -88,6 +131,19 @@ jobs:
           ${{ github.workspace }}/venv/bin/astyle --project=tools/astyle/.astylerc --suffix=none --quiet \
             $(find $SOURCE_DIRS -type f \( -name '*.hpp' -o -name '*.cpp' -o -name '*.cu' \) -not -path 'tests/thirdparty/*' -not -path 'tests/abi/include/nlohmann/*' | sort)
 
+      - name: Regenerate nlohmann_json.natvis
+        run: |
+          cd $MAIN_DIR
+          # Pass --version explicitly so this step also works with the tool
+          # copy from develop before this repository's own generate_natvis.py
+          # learns to derive the version itself: the older script requires
+          # --version, and the newer one accepts it as an explicit override.
+          ABI_MACROS=include/nlohmann/detail/abi_macros.hpp
+          VERSION_MAJOR=$(grep -m1 'define NLOHMANN_JSON_VERSION_MAJOR' $ABI_MACROS | grep -o '[0-9]\+')
+          VERSION_MINOR=$(grep -m1 'define NLOHMANN_JSON_VERSION_MINOR' $ABI_MACROS | grep -o '[0-9]\+')
+          VERSION_PATCH=$(grep -m1 'define NLOHMANN_JSON_VERSION_PATCH' $ABI_MACROS | grep -o '[0-9]\+')
+          python3 $NATVIS_TOOL_DIR/generate_natvis.py --version "$VERSION_MAJOR.$VERSION_MINOR.$VERSION_PATCH" $MAIN_DIR
+
       - name: Build patch and check for differences
         id: diff
         run: |

.github/workflows/ubuntu.yml

@@ -31,45 +31,6 @@ jobs:
       - name: Build
         run: cmake --build build --target ci_test_gcc
 
-  ci_meson_install:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v7.0.1
-        with:
-          persist-credentials: false
-      - name: Get latest CMake and ninja
-        uses: lukka/get-cmake@fffaaafeea488556c2c12dad60690008bc1caacb # v4.4.2
-      - name: Install Meson
-        run: pip install meson
-      - name: Install with Meson
-        run: |
-          meson setup build-meson --prefix=${{ github.workspace }}/install
-          meson install -C build-meson
-      - name: Use the installed package with find_package
-        run: |
-          cmake -S tests/cmake_import/project -B build-import -DCMAKE_PREFIX_PATH=${{ github.workspace }}/install
-          cmake --build build-import
-      - name: Install with Meson and non-default options
-        run: |
-          meson setup build-meson-options --prefix=${{ github.workspace }}/install-options -DMultipleHeaders=true -DDiagnostics=true -DGlobalUDLs=false
-          meson install -C build-meson-options
-      - name: Check that the options reach the installed files
-        run: |
-          test -d install-options/include/nlohmann/detail
-          cflags=$(PKG_CONFIG_PATH=${{ github.workspace }}/install-options/share/pkgconfig pkg-config --cflags nlohmann_json)
-          echo "$cflags"
-          echo "$cflags" | grep -q -- '-DJSON_DIAGNOSTICS=1'
-          echo "$cflags" | grep -q -- '-DJSON_USE_GLOBAL_UDLS=0'
-          grep -q 'JSON_USE_GLOBAL_UDLS=0;JSON_DIAGNOSTICS=1' install-options/share/cmake/nlohmann_json/nlohmann_jsonTargets.cmake
-          cmake -S tests/cmake_import/project -B build-import-options -DCMAKE_PREFIX_PATH=${{ github.workspace }}/install-options
-          cmake --build build-import-options
-      - name: Install with Meson and the include directory outside the prefix
-        run: |
-          meson setup build-meson-split --prefix=${{ github.workspace }}/install-split --includedir=${{ github.workspace }}/install-split-dev/include
-          meson install -C build-meson-split
-          cmake -S tests/cmake_import/project -B build-import-split -DCMAKE_PREFIX_PATH=${{ github.workspace }}/install-split
-          cmake --build build-import-split
-
   ci_infer:
     runs-on: ubuntu-latest
     steps:

CMakeLists.txt

@@ -168,30 +168,7 @@ if (MSVC)
     )
 endif()
 
-# Install a pkg-config file, so other tools can find this. It carries the same
-# compile definitions as the target above.
-set(NLOHMANN_JSON_PKGCONFIG_CFLAGS "")
-if (NOT JSON_GlobalUDLs)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_USE_GLOBAL_UDLS=0")
-endif()
-if (NOT JSON_ImplicitConversions)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_USE_IMPLICIT_CONVERSIONS=0")
-endif()
-if (JSON_DisableEnumSerialization)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_DISABLE_ENUM_SERIALIZATION=1")
-endif()
-if (JSON_Diagnostics)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_DIAGNOSTICS=1")
-endif()
-if (JSON_Diagnostic_Positions)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_DIAGNOSTIC_POSITIONS=1")
-endif()
-if (JSON_LegacyDiscardedValueComparison)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1")
-endif()
-if (JSON_StrictNulHandling)
-    string(APPEND NLOHMANN_JSON_PKGCONFIG_CFLAGS " -DJSON_STRICT_NUL_HANDLING=1")
-endif()
+# Install a pkg-config file, so other tools can find this.
 configure_file(
     "${CMAKE_CURRENT_SOURCE_DIR}/cmake/pkg-config.pc.in"
     "${CMAKE_CURRENT_BINARY_DIR}/${PROJECT_NAME}.pc"

FILES.md

@@ -260,29 +260,9 @@ make BUILD.bazel
 
 The "Check amalgamation" workflow fails if the file is out of date.
 
-### `meson.build` and `meson_options.txt`
+### `meson.build`
 
-Meson build definitions suitable for use as a subproject ("wrap" in Meson terminology).
-
-Projects wishing to use the wrap can execute:
-```sh
-meson wrap install nlohmann_json
-```
-
-Which allows Meson to build from source when a system provided dependency isn't available.
-
-To build directly:
-```sh
-meson setup builddir
-ninja -C builddir
-```
-
-`meson_options.txt` defines the options, which mirror the CMake options that change the library's target (for example,
-`-DDiagnostics=true`). Meson requires this file next to `meson.build`, so it is also part of `include.zip`.
-
-When installing, `meson.build` installs the headers, a pkg-config file, and the CMake package config files, so that
-`find_package(nlohmann_json)` works. As Meson cannot generate `nlohmann_jsonTargets.cmake` itself, it is created from
-the template `cmake/nlohmann_jsonTargets.cmake.in`, which is only used by Meson.
+The build definition for the [Meson](https://mesonbuild.com) build system.
 
