Shamelessly copy Josiah

source/lib/json/tests/benchmarks/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.11...3.14)
+project(JSON_Benchmarks LANGUAGES CXX)
+
+# set compiler flags
+if((CMAKE_CXX_COMPILER_ID MATCHES GNU) OR (CMAKE_CXX_COMPILER_ID MATCHES Clang))
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -flto -DNDEBUG -O3")
+endif()
+
+# configure Google Benchmarks
+include(FetchContent)
+FetchContent_Declare(
+    benchmark
+    GIT_REPOSITORY https://github.com/google/benchmark.git
+    GIT_TAG origin/main
+    GIT_SHALLOW TRUE
+)
+
+FetchContent_GetProperties(benchmark)
+if(NOT benchmark_POPULATED)
+    FetchContent_Populate(benchmark)
+    set(BENCHMARK_ENABLE_TESTING OFF CACHE INTERNAL "" FORCE)
+    add_subdirectory(${benchmark_SOURCE_DIR} ${benchmark_BINARY_DIR})
+endif()
+
+# download test data
+set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/../../cmake ${CMAKE_MODULE_PATH})
+include(download_test_data)
+
+# benchmark binary
+add_executable(json_benchmarks src/benchmarks.cpp)
+target_compile_features(json_benchmarks PRIVATE cxx_std_11)
+target_link_libraries(json_benchmarks benchmark ${CMAKE_THREAD_LIBS_INIT})
+add_dependencies(json_benchmarks download_test_data)
+target_include_directories(json_benchmarks PRIVATE ${CMAKE_SOURCE_DIR}/../../single_include ${CMAKE_BINARY_DIR}/include)