Implement P3016R6 Resolve Inconsistencies In begin/end For valarray And Braced Initializer Lists

stl/inc/initializer_list

@@ -51,20 +51,19 @@ public:
         return static_cast<size_t>(_Last - _First);
     }
 
+    _NODISCARD constexpr bool empty() const noexcept {
+        return _First == _Last;
+    }
+
+    _NODISCARD constexpr const _Elem* data() const noexcept {
+        return _First;
+    }
+
 private:
     const _Elem* _First;
     const _Elem* _Last;
 };
 
-_EXPORT_STD template <class _Elem>
-_NODISCARD constexpr const _Elem* begin(initializer_list<_Elem> _Ilist) noexcept {
-    return _Ilist.begin();
-}
-
-_EXPORT_STD template <class _Elem>
-_NODISCARD constexpr const _Elem* end(initializer_list<_Elem> _Ilist) noexcept {
-    return _Ilist.end();
-}
 _STD_END
 
 // TRANSITION, non-_Ugly attribute tokens

stl/inc/valarray

@@ -59,19 +59,9 @@ class valarray { // store array with various indexing options
 public:
     friend _Tidy_deallocate_guard<valarray>;
 
-    template <class _Ty2>
-    friend _Ty2* begin(valarray<_Ty2>& _Array) noexcept /* strengthened */;
-
-    template <class _Ty2>
-    friend const _Ty2* begin(const valarray<_Ty2>& _Array) noexcept /* strengthened */;
-
-    template <class _Ty2>
-    friend _Ty2* end(valarray<_Ty2>& _Array) noexcept /* strengthened */;
-
-    template <class _Ty2>
-    friend const _Ty2* end(const valarray<_Ty2>& _Array) noexcept /* strengthened */;
-
-    using value_type = _Ty;
+    using value_type     = _Ty;
+    using iterator       = _Ty*;
+    using const_iterator = const _Ty*;
 
     valarray() = default; // construct empty valarray
 
@@ -411,6 +401,22 @@ public:
         return _Mysize;
     }
 
+    _NODISCARD iterator begin() noexcept /* strengthened */ {
+        return _Myptr;
+    }
+
+    _NODISCARD const_iterator begin() const noexcept /* strengthened */ {
+        return _Myptr;
+    }
+
+    _NODISCARD iterator end() noexcept /* strengthened */ {
+        return _Myptr + _Mysize;
+    }
+
+    _NODISCARD const_iterator end() const noexcept /* strengthened */ {
+        return _Myptr + _Mysize;
+    }
+
     _NODISCARD const _Ty& operator[](size_t _Off) const noexcept /* strengthened */ {
 #if _MSVC_STL_HARDENING_VALARRAY || _ITERATOR_DEBUG_LEVEL != 0
         _STL_VERIFY(_Off < _Mysize, "valarray subscript out of range");
@@ -612,26 +618,6 @@ void swap(valarray<_Ty>& _Left, valarray<_Ty>& _Right) noexcept {
     _Left.swap(_Right);
 }
 
-_EXPORT_STD template <class _Ty>
-_NODISCARD _Ty* begin(valarray<_Ty>& _Array) noexcept /* strengthened */ {
-    return _Array._Myptr;
-}
-
-_EXPORT_STD template <class _Ty>
-_NODISCARD const _Ty* begin(const valarray<_Ty>& _Array) noexcept /* strengthened */ {
-    return _Array._Myptr;
-}
-
-_EXPORT_STD template <class _Ty>
-_NODISCARD _Ty* end(valarray<_Ty>& _Array) noexcept /* strengthened */ {
-    return _Array._Myptr + _Array.size();
-}
-
-_EXPORT_STD template <class _Ty>
-_NODISCARD const _Ty* end(const valarray<_Ty>& _Array) noexcept /* strengthened */ {
-    return _Array._Myptr + _Array.size();
-}
-
 _EXPORT_STD template <class _Ty>
 _NODISCARD valarray<_Ty> operator*(const valarray<_Ty>& _Left, const typename valarray<_Ty>::value_type& _Right) {
     const size_t _Size = _Left.size();

