lokinet/vendor/abseil-cpp/CMake/README.md
2019-02-03 01:56:38 +00:00

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# Abseil CMake Build Instructions
Abseil comes with a CMake build script ([CMakeLists.txt](../CMakeLists.txt))
that can be used on a wide range of platforms ("C" stands for cross-platform.).
If you don't have CMake installed already, you can download it for free from
<http://www.cmake.org/>.
CMake works by generating native makefiles or build projects that can
be used in the compiler environment of your choice.
For API/ABI compatibility reasons, we strongly recommend building Abseil in a
subdirectory of your project or as an embedded dependency.
## Incorporating Abseil Into a CMake Project
The recommendations below are similar to those for using CMake within the
googletest framework
(<https://github.com/google/googletest/blob/master/googletest/README.md#incorporating-into-an-existing-cmake-project>)
### Step-by-Step Instructions
1. If you want to build the Abseil tests, integrate the Abseil dependency
[Google Test](https://github.com/google/googletest) into your CMake project. To disable Abseil tests, you have to pass
`-DBUILD_TESTING=OFF` when configuring your project with CMake.
2. Download Abseil and copy it into a subdirectory in your CMake project or add
Abseil as a [git submodule](https://git-scm.com/docs/git-submodule) in your
CMake project.
3. You can then use the CMake command
[`add_subdirectory()`](https://cmake.org/cmake/help/latest/command/add_subdirectory.html)
to include Abseil directly in your CMake project.
4. Add the **absl::** target you wish to use to the
[`target_link_libraries()`](https://cmake.org/cmake/help/latest/command/target_link_libraries.html)
section of your executable or of your library.<br>
Here is a short CMakeLists.txt example of a project file using Abseil.
```cmake
cmake_minimum_required(VERSION 2.8.12)
project(my_project)
set(CMAKE_CXX_FLAGS "-std=c++11 -stdlib=libc++ ${CMAKE_CXX_FLAGS}")
if(MSVC)
# /wd4005 macro-redefinition
# /wd4068 unknown pragma
# /wd4244 conversion from 'type1' to 'type2'
# /wd4267 conversion from 'size_t' to 'type2'
# /wd4800 force value to bool 'true' or 'false' (performance warning)
add_compile_options(/wd4005 /wd4068 /wd4244 /wd4267 /wd4800)
add_definitions(/DNOMINMAX /DWIN32_LEAN_AND_MEAN=1 /D_CRT_SECURE_NO_WARNINGS)
endif()
add_subdirectory(abseil-cpp)
add_executable(my_exe source.cpp)
target_link_libraries(my_exe absl::base absl::synchronization absl::strings)
```
### Running Abseil Tests with CMake
Use the `-DABSL_RUN_TESTS=ON` flag to run Abseil tests. Note that if the `-DBUILD_TESTING=OFF` flag is passed then Abseil tests will not be run.
You will need to provide Abseil with a Googletest dependency. There are two
options for how to do this:
* Use `-DABSL_USE_GOOGLETEST_HEAD`. This will automatically download the latest
Googletest source into the build directory at configure time. Googletest will
then be compiled directly alongside Abseil's tests.
* Manually integrate Googletest with your build. See
https://github.com/google/googletest/blob/master/googletest/README.md#using-cmake
for more information on using Googletest in a CMake project.
For example, to run just the Abseil tests, you could use this script:
```
cd path/to/abseil-cpp
mkdir build
cd build
cmake -DABSL_USE_GOOGLETEST_HEAD=ON -DABSL_RUN_TESTS=ON ..
make -j
ctest
```
Currently, we only run our tests with CMake in a Linux environment, but we are
working on the rest of our supported platforms. See
https://github.com/abseil/abseil-cpp/projects/1 and
https://github.com/abseil/abseil-cpp/issues/109 for more information.
### Available Abseil CMake Public Targets
Here's a non-exhaustive list of Abseil CMake public targets:
```cmake
absl::base
absl::algorithm
absl::container
absl::debugging
absl::memory
absl::meta
absl::numeric
absl::strings
absl::synchronization
absl::time
absl::utility
```