json/tests/CMakeLists.txt

cmake_minimum_required(VERSION 3.13...4.0)

option(JSON_Valgrind    "Execute test suite with Valgrind." OFF)
option(JSON_FastTests   "Skip expensive/slow tests." OFF)
option(JSON_TestSimdutf "Build the unit tests against the simdutf UTF-8 validation backend." OFF)

set(JSON_SIMDUTF_VERSION 9.1.0 CACHE STRING "The simdutf version used by JSON_TestSimdutf.")

set(JSON_32bitTest     AUTO CACHE STRING "Enable the 32bit unit test (ON/OFF/AUTO/ONLY).")
set(JSON_TestStandards "" CACHE STRING "The list of standards to test explicitly.")
set(JSON_TestShard     "" CACHE STRING "Build only a part of the unit tests, given as <index>/<count> (e.g. 0/2), to split them across CI jobs with a time limit.")

# using an env var, since this will also affect targets executing cmake (such as "ci_test_compiler_default")
if (NOT "" STREQUAL "$ENV{JSON_FORCED_GLOBAL_COMPILE_OPTIONS}")
    add_compile_options($ENV{JSON_FORCED_GLOBAL_COMPILE_OPTIONS})
endif()
if (NOT "" STREQUAL "$ENV{JSON_FORCED_GLOBAL_LINK_OPTIONS}")
    add_link_options($ENV{JSON_FORCED_GLOBAL_LINK_OPTIONS})
endif()

include(test)

#############################################################################
# override standard support
#############################################################################

# Clang only supports C++14 starting from Clang 3.5 (lesser versions miss std::enable_if_t)
if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.5)
    unset(compiler_supports_cpp_14)
endif()

# Clang only supports C++17 starting from Clang 5.0
if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 5.0)
    unset(compiler_supports_cpp_17)
endif()
# MSVC 2015 (14.0) does not support C++17
if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.10)
    unset(compiler_supports_cpp_17)
endif()
# GCC 5 and 6 do claim experimental support for C++17, but do not implement <optional>
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 7.0)
    unset(compiler_supports_cpp_17)
endif()

# Clang C++20 support appears insufficient prior to Clang 9.0 (based on CI build failure)
if (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0)
    unset(compiler_supports_cpp_20)
endif()
# MSVC 2017 (15.x) does not support C++20
if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.20)
    unset(compiler_supports_cpp_20)
endif()
# GCC started supporting C++20 features in 8.0 but a test for #3070 segfaults prior to 9.0
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0)
    unset(compiler_supports_cpp_20)
endif()

#############################################################################
# test_main library with shared code to speed up build and common settings
#############################################################################

add_library(test_main OBJECT src/unit.cpp)
target_compile_definitions(test_main PUBLIC
    DOCTEST_CONFIG_SUPER_FAST_ASSERTS
    JSON_TEST_KEEP_MACROS
    JSON_TEST_USING_MULTIPLE_HEADERS=$<BOOL:${JSON_MultipleHeaders}>)
target_compile_features(test_main PRIVATE cxx_std_11)
target_compile_options(test_main PUBLIC
    $<$<CXX_COMPILER_ID:MSVC>:/EHsc>
    # MSVC: Force to always compile with W4
    #       Disable warning C4566: character represented by universal-character-name '\uFF01'
    #                              cannot be represented in the current code page (1252)
    #       Disable warning C4996: 'nlohmann::basic_json<...>::operator <<': was declared deprecated
    #       Disable warning C4702: unreachable code; wide_string_input_adapter::get_elements()
    #                              is annotated JSON_HEDLEY_NO_RETURN (it always throws), which
    #                              makes MSVC flag the code following its call in binary_reader.hpp
    #                              as unreachable for that instantiation, in both Debug and Release
    #       Disable warning C4503: decorated name length exceeded, name was truncated; the deep
    #                              copy support added for #5387 pushes the mangled name of
    #                              std::allocator_traits<...>::construct for the custom-base-class
    #                              test's map type past VS2015's limit. The name is only used for
    #                              debug info, so truncation does not affect the build.
    #       Disable warning C5285: cannot declare a specialization for 'std::tuple'; MSVC 19.51
    #                              reports the forward declarations of standard library
    #                              templates in the vendored doctest.h
    $<$<CXX_COMPILER_ID:MSVC>:/W4;/wd4566;/wd4996;/wd4702;/wd4503;/wd5285>
    # https://github.com/nlohmann/json/issues/1114
    $<$<CXX_COMPILER_ID:MSVC>:/bigobj> $<$<BOOL:${MINGW}>:-Wa,-mbig-obj>

