patsubst on makefile - makefile

Question

I have to create different *.o files from a same set of *.c using various CFLAGS. I wanted to use patsubst to generate different *.o files from same *.c. I am doing something wrong the following statement, please help (I want to generate one set of object files having ($<)_O0.o and the other ($<)_O2.o from the same set of c source files):
$(CC) $(CFLAGS_02) -c $< -o $(patsubst %.c,%_O2.o,$<)
Thanks

Answer 1

Use patsubst to make lists of the objects that you want to build, and then use separate rules for each type of build.
Something like this:
SRC_FILES = source1.c source2.c
OBJ_FILES_O0 = $(patsubst %.c,%_O0.o,$(SRC_FILES))
OBJ_FILES_O2 = $(patsubst %.c,%_O2.o,$(SRC_FILES))
CFLAGS_O0 := -O0
CFLAGS_O2 := -O2
all: $(OBJ_FILES_O0) $(OBJ_FILES_O2)
$(OBJ_FILES_O0): %_O0.o: %.c
$(CC) $(CFLAGS_O0) -c $< -o $#
$(OBJ_FILES_O2): %_O2.o: %.c
$(CC) $(CFLAGS_O2) -c $< -o $#

Answer 2

You can also use wild cards to specify all files in the directory.
eg:
#Generic Makefile.
CC := g++
LD := g++
CFLAGS := -c
LDFLAGS := -L<path to lib> -l<libname> \
-L<path to lib> -l>libname> \
......................
ifeq (${TARGETARCH}, debug)
CFLAGS += -g -O0
elif
CFLAGS += -O4 -DNDEBUG
SRCFILES := $(wildcard *.cpp)
OBJFILES := $(patsubst %.cpp, %.o, ${SRCFILES})
all: main
main: ${OBJFILES}
#echo "[Linking]"$#
${LD} ${LDFLAGS} ${OBJFILES}
%.o: %.cpp
#echo "[Compiling]"$#
${CC} ${CFLAGS} $^ -o $#