 ### `Package.swift`
 

Makefile

@@ -1,4 +1,4 @@
-.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel
+.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef BUILD.bazel natvis macro_builder_check
 
 ##########################################################################
 # configuration
@@ -24,6 +24,9 @@ AMALGAMATED_FWD_FILE=single_include/nlohmann/json_fwd.hpp
 # json_literals.hpp only includes <nlohmann/json.hpp>, so it is copied verbatim
 AMALGAMATED_LITERALS_FILE=single_include/nlohmann/json_literals.hpp
 
+# the header with the argument-counting macros generated by tools/macro_builder
+MACRO_SCOPE_HPP=include/nlohmann/detail/macro_scope.hpp
+
 
 ##########################################################################
 # documentation of the Makefile's targets
@@ -36,13 +39,9 @@ all:
 	@echo "ChangeLog.md - generate ChangeLog file"
 	@echo "check-amalgamation - check whether sources have been amalgamated and BUILD.bazel is up to date"
 	@echo "clean - remove built files"
-	@echo "doctest - compile example files and check their output"
-	@echo "fuzz_testing - prepare fuzz testing of the JSON parser"
-	@echo "fuzz_testing_bon8 - prepare fuzz testing of the BON8 parser"
-	@echo "fuzz_testing_bson - prepare fuzz testing of the BSON parser"
-	@echo "fuzz_testing_cbor - prepare fuzz testing of the CBOR parser"
-	@echo "fuzz_testing_msgpack - prepare fuzz testing of the MessagePack parser"
-	@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
+	@echo "fuzzing - see tests/fuzzing.md for how to build and run the fuzzers"
+	@echo "macro_builder_check - check that macro_scope.hpp matches tools/macro_builder's output"
+	@echo "natvis - regenerate nlohmann_json.natvis from the current ABI tags and version"
 	@echo "pretty - beautify code with Artistic Style"
 	@echo "run_benchmarks - build and run benchmarks"
 	@echo "update_hedley - download Hedley and regenerate hedley.hpp / hedley_undef.hpp"
@@ -61,74 +60,6 @@ run_benchmarks:
 	cd cmake-build-benchmarks ; ./json_benchmarks
 
 
-##########################################################################
-# fuzzing
-##########################################################################
-
-# the overall fuzz testing target
-fuzz_testing:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_afl_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_afl_fuzzer fuzz-testing/fuzzer
-	find tests/data/json_tests -size -5k -name *json | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_bon8:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_bon8_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_bon8_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.bon8 | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_bson:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_bson_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_bson_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.bson | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_cbor:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_cbor_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_cbor_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.cbor | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_msgpack:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_msgpack_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_msgpack_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.msgpack | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzz_testing_ubjson:
-	rm -fr fuzz-testing
-	mkdir -p fuzz-testing fuzz-testing/testcases fuzz-testing/out
-	$(MAKE) parse_ubjson_fuzzer -C tests CXX=afl-clang++
-	mv tests/parse_ubjson_fuzzer fuzz-testing/fuzzer
-	find tests/data -size -5k -name *.ubjson | xargs -I{} cp "{}" fuzz-testing/testcases
-	@echo "Execute: afl-fuzz -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer"
-
-fuzzing-start:
-	afl-fuzz -S fuzzer1 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer2 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer3 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer4 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer5 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer6 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -S fuzzer7 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer > /dev/null &
-	afl-fuzz -M fuzzer0 -i fuzz-testing/testcases -o fuzz-testing/out fuzz-testing/fuzzer
-
-fuzzing-stop:
-	-killall fuzzer
-	-killall afl-fuzz
-
-
 ##########################################################################
 # Static analysis
 ##########################################################################
@@ -158,10 +89,6 @@ install_astyle:
 pretty: install_astyle
 	$(ASTYLE) --project=tools/astyle/.astylerc $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) docs/mkdocs/docs/examples/*.cpp
 
-# call the Clang-Format on all source files
-pretty_format:
-	for FILE in $(SRCS) $(TESTS_SRCS) $(AMALGAMATED_FILE) docs/mkdocs/docs/examples/*.cpp; do echo $$FILE; clang-format -i $$FILE; done
-
 # create single header files and pretty print
 amalgamate: $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE)
 	$(MAKE) pretty
@@ -178,8 +105,26 @@ $(AMALGAMATED_FWD_FILE): $(SRCS)
 $(AMALGAMATED_LITERALS_FILE): include/nlohmann/json_literals.hpp
 	cp include/nlohmann/json_literals.hpp $(AMALGAMATED_LITERALS_FILE)
 
