[libcxx-commits] [PATCH] D101242: [libcxx][nfc] renames test iterator types to `legacy_*_iterator`

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

Quuxplusone requested changes to this revision.
Quuxplusone added inline comments.


================
Comment at: libcxx/test/support/test_iterators.h:64
 public:
     typedef          std::input_iterator_tag                   iterator_category;
     typedef typename Traits::value_type                        value_type;
----------------
@cjdb wrote:
> tl;dr yes. At minimum, the iterator tags are now mandatory.

The existing iterators already have tags, though. So that's not a concern for us.

I suggested to Louis in chat but will put here for the record: If the main concern of this patch is to make sure we have a test iterator which is a "non-comparable input iterator" (comparable only to its sentinel type, but not to itself), then I suggest you leave everything the way it is in main but then add the new C++20-only, sentinel-comparison-only test iterator, like this:
```
#if TEST_STD_VER >= 20
template<class It>
class incomparable_input_iterator {
    // This is an input iterator according to C++>=20, but not according to C++<=17.
    // It is comparable with its sentinel type, but not with its own type.
    [...mostly the same stuff as the regular input iterator test type...]
public:
    struct sentinel {
        constexpr explicit sentinel(It it) : it_(it) {}
    };
    friend constexpr bool operator==(const incomparable_input_iterator& x, const sentinel& y)
        {return x.it_ == y.it_;}
};
#endif
```
This probably belongs right above `contiguous_iterator`, circa line 315, because we intend it to be new in C++20.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D101242/new/

https://reviews.llvm.org/D101242