marlin/buildroot/share/PlatformIO/scripts/common-dependencies-post.py

#
# post:common-dependencies-post.py
# Convenience script to add build flags for Marlin Enabled Features
#
import pioutil
if pioutil.is_pio_build():
    Import("env", "projenv")

    def apply_board_build_flags():
        if not 'BOARD_CUSTOM_BUILD_FLAGS' in env['MARLIN_FEATURES']:
            return
        projenv.Append(CCFLAGS=env['MARLIN_FEATURES']['BOARD_CUSTOM_BUILD_FLAGS'].split())

    # We need to add the board build flags in a post script
    # so the platform build script doesn't overwrite the custom CCFLAGS
    apply_board_build_flags()