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json/tests/CMakeLists.txt
T
Niels Lohmann 6ee5e89803 Scan json_view strings with SIMD and index large objects 
Speed up json_view's parser with SIMD scanning and a hash table
for large objects.

Long runs of string bytes are scanned 16 bytes at a time with NEON
(AArch64, GCC and Clang) and SSE2 (x86-64), both baseline
instruction sets. Keys keep 16 table checks before the vector
loop, because their lengths repeat from record to record; string
values get 8, because their lengths vary more. Non-ASCII text is
validated 16 bytes at a time with simdjson's "lookup4" check
(Keiser and Lemire, 2021), with NEON on AArch64 and, on x86-64,
with SSSE3. SSSE3 is not part of baseline x86-64, so the check is
compiled for SSSE3 with a function attribute and used only where
CPUID reports it, which all x86-64 CPUs since about 2011 do; the
answer is cached in a statically initialized atomic, so there is
no guard of a local static and no global constructor. The same
input is accepted either way. JSON_VIEW_NO_SIMD selects the
portable code.

On x86-64, string runs are now checked vector-first: one SSE2
compare from the first byte finds the end of most keys and short
values, instead of a branch per byte for the first 8-16 bytes.
AArch64 keeps the byte-wise steps, where a NEON mask costs more and
the branches predict well. Entering an object or array no longer
stalls: open() stores the parent's frame field by field instead of
building it on the stack and reading it back with wider loads,
which waited for the narrower stores to retire.

Objects with 128 members or more get an open-addressing hash table
built when the object closes, so operator[], at(), find(),
contains(), count(), value(), and JSON pointers take constant time
on average in such objects; of duplicate keys, the first is kept,
as for the linear search. The idea comes from Boost.JSON.

simdjson is credited in simd.hpp's SPDX block, the README, and
license.md.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
2026-10-06 10:48:07 +02:00

424 lines
19 KiB
CMake
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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 ${NLOHMANN_JSON_TARGET_NAME})
# thirdparty/fifo_map is only used by the #972 regression test, so only
# test-regression1 needs it on its include path (see json_test_set_test_options
# below), rather than every test-* target via test_main.
add_library(fifo_map_include INTERFACE)
target_include_directories(fifo_map_include SYSTEM INTERFACE thirdparty/fifo_map)
#############################################################################
# define test- and standard-specific build settings
#############################################################################
if (CMAKE_CXX_COMPILER_ID STREQUAL "GNU"
AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 8.0
AND CMAKE_CXX_COMPILER_VERSION VERSION_LESS 9.0 AND NOT MINGW)
# fix for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90050
json_test_set_test_options(all CXX_STANDARDS 17 LINK_LIBRARIES stdc++fs)
endif()
if (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC")
# avoid stack overflow, see https://github.com/nlohmann/json/issues/2955
json_test_set_test_options("test-bon8;test-cbor;test-msgpack;test-ubjson;test-bjdata;test-binary_formats" LINK_OPTIONS /STACK:4000000)
endif()
# disable exceptions for test-disabled_exceptions
json_test_set_test_options(test-disabled_exceptions
COMPILE_DEFINITIONS
JSON_NOEXCEPTION
# disabled due to https://github.com/nlohmann/json/discussions/2824
#$<$<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>
)
# raise timeout of expensive Unicode test
json_test_set_test_options(test-unicode4 TEST_PROPERTIES TIMEOUT 3000)
# 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)
#############################################################################
# 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 ${JSON_SIMDUTF_VERSION} for C++17 and later (JSON_USE_SIMDUTF)")
endif()
endif()
# *DO* use json_test_set_test_options() above this line
json_test_should_build_32bit_test(json_32bit_test json_32bit_test_only "${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 json_view parser again with the portable string scanning instead of
# NEON/SSE2, and on x86-64 with the SSSE3 UTF-8 check (JSON_VIEW_USE_SSSE3)
json_test_set_test_options(test-json_view_builder_portable
COMPILE_DEFINITIONS JSON_VIEW_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_DEFINITIONS JSON_VIEW_USE_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()
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