How to compile different c files with different CFLAGS using Makefile?

Question

all. Let\'s say I have a program that contains a long list of C source files, A.c, B.c, ...., Z.c, now I want to compile A.c, B.c with certain CFLAGS, and compile the rest p

Answer 1

I can't answer the question for raw makefiles, but if you are willing to use automake it is trivial:

foo_CFLAGS = [options passed to CC only when building foo]

Answer 2

The approach taken by linux kernel build system:

CFLAGS += $(CFLAGS-$@)

And then,

CFLAGS-A.o += -DEXTRA
CFLAGS-B.o += -DEXTRA

Answer 3

Try using target-specific variables. A target-specific variable is declared like this:

TARGET: VAR := foo  # Any valid form of assignment may be used ( =, :=, +=, ?=)

Now when the target named TARGET is being made, the variable named VAR will have the value "foo".

Using target-specific variables, you could do this, for example:

OBJ=[all other .o files here, e.g. D.o, D.o, E.o .... Z.o]
SPECIAL_OBJS=A.o B.o

all: $(OBJ) $(SPECIAL_OBJS)

$(SPECIAL_OBJS): EXTRA_FLAGS := -std=c99   # Whatever extra flags you need

%.o: %.c
     @echo [Compiling]: $<
     $(CC) $(CFLAGS) $(EXTRA_FLAGS) -o $@ -c $<