[Bug c++/67019] New: [c++-concepts] ICE: canonical types differ for identical types

[Casey at Carter dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67019

            Bug ID: 67019
           Summary: [c++-concepts] ICE: canonical types differ for
                    identical types
           Product: gcc
           Version: c++-concepts
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Casey at Carter dot net
  Target Milestone: ---

Created attachment 36060
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36060&action=edit
Test case

Attached program:

template <bool...> struct bool_sequence {};

template <class T, class...Us>
concept bool Same =
  __is_same_as(bool_sequence<__is_same_as(T, Us)...>,
               bool_sequence<(true || __is_same_as(T, Us))...>);

template <class I>
concept bool A =
  requires (I& i) {
    requires Same<I&, decltype(++i)>;
  };

template <class I>
concept bool B = A<I> && true;

template <A>
constexpr bool f() { return false; }
template <B>
constexpr bool f() { return true; }

int main() {
  static_assert(f<int>());
}

ICEs with:

~/concept-gcc/bin/g++ -std=gnu++1z foo2.cpp -c
foo2.cpp: In function ‘int main()’:
foo2.cpp:23:24: internal compiler error: canonical types differ for identical
types bool_sequence<__is_same_as(I&, decltype(++*i))> and
bool_sequence<__is_same_as(I&, decltype(++*i))>
   static_assert(f<int>());
                        ^
0x72548e comptypes(tree_node*, tree_node*, int)
        ../../gcc/cp/typeck.c:1416
0x798fc9 cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:3075
0x799bf5 cp_tree_equal(tree_node*, tree_node*)
        ../../gcc/cp/tree.c:3122
0x8077d4 match_terms
        ../../gcc/cp/logic.cc:383
0x8077d4 subsumes_atomic_constraint
        ../../gcc/cp/logic.cc:393
0x8077d4 subsumes_constraint
        ../../gcc/cp/logic.cc:444
0x80795e subsumes_conjunction
        ../../gcc/cp/logic.cc:405
0x80795e subsumes_constraint
        ../../gcc/cp/logic.cc:438
0x807b08 subsumes_constraints_nonnull
        ../../gcc/cp/logic.cc:462
0x807b08 subsumes(tree_node*, tree_node*)
        ../../gcc/cp/logic.cc:480
0x6725d1 more_specialized_fn(tree_node*, tree_node*, int)
        ../../gcc/cp/pt.c:19729
0x5dff09 joust
        ../../gcc/cp/call.c:9151
0x5e12b3 joust
        ../../gcc/cp/call.c:8944
0x5e12b3 tourney
        ../../gcc/cp/call.c:9348
0x5e877a perform_overload_resolution
        ../../gcc/cp/call.c:4009
0x5eac8e build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, bool, int)
        ../../gcc/cp/call.c:4082
0x773220 finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        ../../gcc/cp/semantics.c:2391
0x6f2209 cp_parser_postfix_expression
        ../../gcc/cp/parser.c:6410
0x6f6ab9 cp_parser_unary_expression
        ../../gcc/cp/parser.c:7477
0x6f76e7 cp_parser_binary_expression
        ../../gcc/cp/parser.c:8214
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