Re: [Xen-devel] [PATCH v6 10/13] autoconf: xen: move standard path variables to config/Paths.mk.in

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-07-08 at 20:53 +0200, Luis R. Rodriguez wrote:
> On Tue, Jul 08, 2014 at 08:41:09PM +0200, Luis R. Rodriguez wrote:
> > On Fri, Jul 04, 2014 at 03:33:55PM +0100, Ian Campbell wrote:
> > > On Thu, 2014-07-03 at 20:30 +0200, Luis R. Rodriguez wrote:
> > > > On Thu, Jul 03, 2014 at 10:15:13AM +0100, Ian Campbell wrote:
> > > > > On Wed, 2014-07-02 at 21:32 +0200, Luis R. Rodriguez wrote:
> > > > > > On Wed, Jul 02, 2014 at 02:34:14PM +0100, Ian Campbell wrote:
> > > > > > > On Thu, 2014-06-12 at 18:18 -0700, Luis R. Rodriguez wrote:
> > > > > > > > diff --git a/m4/paths.m4 b/m4/paths.m4
> > > > > > > > new file mode 100644
> > > > > > > > index 0000000..717fcd1
> > > > > > > > --- /dev/null
> > > > > > > > +++ b/m4/paths.m4
> > > > > > > > @@ -0,0 +1,61 @@
> > > > > > > > +AC_DEFUN([AX_XEN_EXPAND_CONFIG], [
> > > > > > > > +dnl expand these early so we can use this for substitutions
> > > > > > > > +test "x$prefix" = "xNONE" && prefix=$ac_default_prefix
> > > > > > > > +test "x$exec_prefix" = "xNONE" && 
> > > > > > > > exec_prefix=$ac_default_prefix
> > > > > > > 
> > > > > > > This is a bit of shame. I suppose this needs to happen in the 
> > > > > > > middle of
> > > > > > > AC_OUTPUT which isn't possible?
> > > > > > > 
> > > > > > > autoconf itself seems to quote the prefix so it is not expanded 
> > > > > > > until
> > > > > > > later, i.e. when config.status is run. Would that work here?
> > > > > > 
> > > > > > Its unclear what exactly the recommendation is here.
> > > > > > 
> > > > > > > Or perhaps we should just PREFIX=$prefix AC_SUBST(PREFIX) and put 
> > > > > > > all
> > > > > > > the BINDIR=$PREFIX/bin into Paths.mk.in after PREFIX=@PREFIX@?
> > > > > > 
> > > > > > Why though?
> > > > > 
> > > > > To avoid cutting and pasting the snippet of autoconf internal code:
> > > > >         test "x$prefix" = "xNONE" && prefix=$ac_default_prefix
> > > > > into our m4 code.
> > > > 
> > > > Ah but that would mean not being able to use --prefix then no?
> > > 
> > > I hope not.
> > > 
> > > autoconf generates this snippet in configure itself, by deferring the
> > > evaluation of things I'm hoping that the content of Paths.mk.in can be
> > > evaluated after that snippet has run.
> > 
> > You're right, this works. OK Great.
> 
> Spoke to soon, it only works if and only if --prefix is passed otherwise
> it gets assigned a NONE value. Can I revert back to the old solution?

I guess so. Stupid autoconf :-)

Ian.



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