[libcxx-commits] [PATCH] D119198: [libc++] Remove default_searcher from experimental/functional

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

Quuxplusone requested changes to this revision.
Quuxplusone added inline comments.
This revision now requires changes to proceed.


================
Comment at: libcxx/include/experimental/functional:116
 
+#if _LIBCPP_STD_VER > 11
 template<class _Key, class _Value, class _Hash, class _BinaryPredicate, bool /*useArray*/> class _BMSkipTable;
----------------
Orthogonally: What's the deal with `std::experimental::boyer_moore_searcher`? Have we implemented `std::boyer_moore_searcher` https://en.cppreference.com/w/cpp/utility/functional/boyer_moore_searcher yet? (No. We haven't.)

Ordering-wise, it would sure have made a lot more sense for us to have implemented `std::boyer_moore_{,horspool_}searcher` all at once, and then we could yank `std::experimental::*_searcher` all at once. The current state — where you //need// `std::experimental::` for two of the searchers, but (@jloser proposes) you'll //need// `std::` for the other one — seems really unfortunate to me. But the time for us to fix that was 2 releases ago; it's not @jloser's fault that we didn't do it, and so //maybe// it shouldn't stop us from removing deprecated features according to schedule.


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Comment at: libcxx/include/experimental/functional:106
 
-#if _LIBCPP_STD_VER > 11
-// default searcher
-template<class _ForwardIterator, class _BinaryPredicate = equal_to<>>
-class _LIBCPP_TEMPLATE_VIS default_searcher {
-public:
-    _LIBCPP_INLINE_VISIBILITY
-    default_searcher(_ForwardIterator __f, _ForwardIterator __l,
-                       _BinaryPredicate __p = _BinaryPredicate())
-        : __first_(__f), __last_(__l), __pred_(__p) {}
-
-    template <typename _ForwardIterator2>
-    _LIBCPP_INLINE_VISIBILITY
-    pair<_ForwardIterator2, _ForwardIterator2>
-    operator () (_ForwardIterator2 __f, _ForwardIterator2 __l) const
-    {
-        return _VSTD::__search(__f, __l, __first_, __last_, __pred_,
-            typename iterator_traits<_ForwardIterator>::iterator_category(),
-            typename iterator_traits<_ForwardIterator2>::iterator_category());
-    }
-
-private:
-    _ForwardIterator __first_;
-    _ForwardIterator __last_;
-    _BinaryPredicate __pred_;
-    };
-
+#if _LIBCPP_STD_VER > 14
 template<class _ForwardIterator, class _BinaryPredicate = equal_to<>>
----------------
jloser wrote:
> ldionne wrote:
> > Please don't bump the standard version in this patch, since it's technically an unrelated change (IIUC).
> It's required if we want `make_default_searcher` to work at all since `std::default_searcher` is C++17-or-later only (https://github.com/llvm/llvm-project/blob/main/libcxx/include/__functional/default_searcher.h#L25). Otherwise, we can't remove `std::experimental::default_searcher` if we want these to work in C++14-or-later and not C++17-or-later.
> 
> We could remove `make_default_searcher` entirely, but I think that'd be for a separate patch and I don't see the reason to do so right now.
If you're removing `std::experimental::default_searcher`, you should definitely remove `std::experimental::make_default_searcher` at the same time. The two are tied inextricably together — what you've got now is analogous to removing `std::tr1::shared_ptr` but keeping `std::tr1::weak_ptr`!

Think about the user experience here: as a user of `std::experimental::{make_,}default_searcher`, would you rather have the whole thing yanked, or would you rather have `std::experimental::make_default_searcher` yanked //only// in C++14 mode, and in C++17 mode produce a different return type than it used to? Yanking the whole thing will be much saner from the user's POV.


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  https://reviews.llvm.org/D119198/new/

https://reviews.llvm.org/D119198