[Bug c++/97934] New: Defaulting <=> breaks other equality operators

[barry.revzin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97934

            Bug ID: 97934
           Summary: Defaulting <=> breaks other equality operators
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: barry.revzin at gmail dot com
  Target Milestone: ---

Reduced example:

#include <compare>

struct X
{
    auto operator<=>(X const&) const = default;
    auto operator==(int i) const;
};

bool f(X x) {
    return x == x;
}

gcc trunk rejects this saying no matching candidate. The presence of the
unrelated operator== seems to prevent the generation of X::operator==(X const&)
const from the defaulted <=>.