stl/inc/xutility

@@ -2142,26 +2142,23 @@ constexpr bool disable_sized_sentinel_for<reverse_iterator<_BidIt1>, reverse_ite
 #endif // _HAS_CXX20
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto begin(_Container& _Cont) noexcept(noexcept(_Cont.begin())) /* strengthened */
-    -> decltype(_Cont.begin()) {
+_NODISCARD _CONSTEXPR17 auto begin(_Container& _Cont) noexcept(noexcept(_Cont.begin())) -> decltype(_Cont.begin()) {
     return _Cont.begin();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto begin(const _Container& _Cont) noexcept(noexcept(_Cont.begin())) /* strengthened */
+_NODISCARD _CONSTEXPR17 auto begin(const _Container& _Cont) noexcept(noexcept(_Cont.begin()))
     -> decltype(_Cont.begin()) {
     return _Cont.begin();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto end(_Container& _Cont) noexcept(noexcept(_Cont.end())) /* strengthened */
-    -> decltype(_Cont.end()) {
+_NODISCARD _CONSTEXPR17 auto end(_Container& _Cont) noexcept(noexcept(_Cont.end())) -> decltype(_Cont.end()) {
     return _Cont.end();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto end(const _Container& _Cont) noexcept(noexcept(_Cont.end())) /* strengthened */
-    -> decltype(_Cont.end()) {
+_NODISCARD _CONSTEXPR17 auto end(const _Container& _Cont) noexcept(noexcept(_Cont.end())) -> decltype(_Cont.end()) {
     return _Cont.end();
 }
 
@@ -2188,66 +2185,60 @@ _NODISCARD constexpr auto cend(const _Container& _Cont) noexcept(noexcept(_STD e
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto rbegin(_Container& _Cont) noexcept(noexcept(_Cont.rbegin())) /* strengthened */
-    -> decltype(_Cont.rbegin()) {
+_NODISCARD _CONSTEXPR17 auto rbegin(_Container& _Cont) noexcept(noexcept(_Cont.rbegin())) -> decltype(_Cont.rbegin()) {
     return _Cont.rbegin();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto rbegin(const _Container& _Cont) noexcept(noexcept(_Cont.rbegin())) /* strengthened */
+_NODISCARD _CONSTEXPR17 auto rbegin(const _Container& _Cont) noexcept(noexcept(_Cont.rbegin()))
     -> decltype(_Cont.rbegin()) {
     return _Cont.rbegin();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto rend(_Container& _Cont) noexcept(noexcept(_Cont.rend())) /* strengthened */
-    -> decltype(_Cont.rend()) {
+_NODISCARD _CONSTEXPR17 auto rend(_Container& _Cont) noexcept(noexcept(_Cont.rend())) -> decltype(_Cont.rend()) {
     return _Cont.rend();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto rend(const _Container& _Cont) noexcept(noexcept(_Cont.rend())) /* strengthened */
-    -> decltype(_Cont.rend()) {
+_NODISCARD _CONSTEXPR17 auto rend(const _Container& _Cont) noexcept(noexcept(_Cont.rend())) -> decltype(_Cont.rend()) {
     return _Cont.rend();
 }
 
 _EXPORT_STD template <class _Ty, size_t _Size>
-_NODISCARD _CONSTEXPR17 reverse_iterator<_Ty*> rbegin(_Ty (&_Array)[_Size]) noexcept /* strengthened */ {
+_NODISCARD _CONSTEXPR17 reverse_iterator<_Ty*> rbegin(_Ty (&_Array)[_Size]) noexcept {
     return reverse_iterator<_Ty*>(_Array + _Size);
 }
 
 _EXPORT_STD template <class _Ty, size_t _Size>
-_NODISCARD _CONSTEXPR17 reverse_iterator<_Ty*> rend(_Ty (&_Array)[_Size]) noexcept /* strengthened */ {
+_NODISCARD _CONSTEXPR17 reverse_iterator<_Ty*> rend(_Ty (&_Array)[_Size]) noexcept {
     return reverse_iterator<_Ty*>(_Array);
 }
 
 _EXPORT_STD template <class _Elem>
-_NODISCARD _CONSTEXPR17 reverse_iterator<const _Elem*> rbegin(initializer_list<_Elem> _Ilist) noexcept
-/* strengthened */ {
+_NODISCARD _CONSTEXPR17 reverse_iterator<const _Elem*> rbegin(initializer_list<_Elem> _Ilist) noexcept {
     return reverse_iterator<const _Elem*>(_Ilist.end());
 }
 
