C++ modules using clang and make

app.cc

#include <cstdio>

import bar;

int main()
{
	printf("%d\n", add(2, 3));
}

bar.ccm

export module bar;

export int add(int x, int y) { return x + y; }

Makefile

#
# clang modules-ts example
#

source       = src
modules      = build/modules
objects      = build/objects
output       = build/output

CXX          = clang++
CXX_FLAGS    = -std=c++2a -O2 -fmodules -fmodules-ts -fprebuilt-module-path=$(modules)

#
# To view commands use: make V=1
#

ifdef V
cmd = @mkdir -p $2 ; echo "$3"; $3
else
cmd = @echo "$1"; mkdir -p $2 ; $3
endif

#
# make rules
#

all: modules $(output)/app

modules: $(patsubst $(source)/%.ccm,$(modules)/%.pcm,$(wildcard $(source)/*.ccm))

clean: ; rm -fr build

$(modules)/%.pcm: $(source)/%.ccm
	$(call cmd,CCM $@, $(@D),$(CXX) $(CXX_FLAGS) --precompile $^ -o $@)

$(objects)/%.o : $(source)/%.cc
	$(call cmd,CC $@, $(@D),$(CXX) $(CXX_FLAGS) -c $^ -o $@)

$(output)/%: $(objects)/%.o
	$(call cmd,LD $@, $(@D),$(CXX) $(CXX_FLAGS) $^ -o $@)

Hey there, thanks for the example!
I was wondering which license you consider the Makefile?