Google Benchmark: "Library built in Debug mode"

Question

I have the googlebenchmark source code in ~/usr/local and build the whole thing with cmake -DCMAKE_BUILD_TYPE=Release from inside build: cd build; cmake -DCMAKE_BUILD_TYPE=Release; make, and then in my project's CMakeLists.txt I have the following:

set(BENCHMARK_ROOT ~/local/benchmark/build/src)
set(BENCHMARK_INCLUDE_DIR ~/local/benchmark/include)

I would like to keep the library in my home directory, as is shown here, and it works fine with this set-up; my C++ project can see benchmark. However, the warning ***WARNING*** Library was built as DEBUG. Timings may be affected. is still there, so I believe the README.md does not tell the whole story. How to fix this? I even tried with cmake -DCMAKE_BUILD_TYPE=Release -DBENCHMARK_DOWNLOAD_DEPENDENCIES=ON ../ so that it actually downloads googletest and stores it in third_party directory inside build. However, issuing make leads it to an error: it cannot find the googletest it has just built.

EDIT: I've included

if (NOT CMAKE_BUILD_TYPE MATCHES Debug)
    add_definitions(-DNDEBUG)
endif()

into the CMakeLists.txt of benchmark, still the warning persists. The approach has been suggested https://stackoverflow.com/questions/34302265/does-cmake-build-type-release-imply-dndebug

Answer 1

After including

if (NOT CMAKE_BUILD_TYPE MATCHES Debug)
    add_definitions(-DNDEBUG)
endif()

into benchmark's CMakeLists.txt and re-building it, and linking my executable towards newly built library, voila, here is a sample output:

... { "type": "Unified", "level": 3, "size": 25344000, "num_sharing": 16 } ], "load_avg": [0.4,0.18,0.23], "library_build_type": "release"

Thus, sometimes it makes sense to install the library from sources, in order to build it as Release.

In addition, one does something like

set(BENCHMARK_ROOT ~/local/benchmark/build/src)
target_link_directories(my_executable PUBLIC ${BENCHMARK_ROOT})

after having built the library inside (in my case) ~/local/nechmark/build/