Derive the JSON_HEDLEY_* leak-check test from hedley.hpp at build time

tests/src/unit-no-macro-leak.cpp previously hardcoded a static list of
~151 #ifdef/#error checks, one per JSON_HEDLEY_* macro name known at the
time it was written. That list would silently go stale the next time
`make update_hedley` pulls in a vendor update that adds, removes, or
renames a macro, since nothing would force it to be regenerated.

Add cmake/scripts/gen_hedley_undef_check.cmake, which derives the full
list of JSON_HEDLEY_* macro names directly from
include/nlohmann/thirdparty/hedley/hedley.hpp:

- tests/CMakeLists.txt uses it (MODE=checks) to (re)generate
  hedley_undef_checks.inc at configure and build time, and wires the
  generating custom target as a dependency of the test-no-macro-leak_cpp*
  targets so it can never build against a stale copy. unit-no-macro-leak.cpp
  now just #include-s the generated file inside its TEST_CASE instead of
  carrying the checks itself.
- The Makefile's `update_hedley` target now delegates hedley_undef.hpp
  generation to the same script (MODE=undef, new `update_hedley_undef`
  target), so the vendored header, the generated #undef list, and the
  generated test checks are all derived from the same extraction logic and
  cannot drift apart.

This mirrors the approach taken independently in #5415 for the same
issue (#5408), credited there to a self-regenerating mechanism that
"can never drift again" -- ported into this branch instead of the
static list originally proposed here.

Verified with a local CMake configure + build + ctest, both against
include/ (JSON_MultipleHeaders=ON) and against the amalgamated
single_include/nlohmann/json.hpp (JSON_MultipleHeaders=OFF), and by
temporarily deleting a #undef line from hedley_undef.hpp to confirm the
generated test actually fails on a real leak.

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

Makefile

@@ -1,4 +1,4 @@
-.PHONY: pretty clean ChangeLog.md release
+.PHONY: pretty clean ChangeLog.md release update_hedley update_hedley_undef
 
 ##########################################################################
 # configuration
@@ -41,6 +41,8 @@ all:
 	@echo "fuzz_testing_ubjson - prepare fuzz testing of the UBJSON parser"
 	@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"
+	@echo "update_hedley_undef - rebuild hedley_undef.hpp from the JSON_HEDLEY_* #define names in hedley.hpp"
 
 
 ##########################################################################
@@ -241,11 +243,24 @@ update_hedley:
 	rm -f include/nlohmann/thirdparty/hedley/hedley.hpp include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	curl https://raw.githubusercontent.com/nemequ/hedley/master/hedley.h -o include/nlohmann/thirdparty/hedley/hedley.hpp
 	$(SED) -i 's/HEDLEY_/JSON_HEDLEY_/g' include/nlohmann/thirdparty/hedley/hedley.hpp
-	grep -oE "#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+" include/nlohmann/thirdparty/hedley/hedley.hpp | awk '{print $$NF}' | grep -v "__" | sort -u | $(SED) 's/^/#undef /' > include/nlohmann/thirdparty/hedley/hedley_undef.hpp
 	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley.hpp
-	$(SED) -i '1s/^/#pragma once\n\n/' include/nlohmann/thirdparty/hedley/hedley_undef.hpp
+	$(MAKE) update_hedley_undef
 	$(MAKE) amalgamate
 
+# Rebuild hedley_undef.hpp from every JSON_HEDLEY_* name that hedley.hpp
+# #defines. Hedley does not #undef all of its public macros internally (see
+# #5408), so grepping those #undef lines misses names such as
+# JSON_HEDLEY_PRAGMA. cmake/scripts/gen_hedley_undef_check.cmake is the
+# single source of truth for this extraction (tests/CMakeLists.txt uses the
+# same script, in MODE=checks, to generate the matching leak-check test), so
+# the vendored header, the generated #undef list, and the regression test
+# cannot drift apart.
+update_hedley_undef:
+	cmake -DHEDLEY_HPP=include/nlohmann/thirdparty/hedley/hedley.hpp \
+	      -DOUTPUT=include/nlohmann/thirdparty/hedley/hedley_undef.hpp \
+	      -DMODE=undef \
+	      -P cmake/scripts/gen_hedley_undef_check.cmake
+
 ##########################################################################
 # serve_header.py
 ##########################################################################

