https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99426
--- Comment #1 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> --- in version 20210308 diagnostic changed: In file included from /usr/local/include/c++/11.0.1/iomanip:45: /usr/local/include/c++/11.0.1/bits/quoted_string.h: In destructor ‘constexpr std::allocator< <template-parameter-1-1> >::~allocator() [with _Tp = char32_t]’: /usr/local/include/c++/11.0.1/bits/quoted_string.h:69:29: internal compiler error: tree check: expected template_decl, have function_decl in decl_value, at cp/module.cc:7938 69 | struct _Quoted_string<basic_string_view<_CharT, _Traits>, _CharT> | ^~~~~~~~~~~~~~~~~ 0x875ba8 tree_check_failed(tree_node const*, char const*, int, char const*, ...) ../../gcc/gcc/tree.c:9814 0x6e61c9 tree_check(tree_node*, char const*, int, char const*, tree_code) ../../gcc/gcc/tree.h:3353 0x6e61c9 trees_in::decl_value() ../../gcc/gcc/cp/module.cc:7938 0xa66d17 trees_in::tree_node(bool) ../../gcc/gcc/cp/module.cc:9174 0xa6d36b module_state::read_cluster(unsigned int) ../../gcc/gcc/cp/module.cc:14858 0xa6d86d module_state::load_section(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18125 0xa6d92f module_state::lazy_load(unsigned int, binding_slot*) ../../gcc/gcc/cp/module.cc:18779 0xa70b67 lazy_load_pendings(tree_node*) ../../gcc/gcc/cp/module.cc:18872 0xa79448 maybe_lazily_declare ../../gcc/gcc/cp/name-lookup.c:1922 0xa79448 get_class_binding(tree_node*, tree_node*, bool) ../../gcc/gcc/cp/name-lookup.c:1958 0xb3c3be lookup_field_r ../../gcc/gcc/cp/search.c:1023 0xb3c646 dfs_walk_all(tree_node*, tree_node* (*)(tree_node*, void*), tree_node* (*)(tree_node*, void*), void*) ../../gcc/gcc/cp/search.c:1453 0xb3c646 lookup_member(tree_node*, tree_node*, int, bool, int, access_failure_info*) ../../gcc/gcc/cp/search.c:1166 0xa759c5 get_class_binding ../../gcc/gcc/cp/name-lookup.c:5327 0xa7cebf outer_binding(tree_node*, cxx_binding*, bool) ../../gcc/gcc/cp/name-lookup.c:7641 0xa8182a check_local_shadow ../../gcc/gcc/cp/name-lookup.c:3143 0xa85d8b do_pushdecl ../../gcc/gcc/cp/name-lookup.c:3767 0xa872d2 do_pushdecl ../../gcc/gcc/cp/name-lookup.c:3846 0xa872d2 pushdecl(tree_node*, bool) ../../gcc/gcc/cp/name-lookup.c:3846 0x9c61f1 do_push_parm_decls(tree_node*, tree_node*, tree_node**) ../../gcc/gcc/cp/decl.c:16847 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.