Re: use CPPFLAGS at configure time

[Alexandre Oliva <aoliva at redhat dot com>]

On Apr  4, 2003, Roland McGrath <roland at redhat dot com> wrote:

>> You've dropped CFLAGS from assembly commands.  This is wrong.
>> Assemblers do optimize and generate debugging info, so CFLAGS must not
>> be dropped.

> As I said, I made it consistent with what the build does.

No, you didn't.  The build does use whatever ASFLAGS happens to be
defined by the makefiles, but since ASFLAGS isn't propagated from
configure's environment to the make configuration, you didn't make it
consistent.  FWIW, CPPFLAGS isn't propagated either, even though,
unlike ASFLAGS, it is used in autoconf tests.

>> CFLAGS must be used in every invocation of the C compiler, both those
>> which do compilation and those which do linking.  This is straight
>> from the GNU coding standards.

> That is a reasonable thing to say, but LINK.o does not use CFLAGS.

Then LINK.o should be fixed.

> As I've said, I made configure consistent with what the build actually
> does.

You think you did, but the build system is so convoluted that it makes
it nearly impossible to tell that it will do the right thing.  In
fact, from what you say, I'm pretty sure it will break quite often.

> If there are problems now, there
> were problems before and they were masked or are just different now.

Unfortunately, by introducing ASFLAGS in configure.in, you may have
introduced new problems.  Having ASFLAGS set in the environment will
affect the result of configure tests, even though the build won't use
this ASFLAGS at all.  Ditto for CPPFLAGS.

> You have convinced me that it's reasonable to use CFLAGS in place of
> ASFLAGS.  Feel free to send a patch that does so consistently in the
> makefiles and configure.  When using CFLAGS the ASFLAGS-.os
> variables in now sysdeps Makefiles won't be needed to get -fPIC in
> place.

I'll look into doing it some time.  A nice starting point, however,
would be to revert the patch you checked in.

-- 
Alexandre Oliva   Enjoy Guarana', see http://www.ic.unicamp.br/~oliva/
Red Hat GCC Developer                 aoliva at {redhat dot com, gcc.gnu.org}
CS PhD student at IC-Unicamp        oliva at {lsd dot ic dot unicamp dot br, gnu.org}
Free Software Evangelist                Professional serial bug killer