rsmith added inline comments.
================
Comment at: clang/test/CXX/class/class.compare/class.spaceship/p2.cpp:200
+ struct b3 {
+ auto operator<=>(b3 const &) const = default; // expected-error {{cannot
be deduced because three-way comparison for member 'f' would compare as builtin
type 'void (*)()' which is not currently supported}}
+ // expected-warning@-1 {{implicitly deleted}}
----------------
I think three-way comparison for function pointers is ill-formed, and that the
problem in this case is that [over.built] lists candidates for which a
three-way comparison is invalid. So our overload resolution succeeds, but
results in a meaningless builtin candidate with an undefined return type.
I think the behavior here after this patch is fine -- we should treat the
comparison as deleted -- but the diagnostic is wrong. This isn't a "not
currently supported" case, this is a "not a valid expression" case, per
[class.compare.default]/3.2 (except that the wording currently gets this wrong
and doesn't actually say what happens here, because we're actually in
[class.compare.default]/3.1). Though perhaps the better fix would be to not
even include a builtin candidate for `operator<=>(void (*)(), void (*)())`?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D103850/new/
https://reviews.llvm.org/D103850
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