On 10/11/2016 16:05, Ruslan Baratov via cmake-developers wrote:
Hi,I wonder if it's possible to introduce next variables describing Android tools: * C preprocessor. Similar to CMAKE_CXX_COMPILER the variable that will contain the path to preprocessor. Example: * CMAKE_CXX_COMPILER = <ndk-root>/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-g++ * CMAKE_C_PREPROCESSOR = <ndk-root>/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64/bin/arm-linux-androideabi-cpp * ANDROID_TOOLCHAIN_MACHINE_NAME. In fact I'm not sure what this variable mean but it's an important part of move from taka-no-me toolchain to CMake 3.7. I guess it's like * CMAKE_CXX_COMPILER = <ndk-root>/toolchains/${ANDROID_TOOLCHAIN_MACHINE_NAME}-4.9/prebuilt/linux-x86_64/bin/${ANDROID_TOOLCHAIN_MACHINE_NAME}-g++ Of course if I'm not missing something and they are not already somewhere :) Ruslo
How about ${CMAKE_C/CXX_COMPILER} -E to call the preprocessor? Calling it directly is kind of dangerous though since you will probably be missing the proper language information and other options that might affect the predefined preprocessor defines. gcc has different binaries for different target archs and has some defines baked in, but this won't apply to Clang that uses only one binary and a target triple. You'll also lose the c/c++ language definition (unless you pass -x c++), language standard in use...
gcc (or clang) are just "drivers". They will call the proper programs automatically. Either the preprocessor, the compiler (cc1) or the linker, so you should be able to do everything with it directly!
As for the ANDROID_TOOLCHAIN_MACHINE_NAME that is used for gcc prefix, it shouldn't be needed. If you rely on gcc, you should investigate on using Clang which is the supported compiler now in the NDK. What is your exact usage of the variable?
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