diff options
author | Abseil Team <absl-team@google.com> | 2021-01-05 21:46:37 (GMT) |
---|---|---|
committer | Derek Mauro <dmauro@google.com> | 2021-01-14 01:59:12 (GMT) |
commit | 489283524e3726b7adb9692763c2fb61b235d41a (patch) | |
tree | 0c21fdc64b8978bcac9cee62f14584ce4f024bc9 /docs/pkgconfig.md | |
parent | 996b65e64e415c683d7f15ee5926d66309425ce8 (diff) | |
download | googletest-489283524e3726b7adb9692763c2fb61b235d41a.zip googletest-489283524e3726b7adb9692763c2fb61b235d41a.tar.gz googletest-489283524e3726b7adb9692763c2fb61b235d41a.tar.bz2 |
Googletest export
Move all docs into top-level docs/ directory
PiperOrigin-RevId: 350211277
Diffstat (limited to 'docs/pkgconfig.md')
-rw-r--r-- | docs/pkgconfig.md | 150 |
1 files changed, 150 insertions, 0 deletions
diff --git a/docs/pkgconfig.md b/docs/pkgconfig.md new file mode 100644 index 0000000..aed4ad4 --- /dev/null +++ b/docs/pkgconfig.md @@ -0,0 +1,150 @@ +## Using GoogleTest from various build systems + +<!-- GOOGLETEST_CM0035 DO NOT DELETE --> + +GoogleTest comes with pkg-config files that can be used to determine all +necessary flags for compiling and linking to GoogleTest (and GoogleMock). +Pkg-config is a standardised plain-text format containing + +* the includedir (-I) path +* necessary macro (-D) definitions +* further required flags (-pthread) +* the library (-L) path +* the library (-l) to link to + +All current build systems support pkg-config in one way or another. For all +examples here we assume you want to compile the sample +`samples/sample3_unittest.cc`. + +### CMake + +Using `pkg-config` in CMake is fairly easy: + +```cmake +cmake_minimum_required(VERSION 3.0) + +cmake_policy(SET CMP0048 NEW) +project(my_gtest_pkgconfig VERSION 0.0.1 LANGUAGES CXX) + +find_package(PkgConfig) +pkg_search_module(GTEST REQUIRED gtest_main) + +add_executable(testapp samples/sample3_unittest.cc) +target_link_libraries(testapp ${GTEST_LDFLAGS}) +target_compile_options(testapp PUBLIC ${GTEST_CFLAGS}) + +include(CTest) +add_test(first_and_only_test testapp) +``` + +It is generally recommended that you use `target_compile_options` + `_CFLAGS` +over `target_include_directories` + `_INCLUDE_DIRS` as the former includes not +just -I flags (GoogleTest might require a macro indicating to internal headers +that all libraries have been compiled with threading enabled. In addition, +GoogleTest might also require `-pthread` in the compiling step, and as such +splitting the pkg-config `Cflags` variable into include dirs and macros for +`target_compile_definitions()` might still miss this). The same recommendation +goes for using `_LDFLAGS` over the more commonplace `_LIBRARIES`, which happens +to discard `-L` flags and `-pthread`. + +### Help! pkg-config can't find GoogleTest! + +Let's say you have a `CMakeLists.txt` along the lines of the one in this +tutorial and you try to run `cmake`. It is very possible that you get a failure +along the lines of: + +``` +-- Checking for one of the modules 'gtest_main' +CMake Error at /usr/share/cmake/Modules/FindPkgConfig.cmake:640 (message): + None of the required 'gtest_main' found +``` + +These failures are common if you installed GoogleTest yourself and have not +sourced it from a distro or other package manager. If so, you need to tell +pkg-config where it can find the `.pc` files containing the information. Say you +installed GoogleTest to `/usr/local`, then it might be that the `.pc` files are +installed under `/usr/local/lib64/pkgconfig`. If you set + +``` +export PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig +``` + +pkg-config will also try to look in `PKG_CONFIG_PATH` to find `gtest_main.pc`. + +### Using pkg-config in a cross-compilation setting + +Pkg-config can be used in a cross-compilation setting too. To do this, let's +assume the final prefix of the cross-compiled installation will be `/usr`, and +your sysroot is `/home/MYUSER/sysroot`. Configure and install GTest using + +``` +mkdir build && cmake -DCMAKE_INSTALL_PREFIX=/usr .. +``` + +Install into the sysroot using `DESTDIR`: + +``` +make -j install DESTDIR=/home/MYUSER/sysroot +``` + +Before we continue, it is recommended to **always** define the following two +variables for pkg-config in a cross-compilation setting: + +``` +export PKG_CONFIG_ALLOW_SYSTEM_CFLAGS=yes +export PKG_CONFIG_ALLOW_SYSTEM_LIBS=yes +``` + +otherwise `pkg-config` will filter `-I` and `-L` flags against standard prefixes +such as `/usr` (see https://bugs.freedesktop.org/show_bug.cgi?id=28264#c3 for +reasons why this stripping needs to occur usually). + +If you look at the generated pkg-config file, it will look something like + +``` +libdir=/usr/lib64 +includedir=/usr/include + +Name: gtest +Description: GoogleTest (without main() function) +Version: 1.10.0 +URL: https://github.com/google/googletest +Libs: -L${libdir} -lgtest -lpthread +Cflags: -I${includedir} -DGTEST_HAS_PTHREAD=1 -lpthread +``` + +Notice that the sysroot is not included in `libdir` and `includedir`! If you try +to run `pkg-config` with the correct +`PKG_CONFIG_LIBDIR=/home/MYUSER/sysroot/usr/lib64/pkgconfig` against this `.pc` +file, you will get + +``` +$ pkg-config --cflags gtest +-DGTEST_HAS_PTHREAD=1 -lpthread -I/usr/include +$ pkg-config --libs gtest +-L/usr/lib64 -lgtest -lpthread +``` + +which is obviously wrong and points to the `CBUILD` and not `CHOST` root. In +order to use this in a cross-compilation setting, we need to tell pkg-config to +inject the actual sysroot into `-I` and `-L` variables. Let us now tell +pkg-config about the actual sysroot + +``` +export PKG_CONFIG_DIR= +export PKG_CONFIG_SYSROOT_DIR=/home/MYUSER/sysroot +export PKG_CONFIG_LIBDIR=${PKG_CONFIG_SYSROOT_DIR}/usr/lib64/pkgconfig +``` + +and running `pkg-config` again we get + +``` +$ pkg-config --cflags gtest +-DGTEST_HAS_PTHREAD=1 -lpthread -I/home/MYUSER/sysroot/usr/include +$ pkg-config --libs gtest +-L/home/MYUSER/sysroot/usr/lib64 -lgtest -lpthread +``` + +which contains the correct sysroot now. For a more comprehensive guide to also +including `${CHOST}` in build system calls, see the excellent tutorial by Diego +Elio Pettenò: https://autotools.io/pkgconfig/cross-compiling.html |