GNUmakefile.subdir

# Copyright (c) 2017-2022, University of Tennessee. All rights reserved.
# SPDX-License-Identifier: BSD-3-Clause
# This program is free software: you can redistribute it and/or modify it under
# the terms of the BSD 3-Clause license. See the accompanying LICENSE file.
#
# Subdirectories include this makefile to forward rules to the top level makefile.
# Define ${top} for where the top level is.
# Example: src/GNUmakefile:
#     top = ..
#     include ${top}/GNUmakefile.subdir

.SUFFIXES:

pwd     := ${shell pwd}
abs_top := ${abspath ${top}}
cdir    := ${subst ${abs_top}/,,${pwd}}

.DEFAULT_GOAL: ${cdir}
.PHONY: ${cdir}

${cdir}:
	cd ${top} && ${MAKE} $@

DONT_FORWARD += echo_sub
echo_sub:
	@echo "pwd     ${pwd}"
	@echo "abs_top ${abs_top}"
	@echo "cdir    ${cdir}"

# ------------------------------------------------------------------------------
ifneq (${MAKECMDGOALS},)

# If arguments are given, presumably files like test.o, forward them to top
# with cdir prefix.
# All files are forwarded as one rule, based on first; rest are quietly ignored.
goals   := ${filter-out echo ${DONT_FORWARD}, ${MAKECMDGOALS}}
forward := ${addprefix ${cdir}/, ${goals}}
first   := ${firstword ${goals}}
rest    := ${wordlist 2, ${words ${goals}}, ${goals}}

${first}: force
	cd ${top} && ${MAKE} ${forward}

${rest}: force
	@echo > /dev/null

endif
# ------------------------------------------------------------------------------

force: ;