cmake/scripts/gen_hedley_undef_check.cmake

@@ -0,0 +1,105 @@
+# Shared extractor for the JSON_HEDLEY_* macro names defined in hedley.hpp.
+#
+# Every macro that hedley.hpp #defines must be #undef-ed again once json.hpp
+# has been fully processed (see include/nlohmann/detail/macro_unscope.hpp
+# and https://github.com/nlohmann/json/issues/5408). Deriving the macro list
+# straight from hedley.hpp here -- instead of hand-maintaining it in two
+# places -- means hedley_undef.hpp and the regression test that checks for
+# leaked macros can never drift apart, even after a future `make
+# update_hedley` pulls in new macros from upstream Hedley.
+#
+#   MODE=undef  (default): write hedley_undef.hpp (SPDX header, #pragma once,
+#               one #undef per macro name) -- used by `make update_hedley_undef`
+#   MODE=checks:            write one #ifdef/FAIL_CHECK/#endif per macro name,
+#               meant to be #include-d inside a TEST_CASE -- used by
+#               tests/CMakeLists.txt to (re)generate the include for
+#               tests/src/unit-no-macro-leak.cpp
+#
+# Required variables:
+#   HEDLEY_HPP  path to include/nlohmann/thirdparty/hedley/hedley.hpp
+#   OUTPUT      path of the file to (over)write
+# Optional:
+#   MODE        "undef" (default) or "checks"
+
+if(NOT DEFINED HEDLEY_HPP OR NOT DEFINED OUTPUT)
+    message(FATAL_ERROR "HEDLEY_HPP and OUTPUT must be set")
+endif()
+
+if(NOT EXISTS "${HEDLEY_HPP}")
+    message(FATAL_ERROR "Hedley header not found: ${HEDLEY_HPP}")
+endif()
+
+if(NOT DEFINED MODE)
+    set(MODE undef)
+endif()
+
+if(NOT MODE STREQUAL "undef" AND NOT MODE STREQUAL "checks")
+    message(FATAL_ERROR "MODE must be undef or checks, got: ${MODE}")
+endif()
+
+# Line-anchored, like `grep -oE "^[[:blank:]]*#[[:blank:]]*define[[:blank:]]+JSON_HEDLEY_[A-Za-z0-9_]+"`.
+# Unanchored matching would also pick up JSON_HEDLEY_* mentions inside
+# comments or string literals elsewhere in the file, which must not turn
+# into #undef lines.
+file(STRINGS "${HEDLEY_HPP}" hedley_lines)
+set(macro_names)
+foreach(line IN LISTS hedley_lines)
+    if("${line}" MATCHES "^[ \t]*#[ \t]*define[ \t]+(JSON_HEDLEY_[A-Za-z0-9_]+)")
+        list(APPEND macro_names "${CMAKE_MATCH_1}")
+    endif()
+endforeach()
+
+if(NOT macro_names)
+    message(FATAL_ERROR "No JSON_HEDLEY_* macros found in ${HEDLEY_HPP}")
+endif()
+
+list(REMOVE_DUPLICATES macro_names)
+# Lexicographic, locale-independent (ASCII-only names) -- matches `LC_ALL=C sort`.
+list(SORT macro_names COMPARE STRING)
+list(LENGTH macro_names macro_count)
+
+set(generated "")
+if(MODE STREQUAL "undef")
+    # Same banner `make update_hedley_undef` would stamp by hand, so the
+    # recipe is self-contained and its output is byte-stable across reruns.
+    string(APPEND generated "//     __ _____ _____ _____\n")
+    string(APPEND generated "//  __|  |   __|     |   | |  JSON for Modern C++\n")
+    string(APPEND generated "// |  |  |__   |  |  | | | |  version 3.12.0\n")
+    string(APPEND generated "// |_____|_____|_____|_|___|  https://github.com/nlohmann/json\n")
+    string(APPEND generated "//\n")
+    string(APPEND generated "// SPDX-FileCopyrightText: 2013-2026 Niels Lohmann <https://nlohmann.me>\n")
+    string(APPEND generated "// SPDX-License-Identifier: MIT\n")
+    string(APPEND generated "\n")
+    string(APPEND generated "#pragma once\n")
+    string(APPEND generated "\n")
+    foreach(name IN LISTS macro_names)
+        string(APPEND generated "#undef ${name}\n")
+    endforeach()
+else()
+    string(APPEND generated "// This file is generated by cmake/scripts/gen_hedley_undef_check.cmake\n")
+    string(APPEND generated "// from include/nlohmann/thirdparty/hedley/hedley.hpp. Do not edit it by\n")
+    string(APPEND generated "// hand -- it is regenerated on every build. ${macro_count} macros checked.\n\n")
+    foreach(name IN LISTS macro_names)
+        string(APPEND generated "#ifdef ${name}\n")
+        string(APPEND generated "    FAIL_CHECK(\"${name} leaked after including nlohmann/json.hpp\");\n")
+        string(APPEND generated "#endif\n")
+    endforeach()
+endif()
+
+get_filename_component(output_dir "${OUTPUT}" DIRECTORY)
+if(output_dir)
+    file(MAKE_DIRECTORY "${output_dir}")
+endif()
+
+# Avoid rewriting the file (and busting downstream incremental rebuilds)
+# when the content has not actually changed.
+set(write_output TRUE)
+if(EXISTS "${OUTPUT}")
+    file(READ "${OUTPUT}" existing_content)
+    if(existing_content STREQUAL generated)
+        set(write_output FALSE)
+    endif()
+endif()
+if(write_output)
+    file(WRITE "${OUTPUT}" "${generated}")
+endif()