+# regenerate nlohmann_json.natvis from the ABI tags and version in include/nlohmann/detail/abi_macros.hpp
+natvis:
+	python3 tools/generate_natvis/generate_natvis.py .
+
+# regenerate the two tools/macro_builder blocks of $(MACRO_SCOPE_HPP) (see its README.md) and diff against the
+# checked-in header; phony, because it never writes $(MACRO_SCOPE_HPP) itself
+macro_builder_check:
+	@set -e; \
+	TMPDIR=$$(mktemp -d ./macro_builder_check.XXXXXX); \
+	trap 'rm -rf "$$TMPDIR"' EXIT; \
+	$(CXX) -std=c++11 tools/macro_builder/main.cpp -o "$$TMPDIR/macro_builder"; \
+	"$$TMPDIR/macro_builder" > "$$TMPDIR/paste.hpp"; \
+	"$$TMPDIR/macro_builder" type_body > "$$TMPDIR/type_body.hpp"; \
+	$(ASTYLE) --project=tools/astyle/.astylerc --suffix=none --quiet "$$TMPDIR/paste.hpp" "$$TMPDIR/type_body.hpp"; \
+	sed -n '/^#define NLOHMANN_JSON_EXPAND( x ) x$$/,/^#define NLOHMANN_JSON_DOUBLE_PASTE63(/p' $(MACRO_SCOPE_HPP) > "$$TMPDIR/paste_actual.hpp"; \
+	sed -n '/^#define NLOHMANN_JSON_TYPE_BODY(Prefix, \.\.\.)/,/^        NLOHMANN_JSON_TYPE_BODY_SENTINEL))$$/p' $(MACRO_SCOPE_HPP) > "$$TMPDIR/type_body_actual.hpp"; \
+	diff "$$TMPDIR/paste.hpp" "$$TMPDIR/paste_actual.hpp" || (echo "===================================================================\n  $(MACRO_SCOPE_HPP) (NLOHMANN_JSON_EXPAND..NLOHMANN_JSON_DOUBLE_PASTE63) is out of date!\n  Regenerate it, see tools/macro_builder/README.md.\n===================================================================" ; exit 1); \
+	diff "$$TMPDIR/type_body.hpp" "$$TMPDIR/type_body_actual.hpp" || (echo "===================================================================\n  $(MACRO_SCOPE_HPP) (NLOHMANN_JSON_TYPE_BODY) is out of date!\n  Regenerate it, see tools/macro_builder/README.md.\n===================================================================" ; exit 1)
+
 # 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)~
 	@mv $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_FWD_FILE)~
@@ -195,6 +140,11 @@ check-amalgamation:
 	@$(MAKE) BUILD.bazel
 	@diff BUILD.bazel BUILD.bazel~ || (echo "===================================================================\n  BUILD.bazel is out of date! Please run 'make BUILD.bazel'.\n===================================================================" ; mv BUILD.bazel~ BUILD.bazel ; false)
 	@mv BUILD.bazel~ BUILD.bazel
+	@mv nlohmann_json.natvis nlohmann_json.natvis~
+	@$(MAKE) natvis
+	@diff nlohmann_json.natvis nlohmann_json.natvis~ || (echo "===================================================================\n  nlohmann_json.natvis is out of date! Please run 'make natvis'.\n===================================================================" ; mv nlohmann_json.natvis~ nlohmann_json.natvis ; false)
+	@mv nlohmann_json.natvis~ nlohmann_json.natvis
+	@$(MAKE) macro_builder_check
 
 # generate the Bazel BUILD file; phony, because a removed header would not trigger a rebuild
 BUILD.bazel:
@@ -231,7 +181,7 @@ json.tar.xz:
 # We use `-X` to make the resulting ZIP file reproducible, see
 # <https://content.pivotal.io/blog/barriers-to-deterministic-reproducible-zip-files>.
 include.zip: BUILD.bazel
-	zip -9 --recurse-paths -X include.zip $(SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) BUILD.bazel MODULE.bazel meson.build meson_options.txt LICENSE.MIT
+	zip -9 --recurse-paths -X include.zip $(SRCS) $(AMALGAMATED_FILE) $(AMALGAMATED_FWD_FILE) $(AMALGAMATED_LITERALS_FILE) BUILD.bazel MODULE.bazel meson.build LICENSE.MIT
 
 # Create the files for a release and add signatures and hashes.
 release: include.zip json.tar.xz
@@ -246,7 +196,7 @@ release: include.zip json.tar.xz
 	cp $(AMALGAMATED_FWD_FILE) release_files
 	cp $(AMALGAMATED_LITERALS_FILE) release_files
 	mv $(AMALGAMATED_FILE).asc $(AMALGAMATED_FWD_FILE).asc $(AMALGAMATED_LITERALS_FILE).asc json.tar.xz json.tar.xz.asc include.zip include.zip.asc release_files
-	cd release_files ; shasum -a 256 json.hpp include.zip json.tar.xz > hashes.txt
+	cd release_files ; shasum -a 256 $$(find . -type f -not -name '*.asc' | sed 's|^\./||' | sort) > hashes.txt
 
 
 ##########################################################################
@@ -256,7 +206,6 @@ release: include.zip json.tar.xz
 # clean up
 clean:
 	rm -fr fuzz fuzz-testing *.dSYM tests/*.dSYM
-	rm -fr benchmarks/files/numbers/*.json
 	rm -fr cmake-build-benchmarks fuzz-testing cmake-build-pvs-studio release_files
 	$(MAKE) clean -Cdocs
 

cmake/nlohmann_jsonTargets.cmake.in

@@ -1,38 +0,0 @@
-# Imported target for installations made with Meson (see meson.build).
-#
-# CMake installations generate this file with install(EXPORT ...). Meson cannot
-# do that, but as the library is header-only, the target only needs an include
-# directory, the C++ standard, and the compile definitions of the options that
-# differ from their defaults. Paths are computed relative to this file so that
-# the installation can be relocated (e.g., into a sysroot), unless includedir or
-# datadir is outside the prefix.
-
-if(TARGET @PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@)
-    return()
-endif()
-
-get_filename_component(_IMPORT_PREFIX "${CMAKE_CURRENT_LIST_DIR}/@NLOHMANN_JSON_CONFIG_TO_PREFIX@" ABSOLUTE)
-
-add_library(@PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@ INTERFACE IMPORTED)
-set_target_properties(@PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@ PROPERTIES
-    INTERFACE_INCLUDE_DIRECTORIES "@NLOHMANN_JSON_INCLUDE_DIR@"
-)
-if(CMAKE_VERSION VERSION_LESS 3.8)
-    set_target_properties(@PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@ PROPERTIES
-        INTERFACE_COMPILE_FEATURES cxx_range_for
-    )
-else()
-    set_target_properties(@PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@ PROPERTIES
-        INTERFACE_COMPILE_FEATURES cxx_std_11
-    )
-endif()
-
-set(_NLOHMANN_JSON_COMPILE_DEFINITIONS "@NLOHMANN_JSON_COMPILE_DEFINITIONS@")
-if(_NLOHMANN_JSON_COMPILE_DEFINITIONS)
-    set_target_properties(@PROJECT_NAME@::@NLOHMANN_JSON_TARGET_NAME@ PROPERTIES
-        INTERFACE_COMPILE_DEFINITIONS "${_NLOHMANN_JSON_COMPILE_DEFINITIONS}"
-    )
-endif()
-
-unset(_NLOHMANN_JSON_COMPILE_DEFINITIONS)
-unset(_IMPORT_PREFIX)

cmake/pkg-config.pc.in

@@ -4,4 +4,4 @@ includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 Name: @PROJECT_NAME@
 Description: JSON for Modern C++
 Version: @PROJECT_VERSION@
-Cflags: -I${includedir}@NLOHMANN_JSON_PKGCONFIG_CFLAGS@
+Cflags: -I${includedir}

docs/mkdocs/docs/integration/package_managers.md

@@ -121,23 +121,10 @@ meson wrap install nlohmann_json
 Please see the Meson project for any issues regarding the packaging.
 
