[Bug c++/96576] New: ICE when decltype std::index_sequence

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96576

            Bug ID: 96576
           Summary: ICE when decltype std::index_sequence
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

#include <utility>

auto operator|(auto S, auto) {
  return S;
}

int main()
{
  decltype(std::index_sequence<0>{} | 0 | 0);
}

gives:

<source>: In function 'int main()':
<source>:9:43: internal compiler error: in build_over_call, at cp/call.c:8994
    9 |   decltype(std::index_sequence<0>{} | 0 | 0);
      |                                           ^
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See <https://gcc.gnu.org/bugs/> for instructions.

(https://godbolt.org/z/8ezT44)