[Bug c++/94632] New: [10 Regression] canonical types differ for identical types since r10-7622-g12f55e030ed068d5

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94632

            Bug ID: 94632
           Summary: [10 Regression] canonical types differ for identical
                    types since r10-7622-g12f55e030ed068d5
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: marxin at gcc dot gnu.org
                CC: ppalka at gcc dot gnu.org
  Target Milestone: ---

It affects the build of libqt5-qtwebengine package:

$ cat wtf.ii
template <typename> struct a;
template <bool> struct b;
template <typename> class c {
  template <typename f> void d(f e, typename b<a<decltype(e)>::h>::g);
public:
  static bool h;
};
bool h = c<int>::h;

$ g++ wtf.ii -c
wtf.ii: In instantiation of ‘class c<int>’:
wtf.ii:8:16:   required from here
wtf.ii:4:30: internal compiler error: canonical types differ for identical
types ‘b<a<decltype (e)>::h>’ and ‘b<a<decltype (e)>::h>’
    4 |   template <typename f> void d(f e, typename b<a<decltype(e)>::h>::g);
      |                              ^
0xb29f7d comptypes(tree_node*, tree_node*, int)
        /home/marxin/Programming/gcc/gcc/cp/typeck.c:1519
0xb299d4 structural_comptypes
        /home/marxin/Programming/gcc/gcc/cp/typeck.c:1410
0xace7ba maybe_rebuild_function_decl_type
        /home/marxin/Programming/gcc/gcc/cp/pt.c:13541
0xace7ba tsubst_function_decl
        /home/marxin/Programming/gcc/gcc/cp/pt.c:13778
0xad0c90 tsubst_template_decl
        /home/marxin/Programming/gcc/gcc/cp/pt.c:14018
0xab94ee tsubst_decl
        /home/marxin/Programming/gcc/gcc/cp/pt.c:14140
0xac2ef7 tsubst(tree_node*, tree_node*, int, tree_node*)
        /home/marxin/Programming/gcc/gcc/cp/pt.c:15026
0xade994 instantiate_class_template_1
        /home/marxin/Programming/gcc/gcc/cp/pt.c:11728
0xade994 instantiate_class_template(tree_node*)
        /home/marxin/Programming/gcc/gcc/cp/pt.c:12036
0xb2579d complete_type(tree_node*)
        /home/marxin/Programming/gcc/gcc/cp/typeck.c:137
0xa76193 cp_parser_nested_name_specifier_opt
        /home/marxin/Programming/gcc/gcc/cp/parser.c:6639
0xa7302e cp_parser_simple_type_specifier
        /home/marxin/Programming/gcc/gcc/cp/parser.c:18126
0xa744e7 cp_parser_postfix_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:7173
0xa7d28f cp_parser_unary_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:8560
0xa5421f cp_parser_cast_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:9451
0xa54a59 cp_parser_binary_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:9554
0xa564de cp_parser_assignment_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:9859
0xa5548d cp_parser_constant_expression
        /home/marxin/Programming/gcc/gcc/cp/parser.c:10153
0xa55a51 cp_parser_initializer_clause
        /home/marxin/Programming/gcc/gcc/cp/parser.c:23216
0xa59cc7 cp_parser_initializer
        /home/marxin/Programming/gcc/gcc/cp/parser.c:23154
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