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

#
# common-dependencies-post.py
# Convenience script to add build flags for Marlin Enabled Features
#
Import("env")

# Detect that 'vscode init' is running
from SCons.Script import COMMAND_LINE_TARGETS
if "idedata" in COMMAND_LINE_TARGETS:
    env.Exit(0)

Import("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()