mirror of
https://github.com/google/googletest.git
synced 2024-12-27 10:11:03 +08:00
149 lines
4.9 KiB
Markdown
149 lines
4.9 KiB
Markdown
## Using GoogleTest from various build systems
|
|
|
|
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: 1.11.0
|
|
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>
|