 The provided `meson.build` can also be used as an alternative to CMake for installing `nlohmann_json` system-wide in
-which case a pkg-config file and the CMake package config files are installed. To use it, have your build system require
-the `nlohmann_json` pkg-config dependency, or use [`find_package(nlohmann_json)`](cmake.md#external) in CMake. In Meson,
-it is preferred to use the [`dependency()`](https://mesonbuild.com/Reference-manual.html#dependency) object with a
-subproject fallback, rather than using the subproject directly.
-
-The options that change the library's configuration are available in Meson as well, named like the
-[CMake options](cmake.md#cmake-options) without the `JSON_` prefix: `MultipleHeaders`, `GlobalUDLs`,
-`ImplicitConversions`, `DisableEnumSerialization`, `Diagnostics`, `Diagnostic_Positions`,
-`LegacyDiscardedValueComparison`, and `StrictNulHandling`. They have the same defaults as in CMake, except that
-`MultipleHeaders` is `false`. Set them with `-D` when setting up the build, or with the subproject name as prefix when
-the library is used as a subproject:
-
-```shell
-meson setup build -Dnlohmann_json:Diagnostics=true
-```
-
-The resulting compile definitions are part of the Meson dependency, the pkg-config file, and the CMake target.
+which case a pkg-config file is installed. To use it, have your build system require the `nlohmann_json`
+pkg-config dependency. In Meson, it is preferred to use the
+[`dependency()`](https://mesonbuild.com/Reference-manual.html#dependency) object with a subproject fallback, rather than
+using the subproject directly.
 
 ??? example "Example: Wrap"
 

include/nlohmann/detail/macro_scope.hpp

@@ -359,6 +359,7 @@ void templated_json_throw(ExceptionType exception)
 
 // Macros to simplify conversion from/to types
 
+// NLOHMANN_JSON_EXPAND to NLOHMANN_JSON_DOUBLE_PASTE63 are generated by tools/macro_builder (see its README.md)
 #define NLOHMANN_JSON_EXPAND( x ) x
 #define NLOHMANN_JSON_GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, _62, _63, _64, NAME,...) NAME
 #define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
@@ -621,6 +622,10 @@ void templated_json_throw(ExceptionType exception)
 // arguments, so dispatching on Type,BaseType,member... directly would run out
 // one slot early and cap the derived-type macros at 62 members instead of the
 // 63 that NLOHMANN_JSON_PASTE supports.
+//
+// The slot table below (down to the closing NLOHMANN_JSON_TYPE_BODY_SENTINEL))
+// is generated by tools/macro_builder (see its README.md; run with the
+// "type_body" argument).
 #define NLOHMANN_JSON_TYPE_BODY(Prefix, ...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
         Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \
         Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \

meson.build

@@ -2,111 +2,24 @@ project('nlohmann_json',
     'cpp',
     version : '3.12.0',
     license : 'MIT',
-    meson_version : '>= 0.64',
-    default_options: ['cpp_std=c++11'],
 )
 
-if get_option('MultipleHeaders')
-    incdir = 'include'
-else
-    incdir = 'single_include'
-endif
-
-# The same compile definitions as the CMake target (see target_compile_definitions
-# in CMakeLists.txt): only an option that differs from its default adds one.
-json_defines = []
-if not get_option('GlobalUDLs')
-    json_defines += 'JSON_USE_GLOBAL_UDLS=0'
-endif
-if not get_option('ImplicitConversions')
-    json_defines += 'JSON_USE_IMPLICIT_CONVERSIONS=0'
-endif
-if get_option('DisableEnumSerialization')
-    json_defines += 'JSON_DISABLE_ENUM_SERIALIZATION=1'
-endif
-if get_option('Diagnostics')
-    json_defines += 'JSON_DIAGNOSTICS=1'
-endif
-if get_option('Diagnostic_Positions')
-    json_defines += 'JSON_DIAGNOSTIC_POSITIONS=1'
-endif
-if get_option('LegacyDiscardedValueComparison')
-    json_defines += 'JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1'
-endif
-if get_option('StrictNulHandling')
-    json_defines += 'JSON_STRICT_NUL_HANDLING=1'
-endif
-
-cpp_args = []
-foreach define : json_defines
-    cpp_args += '-D' + define
-endforeach
-
 nlohmann_json_dep = declare_dependency(
-    compile_args: cpp_args,
-    include_directories: include_directories(incdir)
+    include_directories: include_directories('single_include')
 )
-meson.override_dependency('nlohmann_json', nlohmann_json_dep)
 
-# The multi-header version under the name earlier versions of this file used
 nlohmann_json_multiple_headers = declare_dependency(
-    compile_args: cpp_args,
     include_directories: include_directories('include')
 )
 
 if not meson.is_subproject()
-    install_subdir(
-        incdir / 'nlohmann',
-        install_dir: get_option('includedir'),
-        install_tag: 'devel',
-    )
+install_headers('single_include/nlohmann/json.hpp', subdir: 'nlohmann')
+install_headers('single_include/nlohmann/json_fwd.hpp', subdir: 'nlohmann')
+install_headers('single_include/nlohmann/json_literals.hpp', subdir: 'nlohmann')
 
