maintainer mode

[Alexandre Oliva]

On Oct 31, 1998, Andrew Tridgell <tridge at samba.anu.edu.au> wrote:

>> several C compilers do not accept `-c' and `-o' together...

> yes, Dave Dykstra fixed this in rsync recently using the following:

> c.o:
> @OBJ_SAVE@
> 	$(CC) -I. -I$(srcdir) $(CFLAGS) -c $< @CC_SHOBJ_FLAG@
> @OBJ_RESTORE@

Starting to get unreadable, huh? :-D

>> And all the burden of avoiding trouble with parallel
>> builds falls upon the Makefile writer.

> why is a single Makefile more of a problem with parallel builds?

assume you have foo/x.c and bar/x.c; try to compile them both at once
without `-c -o'.  Unless @OBJ_SAVE@ and @OBJ_RESTORE@ do some kind of
locking to avoid trouble, it will probably break.

> I think the best way of avoiding problems on those systems is to
> define CC to be a call to a script that handles the -c and -o
> problem. That way "normal" systems work unimpeded.

It's not easy to write a portable script that takes care of this
problem.  We're discussing this very issue in the libtool mailing
list, and, IMO, I'd prefer not to rely on shell-script based locking
to avoid problems in parallel builds...

-- 
Alexandre Oliva
mailto:oliva at dcc.unicamp.br mailto:oliva at gnu.org mailto:aoliva at acm.org
http://www.dcc.unicamp.br/~oliva
Universidade Estadual de Campinas, SP, Brasil