conan_cmake_run() does not use the current 'os' setting when not using a profile

[mheyse]

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SUMMARY: Contrary to the comment at the top of conan.cmake

# It will take CMake current settings (os, compiler, compiler version, architecture)
# and translate them to conan settings for installing and retrieving dependencies.

calling conan_cmake_run() without a profile does not use CMake's current os setting. This leads to a cross compile build failing because dependencies are compiled for the wrong OS.

STEPS TO REPRODUCE:

• Add a dependency on boost/1.72.0
• cross-compile the project on Linux or OSX for Windows using a x86_64-w64-mingw32 cross compiler
• in CMakeLists.txt run conan with

conan_cmake_run(
        REQUIRES boost/1.72.0
        BASIC_SETUP
        KEEP_RPATHS
        BUILD missing
        )

EXPECTED RESULT:

• Build works

ACTUAL RESULT:

• The output of conan_cmake_run() contains the line os=Linux (expected: os=Windows)
• The generated boost libraries are all in file format elf64-x86-64 (expected: pe-x86-64)
• The linker fails with a segmentation fault

DETAILS AND RESOLUTION: conan_cmake_settings() correctly checks CMAKE_SYSTEM_NAME and sets CONAN_SYSTEM_NAME and _CONAN_SETTING_OS accordingly but never translates this setting into a command line argument because

    if(NOT _SETTINGS OR ARGUMENTS_PROFILE_AUTO STREQUAL "ALL")
        set(ARGUMENTS_PROFILE_AUTO arch build_type compiler compiler.version
                                   compiler.runtime compiler.libcxx compiler.toolset)
    endif()

does not add os to ARGUMENTS_PROFILE_AUTO.

This leads to building dependencies with an incorrect os setting when cross compiling which makes the build fail.

Changing this line to

    if(NOT _SETTINGS OR ARGUMENTS_PROFILE_AUTO STREQUAL "ALL")
        set(ARGUMENTS_PROFILE_AUTO arch build_type compiler compiler.version
                                   compiler.runtime compiler.libcxx compiler.toolset os)
    endif()

(adding os at the end of the third line) fixes the issue.

[czoido]

Hi @mheyse, I think that this phrase was not thought having cross-compilation in mind. If you are doing cross-compilation I would suggest that you use a different profile for that because it's probably not going to automatically be resolved otherwise. Anyway, we are now introducing a new cross-compiling model for Conan 1.24 to use different profiles for build and host.