    # https://github.com/nlohmann/json/pull/3229
    $<$<CXX_COMPILER_ID:Intel>:-diag-disable=2196>

    # several tests call deprecated functions on purpose to keep them covered
    $<$<NOT:$<CXX_COMPILER_ID:MSVC>>:-Wno-deprecated-declarations>
    $<$<CXX_COMPILER_ID:Intel>:-diag-disable=1786>)
target_include_directories(test_main SYSTEM PUBLIC
    thirdparty/doctest)
target_include_directories(test_main PUBLIC
    ${PROJECT_BINARY_DIR}/include)
target_link_libraries(test_main PUBLIC ${NLOHMANN_JSON_TARGET_NAME})

# thirdparty/fifo_map is only used by the #972 regression test, so only
# test-regression1 needs it on its include path (see json_test_set_test_options
# below), rather than every test-* target via test_main.
add_library(fifo_map_include INTERFACE)
target_include_directories(fifo_map_include SYSTEM INTERFACE thirdparty/fifo_map)

#############################################################################
# define test- and standard-specific build settings
#############################################################################

if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
    AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 8.0
    AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0 AND NOT MINGW)
    # fix for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90050
    json_test_set_test_options(all CXX_STANDARDS 17 LINK_LIBRARIES stdc++fs)
endif()

if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
    # avoid stack overflow, see https://github.com/nlohmann/json/issues/2955
    json_test_set_test_options("test-bon8;test-cbor;test-msgpack;test-ubjson;test-bjdata;test-bjdata_round_trip_draft2;test-bjdata_round_trip_draft3;test-binary_formats" LINK_OPTIONS /STACK:4000000)
endif()

# disable exceptions for test-disabled_exceptions
json_test_set_test_options(test-disabled_exceptions
    COMPILE_DEFINITIONS
        JSON_NOEXCEPTION
        # disabled due to https://github.com/nlohmann/json/discussions/2824
        #$<$<CXX_COMPILER_ID:MSVC>:_HAS_EXCEPTIONS=0>
    COMPILE_OPTIONS
        $<$<CXX_COMPILER_ID:AppleClang>:-fno-exceptions> $<$<CXX_COMPILER_ID:Clang>:-fno-exceptions>
        $<$<CXX_COMPILER_ID:GNU>:-fno-exceptions>
        $<$<CXX_COMPILER_ID:Intel>:-fno-exceptions> $<$<CXX_COMPILER_ID:IntelLLVM>:-fno-exceptions>
        # disabled due to https://github.com/nlohmann/json/discussions/2824
        #$<$<CXX_COMPILER_ID:MSVC>:/EH>
)

# only the #972 regression test needs thirdparty/fifo_map on its include path
json_test_set_test_options(test-regression1 LINK_LIBRARIES fifo_map_include)

# Regression test for GCC's false -Warray-bounds error with JSON_DIAGNOSTICS (#5742, fixed in #5585). It only
# showed up when optimizing, so build this test with -O3 and the warning as an error.
# -O3 makes the optimizer-driven warnings of the ci_test_gcc flag set (-Winline,
# -Wsuggest-attribute=...) fire on the library's inline functions; they are not
# what this test checks, so turn them off for it.
json_test_set_test_options(test-diagnostics-optimized
    COMPILE_OPTIONS $<$<CXX_COMPILER_ID:GNU>:-O3 -Werror=array-bounds -Wno-inline -Wno-suggest-attribute=pure -Wno-suggest-attribute=const>
)

#############################################################################
# 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)
else()
    set(test_cxx_standards ${JSON_TestStandards})
    set(test_force FORCE)
endif()

