[libcxx-commits] [libcxx] [libc++] optimization on ranges::drop_view::begin (#72883) (PR #72929)

[Hewill Kang via libcxx-commits]

================
@@ -90,6 +90,10 @@ namespace ranges {
       requires (!(__simple_view<_View> &&
                   random_access_range<const _View> && sized_range<const _View>))
     {
+      if constexpr (random_access_range<_View> && sized_range<_View>) {
+        range_difference_t<_View> __dist = ranges::distance(__base_);
----------------
hewillk wrote:

> maybe
> `range_difference_t<_View> __dist = ranges::size(__base_);`
> is the actual intent of the code?

The standard does not guarantee that the above implicit conversion is well-formed. `ranges::distance` is always preferred over `ranges::size` when deal with iterators.


https://github.com/llvm/llvm-project/pull/72929