Using make to compile for sun3 and sun4

[Kemp at dockmaster.ncsc.mil]

After watching the "make wars" on info-unix between GNU make and AT&T
toolchest make, I am convinced that we Sun users have a pretty good
product that has lots of good features that were added without breaking
compatibility or introducing lots of bugs.

That said, there is one thing I haven't been able to figure out from the
examples in the manual.  I want to do the equivalent of:

    if(sun3) CFLAGS = -f68881
    else     CFLAGS = (nothing)

A conditional macro seems to be the way to do it, but the syntax is

   target-list := macro = value

i.e.  the assignment is conditioned on the target, not on the value of
another macro (TARGET_ARCH).  There is probably a gross solution like
defining identical targets PROGRAM.sun3 and PROGRAM.sun4, but an elegant
solution would be better.

I finally gave up and used a pattern replacement hack.  Here is the
Makefile:

--------------

 SOURCES= prog.c sub.c
 ULIBS= ../lib/$(ARCH)/lib.a
 PROGRAM= prog

 CFLAGS= -O3 $(TARGET_ARCH:-sun3=-f68881)          <<< Gross Hack!!!

 OBJECTS= $(SOURCES:.c=.o)
 ARCH= $(TARGET_ARCH:-%=%)

 all debug profile: $(PROGRAM)

 debug := CFLAGS= -g                             <<< This is where it should
 profile := CFLAGS= -pg -O3                      <<< really be done

 $(PROGRAM):  $(OBJECTS)
         $(LINK.c) -o $@ $(OBJECTS) $(ULIBS)

---------------

This works for a sun3, (when not doing a make debug or profile), but on a
sun4 it gives an ugly but apparently harmless duplicate flag:

  cc -O3 -sun4 -sun4 -c prog.c

It would not work in the general case of more than two alternatives (like
if I gave a hoot about -sun386i) or if the macro must have different
values for each alternative (i.e.  the unmodified value -sun4 is not
acceptable).  Surely this is an extremely common situation; I'm surprised
that Sun's otherwise good make manual has absolutely no examples of
variants depending on TARGET_ARCH.

If you have a concise, sophisticated solution, please mail it to me; I
will summarize for the group.

   Dave Kemp <Kemp at dockmaster.ncsc.mil>