[Bug c++/118180] New: internal compiler error: tree check: expected tree_vec, have identifier_node in tsubst_decl, at cp/pt.cc:15617

[rush102333 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118180

            Bug ID: 118180
           Summary: internal compiler error: tree check: expected
                    tree_vec, have identifier_node in tsubst_decl, at
                    cp/pt.cc:15617
           Product: gcc
           Version: 13.2.0
            Status: UNCONFIRMED
          Keywords: ice-on-invalid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: rush102333 at gmail dot com
  Target Milestone: ---

Simplified test:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
struct c {
  template <typename=int>
  struct b{};
  int b1;
};

template<class... Ts>
struct d{
  using typename Ts::b::type...;
};

template struct d<c>;

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Compiler Output:

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
<source>: In instantiation of 'struct d<c>':
<source>:12:17:   required from here
   12 | template struct d<c>;
      |                 ^~~~
<source>:9:29: error: 'typename c::b' names 'template<class> struct c::b',
which is not a type
    9 |   using typename Ts::b::type...;
      |                             ^~~
<source>:9:29: internal compiler error: tree check: expected tree_vec, have
identifier_node in tsubst_decl, at cp/pt.cc:15617
0x2938075 diagnostic_context::diagnostic_impl(rich_location*,
diagnostic_metadata const*, diagnostic_option_id, char const*, __va_list_tag
(*) [1], diagnostic_t)
        ???:0
0x294ee76 internal_error(char const*, ...)
        ???:0
0x9d5db0 tree_check_failed(tree_node const*, char const*, int, char const*,
...)
        ???:0
0xd479e1 instantiate_class_template(tree_node*)
        ???:0
0xd3c2e5 do_type_instantiation(tree_node*, tree_node*, int)
        ???:0
0xce5603 c_parse_file()
        ???:0
0xe450d9 c_common_parse_file()
        ???:0
Please submit a full bug report, with preprocessed source.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Please note that this currently seems to only happen on the trunk.

https://godbolt.org/z/MThef5Wfe