[libc++][ranges] implement 'ranges::elements_of'

Author: xiaoyang-sde

libcxx/include/__ranges/elements_of.h

@@ -33,22 +33,9 @@ template <range _Range, class _Allocator = allocator<byte>>
 struct elements_of {
   _LIBCPP_NO_UNIQUE_ADDRESS _Range range;
   _LIBCPP_NO_UNIQUE_ADDRESS _Allocator allocator = _Allocator();
-
-#  if !defined(__cpp_aggregate_paren_init)
-  // This explicit constructor is required because AppleClang 15 hasn't
-  // implemented P0960R3.
-  template <std::ranges::range _Range2, class _Allocator2 = std::allocator<byte>>
-  _LIBCPP_HIDE_FROM_ABI explicit constexpr elements_of(_Range2&& __range, _Allocator2&& __alloc = _Allocator())
-      : range(std::forward<_Range2>(__range)), allocator(std::forward<_Allocator2>(__alloc)) {}
-#  endif
 };
 
 template <class _Range, class _Allocator = allocator<byte>>
-#  if defined(_LIBCPP_COMPILER_CLANG_BASED) && defined(_LIBCPP_APPLE_CLANG_VER) && _LIBCPP_APPLE_CLANG_VER < 1600
-// This explicit constraint is required because AppleClang 15 might not deduce
-// the correct type for `_Range` without it.
-  requires range<_Range&&>
-#  endif
 elements_of(_Range&&, _Allocator = _Allocator()) -> elements_of<_Range&&, _Allocator>;
 
 } // namespace ranges

libcxx/test/std/ranges/range.utility/range.elementsof/ctad.compile.pass.cpp

@@ -41,15 +41,11 @@ constexpr bool test() {
           static_assert(std::same_as<decltype(std::ranges::elements_of(Range<Iterator>(), Allocator())),
                                      std::ranges::elements_of<Range<Iterator>&&, Allocator>>);
 
-// AppleClang 15 hasn't implemented P0960R3 and P1816R0
-#if defined(__cpp_aggregate_paren_init) && __cpp_aggregate_paren_init >= 201902L && defined(__cpp_deduction_guides) && \
-    __cpp_deduction_guides >= 201907L
           static_assert(std::same_as<decltype(std::ranges::elements_of{.range = r, .allocator = a}),
                                      std::ranges::elements_of<Range<Iterator>&, Allocator>>);
           static_assert(
               std::same_as<decltype(std::ranges::elements_of{.range = Range<Iterator>(), .allocator = Allocator()}),
                            std::ranges::elements_of<Range<Iterator>&&, Allocator>>);
-#endif
         });
       });
 

libcxx/test/std/ranges/range.utility/range.elementsof/elements_of.pass.cpp

@@ -48,10 +48,7 @@ constexpr bool test_range() {
     [[maybe_unused]] std::same_as<Allocator> decltype(auto) elements_of_allocator = elements_of.allocator;
   }
   {
-// designated initializer
-// AppleClang 15 hasn't implemented P0960R3 and P1816R0
-#if defined(__cpp_aggregate_paren_init) && __cpp_aggregate_paren_init >= 201902L && defined(__cpp_deduction_guides) && \
-    __cpp_deduction_guides >= 201907L
+    // designated initializer
     std::same_as<elements_of_t> decltype(auto) elements_of = std::ranges::elements_of{
         .range     = r,
         .allocator = Allocator(),
@@ -61,7 +58,6 @@ constexpr bool test_range() {
       assert(std::ranges::distance(elements_of_range) == 4);
     }
     [[maybe_unused]] std::same_as<Allocator> decltype(auto) elements_of_allocator = elements_of.allocator;
-#endif
   }
   {
     // copy constructor