[libcxx-commits] [PATCH] D97176: [libcxx] adds concepts std::equality_comparable[_with]

[Arthur O'Dwyer via Phabricator via libcxx-commits]

Quuxplusone accepted this revision.
Quuxplusone added a comment.

Just some nits on tests. The concept definition looks like a straightforward transliteration of
http://eel.is/c++draft/concept.booleantestable
http://eel.is/c++draft/concept.equalitycomparable
so LGTM.



================
Comment at: libcxx/test/std/concepts/comparison/types.h:15
+struct boolean {
+  operator bool() const noexcept;
+};
----------------
Would anything change if this operator were `explicit`? In production code I would expect their `operator bool` to be `explicit`, because all constructors and conversions should always be `explicit` (and for bool conversions in particular, the `explicit` doesn't normally get in the way, because contextual conversion to bool).


================
Comment at: libcxx/test/std/concepts/comparison/types.h:50
+  friend bool operator!=(equality_comparable_with_ec1 const&,
+                         explicit_operators const&) noexcept;
+};
----------------
Utter nit: I don't think most production code would bother to mark `operator==` as `noexcept`, so unless some test is relying on this, it might be better to remove the `noexcept` (for realism and to save characters). Or put it on some and not others (but with a comment explaining that that's on purpose).
```
    friend int operator==(explicit_operators, eq_neq_different_return_types);
```
is already missing the `noexcept`, but without the comment explaining that it was on purpose. ;)


================
Comment at: libcxx/test/std/concepts/comparison/types.h:85
+
+struct no_neq {
+  friend bool operator==(no_neq, no_neq) noexcept;
----------------
I'd say `deleted_ne`. This case is (intentionally) non-parallel to the `no_eq` case above.


================
Comment at: libcxx/test/std/concepts/comparison/types.h:163
+  bool operator==(one_way_ne const&) const = default;
+  friend bool operator==(one_way_ne, explicit_operators);
+  friend bool operator!=(one_way_ne, explicit_operators) = delete;
----------------
Should this `==` say `!=`? At a glance, I have //no// idea what the overload set ends up looking like here. Which if that's the point, it needs a comment. ;)


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