https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99861
--- Comment #3 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> --- There is a shorter sequence: /usr/local/bin/g++ -std=c++20 -fmodules-ts -x c++-system-header map /usr/local/bin/g++ -std=c++20 -fmodules-ts -x c++-system-header clocale /usr/local/bin/g++ -std=c++20 -fmodules-ts -x c++-system-header regex ---- hash table checking failed: equal operator returns true for a pair of values with a different hash value In file included from /usr/local/include/c++/11.0.1/bits/unique_ptr.h:42, from /usr/local/include/c++/11.0.1/bits/locale_conv.h:41, from /usr/local/include/c++/11.0.1/locale:43, from /usr/local/include/c++/11.0.1/regex:44: /usr/local/include/c++/11.0.1/ostream: In substitution of ‘template<class _Ostream, class _Tp> typename std::enable_if<std::__and_<std::__not_<std::is_lvalue_reference<_Tp> >, std::__is_convertible_to_basic_ostream<_Ostream>, std::__is_insertable<typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type, const _Tp&, void> >::value, typename std::__is_convertible_to_basic_ostream<_Tp>::__ostream_type>::type std::operator<<(_Ostream&&, const _Tp&) [with _Ostream = int; _Tp = std::regex_constants::__syntax_option]’: /usr/local/include/c++/11.0.1/bits/regex_constants.h:88:42: required from here /usr/local/include/c++/11.0.1/ostream:773:5: internal compiler error: in hashtab_chk_error, at hash-table.c:137 773 | operator<<(_Ostream&& __os, const _Tp& __x) | ^~~~~~~~ 0x92f047 hashtab_chk_error() ../../gcc/gcc/hash-table.c:137 0xb3ddf5 hash_table<spec_hasher, false, xcallocator>::verify(spec_entry* const&, unsigned int) ../../gcc/gcc/hash-table.h:1033 0xb3e37e hash_table<spec_hasher, false, xcallocator>::find_slot_with_hash(spec_entry* const&, unsigned int, insert_option) ../../gcc/gcc/hash-table.h:968 0xafb10b match_mergeable_specialization(bool, spec_entry*) ../../gcc/gcc/cp/pt.c:29961 0xa74528 trees_in::key_mergeable(int, merge_kind, tree_node*, tree_node*, tree_node*, tree_node*, bool) ../../gcc/gcc/cp/module.cc:10670 0xa78124 trees_in::decl_value() ../../gcc/gcc/cp/module.cc:7903 0xa70f87 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9153 0xa70ef9 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9203 0xa7182d trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9346 0xa72987 trees_in::core_vals(tree_node*) ../../gcc/gcc/cp/module.cc:6537 0xa781f9 trees_in::tree_node_vals(tree_node*) ../../gcc/gcc/cp/module.cc:7061 0xa781f9 trees_in::decl_value() ../../gcc/gcc/cp/module.cc:7942 0xa70f87 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9153 0xa775ab module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14811 0xa77aad module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18082 0xa77b6f module_state::lazy_load(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18740 0xa71df0 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9664 0xa772ab module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14717 0xa77aad module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18082 0xa77b6f module_state::lazy_load(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18740 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 20210409 (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.