Per-source CFLAGS

[Ruslan Ermilov]

On Sun, Jun 22, 2003 at 06:23:20PM +1000, Bruce Evans wrote:
[...]
> > > Some rules are specified by POSIX, so they can't be changed.  I don't
> > > see how ${CFLAGS} can be per-file directly, so the POSIX spec seems to
> > > be actively opposed to per-file CFLAGS.
> >
> > ???  You mean we can't add a variable that will normally expand to
> > nil?  This seems like a compatible change, unless you're worried
> > about someone's makefile breaking because they defined
> > CFLAGS_foo.c to mean something else.
> 
> >From POSIX.1-200x-draft7.txt:
> 
> % 23836                 Default Rules
> % 23837                 The default rules for make shall achieve results that are the same as if the following were used.
> % ...
> % 23864            SINGLE SUFFIX RULES
> % 23865            .c:
> % 23866                    $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
> 
> This leaves little scope for modifying the default rules.
> 
A double suffix rule would be more appropriate here:

23883            DOUBLE SUFFIX RULES
23884            .c.o:
23885                    $(CC) $(CFLAGS) -c $<
23886            .f.o:
23887                    $(FC) $(FFLAGS) -c $<
23888            .y.o:
23889                    $(YACC) $(YFLAGS) $<
23890                    $(CC) $(CFLAGS) -c y.tab.c
23891                    rm -f y.tab.c
23892                    mv y.tab.o $@

Anyway, this only means we should not add the support for
per-source CFLAGS to the %POSIX section of sys.mk.

I still have some concerns with the proposed implementation.
All already existing per-file knobs override the global knob,
and I think that maybe the per-source CFLAGS should behave
the same?  Doing it this way is more flexible; you're free
to augment the global CFLAGS by saying

CFLAGS_foo.c=	${CFLAGS} -DFOO


Cheers,
-- 
Ruslan Ermilov		Sysadmin and DBA,
ru at sunbay.com		Sunbay Software Ltd,
ru at FreeBSD.org		FreeBSD committer
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