Re: Per-source CFLAGS

From: Ruslan Ermilov (ru_at_freebsd.org)
Date: 06/22/03

  • Next message: David Schultz: "Re: Per-source CFLAGS" 
    Date: Sun, 22 Jun 2003 11:37:14 +0300
To: Bruce Evans <bde@zeta.org.au>

    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@sunbay.com		Sunbay Software Ltd,
ru@FreeBSD.org		FreeBSD committer

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