esp-idf/tools/cmake/targets.cmake

#
# Get target from single sdkconfig file
#
function(__target_from_config config target_out file_out)
    set(${target_out} NOTFOUND PARENT_SCOPE)
    set(${file_out} NOTFOUND PARENT_SCOPE)

    if(NOT EXISTS "${config}")
        return()
    endif()

    file(STRINGS "${config}" lines)
    foreach(line ${lines})
        if(NOT "${line}" MATCHES "^CONFIG_IDF_TARGET=\"[^\"]+\"$")
            continue()
        endif()

        string(REGEX REPLACE "CONFIG_IDF_TARGET=\"([^\"]+)\"" "\\1" target "${line}")
        set(${target_out} ${target} PARENT_SCOPE)
        set(${file_out} ${config} PARENT_SCOPE)
        return()
    endforeach()
endfunction()

#
# Get target from list of sdkconfig files
#
function(__target_from_configs configs target_out file_out)
    set(target NOTFOUND)
    set(file NOTFOUND)

    foreach(config ${configs})
        message(DEBUG "Searching for target in '${config}'")
        get_filename_component(config "${config}" ABSOLUTE)
        __target_from_config("${config}" target file)
        if(target)
            break()
        endif()
    endforeach()

    set(${target_out} ${target} PARENT_SCOPE)
    set(${file_out} ${file} PARENT_SCOPE)
endfunction()

#
# Search for target in config files in the following order.
# SDKCONFIG cmake var, default sdkconfig, SDKCONFIG_DEFAULTS cmake var
# if non-empty or SDKCONFIG_DEFAULTS env var if non-empty or
# sdkconfig.defaults.
#
function(__target_guess target_out file_out)
    # Select sdkconfig_defaults to look for target
    if(SDKCONFIG_DEFAULTS)
        set(defaults "${SDKCONFIG_DEFAULTS}")
    elseif(DEFINED ENV{SDKCONFIG_DEFAULTS})
        set(defaults "$ENV{SDKCONFIG_DEFAULTS}")
    endif()

    if(NOT defaults)
        set(defaults "${CMAKE_SOURCE_DIR}/sdkconfig.defaults")
    endif()

    set(configs "${SDKCONFIG}" "${CMAKE_SOURCE_DIR}/sdkconfig" "${defaults}")
    message(DEBUG "Searching for target in '${configs}'")
    __target_from_configs("${configs}" target file)
    set(${target_out} ${target} PARENT_SCOPE)
    set(${file_out} ${file} PARENT_SCOPE)
endfunction()

#
# Set the target used for the standard project build.
#
macro(__target_init config_file)
    # Input is IDF_TARGET environement variable
    set(env_idf_target $ENV{IDF_TARGET})

    if(NOT env_idf_target)
        # IDF_TARGET not set in environment, see if it is set in cache
        if(IDF_TARGET)
            set(env_idf_target ${IDF_TARGET})
        else()
            # Try to guess IDF_TARGET from sdkconfig files while honoring
            # SDKCONFIG and SDKCONFIG_DEFAULTS values
            __target_guess(env_idf_target where)
            if(env_idf_target)
                message(STATUS "IDF_TARGET is not set, guessed '${env_idf_target}' from sdkconfig '${where}'")
            else()
                set(env_idf_target esp32)
                message(STATUS "IDF_TARGET not set, using default target: ${env_idf_target}")
            endif()
        endif()
    endif()

    # Check if selected target is consistent with CMake cache
    if(DEFINED CACHE{IDF_TARGET})
        if(NOT $CACHE{IDF_TARGET} STREQUAL ${env_idf_target})
            message(FATAL_ERROR " IDF_TARGET '$CACHE{IDF_TARGET}' in CMake"
                " cache does not match currently selected IDF_TARGET '${env_idf_target}'."
                " To change the target, clear the build directory and sdkconfig file,"
                " and build the project again.")
        endif()
    endif()

    # Check if selected target is consistent with sdkconfig
    __target_from_config("${config_file}" sdkconfig_target where)
    if(sdkconfig_target)
        if(NOT ${sdkconfig_target} STREQUAL ${env_idf_target})
            message(FATAL_ERROR " Target '${sdkconfig_target}' in sdkconfig '${where}'"
                " does not match currently selected IDF_TARGET '${IDF_TARGET}'."
                " To change the target, clear the build directory and sdkconfig file,"
                " and build the project again.")
        endif()
    endif()

    # IDF_TARGET will be used by component manager, make sure it is set
    set(ENV{IDF_TARGET} ${env_idf_target})

    # Finally, set IDF_TARGET in cache
    set(IDF_TARGET ${env_idf_target} CACHE STRING "IDF Build Target")
endmacro()

#
# Used by the project CMake file to set the toolchain before project() call.
#
macro(__target_set_toolchain)
    idf_build_get_property(idf_path IDF_PATH)

    # See if Clang toolchain should be used
    set(env_idf_toolchain $ENV{IDF_TOOLCHAIN})
    if(NOT env_idf_toolchain)
        # IDF_TOOLCHAIN not set in environment, see if it is set in cache
        if(IDF_TOOLCHAIN)
            set(env_idf_toolchain ${IDF_TOOLCHAIN})
        else()
            set(env_idf_toolchain gcc)
        endif()
    elseif(DEFINED CACHE{IDF_TOOLCHAIN})
        # IDF_TOOLCHAIN set both in environment and in cache, must be the same
        if(NOT $CACHE{IDF_TOOLCHAIN} STREQUAL ${env_idf_toolchain})
            message(FATAL_ERROR " IDF_TOOLCHAIN '$CACHE{IDF_TOOLCHAIN}' in CMake cache does not match"
                    " currently selected IDF_TOOLCHAIN '${env_idf_toolchain}'. To change the toolchain, clear"
                    " the build directory and sdkconfig file, and build the project again.")
        endif()
    endif()

    # Finally, set IDF_TOOLCHAIN in cache
    set(IDF_TOOLCHAIN ${env_idf_toolchain} CACHE STRING "IDF Build Toolchain Type")

    if(${env_idf_toolchain} STREQUAL "clang")
        set(toolchain_type "clang-")
    endif()

    # Check if selected target is consistent with toolchain file in CMake cache
    if(DEFINED CMAKE_TOOLCHAIN_FILE)
        string(FIND "${CMAKE_TOOLCHAIN_FILE}" "-${toolchain_type}${IDF_TARGET}.cmake" found)
        if(${found} EQUAL -1)
            get_filename_component(toolchain "${CMAKE_TOOLCHAIN_FILE}" NAME_WE)
            message(FATAL_ERROR " CMAKE_TOOLCHAIN_FILE '${toolchain}'"
                " does not match currently selected IDF_TARGET '${IDF_TARGET}'."
                " To change the target, clear the build directory and sdkconfig file,"
                " and build the project again.")
        endif()
    endif()

    # First try to load the toolchain file from the tools/cmake/directory of IDF
    set(toolchain_file_global ${idf_path}/tools/cmake/toolchain-${toolchain_type}${IDF_TARGET}.cmake)
    if(EXISTS ${toolchain_file_global})
        set(CMAKE_TOOLCHAIN_FILE ${toolchain_file_global})
    else()
        message(FATAL_ERROR "Toolchain file ${toolchain_file_global} not found")
    endif()
endmacro()