[Bug c++/99734] [modules] ICE in most_specialized_instantiation

["alexander.lelyakin at googlemail dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99734

--- Comment #1 from Alexander Lelyakin <alexander.lelyakin at googlemail dot com> ---
/usr/local/bin/g++ -std=c++20 -fmodules-ts -x c++-system-header stdexcept
/usr/local/bin/g++ -std=c++20 -fmodules-ts -x c++-system-header filesystem
----
In file included from /usr/local/include/c++/11.0.1/bits/locale_classes.h:857,
                 from /usr/local/include/c++/11.0.1/locale:39,
                 from /usr/local/include/c++/11.0.1/bits/fs_path.h:37,
                 from /usr/local/include/c++/11.0.1/filesystem:45:
/usr/local/include/c++/11.0.1/bits/locale_classes.tcc:275:44: internal compiler
error: in most_specialized_instantiation, at cp/pt.c:24830
  275 |     use_facet<collate<char> >(const locale&);
      |                                            ^
0x725070 most_specialized_instantiation(tree_node*)
        ../../gcc/gcc/cp/pt.c:24830
0xb2e1e9 determine_specialization
        ../../gcc/gcc/cp/pt.c:2457
0xb3418c determine_specialization
        ../../gcc/gcc/cp/pt.c:2156
0xb3418c check_explicit_specialization(tree_node*, tree_node*, int, int,
tree_node*)
        ../../gcc/gcc/cp/pt.c:3121
0x9d481e grokfndecl
        ../../gcc/gcc/cp/decl.c:10064
0x9db1f3 grokdeclarator(cp_declarator const*, cp_decl_specifier_seq*,
decl_context, int, tree_node**)
        ../../gcc/gcc/cp/decl.c:13910
0xac82c1 cp_parser_explicit_instantiation
        ../../gcc/gcc/cp/parser.c:18240
0xad8840 cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:14096
0xad80e9 cp_parser_toplevel_declaration
        ../../gcc/gcc/cp/parser.c:14159
0xad80e9 cp_parser_declaration_seq_opt
        ../../gcc/gcc/cp/parser.c:13947
0xad8582 cp_parser_namespace_body
        ../../gcc/gcc/cp/parser.c:20447
0xad8582 cp_parser_namespace_definition
        ../../gcc/gcc/cp/parser.c:20425
0xad8cd8 cp_parser_declaration
        ../../gcc/gcc/cp/parser.c:14110
0xad952c cp_parser_toplevel_declaration
        ../../gcc/gcc/cp/parser.c:14159
0xad952c cp_parser_translation_unit
        ../../gcc/gcc/cp/parser.c:4942
0xad952c c_parse_file()
        ../../gcc/gcc/cp/parser.c:45250
0xbfd51d c_common_parse_file()
        ../../gcc/gcc/c-family/c-opts.c:1218
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----
g++ (GCC) 11.0.1 20210323 (experimental)
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