On Oct 29, 10:13 pm, "Laurent Sansonetti"
<laurent.sansone...@[...].com>  wrote:
> 
>  Maybe this is because Leopard's Ruby builds its extensions universal
>  (for both i386 and ppc architectures), and that
>  "/usr/local/lib/libantlr3c.a" isn't universal.
> 
>  You can verify this using:
> 
>  $ file /usr/local/lib/libantlr3c.a
> 
>  If the library is only compiled for your arch, the solution is to
>  appropriately set the ARCHFLAGS environment variable.
> 
>  The following page has some information regarding ARCHFLAGS:
> 
>  http://trac.macosforge.org/projects/ruby/wiki/WhatsNewInLeopard#Ruby

Many thanks, Laurent; that was it. Running mkmf as follows allows it
to find the function:

    ARCHFLAGS="-arch i386" ruby extconf.rb

Good to know that this workaround works. As a longer term solution
I'll try building a universal binary version of the ANTLR runtime.

Cheers,
Wincent