CMakeVersionExample

Example experimenting for abseil/abseil-cpp#259. Specifically, outputs CMAKE_CXX_STANDARD, the client C++ standard level, and the lib C++ standard level for when the lib has a private usage requirement of cxx_std_11.

There are two binaries. version uses whatever CMake does behind the scenes to determine level, either the compiler default or CMAKE_CXX_STANDARD. version_with_requirements sets a compile feature of cxx_std_11.

To run

git clone https://github.com/JonathanDCohen/CMakeVersionExample.git
cd CMakeVersionExample
mkdir build && cd build
cmake .. <-DCMAKE_CXX_STANDARD=(98,11,14)> && cmake --build . --target version && ./version

Example outputs (extraneous stuff removed):

AppleClang 10 (defaults to C++98)

$ cmake .. && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD:
client: 199711
lib: 201103

$ cmake .. -DCMAKE_CXX_STANDARD=98 && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 98
client: 199711
lib: 201103

$ cmake .. -DCMAKE_CXX_STANDARD=11 && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 11
client: 201103
lib: 201103

$ cmake -DCMAKE_CXX_STANDARD=14 .. && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 14
client: 201402
lib: 201402

$ cmake .. && cmake --build . --target version_with_requirements && ./version_with_requirements
-- CMAKE_CXX_STANDARD:
client: 201103
lib: 201103

GCC 7.3.0 (defaults to C++14)

$ cmake .. && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 14
client: 201402
lib: 201402

cmake .. -DCMAKE_CXX_STANDARD=98 && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 98
client: 199711
lib: 201103

cmake .. -DCMAKE_CXX_STANDARD=11 && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 11
client: 201103
lib: 201103

$ cmake .. -DCMAKE_CXX_STANDARD=14 && cmake --build . --target version && ./version
-- CMAKE_CXX_STANDARD: 14
client: 201402
lib: 201402

$ cmake .. && cmake --build . --target version_with_requirements && ./version_with_requirements
-- CMAKE_CXX_STANDARD:
client: 201103
lib: 201103