https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99283
--- Comment #20 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> --- Just make: git pull make make install That is: just make in previously configured dir. Then: --- g++ -std=c++20 -fmodules-ts -x c++-system-header string g++ -std=c++20 -fmodules-ts -x c++-system-header type_traits g++ -std=c++20 -fmodules-ts -x c++-system-header iostream ---- In file included from /home/sasha/GCC/include/c++/11.0.1/bits/ios_base.h:41, from /home/sasha/GCC/include/c++/11.0.1/ios:42, from /home/sasha/GCC/include/c++/11.0.1/ostream:38, from /home/sasha/GCC/include/c++/11.0.1/iostream:39: /home/sasha/GCC/include/c++/11.0.1/bits/locale_classes.h:163:23: internal compiler error: in assert_definition, at cp/module.cc:4492 163 | locale(const std::string& __s) : locale(__s.c_str()) { } | ^~~~~~ 0x6e31c7 trees_in::assert_definition(tree_node*, bool) ../../gcc/gcc/cp/module.cc:4492 0xa5eed0 trees_in::odr_duplicate(tree_node*, bool) ../../gcc/gcc/cp/module.cc:11323 0xa6e5af trees_in::read_function_def(tree_node*, tree_node*) ../../gcc/gcc/cp/module.cc:11403 0xa70aa1 module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14817 0xa7111d module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18079 0xa711df module_state::lazy_load(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18737 0xa6b460 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9661 0xa7091b module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14714 0xa7111d module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18079 0xa711df module_state::lazy_load(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18737 0xa6b460 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9661 0xa7091b module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14714 0xa7111d module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18079 0xa712d8 lazy_load_binding(unsigned int, tree_node*, tree_node*, binding_slot*) ../../gcc/gcc/cp/module.cc:18770 0xa8301e name_lookup::search_namespace_only(tree_node*) ../../gcc/gcc/cp/name-lookup.c:928 0xa8321a name_lookup::search_namespace(tree_node*) ../../gcc/gcc/cp/name-lookup.c:1014 0xa8321a name_lookup::search_namespace(tree_node*) ../../gcc/gcc/cp/name-lookup.c:1007 0xa8331c name_lookup::search_qualified(tree_node*, bool) ../../gcc/gcc/cp/name-lookup.c:1075 0xa8785f qualified_namespace_lookup ../../gcc/gcc/cp/name-lookup.c:7161 0xa88878 lookup_qualified_name(tree_node*, tree_node*, LOOK_want, bool) ../../gcc/gcc/cp/name-lookup.c:7122 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 20210323 (experimental) Copyright (C) 2021 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. --- Will do full rebuild in clean directory to make test cleaner.