 _EXPORT_STD template <class _Elem>
-_NODISCARD _CONSTEXPR17 reverse_iterator<const _Elem*> rend(initializer_list<_Elem> _Ilist) noexcept
-/* strengthened */ {
+_NODISCARD _CONSTEXPR17 reverse_iterator<const _Elem*> rend(initializer_list<_Elem> _Ilist) noexcept {
     return reverse_iterator<const _Elem*>(_Ilist.begin());
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto crbegin(const _Container& _Cont) noexcept(noexcept(_STD rbegin(_Cont))) /* strengthened */
+_NODISCARD _CONSTEXPR17 auto crbegin(const _Container& _Cont) noexcept(noexcept(_STD rbegin(_Cont)))
     -> decltype(_STD rbegin(_Cont)) {
     return _STD rbegin(_Cont);
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD _CONSTEXPR17 auto crend(const _Container& _Cont) noexcept(noexcept(_STD rend(_Cont))) /* strengthened */
+_NODISCARD _CONSTEXPR17 auto crend(const _Container& _Cont) noexcept(noexcept(_STD rend(_Cont)))
     -> decltype(_STD rend(_Cont)) {
     return _STD rend(_Cont);
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD constexpr auto size(const _Container& _Cont) noexcept(noexcept(_Cont.size())) /* strengthened */
-    -> decltype(_Cont.size()) {
+_NODISCARD constexpr auto size(const _Container& _Cont) noexcept(noexcept(_Cont.size())) -> decltype(_Cont.size()) {
     return _Cont.size();
 }
 
@@ -2258,8 +2249,7 @@ _NODISCARD constexpr size_t size(const _Ty (&)[_Size]) noexcept {
 
 #if _HAS_CXX20
 _EXPORT_STD template <class _Container>
-_NODISCARD constexpr auto ssize(const _Container& _Cont) noexcept(noexcept(
-    static_cast<common_type_t<ptrdiff_t, make_signed_t<decltype(_Cont.size())>>>(_Cont.size()))) /* strengthened */
+_NODISCARD constexpr auto ssize(const _Container& _Cont) noexcept(noexcept(_Cont.size()))
     -> common_type_t<ptrdiff_t, make_signed_t<decltype(_Cont.size())>> {
     using _Common = common_type_t<ptrdiff_t, make_signed_t<decltype(_Cont.size())>>;
     return static_cast<_Common>(_Cont.size());
@@ -2272,8 +2262,7 @@ _NODISCARD constexpr ptrdiff_t ssize(const _Ty (&)[_Size]) noexcept {
 #endif // _HAS_CXX20
 
 _EXPORT_STD template <class _Container>
-_NODISCARD_EMPTY_NON_MEMBER constexpr auto empty(const _Container& _Cont)
-    noexcept(noexcept(_Cont.empty())) /* strengthened */
+_NODISCARD_EMPTY_NON_MEMBER constexpr auto empty(const _Container& _Cont) noexcept(noexcept(_Cont.empty()))
     -> decltype(_Cont.empty()) {
     return _Cont.empty();
 }
@@ -2283,20 +2272,13 @@ _NODISCARD_EMPTY_NON_MEMBER constexpr bool empty(const _Ty (&)[_Size]) noexcept
     return false;
 }
 
-_EXPORT_STD template <class _Elem>
-_NODISCARD_EMPTY_NON_MEMBER constexpr bool empty(initializer_list<_Elem> _Ilist) noexcept {
-    return _Ilist.size() == 0;
-}
-
 _EXPORT_STD template <class _Container>
-_NODISCARD constexpr auto data(_Container& _Cont) noexcept(noexcept(_Cont.data())) /* strengthened */
-    -> decltype(_Cont.data()) {
+_NODISCARD constexpr auto data(_Container& _Cont) noexcept(noexcept(_Cont.data())) -> decltype(_Cont.data()) {
     return _Cont.data();
 }
 
 _EXPORT_STD template <class _Container>
-_NODISCARD constexpr auto data(const _Container& _Cont) noexcept(noexcept(_Cont.data())) /* strengthened */
-    -> decltype(_Cont.data()) {
+_NODISCARD constexpr auto data(const _Container& _Cont) noexcept(noexcept(_Cont.data())) -> decltype(_Cont.data()) {
     return _Cont.data();
 }
 
