[11 Regression] #include <utility> template<class...> struct Tuple {}; template<std::size_t... Is> using tuple_t = Tuple<std::make_index_sequence<Is>...>; int main() { []<std::size_t... Is>(std::index_sequence<Is...>) { tuple_t<Is...> t; }(std::make_index_sequence<5>{}); } https://godbolt.org/z/YKWEs5snW
Confirmed.
Started with r11-7931. Reduced rejects-valid testcase: template<int...> struct integer_sequence; template<int _Num> using make_index_sequence = integer_sequence<__integer_pack(_Num)...>; template<class...> struct Tuple; template<int... Is> using tuple_t = Tuple<make_index_sequence<Is>...>; template<int... Is> void f() { tuple_t<Is...> t; }
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>: https://gcc.gnu.org/g:fc50d9a252c89c1bac78192bd0884ff23f2bf48b commit r12-7857-gfc50d9a252c89c1bac78192bd0884ff23f2bf48b Author: Jason Merrill <jason@redhat.com> Date: Fri Mar 25 13:13:35 2022 -0400 c++: hash table ICE with variadic alias [PR105003] For PR104008 we thought it might be enough to keep strip_typedefs from removing this alias template specialization, but this PR demonstrates that other parts of the compiler also need to know to consider it dependent. So, this patch changes complex_alias_template_p to no longer consider template parameters used when their only use appears in a pack expansion, unless they are the parameter packs being expanded. To do that I also needed to change it to use cp_walk_tree instead of for_each_template_parm. It occurs to me that find_template_parameters should probably also use cp_walk_tree, but I'm not messing with that now. PR c++/105003 PR c++/104008 PR c++/102869 gcc/cp/ChangeLog: * pt.cc (complex_alias_template_r): walk_tree callback, replacing uses_all_template_parms_r, complex_pack_expansion_r. (complex_alias_template_p): Adjust. * tree.cc (strip_typedefs): Revert r12-7710 change. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/variadic-alias6.C: New test. * g++.dg/cpp0x/variadic-alias7.C: New test.
The releases/gcc-11 branch has been updated by Jason Merrill <jason@gcc.gnu.org>: https://gcc.gnu.org/g:00e7d6e66638b8d2d93ff6659a140f8b3cf37aeb commit r11-9827-g00e7d6e66638b8d2d93ff6659a140f8b3cf37aeb Author: Jason Merrill <jason@redhat.com> Date: Fri Mar 25 13:13:35 2022 -0400 c++: hash table ICE with variadic alias [PR105003] For PR104008 we thought it might be enough to keep strip_typedefs from removing this alias template specialization, but this PR demonstrates that other parts of the compiler also need to know to consider it dependent. So, this patch changes complex_alias_template_p to no longer consider template parameters used when their only use appears in a pack expansion, unless they are the parameter packs being expanded. To do that I also needed to change it to use cp_walk_tree instead of for_each_template_parm. It occurs to me that find_template_parameters should probably also use cp_walk_tree, but I'm not messing with that now. PR c++/105003 PR c++/104008 PR c++/102869 gcc/cp/ChangeLog: * pt.c (complex_alias_template_r): walk_tree callback, replacing uses_all_template_parms_r, complex_pack_expansion_r. (complex_alias_template_p): Adjust. gcc/testsuite/ChangeLog: * g++.dg/cpp0x/variadic-alias6.C: New test. * g++.dg/cpp0x/variadic-alias7.C: New test.
Fixed for 11.3/12.