P2251R1 Update yvals_core.h and the comments in the tests

stl/inc/yvals_core.h

@@ -119,6 +119,8 @@
 //     (the std::invoke function only; other components like bind and reference_wrapper are C++20 only)
 // P1518R2 Stop Overconstraining Allocators In Container Deduction Guides
 // P2162R2 Inheriting From variant
+// P2251R1 Require span And basic_string_view To Be Trivially Copyable
+//     (basic_string_view always provides this behavior)
 
 // _HAS_CXX17 indirectly controls:
 // N4190 Removing auto_ptr, random_shuffle(), And Old <functional> Stuff
@@ -255,6 +257,8 @@
 // P2116R0 Removing tuple-Like Protocol Support From Fixed-Extent span
 // P2210R2 Superior String Splitting
 // P2231R1 Completing constexpr In optional And variant
+// P2251R1 Require span And basic_string_view To Be Trivially Copyable
+//     (span always provides this behavior)
 // P2259R1 Repairing Input Range Adaptors And counted_iterator
 // P2281R1 Clarifying Range Adaptor Objects
 // P2325R3 Views Should Not Be Required To Be Default Constructible

tests/std/tests/P0122R7_span/test.cpp

@@ -79,19 +79,14 @@ static_assert(ranges::enable_borrowed_range<span<int>>);
 static_assert(ranges::enable_borrowed_range<span<int, 3>>);
 #endif // __cpp_lib_concepts
 
-// We provide non-standard guarantees that span and its iterator types are trivially copyable;
-// P2251 may eventually standardize that guarantee for span itself.
+// N4901 [span.overview]/3
 static_assert(is_trivially_copyable_v<span<int>>);
-static_assert(is_trivially_copyable_v<span<int>::iterator>);
 static_assert(is_trivially_copyable_v<span<int, 3>>);
-static_assert(is_trivially_copyable_v<span<int, 3>::iterator>);
 static_assert(is_trivially_copyable_v<span<const int>>);
-static_assert(is_trivially_copyable_v<span<const int>::iterator>);
 static_assert(is_trivially_copyable_v<span<const int, 3>>);
-static_assert(is_trivially_copyable_v<span<const int, 3>::iterator>);
 
-// For portability, our implementation provides an additional guarantee beyond the Standard
-// that span and its iterators are standard-layout.
+// Our implementation provides additional guarantees beyond the Standard
+// that span and its iterators are standard-layout, and that the iterators are trivially copyable.
 static_assert(is_standard_layout_v<span<int>>);
 static_assert(is_standard_layout_v<span<int>::iterator>);
 static_assert(is_standard_layout_v<span<int, 3>>);
@@ -100,6 +95,10 @@ static_assert(is_standard_layout_v<span<const int>>);
 static_assert(is_standard_layout_v<span<const int>::iterator>);
 static_assert(is_standard_layout_v<span<const int, 3>>);
 static_assert(is_standard_layout_v<span<const int, 3>::iterator>);
+static_assert(is_trivially_copyable_v<span<int>::iterator>);
+static_assert(is_trivially_copyable_v<span<int, 3>::iterator>);
+static_assert(is_trivially_copyable_v<span<const int>::iterator>);
+static_assert(is_trivially_copyable_v<span<const int, 3>::iterator>);
 
 // For performance, our implementation provides an additional guarantee beyond the Standard
 // that fixed-size span has only the size of a pointer.

tests/std/tests/P0220R1_string_view/test.cpp

@@ -69,12 +69,11 @@ const evil_conversion_to_string_view_lvalue_only convert_lvalue_only{};
 #pragma clang diagnostic pop
 #endif // __clang__
 
-// We provide a non-standard guarantee that basic_string_view is trivially copyable;
-// P2251 may eventually standardize that guarantee.
+// N4901 [string.view.template.general]/4
 static_assert(is_trivially_copyable_v<string_view>);
 static_assert(is_trivially_copyable_v<wstring_view>);
 
-// Similar non-standard guarantees
+// Implied by N4901 [class.prop]/1
 static_assert(is_trivially_move_constructible_v<string_view>);
 static_assert(is_trivially_copy_constructible_v<string_view>);
 static_assert(is_trivially_move_assignable_v<string_view>);