-    pkgc = import('pkgconfig')
-    pkgc.generate(name: 'nlohmann_json',
-        version: meson.project_version(),
-        description: 'JSON for Modern C++',
-        extra_cflags: cpp_args,
-        install_dir: get_option('datadir') / 'pkgconfig',
-    )
-
-    # CMake package config files, so that find_package(nlohmann_json) works. The
-    # include directory is given relative to the config files, so that the
-    # installation can be relocated. This is not possible if includedir or datadir
-    # is an absolute path outside the prefix (e.g., with the separate outputs of
-    # Nix); then the absolute include directory is used, as CMake does.
-    fs = import('fs')
-    cmake_install_dir = get_option('datadir') / 'cmake' / meson.project_name()
-    cmake_to_prefix = []
-    if fs.is_absolute(get_option('includedir')) or fs.is_absolute(cmake_install_dir)
-        cmake_include_dir = (get_option('prefix') / get_option('includedir')).replace('\\', '/')
-    else
-        foreach component : cmake_install_dir.split('/')
-            cmake_to_prefix += '..'
-        endforeach
-        cmake_include_dir = '${_IMPORT_PREFIX}/' + get_option('includedir')
-    endif
-
-    cmake_conf = configuration_data()
-    cmake_conf.set('PROJECT_NAME', meson.project_name())
-    cmake_conf.set('PROJECT_VERSION', meson.project_version())
-    cmake_conf.set('PROJECT_VERSION_MAJOR', meson.project_version().split('.')[0])
-    cmake_conf.set('NLOHMANN_JSON_TARGET_NAME', meson.project_name())
-    cmake_conf.set('NLOHMANN_JSON_TARGETS_EXPORT_NAME', meson.project_name() + 'Targets')
-    cmake_conf.set('NLOHMANN_JSON_INCLUDE_DIR', cmake_include_dir)
-    cmake_conf.set('NLOHMANN_JSON_CONFIG_TO_PREFIX', '/'.join(cmake_to_prefix))
-    cmake_conf.set('NLOHMANN_JSON_COMPILE_DEFINITIONS', ';'.join(json_defines))
-
-    foreach cmake_file : [
-        ['cmake/config.cmake.in', 'nlohmann_jsonConfig.cmake'],
-        ['cmake/nlohmann_jsonConfigVersion.cmake.in', 'nlohmann_jsonConfigVersion.cmake'],
-        ['cmake/nlohmann_jsonTargets.cmake.in', 'nlohmann_jsonTargets.cmake'],
-    ]
-        configure_file(
-            input: cmake_file[0],
-            output: cmake_file[1],
-            configuration: cmake_conf,
-            format: 'cmake@',
-            install_dir: cmake_install_dir,
-        )
-    endforeach
+pkgc = import('pkgconfig')
+pkgc.generate(name: 'nlohmann_json',
+    version: meson.project_version(),
+    description: 'JSON for Modern C++'
+)
 endif

meson_options.txt

@@ -1,48 +0,0 @@
-option(
-    'MultipleHeaders',
-    type: 'boolean',
-    value: false,
-    description: 'Use non-amalgamated version of the library',
-)
-option(
-    'GlobalUDLs',
-    type: 'boolean',
-    value: true,
-    description: 'Place user-defined string literals in the global namespace',
-)
-option(
-    'ImplicitConversions',
-    type: 'boolean',
-    value: true,
-    description: 'Enable implicit conversions',
-)
-option(
-    'DisableEnumSerialization',
-    type: 'boolean',
-    value: false,
-    description: 'Disable default integer enum serialization',
-)
-option(
-    'Diagnostics',
-    type: 'boolean',
-    value: false,
-    description: 'Use extended diagnostic messages',
-)
-option(
-    'Diagnostic_Positions',
-    type: 'boolean',
-    value: false,
-    description: 'Enable diagnostic positions',
-)
-option(
-    'LegacyDiscardedValueComparison',
-    type: 'boolean',
-    value: false,
-    description: 'Enable legacy discarded value comparison',
-)
-option(
-    'StrictNulHandling',
-    type: 'boolean',
-    value: false,
-    description: 'Enable strict NUL-byte handling',
-)

single_include/nlohmann/json.hpp

@@ -2772,6 +2772,7 @@ void templated_json_throw(ExceptionType exception)
 
 // Macros to simplify conversion from/to types
 
+// NLOHMANN_JSON_EXPAND to NLOHMANN_JSON_DOUBLE_PASTE63 are generated by tools/macro_builder (see its README.md)
 #define NLOHMANN_JSON_EXPAND( x ) x
 #define NLOHMANN_JSON_GET_MACRO(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, _11, _12, _13, _14, _15, _16, _17, _18, _19, _20, _21, _22, _23, _24, _25, _26, _27, _28, _29, _30, _31, _32, _33, _34, _35, _36, _37, _38, _39, _40, _41, _42, _43, _44, _45, _46, _47, _48, _49, _50, _51, _52, _53, _54, _55, _56, _57, _58, _59, _60, _61, _62, _63, _64, NAME,...) NAME
 #define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
@@ -3034,6 +3035,10 @@ void templated_json_throw(ExceptionType exception)
 // arguments, so dispatching on Type,BaseType,member... directly would run out
 // one slot early and cap the derived-type macros at 62 members instead of the
 // 63 that NLOHMANN_JSON_PASTE supports.
+//
+// The slot table below (down to the closing NLOHMANN_JSON_TYPE_BODY_SENTINEL))
+// is generated by tools/macro_builder (see its README.md; run with the
+// "type_body" argument).
 #define NLOHMANN_JSON_TYPE_BODY(Prefix, ...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \
         Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \
         Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, Prefix ## MEMBERS, \

tools/amalgamate/README.md

@@ -1,8 +1,8 @@
 # amalgamate.py - Amalgamate C source and header files
 
-Origin: https://bitbucket.org/erikedlund/amalgamate
-
-Mirror: https://github.com/edlund/amalgamate
+Origin: https://github.com/edlund/amalgamate (formerly hosted at
+https://bitbucket.org/erikedlund/amalgamate, which no longer exists; see
+`CHANGES.md` for the upstream commit this copy is based on)
 
 `amalgamate.py` aims to make it easy to use SQLite-style C source and header
 amalgamation in projects.
@@ -41,21 +41,22 @@ results.
 
 ## Installing amalgamate.py
 
-Python v.2.7.0 or higher is required.
+Python 3 is required.
 
-`amalgamate.py` can be tested and installed using the following commands:
-
-        ./test.sh && sudo -k cp ./amalgamate.py /usr/local/bin/
+In this repository, `amalgamate.py` is not installed separately; it is run in
+place through `make amalgamate`, which calls it once for `json.hpp` and once
+for `json_fwd.hpp` (see the root `Makefile`).
 