# Print selected standards marking unavailable ones with brackets
set(msg_standards "")
foreach(cxx_standard ${test_cxx_standards})
    if(compiler_supports_cpp_${cxx_standard})
        list(APPEND msg_standards ${cxx_standard})
    else()
        list(APPEND msg_standards [${cxx_standard}])
    endif()
endforeach()
string(JOIN " " msg_standards ${msg_standards})
set(msg "Testing standards: ${msg_standards}")
if(test_force)
    string(APPEND msg " (forced)")
endif()
message(STATUS "${msg}")

#############################################################################
# optionally validate UTF-8 with simdutf (JSON_USE_SIMDUTF)
#############################################################################

# The simdutf backend is opt-in and not vendored, so it is fetched here rather
# than being a checked-in dependency. Everything below hangs off test_main,
# whose usage requirements every test target inherits; the library target and
# the installed CMake package are deliberately left untouched.
if (JSON_TestSimdutf)
    # simdutf requires C++17, both to compile itself and to be reachable from
    # the library, which keeps its scalar validator below that. Find a tested
    # standard that satisfies it.
    set(simdutf_standard "")
    foreach(cxx_standard ${test_cxx_standards})
        if(NOT cxx_standard LESS 17 AND compiler_supports_cpp_${cxx_standard})
            set(simdutf_standard ${cxx_standard})
            break()
        endif()
    endforeach()

    if("${simdutf_standard}" STREQUAL "")
        # Building simdutf would fail outright without a C++17 compiler, and
        # even with one it would go unused if no C++17-or-later standard is
        # tested. Say so and fall back to the scalar validator rather than
        # failing the build.
        if(NOT compiler_supports_cpp_17)
            set(simdutf_reason "the compiler does not support C++17")
        else()
            set(simdutf_reason "no tested standard is C++17 or later (testing ${msg_standards})")
        endif()
        message(WARNING
            "JSON_TestSimdutf is enabled, but ${simdutf_reason}. simdutf requires C++17, so it "
            "is not fetched and JSON_USE_SIMDUTF is not defined: the tests run against the "
            "built-in scalar UTF-8 validator instead. Set JSON_TestStandards to include 17 or "
            "later, or build with a compiler that supports C++17.")
    else()
        if (CMAKE_VERSION VERSION_LESS 3.18)
            message(FATAL_ERROR "JSON_TestSimdutf requires CMake 3.18 or later (simdutf's minimum).")
        endif()

        include(FetchContent)

        # simdutf builds its tests and tools by default, and its tests pull
        # further dependencies of their own; only the library is needed here
        set(SIMDUTF_TESTS OFF CACHE BOOL "" FORCE)
        set(SIMDUTF_TOOLS OFF CACHE BOOL "" FORCE)
        set(SIMDUTF_BENCHMARKS OFF CACHE BOOL "" FORCE)
        set(SIMDUTF_ICONV OFF CACHE BOOL "" FORCE)

        FetchContent_Declare(simdutf
            URL https://github.com/simdutf/simdutf/archive/refs/tags/v${JSON_SIMDUTF_VERSION}.tar.gz
            DOWNLOAD_EXTRACT_TIMESTAMP TRUE
        )
        FetchContent_MakeAvailable(simdutf)

        target_compile_definitions(test_main PUBLIC JSON_USE_SIMDUTF)
        target_link_libraries(test_main PUBLIC simdutf::simdutf)

        # simdutf.h requires C++17; below that the library keeps its scalar
        # validator, so any C++11/14 test targets exercise the fallback and the
        # C++17-and-later ones exercise simdutf. Both must agree.
        message(STATUS "UTF-8 validation delegated to simdutf ${JSON_SIMDUTF_VERSION} for C++17 and later (JSON_USE_SIMDUTF)")
    endif()
endif()

# test-file_input checks from a second thread that parsing from a FILE* releases the file's lock
find_package(Threads REQUIRED)
json_test_set_test_options("test-file_input;test-file_input_unlocked_io_disabled" LINK_LIBRARIES Threads::Threads)

# *DO* use json_test_set_test_options() above this line

json_test_should_build_32bit_test(json_32bit_test json_32bit_test_only "${JSON_32bitTest}")
file(GLOB files CONFIGURE_DEPENDS src/unit-*.cpp)
if(json_32bit_test_only)
    set(files src/unit-32bit.cpp)
elseif(NOT json_32bit_test)
    list(FILTER files EXCLUDE REGEX src/unit-32bit.cpp)
endif()

