Modify makefile to use incremental compilation

makefile

@@ -1,11 +1,11 @@
-.PHONY: all test
+.PHONY: all test clean
 
 DC ?= dmd
 GIT ?= git
 DMD := $(DC)
 GDC := gdc
 LDC := ldc2
-OBJ_DIR := obj
+
 LIB_SRC := \
 	$(shell find containers/src -name "*.d")\
 	$(shell find dsymbol/src -name "*.d")\
@@ -17,6 +17,13 @@ LIB_SRC := \
 	$(shell find stdx-allocator/source -name "*.d")
 PROJECT_SRC := $(shell find src/ -name "*.d")
 SRC := $(LIB_SRC) $(PROJECT_SRC)
+
+UT_OBJ_DIR = unittest-obj
+OBJ_DIR := obj
+OBJ = $(SRC:.d=.o)
+PROJECT_OBJ = $(PROJECT_SRC:.d=.o)
+LIB_OBJ = $(LIB_SRC:.d=.o)
+
 INCLUDE_PATHS = \
 	-Isrc \
 	-Iinifiled/source \
@@ -33,41 +40,78 @@ override DMD_FLAGS += $(DFLAGS)
 override LDC_FLAGS += $(DFLAGS)
 override GDC_FLAGS += $(DFLAGS)
 DMD_TEST_FLAGS = -w -g -Jbin -version=StdLoggerDisableWarning
-override LDC_FLAGS += -O5 -release -oq -d-version=StdLoggerDisableWarning
-override GDC_FLAGS += -O3 -frelease -d-version=StdLoggerDisableWarning
+override LDC_FLAGS += -O5 -release -oq -d-version=StdLoggerDisableWarning -Jbin
+override GDC_FLAGS += -O3 -frelease -d-version=StdLoggerDisableWarning -Jbin
 SHELL:=/usr/bin/env bash
 
-all: dmdbuild
-ldc: ldcbuild
-gdc: gdcbuild
+DMD_BIN = bin/dmd/dscanner
+LDC_BIN = bin/ldc/dscanner
+GDC_BIN = bin/gdc/dscanner
 
-githash:
-	mkdir -p bin && ${GIT} describe --tags > bin/githash.txt
+GITHASH = bin/githash.txt
 
-debug: githash
+OBJ_BY_DMD = $(addprefix $(OBJ_DIR)/dmd/, $(OBJ))
+UT_OBJ_BY_DMD = $(addprefix $(UT_OBJ_DIR)/dmd/, $(PROJECT_OBJ))
+
+OBJ_BY_LDC = $(addprefix $(OBJ_DIR)/ldc/, $(OBJ))
+UT_OBJ_BY_LDC = $(addprefix $(UT_OBJ_DIR)/ldc/, $(PROJECT_OBJ))
+
+OBJ_BY_GDC = $(addprefix $(OBJ_DIR)/gdc/, $(OBJ))
+UT_OBJ_BY_GDC = $(addprefix $(UT_OBJ_DIR)/gdc/, $(PROJECT_OBJ))
+
+$(OBJ_DIR)/dmd/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${DMD_FLAGS} ${VERSIONS} ${INCLUDE_PATHS} -c $< -of=$@
+
+$(UT_OBJ_DIR)/dmd/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${DMD_TEST_FLAGS} ${VERSIONS} -unittest ${INCLUDE_PATHS} -c $< -of=$@
+
+$(OBJ_DIR)/ldc/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${LDC_FLAGS} ${VERSIONS} ${INCLUDE_PATHS} -c $< -of=$@
+
+$(UT_OBJ_DIR)/ldc/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${LDC_TEST_FLAGS} ${VERSIONS} -unittest ${INCLUDE_PATHS} -c $< -of=$@
+
+$(OBJ_DIR)/gdc/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${GDC_FLAGS} ${VERSIONS} ${INCLUDE_PATHS} -c $< -o $@
+
+$(UT_OBJ_DIR)/gdc/%.o: %.d
+	@test -d $(dir $@) || mkdir -p $(dir $@)
+	${DC} ${GDC_TEST_FLAGS} ${VERSIONS} -unittest ${INCLUDE_PATHS} -c $< -o $@
+
+all: ${DMD_BIN}
+ldc: ${LDC_BIN}
+gdc: ${GDC_BIN}
+
+${GITHASH}:
+	mkdir -p bin && ${GIT} describe --tags --always > ${GITHASH}
+
+debug: ${GITHASH}
 	${DC} -w -g -Jbin -ofdsc ${VERSIONS} ${DEBUG_VERSIONS} ${INCLUDE_PATHS} ${SRC}
 
-dmdbuild: githash
-	${DC} ${DMD_FLAGS} -ofbin/dscanner ${VERSIONS} ${INCLUDE_PATHS} ${SRC}
-	rm -f bin/dscanner.o
+${DMD_BIN}: ${GITHASH} ${OBJ_BY_DMD}
+	${DC} -of${DMD_BIN} ${OBJ_BY_DMD}
 
-gdcbuild: githash
-	${GDC} ${GDC_FLAGS} -obin/dscanner ${VERSIONS} ${INCLUDE_PATHS} ${SRC} -Jbin
+${GDC_BIN}: ${GITHASH} ${OBJ_BY_GDC}
+	${GDC} -o${GDC_BIN} ${OBJ_BY_GDC}
 
-ldcbuild: githash
-	${LDC} ${LDC_FLAGS} -of=bin/dscanner ${VERSIONS} ${INCLUDE_PATHS} ${SRC} -Jbin
+${LDC_BIN}: ${GITHASH} ${OBJ_BY_LDC}
+	${LDC} -of=${DMD_BIN} ${OBJ_BY_LDC}
 
 # compile the dependencies separately, s.t. their unittests don't get executed
-bin/dscanner-unittest-lib.a: ${LIB_SRC}
-	${DC} ${DMD_TEST_FLAGS} -c ${INCLUDE_PATHS} ${LIB_SRC} -of$@
+bin/dmd/dscanner-unittest-lib.a: ${LIB_SRC}
+	${DC} ${DMD_TEST_FLAGS} -c ${VERSIONS} ${INCLUDE_PATHS} ${LIB_SRC} -of$@
 
-test: bin/dscanner-unittest-lib.a githash
-	${DC} ${DMD_TEST_FLAGS} -unittest ${INCLUDE_PATHS} bin/dscanner-unittest-lib.a ${PROJECT_SRC} -ofbin/dscanner-unittest
-	./bin/dscanner-unittest
-	rm -f bin/dscanner-unittest
+test: bin/dmd/dscanner-unittest-lib.a ${GITHASH} ${UT_OBJ_BY_DMD}
+	${DC} bin/dmd/dscanner-unittest-lib.a ${UT_OBJ_BY_DMD} -ofbin/dmd/dscanner-unittest
+	./bin/dmd/dscanner-unittest
 
-lint: dmdbuild
-	./bin/dscanner --config .dscanner.ini --styleCheck src
+lint: ${DMD_BIN}
+	./${DMD_BIN} --config .dscanner.ini --styleCheck src
 
 clean:
 	rm -rf dsc