https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99283
--- Comment #3 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> --- Following sequence: ----- g++ -std=c++20 -fmodules-ts -x c++-system-header ostream g++ -std=c++20 -fmodules-ts -x c++-system-header any g++ -std=c++20 -fmodules-ts -x c++-system-header execution g++ -std=c++20 -fmodules-ts -x c++-system-header limits g++ -std=c++20 -fmodules-ts -x c++-system-header cstdarg g++ -std=c++20 -fmodules-ts -x c++-system-header type_traits g++ -std=c++20 -fmodules-ts -x c++-system-header ctime g++ -std=c++20 -fmodules-ts -x c++-system-header locale ----- Before it produce ICE in assert_definition. Now it produces another error: ----- In file included from /usr/local/include/c++/11.0.1/bits/locale_conv.h:41, from /usr/local/include/c++/11.0.1/locale:43: /usr/local/include/c++/11.0.1/bits/unique_ptr.h:74:60: internal compiler error: tree check: expected tree_vec, have ggc_freed in lookup_template_class_1, at cp/pt.c:9803 74 | typename = _Require<is_convertible<_Up*, _Tp*>>> | ^ 0x875966 tree_check_failed(tree_node const*, char const*, int, char const*, ...) ../../gcc/gcc/tree.c:9814 0x71d27b tree_check(tree_node*, char const*, int, char const*, tree_code) ../../gcc/gcc/tree.h:3353 0x71d27b lookup_template_class_1 ../../gcc/gcc/cp/pt.c:9803 0xb21d1c lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*, int, int) ../../gcc/gcc/cp/pt.c:10237 0xb49afb finish_template_type(tree_node*, tree_node*, int) ../../gcc/gcc/cp/semantics.c:3498 0xabbd21 cp_parser_template_id ../../gcc/gcc/cp/parser.c:17444 0xabbf0b cp_parser_class_name ../../gcc/gcc/cp/parser.c:24671 0xab349a cp_parser_qualifying_entity ../../gcc/gcc/cp/parser.c:6994 0xab349a cp_parser_nested_name_specifier_opt ../../gcc/gcc/cp/parser.c:6676 0xac8bf4 cp_parser_simple_type_specifier ../../gcc/gcc/cp/parser.c:18837 0xaa798d cp_parser_type_specifier ../../gcc/gcc/cp/parser.c:18495 0xab9753 cp_parser_type_specifier_seq ../../gcc/gcc/cp/parser.c:23346 0xab7dd4 cp_parser_type_id_1 ../../gcc/gcc/cp/parser.c:23149 0xaba3b3 cp_parser_template_type_arg ../../gcc/gcc/cp/parser.c:23254 0xaba4df cp_parser_template_argument ../../gcc/gcc/cp/parser.c:17894 0xaba4df cp_parser_template_argument_list ../../gcc/gcc/cp/parser.c:17805 0xaba4df cp_parser_enclosed_template_argument_list ../../gcc/gcc/cp/parser.c:30775 0xabb80c cp_parser_template_id ../../gcc/gcc/cp/parser.c:17377 0xabbf0b cp_parser_class_name ../../gcc/gcc/cp/parser.c:24671 0xab349a cp_parser_qualifying_entity ../../gcc/gcc/cp/parser.c:6994 Please submit a full bug report, with preprocessed source if appropriate. Please include the complete backtrace with any bug report. See <https://gcc.gnu.org/bugs/> for instructions. ------ g++ (GCC) 11.0.1 20210305 (experimental)