[libc++] Guard much of std::ranges under _LIBCPP_HAS_NO_INCOMPLETE_RANGES.

The logic here is that we are disabling *only* things in `std::ranges::`.
Everything in `std::` is permitted, including `default_sentinel`, `contiguous_iterator`,
`common_iterator`, `projected`, `swappable`, and so on. Then, we include
anything from `std::ranges::` that is required in order to make those things
work: `ranges::swap`, `ranges::swap_ranges`, `input_range`, `ranges::begin`,
`ranges::iter_move`, and so on. But then that's all. Everything else (including
notably all of the "views" and the `std::views` namespace itself) is still
locked up behind `_LIBCPP_HAS_NO_INCOMPLETE_RANGES`.

Differential Revision: https://reviews.llvm.org/D118736

Author: Quuxplusone

libcxx/include/__algorithm/in_in_out_result.h

@@ -20,7 +20,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 namespace ranges {
 
@@ -47,7 +47,7 @@ struct in_in_out_result {
 
 } // namespace ranges
 
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__algorithm/in_out_result.h

@@ -20,7 +20,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 namespace ranges {
 
@@ -47,7 +47,7 @@ struct in_out_result {
 
 } // namespace ranges
 
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__algorithm/ranges_min_element.h

@@ -24,7 +24,7 @@
 #  pragma GCC system_header
 #endif
 
-#ifndef _LIBCPP_HAS_NO_CONCEPTS
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
@@ -67,6 +67,6 @@ inline namespace __cpo {
 
 _LIBCPP_END_NAMESPACE_STD
 
-#endif // _LIBCPP_HAS_NO_RANGES
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 #endif // _LIBCPP___ALGORITHM_RANGES_MIN_ELEMENT_H

libcxx/include/__filesystem/directory_iterator.h

@@ -147,7 +147,7 @@ template <>
 _LIBCPP_AVAILABILITY_FILESYSTEM
 inline constexpr bool _VSTD::ranges::enable_view<_VSTD_FS::directory_iterator> = true;
 
-#endif
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
 
 #endif // _LIBCPP_CXX03_LANG
 

libcxx/include/__filesystem/recursive_directory_iterator.h

@@ -178,7 +178,7 @@ template <>
 _LIBCPP_AVAILABILITY_FILESYSTEM
 inline constexpr bool _VSTD::ranges::enable_view<_VSTD_FS::recursive_directory_iterator> = true;
 
-#endif
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
 
 #endif // _LIBCPP_CXX03_LANG
 

libcxx/include/__functional/ranges_operations.h

@@ -20,7 +20,8 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
+
 namespace ranges {
 
 struct equal_to {
@@ -90,7 +91,7 @@ struct greater_equal {
 };
 
 } // namespace ranges
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__iterator/advance.h

@@ -65,7 +65,7 @@ void advance(_InputIter& __i, _Distance __orig_n) {
   _VSTD::__advance(__i, __n, typename iterator_traits<_InputIter>::iterator_category());
 }
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 // [range.iter.op.advance]
 
@@ -193,7 +193,7 @@ inline namespace __cpo {
 } // namespace __cpo
 } // namespace ranges
 
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__iterator/distance.h

@@ -52,7 +52,7 @@ distance(_InputIter __first, _InputIter __last)
     return _VSTD::__distance(__first, __last, typename iterator_traits<_InputIter>::iterator_category());
 }
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 // [range.iter.op.distance]
 
@@ -100,7 +100,7 @@ inline namespace __cpo {
 } // namespace __cpo
 } // namespace ranges
 
-#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 
 _LIBCPP_END_NAMESPACE_STD
 

libcxx/include/__iterator/insert_iterator.h

@@ -24,7 +24,7 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-#if !defined(_LIBCPP_HAS_NO_CONCEPTS)
+#if !defined(_LIBCPP_HAS_NO_CONCEPTS) && !defined(_LIBCPP_HAS_NO_INCOMPLETE_RANGES)
 template <class _Container>
 using __insert_iterator_iter_t = ranges::iterator_t<_Container>;
 #else

libcxx/include/__iterator/iter_move.h

@@ -86,7 +86,7 @@ template<__dereferenceable _Tp>
   requires requires(_Tp& __t) { { ranges::iter_move(__t) } -> __can_reference; }
 using iter_rvalue_reference_t = decltype(ranges::iter_move(declval<_Tp&>()));
 
-#endif // !_LIBCPP_HAS_NO_CONCEPTS
+#endif // !defined(_LIBCPP_HAS_NO_CONCEPTS)
 
 _LIBCPP_END_NAMESPACE_STD