You may be running into a bug that was introduced in version 2.6.1
(and is still present in 2.6.3) that generated external linkage
for templates even when neither -fexternal-templates nor
-fno-implicit-templates is specified. There is a patch for
this problem at
`ftp://ftp.cygnus.com/pub/g++/gcc-2.6.3-template-fix'.
I recommend either applying the patch or
using -fno-implicit-templates
together with explicit template instantiation as described in previous
sections.
This bug is fixed in 2.7.0.