# with JSON_TestShard=<index>/<count>, keep every <count>-th unit test file,
# starting at <index> (the glob is sorted, so the split is stable)
set(test_shard_index 0)
if(NOT "${JSON_TestShard}" STREQUAL "")
    if(NOT JSON_TestShard MATCHES "^([0-9]+)/([1-9][0-9]*)$")
        message(FATAL_ERROR "JSON_TestShard must be <index>/<count>, e.g. 0/2, not '${JSON_TestShard}'.")
    endif()
    set(test_shard_index ${CMAKE_MATCH_1})
    set(test_shard_count ${CMAKE_MATCH_2})
    if(NOT test_shard_index LESS test_shard_count)
        message(FATAL_ERROR "JSON_TestShard: the index must be less than the count, not '${JSON_TestShard}'.")
    endif()
    list(LENGTH files test_file_count)
    set(shard_files "")
    set(file_position 0)
    foreach(file ${files})
        math(EXPR file_shard "${file_position} % ${test_shard_count}")
        if(file_shard EQUAL test_shard_index)
            list(APPEND shard_files ${file})
        endif()
        math(EXPR file_position "${file_position} + 1")
    endforeach()
    set(files ${shard_files})
    list(LENGTH files shard_file_count)
    message(STATUS "Test shard ${JSON_TestShard}: ${shard_file_count} of ${test_file_count} unit test files")
endif()

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()
endif()

# the following variants of single test files are only built in the first shard
if(test_shard_index EQUAL 0)

# test legacy comparison of discarded values
json_test_set_test_options(test-comparison_legacy
    COMPILE_DEFINITIONS JSON_USE_LEGACY_DISCARDED_VALUE_COMPARISON=1
)
json_test_add_test_for(src/unit-comparison.cpp
    NAME test-comparison_legacy
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# test the parser again with JSON_DIAGNOSTIC_POSITIONS enabled
json_test_set_test_options(test-class_parser_diagnostic_positions
    COMPILE_DEFINITIONS JSON_DIAGNOSTIC_POSITIONS=1
)
json_test_add_test_for(src/unit-class_parser.cpp
    NAME test-class_parser_diagnostic_positions
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# test diagnostic positions again without regular diagnostics (JSON pointer paths)
json_test_set_test_options(test-diagnostic-positions_only
    COMPILE_DEFINITIONS JSON_DIAGNOSTICS=0
)
json_test_add_test_for(src/unit-diagnostic-positions.cpp
    NAME test-diagnostic-positions_only
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# the lexer again with the portable string scanning instead of SSE2/NEON, and on
# x86-64 with SSSE3 compiled in (no check of the CPU)
json_test_set_test_options(test-class_lexer_no_simd
    COMPILE_DEFINITIONS JSON_NO_SIMD
)
json_test_add_test_for(src/unit-class_lexer.cpp
    NAME test-class_lexer_no_simd
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)
if(CMAKE_SYSTEM_PROCESSOR MATCHES "^(x86_64|AMD64|amd64)$" AND NOT MSVC)
    json_test_set_test_options(test-class_lexer_ssse3
        COMPILE_OPTIONS -mssse3
    )
    json_test_add_test_for(src/unit-class_lexer.cpp
        NAME test-class_lexer_ssse3
        MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
    )
endif()