@@ -2305,11 +2287,6 @@ _NODISCARD constexpr _Ty* data(_Ty (&_Array)[_Size]) noexcept {
     return _Array;
 }
 
-_EXPORT_STD template <class _Elem>
-_NODISCARD constexpr const _Elem* data(initializer_list<_Elem> _Ilist) noexcept {
-    return _Ilist.begin();
-}
-
 #if _HAS_CXX20
 #if _HAS_CXX23
 _EXPORT_STD template <indirectly_readable _Ty>

stl/inc/yvals_core.h

@@ -80,6 +80,7 @@
 //     (__cpp_lib_freestanding_algorithm and __cpp_lib_freestanding_array only)
 // P2937R0 Freestanding Library: Remove strtok
 // P2968R2 Make std::ignore A First-Class Object
+// P3016R6 Resolve Inconsistencies In begin/end For valarray And Braced Initializer Lists
 // P3223R2 Making istream::ignore() Less Surprising
 // P3323R1 Forbid atomic<cv T>, Specify atomic_ref<cv T>
 //     (for atomic<cv T>)
@@ -1578,6 +1579,7 @@ _EMIT_STL_ERROR(STL1004, "C++98 unexpected() is incompatible with C++23 unexpect
 #define __cpp_lib_freestanding_tuple               202306L
 #define __cpp_lib_freestanding_utility             202306L
 #define __cpp_lib_generic_associative_lookup       201304L
+#define __cpp_lib_initializer_list                 202511L
 #define __cpp_lib_integer_sequence                 201304L
 #define __cpp_lib_integral_constant_callable       201304L
 #define __cpp_lib_is_final                         201402L
@@ -1595,6 +1597,7 @@ _EMIT_STL_ERROR(STL1004, "C++98 unexpected() is incompatible with C++23 unexpect
 #define __cpp_lib_transformation_trait_aliases 201304L
 #define __cpp_lib_tuple_element_t              201402L
 #define __cpp_lib_tuples_by_type               201304L
+#define __cpp_lib_valarray                     202511L
 
 // C++17
 #define __cpp_lib_addressof_constexpr              201603L

tests/libcxx/expected_results.txt

@@ -136,6 +136,9 @@ std/language.support/support.limits/support.limits.general/mdspan.version.compil
 # libc++ has not implemented P2937R0: "Freestanding Library: Remove strtok"
 std/language.support/support.limits/support.limits.general/cstring.version.compile.pass.cpp FAIL
 
+# libc++ has not implemented P3016R6: "Resolve Inconsistencies In begin/end For valarray And Braced Initializer Lists"
+std/language.support/support.initlist/support.initlist.range/begin_end.pass.cpp FAIL
+
 # libc++ has not implemented P3323R1: "Forbid atomic<cv T>, Specify atomic_ref<cv T>"
 std/atomics/atomics.ref/member_types.compile.pass.cpp FAIL
 

tests/std/test.lst

@@ -725,6 +725,7 @@ tests\P2693R1_text_formatting_header_stacktrace
 tests\P2693R1_text_formatting_header_thread
 tests\P2693R1_text_formatting_stacktrace
 tests\P2693R1_text_formatting_thread_id
+tests\P3016R6_inconsistent_begin_end
 tests\P3107R5_enabled_specializations
 tests\P3349R1_contiguous_iterators_to_pointers
 tests\P3503R3_packaged_task_promise_with_allocator

tests/std/tests/Dev11_1074023_constexpr/test.cpp

@@ -53,7 +53,9 @@ constexpr auto int64_max = numeric_limits<int64_t>::max();
 constexpr initializer_list<int> il;
 STATIC_ASSERT(il.size() == 0);
 STATIC_ASSERT(il.begin() == il.end());
+#if _HAS_CXX17
 STATIC_ASSERT(begin(il) == end(il));
+#endif // _HAS_CXX17
 
 // TRANSITION,
 // constexpr error_category() noexcept;

tests/std/tests/P3016R6_inconsistent_begin_end/env.lst

@@ -0,0 +1,4 @@
+# Copyright (c) Microsoft Corporation.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+RUNALL_INCLUDE ..\usual_matrix.lst