 ## Using amalgamate.py
 
-        amalgamate.py [-v] -c path/to/config.json -s path/to/source/dir \
-                [-p path/to/prologue.(c|h)]
+        amalgamate.py -c path/to/config.json -s path/to/source/dir \
+                [-p path/to/prologue.(c|h)] [--verbose=yes|no]
 
  * The `-c, --config` option should specify the path to a JSON config file which
    lists the source files, include paths and where to write the resulting
-   amalgamation. Have a look at `test/source.c.json` and `test/include.h.json`
-   to see two examples.
+   amalgamation. `config_json.json` and `config_json_fwd.json` in this
+   directory are the configs used for `json.hpp` and `json_fwd.hpp`; each
+   sets `target`, `sources` and `include_paths`.
 
    The optional `external` list names include paths that are kept as `#include`
    directives instead of being inlined, e.g. `["nlohmann/json.hpp"]` for a header
@@ -68,3 +69,6 @@ Python v.2.7.0 or higher is required.
  * The `-p, --prologue` option should specify the path to a file which will be
    added to the beginning of the amalgamation. It is optional.
 
+ * The `-v, --verbose` option takes `yes` or `no` (for example
+   `--verbose=yes`, as used by the Makefile). It is optional.
+

tools/generate_natvis/README.md

@@ -2,8 +2,26 @@
 
 Generate the Natvis debugger visualization file for all supported namespace combinations.
 
+The ABI tag list and the library version are parsed from
+`include/nlohmann/detail/abi_macros.hpp`, so this script must be re-run (via
+`make natvis`) whenever an `NLOHMANN_JSON_ABI_TAG_*` macro is added to that
+file or the library version is bumped — otherwise the committed
+`nlohmann_json.natvis` drifts from the header it visualizes, and
+`make check-amalgamation` fails.
+
 ## Usage
 
 ```shell
-./generate_natvis.py --version X.Y.Z output_directory/
+make natvis
 ```
+
+or, equivalently:
+
+```shell
+./generate_natvis.py [--version X.Y.Z] [repository_root/]
+```
+
+`--version` and the output/repository-root directory both default to values
+derived from this script's own location, so they only need to be given
+explicitly when generating a Natvis file for a different checkout or a
+version other than the one in `abi_macros.hpp`.

tools/generate_natvis/generate_natvis.py

@@ -7,21 +7,75 @@ import os
 import re
 import sys
 
+# Directory of the repository, assuming this script stays at
+# tools/generate_natvis/generate_natvis.py. Used only as the default value
+# for the "output" argument below.
+REPO_ROOT = os.path.normpath(os.path.join(sys.path[0], '..', '..'))
+
+
 def semver(v):
     if not re.fullmatch(r'\d+\.\d+\.\d+', v):
         raise ValueError
     return v
 
+
+def abi_info(repo_root):
+    """Derive the ABI tag list (in NLOHMANN_JSON_ABI_TAGS_CONCAT order) and the
+    library version from <repo_root>/include/nlohmann/detail/abi_macros.hpp,
+    so this script cannot drift from the header it visualizes."""
+    abi_macros_hpp = os.path.join(repo_root, 'include', 'nlohmann', 'detail', 'abi_macros.hpp')
+    with open(abi_macros_hpp) as f:
+        content = f.read()
+
+    # find the NLOHMANN_JSON_ABI_TAGS_CONCAT(...) invocation that lists the
+    # NLOHMANN_JSON_ABI_TAG_* identifiers in order (not its own #define, which
+    # only names its formal parameters a, b, c, ...)
+    tag_idents = None
+    for args in re.findall(r'NLOHMANN_JSON_ABI_TAGS_CONCAT\(\s*(.*?)\)', content, re.S):
+        idents = re.findall(r'NLOHMANN_JSON_ABI_TAG_\w+', args)
+        if idents:
+            tag_idents = idents
+            break
+    if not tag_idents:
+        raise ValueError(f'could not find NLOHMANN_JSON_ABI_TAGS_CONCAT(...) in {abi_macros_hpp}')
+
+    abi_tags = []
+    for ident in tag_idents:
+        # each tag is #define'd to its suffix (e.g. _diag) when the matching
+        # JSON_* option is enabled, and to nothing in the #else branch; only
+        # the non-empty definition matches here
+        match = re.search(r'#define\s+' + re.escape(ident) + r'\s+(_\w+)\s*\n', content)
+        if not match:
+            raise ValueError(f'could not find a non-empty #define for {ident} in {abi_macros_hpp}')
+        abi_tags.append(match.group(1))
+
+    version = {}
+    for part in ('MAJOR', 'MINOR', 'PATCH'):
+        match = re.search(r'#define\s+NLOHMANN_JSON_VERSION_' + part + r'\s+(\d+)', content)
+        if not match:
+            raise ValueError(f'could not find NLOHMANN_JSON_VERSION_{part} in {abi_macros_hpp}')
+        version[part] = match.group(1)
+
+    return abi_tags, '{MAJOR}.{MINOR}.{PATCH}'.format(**version)
+
+
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
-    parser.add_argument('--version', required=True, type=semver, help='Library version number')
-    parser.add_argument('output', help='Output directory for nlohmann_json.natvis')
+    parser.add_argument('--version', type=semver,
+                         help='Library version number (default: parsed from '
+                              'include/nlohmann/detail/abi_macros.hpp below "output")')
+    parser.add_argument('output', nargs='?', default=REPO_ROOT,
+                         help='Repository root: where include/nlohmann/detail/abi_macros.hpp is '
+                              'read from and where nlohmann_json.natvis is written '
+                              '(default: the repository root this script lives in)')
     args = parser.parse_args()
 
+    derived_tags, derived_version = abi_info(args.output)
+
     namespaces = ['nlohmann']
     abi_prefix = 'json_abi'
-    abi_tags = ['_diag', '_ldvcmp', '_dp', '_bics', '_psp', '_snul']
-    version = '_v' + args.version.replace('.', '_')
+    abi_tags = derived_tags
+    version = '_v' + (args.version or derived_version).replace('.', '_')
     inline_namespaces = []
 
