On Fri, Nov 9, 2012 at 7:25 PM, Michael Witten <mfwitten@xxxxxxxxx> wrote: > > However, Ian, you're missing the most interesting bit from Angelo's email, > namely that a GCC toolchain doesn't always have a problem with multiple > instantiations: ... > How does that make sense? Is a different linker being used with the > GCC toolchain? If so, which one? GNU ld doesn't support Mach-O, and > even if it did, GNU ld doesn't appear to mind the error on at least > a few other systems. GCC does not come with a linker. There are two different linkers in use on GNU/Linux: GNU ld and gold. Other systems, such as MacOS, have other linkers. Different linkers can have different behaviours. Probably more important here, though, is how GCC marks the instantiated template. If it marks it as weak in the sense used on ELF or as COMDAT in the sense used on Windows, then multiple instantiations will be permitted--the linker will discard later ones. I haven't looked into the details here to see what GCC is actually doing. Since a correct program can only have a single explicit instantiation, it doesn't matter too much. Ian
