[libcxx-commits] [PATCH] D128744: [libc++][ranges] Implement `ranges::partial_sort`.

[Konstantin Varlamov via Phabricator via libcxx-commits]

var-const marked 3 inline comments as done.
var-const added inline comments.


================
Comment at: libcxx/include/__algorithm/make_heap.h:30
 {
     typedef typename iterator_traits<_RandomAccessIterator>::difference_type difference_type;
     difference_type __n = __last - __first;
----------------
huixie90 wrote:
> huixie90 wrote:
> > For C++20 algorithms, we should use `iter_difference_t `.
> > 
> > the `difference_type` is coming from `incrementable_traits` when `iterator_traits` is not specialized
> > 
> > (Note this applies to all other usages of `difference_type`)
> Actually, it is fine for this algorithm to use iterator_traits
> 
> since the input are required to model c++20 random_access_iterator and C++ 20 random_access_iterator implies c++17 input iterator and that makes sure that iterator_traits exists and consistent with c++20’s iter_differnece_t (and iter_value_t for the value_type)
> 
> I think this can be a problem only in algorithms that take c++20 input iterators, because c++ 20 input_iterators can have empty iterator_traits
Thanks a lot for spotting this. I've added checking algorithms that take input iterators to my backlog.


Repository:
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  https://reviews.llvm.org/D128744/new/

https://reviews.llvm.org/D128744