[Bug c++/96605] New: ICE on C++20 code

[Bug c++/96605] New: ICE on C++20 code

[dimitri.gorokhovik at free dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96605

            Bug ID: 96605
           Summary: ICE on C++20 code
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dimitri.gorokhovik at free dot fr
  Target Milestone: ---

The following code:

#include <tuple>

template <auto T> concept Expression_Term = true;
template <auto T> concept Array_Term = true;

template <Expression_Term ... > struct dictionary {};
template <Array_Term ... > struct tuple {};

template <auto Dict, auto Lhs, auto Rhs> struct flow_graph {};

template <template <Expression_Term, Array_Term, Array_Term> class node,
          Expression_Term ... exps, Array_Term ... lhs, Array_Term ... rhs>
constexpr auto apply (flow_graph <dictionary <exps...> {},
                      tuple <lhs...> {},
                      tuple <rhs...> {}>)
{
  return std::tuple <node <exps, lhs, rhs>...> {};
};



produces this ICE: [version: g++ (GCC) 11.0.0 20200812 (experimental)]



g++ -o test-1 -std=c++2a -fconcepts-ts test-1.i

test-1.i: In function ‘constexpr auto apply(flow_graph<dictionary<exps ...>{},
tuple<lhs ...>{}, tuple<rhs ...>{}>)’:
test-1.i:11511:42: internal compiler error: in tsubst, at cp/pt.c:15388
11511 |   return std::tuple <node <exps, lhs, rhs>...> {};
      |                                          ^
0x688eab tsubst(tree_node*, tree_node*, int, tree_node*)
        ../../src/gcc/cp/pt.c:15388
0xa101d6 do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int)
        ../../src/gcc/cp/pt.c:29159
0xa39d02 convert_template_argument
        ../../src/gcc/cp/pt.c:8428
0xa3ca43 coerce_template_parms
        ../../src/gcc/cp/pt.c:8932
0xa285a8 lookup_template_class_1
        ../../src/gcc/cp/pt.c:9710
0xa2a0fc lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ../../src/gcc/cp/pt.c:10140
0xa641ab finish_template_type(tree_node*, tree_node*, int)
        ../../src/gcc/cp/semantics.c:3446
0x9ddb51 cp_parser_template_id
        ../../src/gcc/cp/parser.c:16833
0x9ddd43 cp_parser_class_name
        ../../src/gcc/cp/parser.c:23811
0x9d9c65 cp_parser_qualifying_entity
        ../../src/gcc/cp/parser.c:6844
0x9d9c65 cp_parser_nested_name_specifier_opt
        ../../src/gcc/cp/parser.c:6526
0x9e2815 cp_parser_simple_type_specifier
        ../../src/gcc/cp/parser.c:18229
0x9c642d cp_parser_type_specifier
        ../../src/gcc/cp/parser.c:17887
0x9dc143 cp_parser_type_specifier_seq
        ../../src/gcc/cp/parser.c:22493
0x9d4e54 cp_parser_type_id_1
        ../../src/gcc/cp/parser.c:22310
0x9d78e3 cp_parser_template_type_arg
        ../../src/gcc/cp/parser.c:22401
0x9dc2bf cp_parser_template_argument
        ../../src/gcc/cp/parser.c:17283
0x9dc2bf cp_parser_template_argument_list
        ../../src/gcc/cp/parser.c:17194
0x9dc2bf cp_parser_enclosed_template_argument_list
        ../../src/gcc/cp/parser.c:29886
0x9dd620 cp_parser_template_id
        ../../src/gcc/cp/parser.c:16766
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.

[Bug c++/96605] ICE in tsubst, at cp/pt.c:14929 on C++20 code

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96605

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE on C++20 code           |ICE in tsubst, at
                   |                            |cp/pt.c:14929 on C++20 code
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-08-14
             Status|UNCONFIRMED                 |NEW
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, started with the revision that added -fconcepts-ts
r10-3735-gcb57504a55015891.

[Bug c++/96605] ICE in tsubst, at cp/pt.c:14929 on C++20 code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96605

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I think this was fixed in GCC 11.1.0:
I get:
<source>:7:11: error: 'Expression_Term' does not constrain a type
    7 | template <Expression_Term  ... > struct dictionary {};
      |           ^~~~~~~~~~~~~~~

And I think the code is invalid too.
If I change the first two concepts to:
template <typename T> concept Expression_Term = true;
template <typename T> concept Array_Term = true;

We accept the code as expected.