[Bug c++/100853] New: internal compiler error: in cp_tree_equal, at cp/tree.c:4148

["iii at linux dot ibm.com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100853

            Bug ID: 100853
           Summary: internal compiler error: in cp_tree_equal, at
                    cp/tree.c:4148
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: iii at linux dot ibm.com
  Target Milestone: ---

$ cat cp-tree-equal.cpp 
typedef struct a *b;
template <typename> struct c
{          d({
    b *e;                 __typeof (*({
      __typeof *e f;
      f}                )).g const f (({              __typeof (*({
        int h;
        f}             )).g const f (

$ gcc/cc1plus -fno-PIE -g -O2 -fno-checking -gtoggle -DIN_GCC    
-fno-exceptions -fno-rtti -fasynchronous-unwind-tables cp-tree-equal.cpp
...
cp-tree-equal.cpp:8:37: internal compiler error: in cp_tree_equal, at
cp/tree.c:4148
    8 |         f}             )).g const f (
      |                                     ^
0x7062e9 cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:4148
0xbd1d3e cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:4138
0xbd1d3e cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:4138
0xbd1d3e cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:4138
0xbd1d3e cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:4138
0xbdc784 structural_comptypes
        ../../gcc/cp/typeck.c:1491
0xae2ffc check_local_shadow
        ../../gcc/cp/name-lookup.c:3264
0xae2ffc do_pushdecl
        ../../gcc/cp/name-lookup.c:3773
0xae39b4 pushdecl(tree_node*, bool)
        ../../gcc/cp/name-lookup.c:3852
0xa3995e start_decl(cp_declarator const*, cp_decl_specifier_seq*, int,
tree_node*, tree_node*, tree_node**)
        ../../gcc/cp/decl.c:5591
0xb2dd61 cp_parser_init_declarator
        ../../gcc/cp/parser.c:21802
0xb093cd cp_parser_simple_declaration
        ../../gcc/cp/parser.c:14487
0xb0b0a9 cp_parser_declaration_statement
        ../../gcc/cp/parser.c:13622
0xb0bc0b cp_parser_statement
        ../../gcc/cp/parser.c:11848
0xb0ce0e cp_parser_statement_seq_opt
        ../../gcc/cp/parser.c:12215
0xb0cee8 cp_parser_compound_statement
        ../../gcc/cp/parser.c:12164
0xb10473 cp_parser_statement_expr
        ../../gcc/cp/parser.c:5142
0xb10473 cp_parser_primary_expression
        ../../gcc/cp/parser.c:5549
0xb11b80 cp_parser_postfix_expression
        ../../gcc/cp/parser.c:7528
0xb243af cp_parser_unary_expression
        ../../gcc/cp/parser.c:8849

Found when reducing a testcase for another problem.