how to build pkgsrc with clang

[Thomas Klausner <wiz%NetBSD.org@localhost>]

On Fri, Jun 01, 2012 at 07:16:04AM +0200, Thomas Klausner wrote:
> On Fri, Jun 01, 2012 at 12:31:46AM +0200, Thomas Klausner wrote:
> > On Sun, Apr 15, 2012 at 05:48:49PM +0200, Thomas Klausner wrote:
> > > On Wed, Apr 11, 2012 at 04:57:35PM +0200, Joerg Sonnenberger wrote:
> > > > On Wed, Apr 11, 2012 at 04:40:52PM +0200, Thomas Klausner wrote:
> > > > > On Wed, Apr 11, 2012 at 04:35:20PM +0200, Joerg Sonnenberger wrote:
> > > > > > As I said, check the wrapper.log.
> > > > > 
> > > > > I don't remember you saying that, but here goes work/.work.log:
> > > > > [*] /scratch/devel/libf2c/work/.wrapper/bin/libtool 
> > > > > /scratch/devel/libf2c/work/.wrapper/bin/libtool --mode=compile gcc 
> > > > > -O2 -std=gnu99 -Werror -I/usr/include -I. -DSkip_f2c_Undefs 
> > > > > -DNO_My_ctype -c -o f77_aloc.lo f77_aloc.c
> > > > > ...
> > > > > <.> /usr/pkg/bin/libtool --mode=compile gcc -O2 -std=gnu99 -I. 
> > > > > -DSkip_f2c_Undefs -DNO_My_ctype -c -o f77_aloc.lo f77_aloc.c 
> > > > > 
> > > > > If that's not what you're looking for, whole work/.[A-z]* is attached.
> > > > >  Thomas
> > > > 
> > > > Hm. That's definitely not what I am seeing. That's sending everything to
> > > > /usr/bin/gcc, which it shouldn't.
> > > 
> > > I agree. How can we find out what's different on my system compared to 
> > > yours?
> > 
> > I've updated my system to 6.99.7/amd64 and switched X to "modular"
> > (the bulk build was using native X before) and libf2c now built fine.
> > I don't know which of the changes "fixed" it; I hope the issue doesn't
> > reappear.
> 
> I retract that statement, it was just user confusion -- f2c built,
> libf2c still doesn't.

With more help from joerg, we tracked it down.
I had HAVE_LLVM=yes and PKGSRC_COMPILER=clang set; this works for most packages.
However, libf2c needs
         PKGSRC_COMPILER=clang
         CLANGBASE=/usr
instead (and a rebuild of libtool).

I wanted to document this, but didn't find a good place yet. Suggestions 
welcome.
 Thomas