     # generate all combinations of inline namespace names

tools/macro_builder/README.md

@@ -0,0 +1,51 @@
+# macro_builder
+
+Generates the argument-counting macros behind the `NLOHMANN_DEFINE_TYPE_*` and `NLOHMANN_DEFINE_DERIVED_TYPE_*`
+macros in [`include/nlohmann/detail/macro_scope.hpp`](../../include/nlohmann/detail/macro_scope.hpp):
+
+- `NLOHMANN_JSON_EXPAND`
+- `NLOHMANN_JSON_GET_MACRO`, which selects a macro by the number of its arguments (64 slots)
+- `NLOHMANN_JSON_PASTE`, which calls a function-like macro for each member, and its helpers `NLOHMANN_JSON_PASTE2`
+  to `NLOHMANN_JSON_PASTE64`
+- `NLOHMANN_JSON_DOUBLE_PASTE`, which the `*_WITH_NAMES` macros use to call a function-like macro for each
+  (JSON name, member) pair, and its helpers `NLOHMANN_JSON_DOUBLE_PASTE3` to `NLOHMANN_JSON_DOUBLE_PASTE63`
+- the slot table of `NLOHMANN_JSON_TYPE_BODY`, which dispatches `NLOHMANN_DEFINE_TYPE_*(Type)` (no further
+  arguments) to the zero-member implementation and every other argument count to the one-or-more-member
+  implementation
+
+The number of slots (`max_args` in [`main.cpp`](main.cpp)) sets the member limit of these macros.
+`NLOHMANN_JSON_PASTE` and `NLOHMANN_JSON_TYPE_BODY` take the function/prefix as their first argument, so 64 slots
+allow 63 members; `NLOHMANN_JSON_DOUBLE_PASTE` additionally consumes its members two at a time (name, member), so
+it only defines the odd helpers up to `NLOHMANN_JSON_DOUBLE_PASTE63`.
+
+## Usage
+
+From the project root:
+
+```shell
+c++ -std=c++11 tools/macro_builder/main.cpp -o macro_builder
+./macro_builder
+./macro_builder type_body
+```
+
+1. Run `./macro_builder` (no arguments). In `include/nlohmann/detail/macro_scope.hpp`, replace the lines from
+   `#define NLOHMANN_JSON_EXPAND( x ) x` to the `#define NLOHMANN_JSON_DOUBLE_PASTE63(...)` line with the output,
+   without its trailing empty line.
+2. Run `./macro_builder type_body`. Replace the lines from `#define NLOHMANN_JSON_TYPE_BODY(Prefix, ...)` to the
+   `NLOHMANN_JSON_TYPE_BODY_SENTINEL))` line with the output.
+3. Run `make amalgamate`. It updates `single_include/nlohmann/json.hpp` and runs `make pretty`, which indents the
+   continuation lines that the tool writes unindented.
+
+With an unchanged `main.cpp`, these steps reproduce both blocks of `macro_scope.hpp` byte for byte. `make
+macro_builder_check` (also run by CI, see `.github/workflows/check_amalgamation.yml`) automates this: it builds
+`main.cpp`, regenerates both blocks, and fails on a diff against the checked-in header.
+
+## Maintained by hand
+
+The tool does not generate everything that depends on the number of slots. When changing `max_args`, also update:
+
+- the documented limit of 63 members in `docs/mkdocs/docs` and the tests at that limit in
+  `tests/src/unit-udt_macro.cpp`
+
+All three tables pass one macro name per slot to `NLOHMANN_JSON_GET_MACRO`, so they need exactly as many entries as
+it has slots.

tools/macro_builder/main.cpp

@@ -1,10 +1,14 @@
 #include <cstdlib>
 #include <iostream>
 #include <sstream>
+#include <string>
 
 using namespace std;
 
-void build_code(int max_args)
+// Builds NLOHMANN_JSON_EXPAND, NLOHMANN_JSON_GET_MACRO, and the
+// NLOHMANN_JSON_PASTE / NLOHMANN_JSON_PASTE2..PASTE<max_args> dispatch table
+// and recursive definitions.
+string build_paste_code(int max_args)
 {
     stringstream ss;
     ss << "#define NLOHMANN_JSON_EXPAND( x ) x" << endl;
@@ -12,32 +16,93 @@ void build_code(int max_args)
     for (int i = 0 ; i < max_args ; i++)
         ss << "_" << i + 1 << ", ";
     ss << "NAME,...) NAME" << endl;
-    
+
     ss << "#define NLOHMANN_JSON_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
     for (int i = max_args ; i > 1 ; i--)
         ss << "NLOHMANN_JSON_PASTE" << i << ", \\" << endl;
     ss << "NLOHMANN_JSON_PASTE1)(__VA_ARGS__))" << endl;
-    
+
     ss << "#define NLOHMANN_JSON_PASTE2(func, v1) func(v1)" << endl;
     for (int i = 3 ; i <= max_args ; i++)
     {
-        ss << "#define NLOHMANN_JSON_PASTE" << i << "(func, "; 
+        ss << "#define NLOHMANN_JSON_PASTE" << i << "(func, ";
         for (int j = 1 ; j < i -1 ; j++)
-            ss << "v" << j << ", "; 
+            ss << "v" << j << ", ";
         ss << "v" << i-1 << ") NLOHMANN_JSON_PASTE2(func, v1) NLOHMANN_JSON_PASTE" << i-1 << "(func, ";
         for (int j = 2 ; j < i-1 ; j++)
             ss << "v" << j << ", ";
         ss << "v" << i-1 << ")" << endl;
     }
-    
-    cout << ss.str() << endl;
+
+    return ss.str();
 }
 
