Infer Conan profile from CMake toolchain file for cross-building?

I try to integrate Conan in a CMake project using CMake toolchain files for cross-building.

The only way I could get it working was creating an additional Conan profile file matching the toolchain file settings. I wonder if it’s possible to infer those information from the CMake toolchain file to simply (cross-)building:

conan_cmake_run(
    CONANFILE conanfile.txt
    BASIC_SETUP
    PROFILE ${CMAKE_SOURCE_DIR}/profile-armv7.conan  # <- neccessary?
    PROFILE_AUTO ALL
    BUILD missing
)

I created a small example project to showcase the current state and goals: https://github.com/lukasberbuer/cmake-conan-crossbuild

PS: I’m pretty new to Conan and very impressed so far - solves a lot of problems for me. Great project!

[lukasberbuer]

@uyha: It seems to work, thanks! I updated the repository with your recommended solution.

The arch variable needs to be specified in the CMake toolchain file:

set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)
set(CONAN_ARCHITECTURE armv7)
...

Everything else can be derived from CMake. The Conan profile file is not necessary any more:

if(CMAKE_CROSSCOMPILING AND NOT CONAN_ARCHITECTURE)
    message(FATAL_ERROR "The variable CONAN_ARCHITECTURE must be specified for cross-compiling")
endif()

conan_cmake_run(
    CONANFILE conanfile.txt
    BASIC_SETUP
    ARCH ${CONAN_ARCHITECTURE}
    ENV CC=${CMAKE_C_COMPILER}
    ENV CXX=${CMAKE_CXX_COMPILER}
    ENV CFLAGS=${CMAKE_C_FLAGS}
    ENV CXXFLAGS=${CMAKE_CXX_FLAGS}
    PROFILE_AUTO ALL
    BUILD missing
)

[gabyx]

Note: Beware of strange paths on Windows:

ENV CC=${CMAKE_C_COMPILER}

I think these should be native patchs with cmake_path(NATIVE CMAKE_C_COMPILER NORMALIZE cc) like ENV CC=${cc} but ninja, still has troubles when this resolves to something C:/Program Files which is treaded as

"C:/Program" "Files" in Ninja…