tests/CMakeLists.txt

@@ -125,6 +125,51 @@ json_test_set_test_options(test-unicode4 TEST_PROPERTIES TIMEOUT 3000)
 # add unit tests
 #############################################################################
 
+# Generate the leak checks for every JSON_HEDLEY_* macro defined in
+# hedley.hpp; tests/src/unit-no-macro-leak.cpp #include-s the result after
+# nlohmann/json.hpp (see issue #5408). Using the shared
+# cmake/scripts/gen_hedley_undef_check.cmake script (also used by `make
+# update_hedley_undef`) instead of a hand-maintained list of macro names
+# means this test can never go stale after a future `make update_hedley`.
+set(hedley_hpp "${PROJECT_SOURCE_DIR}/include/nlohmann/thirdparty/hedley/hedley.hpp")
+set(hedley_undef_check_script "${PROJECT_SOURCE_DIR}/cmake/scripts/gen_hedley_undef_check.cmake")
+set(hedley_undef_checks "${PROJECT_BINARY_DIR}/include/hedley_undef_checks.inc")
+
+# Reconfigure whenever the vendored header or the generator script changes,
+# so a `cmake --build` after `make update_hedley` does not silently keep a
+# stale generated file around.
+set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS
+    "${hedley_hpp}"
+    "${hedley_undef_check_script}")
+
+# Generate once at configure time, so the very first build (before any
+# custom-command build step has run) already has an up-to-date file.
+execute_process(
+    COMMAND ${CMAKE_COMMAND}
+        "-DHEDLEY_HPP=${hedley_hpp}"
+        "-DOUTPUT=${hedley_undef_checks}"
+        -DMODE=checks
+        -P "${hedley_undef_check_script}"
+    RESULT_VARIABLE hedley_undef_check_result
+)
+if(NOT hedley_undef_check_result EQUAL 0)
+    message(FATAL_ERROR "Failed to generate ${hedley_undef_checks}")
+endif()
+
+# Also (re)generate as a build step, so an incremental build after editing
+# hedley.hpp without a full reconfigure still picks up the change.
+add_custom_command(
+    OUTPUT "${hedley_undef_checks}"
+    COMMAND ${CMAKE_COMMAND}
+        "-DHEDLEY_HPP=${hedley_hpp}"
+        "-DOUTPUT=${hedley_undef_checks}"
+        -DMODE=checks
+        -P "${hedley_undef_check_script}"
+    DEPENDS "${hedley_hpp}" "${hedley_undef_check_script}"
+    COMMENT "Generating Hedley undef leak checks"
+    VERBATIM)
+add_custom_target(generate_hedley_undef_checks DEPENDS "${hedley_undef_checks}")
+
 if("${JSON_TestStandards}" STREQUAL "")
     set(test_cxx_standards 11 14 17 20 23)
     unset(test_force)
@@ -163,6 +208,14 @@ foreach(file ${files})
     json_test_add_test_for(${file} MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force})
 endforeach()
 
