[vox-tech] makefile question - auto dependencies

[Mike Simons]

On Fri, Mar 21, 2003 at 10:18:21AM -0800, Peter Jay Salzman wrote:
> i was playing around with auto-dependencies with makefiles the other
> day.  here's a hello world example of the technique:
> 

>    OBJS   = $(patsubst %.c, %.o, $(wildcard *.c))
>    SRCS   = $(wildcard *.c)

should use SRCS in OBJS list.

>    DEPDIR = .deps
>    vpath %.d ${DEPDIR}

I don't use vpath in the sample above... can add if you want.

> into a single line saying that all .o files depend on the corresponding
> .d file?

  I used to use a nasty sed expression to make the .d files, but for
some reason decided that they were not needed.

  The .o's do not depend on the .d.

  Both the .d and .o the depend on the .c.

  Here is a current sample of Makefile which I use to build programs
with, stripped down to only work on C code... below no user servicable
parts is the stuff that does auto building.
  Rules are written for C++, ProC, LaTeX, etc.

  If you only want a single target to make life simplier you can replace 
go,s2,s3 with:
===
${TARGET}: ${OFILES}
	gcc ${CFLAGS} -o $@ $^ ${LFLAGS}
===

  If you care to use a special LD variable to id the linker
stuff ...

====
TARGET := go

CC := gcc
CFLAGS := -g -Wall -W -O9
CFLAGS := -g -Wall -W
LFLAGS := -lm

all: ${TARGET}

go: main.o
	gcc ${CFLAGS} -o $@ $^ ${LFLAGS}
s2: s2.o
	gcc ${CFLAGS} -o $@ $^ ${LFLAGS}
s3: s3.o
	gcc ${CFLAGS} -o $@ $^ ${LFLAGS}

################
# no user servicable parts below here... so don't change below here
################
%.o: %.c
	gcc ${CFLAGS} -c $^

.%.d: %.c
	@gcc -MM ${CFLAGS} -o $@ $^

clean:
	rm -rf *.o

nuke: clean
	rm -rf ${DFILES} $(TARGET)

CFILES := ${wildcard *.c}
OFILES := ${patsubst %.c,%.o,${CFILES}}
DFILES := ${patsubst %.c,.%.d,${CFILES}}

ifneq ($(MAKECMDGOALS),nuke)
-include ${DFILES}
endif