# test reading from a std::istream again without scanning the get area in bulk
json_test_set_test_options(test-stream-bulk-scan_disabled
    COMPILE_DEFINITIONS JSON_DISABLE_STREAM_BULK_SCAN=1
)
json_test_add_test_for(src/unit-stream-bulk-scan.cpp
    NAME test-stream-bulk-scan_disabled
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# test reading from a std::istream again with JSON_PRECISE_STREAM_POSITION
json_test_set_test_options(test-stream-bulk-scan_precise
    COMPILE_DEFINITIONS JSON_PRECISE_STREAM_POSITION=1
)
json_test_add_test_for(src/unit-stream-bulk-scan.cpp
    NAME test-stream-bulk-scan_precise
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# test the budget for the elements of UBJSON containers of a valueless type again
# with other values of JSON_UBJSON_VALUELESS_ELEMENTS_PER_BYTE: 1 (the smallest),
# 1000000 (so large that the budget cannot be reached), and the largest value of
# a 64-bit integer (which saturates the limit already at the first byte, and is
# clamped to the largest std::size_t where that has 32 bits). The file does not
# mention JSON_HAS_CPP_<n>, so only C++11 is built unless the standards are forced
json_test_set_test_options(test-ubjson_valueless_rate_1
    COMPILE_DEFINITIONS JSON_UBJSON_VALUELESS_ELEMENTS_PER_BYTE=1
)
json_test_add_test_for(src/unit-ubjson_valueless.cpp
    NAME test-ubjson_valueless_rate_1
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)
json_test_set_test_options(test-ubjson_valueless_rate_1000000
    COMPILE_DEFINITIONS JSON_UBJSON_VALUELESS_ELEMENTS_PER_BYTE=1000000
)
json_test_add_test_for(src/unit-ubjson_valueless.cpp
    NAME test-ubjson_valueless_rate_1000000
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)
json_test_set_test_options(test-ubjson_valueless_rate_max
    COMPILE_DEFINITIONS JSON_UBJSON_VALUELESS_ELEMENTS_PER_BYTE=0xFFFFFFFFFFFFFFFFu
)
json_test_add_test_for(src/unit-ubjson_valueless.cpp
    NAME test-ubjson_valueless_rate_max
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# test reading from a FILE* again with the locking stdio functions
json_test_set_test_options(test-file_input_unlocked_io_disabled
    COMPILE_DEFINITIONS JSON_DISABLE_UNLOCKED_FILE_IO=1
)
json_test_add_test_for(src/unit-file_input.cpp
    NAME test-file_input_unlocked_io_disabled
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)

# the json_view parser again with the portable string scanning instead of
# NEON/SSE2 (JSON_NO_SIMD), and on x86-64 compiled for SSSE3 (no CPU check)
json_test_set_test_options(test-json_view_builder_portable
    COMPILE_DEFINITIONS JSON_NO_SIMD
)
json_test_add_test_for(src/unit-json_view_builder.cpp
    NAME test-json_view_builder_portable
    MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
)
if(CMAKE_SYSTEM_PROCESSOR MATCHES "^(x86_64|AMD64|amd64)$" AND NOT MSVC)
    json_test_set_test_options(test-json_view_builder_ssse3
        COMPILE_OPTIONS -mssse3
    )
    json_test_add_test_for(src/unit-json_view_builder.cpp
        NAME test-json_view_builder_ssse3
        MAIN test_main CXX_STANDARDS ${test_cxx_standards} ${test_force}
    )
endif()
endif()

# *DO NOT* use json_test_set_test_options() below this line

#############################################################################
# test ABI compatibility
#############################################################################

add_subdirectory(abi)

#############################################################################
# Test the generated build configs
#############################################################################

# these tests depend on the generated file nlohmann_jsonConfig.cmake
if (JSON_Install)
    add_subdirectory(cmake_import)
    add_subdirectory(cmake_import_minver)
endif()

add_subdirectory(cmake_add_subdirectory)
add_subdirectory(cmake_fetch_content)
add_subdirectory(cmake_fetch_content2)
add_subdirectory(cmake_target_include_directories)

# fmt (fetched by tests/fmt_formatter) requires a genuinely modern, C++17-capable
# toolchain; skip it on legacy/niche toolchains where fmt itself is known not to build
set(JSON_FMT_FORMATTER_TEST_SUPPORTED ${compiler_supports_cpp_17})
# fmt 12's 128-bit integer emulation does not build with 32-bit MinGW
if (MINGW AND CMAKE_SIZEOF_VOID_P EQUAL 4)
    set(JSON_FMT_FORMATTER_TEST_SUPPORTED FALSE)
endif()
# the MSVC STL rejects Clang versions older than 19 as a host compiler
if (WIN32 AND CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 19.0)
    set(JSON_FMT_FORMATTER_TEST_SUPPORTED FALSE)
endif()
if (JSON_FMT_FORMATTER_TEST_SUPPORTED)
    add_subdirectory(fmt_formatter)
endif()