Make file Related

[Anil Kumar Malepati]

How to make .o files to get created in a different directory and how to make use of them (from different directories) in linking?

[Dennis Handly]

You can create your own compile rules:
$(objdir)/foo.o: foo.c
         $(CC) -o $@ -c foo.c $(CFLAGS)

And when you link, you use a macro with a list of all of the objects created as above.

[Peter Nikitka]

Hi,

you can else use the VPATH macro to reference source files not residing in the current dir (see manual).

For linking it's best to build libraries out of your object files (perhaps one lib per directory?) and reference these.

In dir1/Makefile:
...
OBJS=$(SRCS:.c=.o)
$(LIBDIR)/libdir1.a: $(OBJS)
ar c $@ $(OBJS)

In exe/Makefile:
...
USERLIBS=-L$(LIBDIR) -ldir1 -ldir2 ...
...
myexe:
$(CC) -o $@ ... $(USERLIBS) ...


mfG Peter

[Anil Kumar Malepati]

I tried using VPATH. But it doesn't find the source files in a different directory. Following is the make file contents.

LIBDIR=${PWD}/lib
BINDIR=${PWD}/bin
SRCDIR=${PWD}/src

VPATH=${SRCDIR}

all: clean ${LIBDIR}/session.o
#${LIBDIR}/session.o: ${SRCDIR}/session.c ${SRCDIR}/session.h
# ${CC} ${CFLAGS} -o $@ -c ${SRCDIR}/session.c

${LIBDIR}/session.o: session.c session.h
${CC} ${CFLAGS} -o $@ -c session.c

clean:
rm -f ${LIBDIR}/*.o
rm -f ${BINDIR}/*

Make fails with the following error

[Anil Kumar Malepati]

Forgot pasting the error in my reply (above).
(Bundled) cc: error 1913: `session.c' does not exist or cannot be read
*** Error exit code 1

[Dennis Handly]

>I tried using VPATH. But it doesn't find the source files in a different directory.

Why are you using new-fangled VPATH?
Why not the tried and true relative path that points exactly to it?

If you use VPATH, as with any new and hard to use option, you need to read the documentation:
http://www.gnu.org/software/automake/manual/make/General-Search.html#General-Search
http://www.gnu.org/software/automake/manual/make/Commands_002fSearch.html#Commands_002fSearch

The second link indicates you need to use "$^" instead of session.c.
Unfortunately, make(1) while it documents VPATH, it is almost useless since it doesn't mention "$^" nor say that "$<" works for anything except inference rules.

#${LIBDIR}/session.o: ${SRCDIR}/session.c ${SRCDIR}/session.h
# ${CC} ${CFLAGS} -o $@ -c ${SRCDIR}/session.c

I assume this works?

>(Bundled) cc: error 1913: `session.c' does not exist or cannot be read

This indicates that VPATH isn't working.
Also, why are you using cc_bundled(1)?