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Re: Obeying users CFLAGS
From: |
Tim Post |
Subject: |
Re: Obeying users CFLAGS |
Date: |
Thu, 12 Jun 2008 15:15:13 +0800 |
On Thu, 2008-06-12 at 09:02 +0200, Ralf Wildenhues wrote:
> Hello Tim,
>
> * Tim Post wrote on Thu, Jun 12, 2008 at 06:53:29AM CEST:
> >
> > I have noticed that if the CFLAGS environment is not set, @CFLAGS@ is
> > expanded to -g -O2 Is this expected behavior?
>
> Yes, that is documented in
> <http://www.gnu.org/software/autoconf/manual/html_node/C-Compiler.html>.
> The first macro invoked, of AC_PROG_{CC,CXX,F77,FC} does this.
Ahh, Thanks. The documentation is rather extensive, I missed that.
Note, I'm not in any way complaining about extensive documentation! :)
> Well, if you as a user set './configure CFLAGS=...' then that is not
> overridden: the user is assumed to be always right. If you as a
> developer want to modify CFLAGS in configure.ac, then I suggest you do
> so only if the user hasn't set it. You can find this out with
> test "${CFLAGS+set}" = set
Yes, that's my goal. The user is always right. They know their computer,
obey their preferences. But, since I know my program better than they
do, I wanted to be as descriptive as possible when issuing configure
errors.
> before AC_PROG_CC, and modifying CFLAGS in that case, preferably after
> the AC_PROG_CC invocation so that you get the -g/-O2 testing done by
> this macro. To find out whether your flags work you could just try to
> compile or link a simple test program (see AC_COMPILE_IFELSE).
That clears it up, thanks Ralf!
Regards,
--Tim