Date: Sun, 22 Jun 2003 12:07:58 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: David Schultz <dschultz@OCF.Berkeley.EDU> Cc: arch@freebsd.org Subject: Re: Per-source CFLAGS Message-ID: <20030622114150.L54976@gamplex.bde.org> In-Reply-To: <20030622005124.GA59673@HAL9000.homeunix.com> References: <20030622005124.GA59673@HAL9000.homeunix.com>
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On Sat, 21 Jun 2003, David Schultz wrote:
> The following patch adds support for per-file CFLAGS, which gets
> appended to the command line after the global CFLAGS. I would
> ...
> I intend to use this feature for gdtoa, which is technically part
> of libc, but also on a vendor branch and intended to stay that
> way. The problem being addressed is that gcc at higher warning
> levels has some inane warnings that the vendor and I consider
> wrong, and yet people want to be able to compile libc cleanly at
> these warning levels. As an example, gcc complains that the
> expression 'a << b - c' must have parentheses because obviously
> nobody remembers C's precedence rules. So here's just one
> potential use of the new feature:
For this, you really want per-file WARNS, since among other reasons
compiler-dependent flags shouldn't be put in individual Makefiles.
> Index: lib/libc/gdtoa/Makefile.inc
> ===================================================================
> RCS file: /cvs/src/lib/libc/gdtoa/Makefile.inc,v
> retrieving revision 1.3
> diff -u -r1.3 Makefile.inc
> --- lib/libc/gdtoa/Makefile.inc 5 Apr 2003 22:10:13 -0000 1.3
> +++ lib/libc/gdtoa/Makefile.inc 2 May 2003 09:31:15 -0000
> @@ -16,6 +16,7 @@
> .for src in ${GDTOASRCS}
> MISRCS+=gdtoa_${src}
> CLEANFILES+=gdtoa_${src}
> +CFLAGS_gdtoa_${src}+=-w
Do you need to turn off all warnings or just ones for non-broken
precedence and a few other non-broken things? gcc doesn't give
enough control over individual warnings, but it has -Wno-parentheses
for turning off not much more than bogus warnings about natural
precedence.
> The patch I would actually like reviewed is this one:
> ...
> Index: share/mk/sys.mk
> ===================================================================
> RCS file: /cvs/src/share/mk/sys.mk,v
> retrieving revision 1.67
> diff -u -r1.67 sys.mk
> --- share/mk/sys.mk 1 Jun 2003 22:13:45 -0000 1.67
> +++ share/mk/sys.mk 21 Jun 2003 08:56:15 -0000
> ...
> @@ -117,7 +117,8 @@
>
> # SINGLE SUFFIX RULES
> .c:
> - ${CC} ${CFLAGS} ${LDFLAGS} -o ${.TARGET} ${.IMPSRC}
> + ${CC} ${CFLAGS} ${CFLAGS_${.IMPSRC}} ${LDFLAGS} \
> + -o ${.TARGET} ${.IMPSRC}
> ...
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.
Bruce
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