On Fri, Nov 9, 2012 at 12:34 PM, Angelo Graziosi <graziosi.ang...@gmail.com> wrote: > > $ cat foo01.cc > #include "foo.hh" > > MYCLASS_INSTANTIATE_TYPES > > $ cat foo02.cc > #include "foo.hh" > > MYCLASS_INSTANTIATE_TYPES > > $ cat foo.hh > > #define MYCLASS_INSTANTIATE(g) g(int) > > #define MYCLASS_INSTANTIATE_BASE(type) \ > template class MyClassBase<type>; > > #define MYCLASS_INSTANTIATE_TYPES \ > MYCLASS_INSTANTIATE(MYCLASS_INSTANTIATE_BASE) > > Now what happens is this: > > Building on *** MAC OSX *** with gcc45, gcc46, gcc47 installed by means of > MacPorts, fails as > > $ g++ foomain.o foo01.o foo02.o -o foo.out > duplicate symbol MyClassBase<int>::ClassWrapper::ClassWrapper() in: > foo01.o > foo02.o > duplicate symbol MyClassBase<int>::ClassWrapper::ClassWrapper() in: > foo01.o > foo02.o > ld: 2 duplicate symbols for architecture x86_64 > collect2: error: ld returned 1 exit status > > instead it builds (on MAC OSX) using clang++,
This question is not appropriate for the mailing list gcc@gcc.gnu.org. It would be appropriate for gcc-h...@gcc.gnu.org. Please take any followups to gcc-help. Thanks. Instantiating a template creates all the instantiations in that compilation unit. There is no reason to instantiate a template in more than one compilation unit. The implementation that GCC uses does not permit you to do that. I don't know what LLVM does. Ian