-int main(int argc, char** argv) 
+// Builds the NLOHMANN_JSON_DOUBLE_PASTE dispatch table and recursive
+// definitions used by the *_WITH_NAMES macros. Its GET_MACRO dispatch reuses
+// the same max_args slots as NLOHMANN_JSON_PASTE, but DOUBLE_PASTE consumes
+// its arguments two at a time (name, member), so an even slot count falls
+// back to the next lower odd NLOHMANN_JSON_DOUBLE_PASTE<N>.
+string build_double_paste_code(int max_args)
+{
+    stringstream ss;
+    ss << "#define NLOHMANN_JSON_DOUBLE_PASTE(...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
+    for (int i = max_args ; i > 1 ; i--)
+    {
+        int k = (i % 2 == 1) ? i : i - 1;
+        ss << "NLOHMANN_JSON_DOUBLE_PASTE" << k << ", \\" << endl;
+    }
+    ss << "NLOHMANN_JSON_DOUBLE_PASTE1)(__VA_ARGS__))" << endl;
+
+    ss << "#define NLOHMANN_JSON_DOUBLE_PASTE3(func, v1, v2) func(v1, v2)" << endl;
+    for (int k = 5 ; k <= max_args - 1 ; k += 2)
+    {
+        ss << "#define NLOHMANN_JSON_DOUBLE_PASTE" << k << "(func, ";
+        for (int j = 1 ; j < k - 1 ; j++)
+            ss << "v" << j << ", ";
+        ss << "v" << k - 1 << ") NLOHMANN_JSON_DOUBLE_PASTE3(func, v1, v2) NLOHMANN_JSON_DOUBLE_PASTE" << k - 2 << "(func, ";
+        for (int j = 3 ; j < k - 1 ; j++)
+            ss << "v" << j << ", ";
+        ss << "v" << k - 1 << ")" << endl;
+    }
+
+    return ss.str();
+}
+
+// Builds the NLOHMANN_JSON_TYPE_BODY dispatch table: max_args - 1 slots
+// selecting the *_MEMBERS implementation and a final slot selecting
+// *_EMPTY, so NLOHMANN_DEFINE_TYPE_*(Type) with no further arguments still
+// resolves (issue #4041).
+string build_type_body_table(int max_args)
+{
+    stringstream ss;
+    ss << "#define NLOHMANN_JSON_TYPE_BODY(Prefix, ...) NLOHMANN_JSON_EXPAND(NLOHMANN_JSON_GET_MACRO(__VA_ARGS__, \\" << endl;
+    const int per_line = 8;
+    for (int i = 1 ; i <= max_args ; i++)
+    {
+        ss << (i == max_args ? "Prefix ## EMPTY" : "Prefix ## MEMBERS") << ", ";
+        if (i % per_line == 0)
+            ss << "\\" << endl;
+    }
+    ss << "NLOHMANN_JSON_TYPE_BODY_SENTINEL))" << endl;
+
+    return ss.str();
+}
+
+int main(int argc, char** argv)
 {
     int max_args = 64;
-    build_code(max_args);
-       
+
+    // With "type_body", print only the NLOHMANN_JSON_TYPE_BODY dispatch
+    // table (a separate insertion point in macro_scope.hpp); otherwise
+    // print the EXPAND/GET_MACRO/PASTE/DOUBLE_PASTE block that precedes it.
+    if (argc > 1 && string(argv[1]) == "type_body")
+    {
+        cout << build_type_body_table(max_args);
+    }
+    else
+    {
+        cout << build_paste_code(max_args) << build_double_paste_code(max_args);
+    }
+
     return 0;
 }
-

tools/serve_header/serve_header.py

@@ -5,6 +5,8 @@ import logging
 import os
 import re
 import shutil
+import socket
+import ssl
 import sys
 import subprocess
 
@@ -34,7 +36,7 @@ JSON_VERSION_RE = re.compile(r'\s*#\s*define\s+NLOHMANN_JSON_VERSION_MAJOR\s+')
 
 class ExitHandler(logging.StreamHandler):
     def __init__(self, level):
-        """."""
+        """Exit the process on log records at or above level."""
         super().__init__()
         self.level = level
 
@@ -54,7 +56,7 @@ def is_project_root(test_dir='.'):
 
 class DirectoryEventBucket:
     def __init__(self, callback, delay=1.2, threshold=0.8):
-        """."""
+        """Batch directory events and pass their common path to callback."""
         self.delay = delay
         self.threshold = timedelta(seconds=threshold)
         self.callback = callback
@@ -99,7 +101,7 @@ class WorkTree:
     make_command = 'make'
 
     def __init__(self, root_dir, tree_dir):
-        """."""
+        """Track the working tree at tree_dir and its amalgamated header."""
         self.root_dir = root_dir
         self.tree_dir = tree_dir
         self.rel_dir = os.path.relpath(tree_dir, root_dir)
@@ -114,11 +116,11 @@ class WorkTree:
         self.build_time = t.strftime(DATETIME_FORMAT)
 
     def __hash__(self):
-        """."""
+        """Hash by working tree directory."""
         return hash((self.tree_dir))
 
     def __eq__(self, other):
-        """."""
+        """Compare by working tree directory."""
         if not isinstance(other, type(self)):
             return NotImplemented
         return self.tree_dir == other.tree_dir
@@ -150,7 +152,7 @@ class WorkTree:
 
 class WorkTrees(FileSystemEventHandler):
     def __init__(self, root_dir):
-        """."""
+        """Find the working trees below root_dir and watch it for changes."""
         super().__init__()
         self.root_dir = root_dir
         self.trees = set([])
@@ -250,11 +252,11 @@ class WorkTrees(FileSystemEventHandler):
         self.observer.stop()
         self.observer.join()
 
-class HeaderRequestHandler(SimpleHTTPRequestHandler): # lgtm[py/missing-call-to-init]
+class HeaderRequestHandler(SimpleHTTPRequestHandler):
     cors_origins = DEFAULT_CORS_ORIGINS
 
     def __init__(self, request, client_address, server):
-        """."""
+        """Handle a request for a header below the working trees' root directory."""
         self.worktrees = server.worktrees
         self.worktree = None
         try:
@@ -336,7 +338,7 @@ class HeaderRequestHandler(SimpleHTTPRequestHandler): # lgtm[py/missing-call-to-
 
 class DualStackServer(ThreadingHTTPServer):
     def __init__(self, addr, worktrees):
-        """."""
+        """Serve the headers of worktrees on addr."""
         self.worktrees = worktrees
         super().__init__(addr, HeaderRequestHandler)
 
@@ -349,8 +351,6 @@ class DualStackServer(ThreadingHTTPServer):
 
 if __name__ == '__main__':
     import argparse
-    import ssl
-    import socket
     import yaml
 
     # exit code