https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105320
Patrick Palka <ppalka at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Last reconfirmed| |2024-03-06 Ever confirmed|0 |1 Keywords| |rejects-valid CC| |ppalka at gcc dot gnu.org Status|UNCONFIRMED |NEW --- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> --- GCC doesn't ICE, but it rejects with: error: conflicting declaration of template ‘template<class _Tp1, __gnu_cxx::_Lock_policy@test_support _Lp1> class std::__shared_ptr’ note: previous declaration ‘template<class _Tp, __gnu_cxx::_Lock_policy@test_support _Lp> class std::__shared_ptr@test_support’ error: conflicting declaration of template ‘template<class _Tp1, __gnu_cxx::_Lock_policy@test_support _Lp1> class std::__weak_ptr’ note: previous declaration ‘template<class _Tp, __gnu_cxx::_Lock_policy@test_support _Lp> class std::__weak_ptr@test_support’ Reduced: $ cat 105320_a.C module; template<class> struct _Sp_atomic; template<class> struct shared_ptr { template<class> friend struct _Sp_atomic; using atomic_type = _Sp_atomic<int>; }; export module test_support; export template<class T> struct A { shared_ptr<T> data; }; $ cat 105320_b.C import test_support; A<int> a; $ g++ -fmodules-ts 105320_{a,b}.C 105320_a.C:2:1: warning: global module fragment contents must be from preprocessor inclusion [-Wglobal-module] 2 | template<class> struct _Sp_atomic; | ^~~~~~~~ In module test_support, imported at 105320_b.C:1: 105320_a.C: In instantiation of ‘struct shared_ptr@test_support<int>’: 105320_a.C:11:18: required from ‘struct A@test_support<int>’ 11 | shared_ptr<T> data; | ^~~~ 105320_b.C:3:8: required from here 3 | A<int> a; | ^ 105320_a.C:4:33: error: conflicting declaration of template ‘template<class> struct _Sp_atomic’ 4 | template<class> friend struct _Sp_atomic; | ^~~~~~~~~~ 105320_a.C:2:24: note: previous declaration ‘template<class> struct _Sp_atomic@test_support’ 2 | template<class> struct _Sp_atomic; | ^~~~~~~~~~