make_example/Makefile

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Makefile
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2020-02-23 15:53:52 +01:00
######################################################################
# Makefile
#
# This makefile is the one called by user, but it's only a trampoline
# to create the build directory and call the real Makefile.build
#
# make can be invoqued with 'make build=<your_build_directory> ...'
# all other options and target are passed to the real makefile.
#
# As an exception to the rule of not modifying source directory, a
# .build.mak file is created to cache the configured build directory.
# Subsequent invocations of make could be done without passing
# 'build=...' parameter.
#
# distclean target is catched to destroy both the .build.mak and
# the whole build directory.
#
######################################################################
# build directory is cached in BUILD_MAK file between make invocations
BUILD_MAK = .build.mak
ifneq ($(wildcard $(BUILD_MAK)),)
include $(BUILD_MAK)
endif
# default build directory 'build'
build ?= build
# ($call quiet-command,CMD,MSG)
# execute CMD and display MSG
# if verbose mode is enabled (with 'make V=1`) print full CMD instead of MSG
quiet-command = $(if $(V),$1,$(if $(2),@echo $2 && $1, @$1))
# if the target is distclean, skip allmost rules
# to doing anything which will be immediately
# deleted after
ifeq ($(filter distclean,$(MAKECMDGOALS)),)
# default target (when one invokes 'make' without target)
# so we have a non-empty target which could be catched by
# the catch-all target below.
default-all:
# The catch-all target, which pass build to the main
# makefile in the build directory.
# strip-out 'default-all' for targets' list
%: | $(build)
$(call quiet-command, \
$(MAKE) -C $(build) $(filter-out default-all,$@) \
, "MAKE $(filter-out default-all,$@)")
# Creates the buld directory
# and populates it with a link to the build makefile
$(build): | $(BUILD_MAK)
$(call quiet-command,\
mkdir -p $@; \
ln -sf $(CURDIR)/Makefile.build $@/Makefile \
, "MKBUILD $@")
# always create BUILD_MAK to cache build configuration
# but don't update it if not changed
$(BUILD_MAK): FORCE
@echo build=$(build) > $@.tmp
@cmp -s $@.tmp $@ || (mv $@.tmp $@ && echo "GEN $@")
@rm -f $@.tmp
else # if distclean
distclean:
$(call quiet-command, rm -rf $(build) $(BUILD_MAK), "DISTCLEAN $(build)")
endif # distclean
.PHONY: distclean FORCE
#ifndef V
#.SILENT:
#endif