+# tests/src/unit-no-macro-leak.cpp #include-s the generated leak-check file,
+# so its test targets must be built after generate_hedley_undef_checks.
+foreach(cxx_standard ${test_cxx_standards})
+    if(TARGET test-no-macro-leak_cpp${cxx_standard})
+        add_dependencies(test-no-macro-leak_cpp${cxx_standard} generate_hedley_undef_checks)
+    endif()
+endforeach()
+
 if(json_32bit_test_only)
     # Skip all other tests in this file
     return()

tests/src/unit-no-macro-leak.cpp

@@ -16,471 +16,19 @@
 // and JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE escaped this cleanup because
 // hedley_undef.hpp had no matching #undef for them.
 //
-// The #ifdef/#error checks below are mechanically derived from the full list
-// of macro names in hedley_undef.hpp, so every JSON_HEDLEY_* macro is covered
-// -- not just the four that leaked historically.
+// hedley_undef_checks.inc (included below) is generated at CMake configure/
+// build time by cmake/scripts/gen_hedley_undef_check.cmake, which derives the
+// full list of JSON_HEDLEY_* macro names directly from hedley.hpp. That way
+// this test covers every macro Hedley actually defines -- not a hardcoded
+// snapshot that would silently go stale the next time `make update_hedley`
+// runs -- and can never drift from the vendored header.
 
 #include "doctest_compatibility.h"
 
