With gcc 4.1 on Alpha Linux, I get:

gcc -o Xorg [...]
os/libos.a(transport.o)(.text+0x3c3c): In function
`_XSERVTransSocketINETCreateListener':
: undefined reference to `local_in6addr_any'
../../lib/font/libXfont.a(transport.o)(.text+0x634c): In function
`_FontTransSocketINETCreateListener':
: undefined reference to `local_in6addr_any'
collect2: ld returned 1 exit status
make[3]: *** [Xorg] Error 1

Apparently, gcc thinks it can optimize out the "unused" static variable.

This patch fixes it. Most likely it is not the real solution, I don't
fully understand this symbol trickery.

--- lib/xtrans/Xtranssock.c~    2005-06-28 15:28:26.000000000 +0200
+++ lib/xtrans/Xtranssock.c     2005-06-28 20:59:33.000000000 +0200
@@ -282,7 +282,7 @@
  * that don't have IPv6 support.
  */
 #if defined(IPv6) && defined(AF_INET6)
-static const struct in6_addr local_in6addr_any = IN6ADDR_ANY_INIT;
+static const struct in6_addr local_in6addr_any __attribute__((used)) =
IN6ADDR_ANY_INIT;
 #pragma weak in6addr_any = local_in6addr_any
 #ifndef __USLC__
 #pragma weak getaddrinfo