[PATCH] D103855: [clang] Exclude function pointers on DefaultedComparisonAnalyzer

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

I think we need to take this to the C++ committee. For example, consider a case like:

  struct A {
    using T1 = void(*)();
    using T2 = int;
    operator T1();
    operator T2();
  };
  struct B {
    A a;
    friend auto operator<=>(B, B) = default;
  };

Under the standard rules, the `operator<=>` is deleted due to ambiguity, but with this change we'd unambiguously pick the conversion to `T2`. The old behavior here better matches the current standard wording -- in particular, the special case is in [class.compare.default]/3.2 and only applies when neither operand is of overloadable type -- but perhaps the right approach here would be to fix the language rules so that `operator<=>` is only provided for object pointer types, not for all pointer types, in general.


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  https://reviews.llvm.org/D103855/new/

https://reviews.llvm.org/D103855