 #include <nlohmann/json.hpp>
 
-#ifdef JSON_HEDLEY_ALWAYS_INLINE
-    #error "JSON_HEDLEY_ALWAYS_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARM_VERSION
-    #error "JSON_HEDLEY_ARM_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARM_VERSION_CHECK
-    #error "JSON_HEDLEY_ARM_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ARRAY_PARAM
-    #error "JSON_HEDLEY_ARRAY_PARAM must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_ASSUME
-    #error "JSON_HEDLEY_ASSUME must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_BEGIN_C_DECLS
-    #error "JSON_HEDLEY_BEGIN_C_DECLS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_BUILTIN
-    #error "JSON_HEDLEY_CLANG_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_CLANG_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_EXTENSION
-    #error "JSON_HEDLEY_CLANG_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_FEATURE
-    #error "JSON_HEDLEY_CLANG_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CLANG_HAS_WARNING
-    #error "JSON_HEDLEY_CLANG_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_COMPCERT_VERSION
-    #error "JSON_HEDLEY_COMPCERT_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_COMPCERT_VERSION_CHECK
-    #error "JSON_HEDLEY_COMPCERT_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT
-    #error "JSON_HEDLEY_CONCAT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT3
-    #error "JSON_HEDLEY_CONCAT3 must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT3_EX
-    #error "JSON_HEDLEY_CONCAT3_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONCAT_EX
-    #error "JSON_HEDLEY_CONCAT_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONST
-    #error "JSON_HEDLEY_CONST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONSTEXPR
-    #error "JSON_HEDLEY_CONSTEXPR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CONST_CAST
-    #error "JSON_HEDLEY_CONST_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CPP_CAST
-    #error "JSON_HEDLEY_CPP_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CRAY_VERSION
-    #error "JSON_HEDLEY_CRAY_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_CRAY_VERSION_CHECK
-    #error "JSON_HEDLEY_CRAY_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_C_DECL
-    #error "JSON_HEDLEY_C_DECL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DEPRECATED
-    #error "JSON_HEDLEY_DEPRECATED must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DEPRECATED_FOR
-    #error "JSON_HEDLEY_DEPRECATED_FOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_CAST_QUAL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_CPP98_COMPAT_WRAP_ must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_DEPRECATED must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_CPP_ATTRIBUTES must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNKNOWN_PRAGMAS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNUSED_FUNCTION
-    #error "JSON_HEDLEY_DIAGNOSTIC_DISABLE_UNUSED_FUNCTION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_POP
-    #error "JSON_HEDLEY_DIAGNOSTIC_POP must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DIAGNOSTIC_PUSH
-    #error "JSON_HEDLEY_DIAGNOSTIC_PUSH must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DMC_VERSION
-    #error "JSON_HEDLEY_DMC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_DMC_VERSION_CHECK
-    #error "JSON_HEDLEY_DMC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMPTY_BASES
-    #error "JSON_HEDLEY_EMPTY_BASES must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMSCRIPTEN_VERSION
-    #error "JSON_HEDLEY_EMSCRIPTEN_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK
-    #error "JSON_HEDLEY_EMSCRIPTEN_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_END_C_DECLS
-    #error "JSON_HEDLEY_END_C_DECLS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FALL_THROUGH
-    #error "JSON_HEDLEY_FALL_THROUGH must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FLAGS
-    #error "JSON_HEDLEY_FLAGS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_FLAGS_CAST
-    #error "JSON_HEDLEY_FLAGS_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_BUILTIN
-    #error "JSON_HEDLEY_GCC_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_GCC_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_EXTENSION
-    #error "JSON_HEDLEY_GCC_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_FEATURE
-    #error "JSON_HEDLEY_GCC_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_HAS_WARNING
-    #error "JSON_HEDLEY_GCC_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK
-    #error "JSON_HEDLEY_GCC_NOT_CLANG_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_VERSION
-    #error "JSON_HEDLEY_GCC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GCC_VERSION_CHECK
-    #error "JSON_HEDLEY_GCC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_BUILTIN
-    #error "JSON_HEDLEY_GNUC_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_GNUC_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_EXTENSION
-    #error "JSON_HEDLEY_GNUC_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_FEATURE
-    #error "JSON_HEDLEY_GNUC_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_HAS_WARNING
-    #error "JSON_HEDLEY_GNUC_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_VERSION
-    #error "JSON_HEDLEY_GNUC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_GNUC_VERSION_CHECK
-    #error "JSON_HEDLEY_GNUC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_BUILTIN
-    #error "JSON_HEDLEY_HAS_BUILTIN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_CPP_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_CPP_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS
-    #error "JSON_HEDLEY_HAS_CPP_ATTRIBUTE_NS must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE
-    #error "JSON_HEDLEY_HAS_DECLSPEC_ATTRIBUTE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_EXTENSION
-    #error "JSON_HEDLEY_HAS_EXTENSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_FEATURE
-    #error "JSON_HEDLEY_HAS_FEATURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_HAS_WARNING
-    #error "JSON_HEDLEY_HAS_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IAR_VERSION
-    #error "JSON_HEDLEY_IAR_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IAR_VERSION_CHECK
-    #error "JSON_HEDLEY_IAR_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IBM_VERSION
-    #error "JSON_HEDLEY_IBM_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IBM_VERSION_CHECK
-    #error "JSON_HEDLEY_IBM_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IMPORT
-    #error "JSON_HEDLEY_IMPORT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INLINE
-    #error "JSON_HEDLEY_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_CL_VERSION
-    #error "JSON_HEDLEY_INTEL_CL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_CL_VERSION_CHECK
-    #error "JSON_HEDLEY_INTEL_CL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_VERSION
-    #error "JSON_HEDLEY_INTEL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_INTEL_VERSION_CHECK
-    #error "JSON_HEDLEY_INTEL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IS_CONSTANT
-    #error "JSON_HEDLEY_IS_CONSTANT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_IS_CONSTEXPR_
-    #error "JSON_HEDLEY_IS_CONSTEXPR_ must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_LIKELY
