The program below fails to link with g++ 4.0 on Solaris 9 (I didn't try Linux). It appears that symbols defined after the explicit instantiation directive aren't emitted even when referenced. This works fine with prior versions of gcc.
$ cat u.cpp && g++ u.cpp template <class T> struct S { T foo (); T bar (); }; template <class T> T S<T>::foo () { return bar (); } template struct S<int>; template <class T> T S<T>::bar () { return T (); } int main () { return S<int>().foo (); } Undefined first referenced symbol in file S<int>::bar() /var/tmp//cc4BNMlG.o ld: fatal: Symbol referencing errors. No output written to a.out collect2: ld returned 1 exit status -- Summary: explicit instantiation fails to emit symbols defined later Product: gcc Version: 4.0.0 Status: UNCONFIRMED Severity: critical Priority: P2 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: sebor at roguewave dot com CC: gcc-bugs at gcc dot gnu dot org GCC build triplet: sparc-sun-solaris2.9 GCC host triplet: sparc-sun-solaris2.9 GCC target triplet: sparc-sun-solaris2.9 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22263