BUILD_DIR := build
PREBUILT_DIR := $(BUILD_DIR)/prebuilt
DIRS := $(BUILD_DIR) $(PREBUILT_DIR)

#USE_CLANG := YES

ifdef USE_CLANG

CXX := clang++
CXXFLAGS := \
	-std=c++2b -stdlib=libc++ \
	-fimplicit-modules -fimplicit-module-maps \
	-fprebuilt-module-path=$(PREBUILT_DIR) \
	-fmodules-cache-path=$(PREBUILT_DIR)
#	-fmodule-map-file=/usr/include/c++/v1/module.modulemap
#	-fbuiltin-module-map

MODFLAGS := -Xclang -emit-module-interface

else # COMPILER != clang

CXX := g++
CXXFLAGS := -std=c++2b -fmodules-ts
MODFLAGS :=

# libstdc++ 12.2 does not bundle pre-built modules:
# g++ -std=c++2b -fmodules-ts -fmodule-header=system -x c++-system-header string iostream

endif


APP = hellomodules
SRCS = main.cc helloworld.cc
MODS = helloworld

OBJS = $(patsubst %.cc, build/%.o, $(SRCS))
PCMS = $(patsubst %, $(PREBUILT_DIR)/%.pcm, $(MODS))

all: $(DIRS) $(APP)

clean:
	rm -f $(APP)
	rm -f $(OBJS)
	rm -f $(PCMS)
	rm -rf $(PREBUILT_DIR)
	rm -rf gcm.cache

$(DIRS):
	mkdir -p $(DIRS)

$(APP): $(OBJS) $(PCMS)
	$(CXX) $(CXXFLAGS) -o $@ $(OBJS)

$(BUILD_DIR)/%.o: %.cc $(PCMS)
	$(CXX) $(CXXFLAGS) -o $@ -c $<

$(PREBUILT_DIR)/%.pcm: %.cc
	$(CXX) $(MODFLAGS) $(CXXFLAGS) -o $@ -c $<