-    #error "JSON_HEDLEY_LIKELY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MALLOC
-    #error "JSON_HEDLEY_MALLOC must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MCST_LCC_VERSION
-    #error "JSON_HEDLEY_MCST_LCC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MCST_LCC_VERSION_CHECK
-    #error "JSON_HEDLEY_MCST_LCC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MESSAGE
-    #error "JSON_HEDLEY_MESSAGE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MSVC_VERSION
-    #error "JSON_HEDLEY_MSVC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_MSVC_VERSION_CHECK
-    #error "JSON_HEDLEY_MSVC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NEVER_INLINE
-    #error "JSON_HEDLEY_NEVER_INLINE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NON_NULL
-    #error "JSON_HEDLEY_NON_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_ESCAPE
-    #error "JSON_HEDLEY_NO_ESCAPE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_RETURN
-    #error "JSON_HEDLEY_NO_RETURN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NO_THROW
-    #error "JSON_HEDLEY_NO_THROW must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_NULL
-    #error "JSON_HEDLEY_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PELLES_VERSION
-    #error "JSON_HEDLEY_PELLES_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PELLES_VERSION_CHECK
-    #error "JSON_HEDLEY_PELLES_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PGI_VERSION
-    #error "JSON_HEDLEY_PGI_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PGI_VERSION_CHECK
-    #error "JSON_HEDLEY_PGI_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRAGMA
-    #error "JSON_HEDLEY_PRAGMA must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT
-    #error "JSON_HEDLEY_PREDICT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT_FALSE
-    #error "JSON_HEDLEY_PREDICT_FALSE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PREDICT_TRUE
-    #error "JSON_HEDLEY_PREDICT_TRUE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRINTF_FORMAT
-    #error "JSON_HEDLEY_PRINTF_FORMAT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PRIVATE
-    #error "JSON_HEDLEY_PRIVATE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PUBLIC
-    #error "JSON_HEDLEY_PUBLIC must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_PURE
-    #error "JSON_HEDLEY_PURE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REINTERPRET_CAST
-    #error "JSON_HEDLEY_REINTERPRET_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE
-    #error "JSON_HEDLEY_REQUIRE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE_CONSTEXPR
-    #error "JSON_HEDLEY_REQUIRE_CONSTEXPR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_REQUIRE_MSG
-    #error "JSON_HEDLEY_REQUIRE_MSG must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_RESTRICT
-    #error "JSON_HEDLEY_RESTRICT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_RETURNS_NON_NULL
-    #error "JSON_HEDLEY_RETURNS_NON_NULL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SENTINEL
-    #error "JSON_HEDLEY_SENTINEL must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STATIC_ASSERT
-    #error "JSON_HEDLEY_STATIC_ASSERT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STATIC_CAST
-    #error "JSON_HEDLEY_STATIC_CAST must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STRINGIFY
-    #error "JSON_HEDLEY_STRINGIFY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_STRINGIFY_EX
-    #error "JSON_HEDLEY_STRINGIFY_EX must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SUNPRO_VERSION
-    #error "JSON_HEDLEY_SUNPRO_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_SUNPRO_VERSION_CHECK
-    #error "JSON_HEDLEY_SUNPRO_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TINYC_VERSION
-    #error "JSON_HEDLEY_TINYC_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TINYC_VERSION_CHECK
-    #error "JSON_HEDLEY_TINYC_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_ARMCL_VERSION
-    #error "JSON_HEDLEY_TI_ARMCL_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_ARMCL_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_ARMCL_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL2000_VERSION
-    #error "JSON_HEDLEY_TI_CL2000_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL2000_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL2000_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL430_VERSION
-    #error "JSON_HEDLEY_TI_CL430_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL430_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL430_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL6X_VERSION
-    #error "JSON_HEDLEY_TI_CL6X_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL6X_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL6X_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL7X_VERSION
-    #error "JSON_HEDLEY_TI_CL7X_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CL7X_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CL7X_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CLPRU_VERSION
-    #error "JSON_HEDLEY_TI_CLPRU_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_CLPRU_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_CLPRU_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_VERSION
-    #error "JSON_HEDLEY_TI_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_TI_VERSION_CHECK
-    #error "JSON_HEDLEY_TI_VERSION_CHECK must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNAVAILABLE
-    #error "JSON_HEDLEY_UNAVAILABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNLIKELY
-    #error "JSON_HEDLEY_UNLIKELY must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNPREDICTABLE
-    #error "JSON_HEDLEY_UNPREDICTABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNREACHABLE
-    #error "JSON_HEDLEY_UNREACHABLE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_UNREACHABLE_RETURN
-    #error "JSON_HEDLEY_UNREACHABLE_RETURN must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION
-    #error "JSON_HEDLEY_VERSION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_MAJOR
-    #error "JSON_HEDLEY_VERSION_DECODE_MAJOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_MINOR
-    #error "JSON_HEDLEY_VERSION_DECODE_MINOR must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_DECODE_REVISION
-    #error "JSON_HEDLEY_VERSION_DECODE_REVISION must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_VERSION_ENCODE
-    #error "JSON_HEDLEY_VERSION_ENCODE must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARNING
-    #error "JSON_HEDLEY_WARNING must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARN_UNUSED_RESULT
-    #error "JSON_HEDLEY_WARN_UNUSED_RESULT must not remain defined after including json.hpp"
-#endif
-#ifdef JSON_HEDLEY_WARN_UNUSED_RESULT_MSG
-    #error "JSON_HEDLEY_WARN_UNUSED_RESULT_MSG must not remain defined after including json.hpp"
-#endif
-
-TEST_CASE("no JSON_HEDLEY_* macro leaks after including json.hpp")
+TEST_CASE("JSON_HEDLEY macros do not leak after including json.hpp")
 {
-    // if this test compiles at all, none of the JSON_HEDLEY_* macros checked
-    // above remained defined after including <nlohmann/json.hpp>
-    CHECK(true);
+#include "hedley_undef_checks.inc"
+    CHECK(true); // keep an assertion when nothing leaked
 }