Prepare the constexpr machinery needed for string and vector

stl/inc/regex

@@ -2466,7 +2466,7 @@ public:
                 _MyRe = nullptr;
 
 #if _ITERATOR_DEBUG_LEVEL == 2
-                this->_Orphan_me();
+                this->_Orphan_me_v2();
 #endif // _ITERATOR_DEBUG_LEVEL
 
                 return *this;

stl/inc/xutility

@@ -131,18 +131,26 @@ _NODISCARD constexpr void* _Voidify_iter(_Iter _It) noexcept {
 
 // FUNCTION TEMPLATE construct_at
 #if _HAS_CXX20
-template <class _Ty, class... _Types>
-_CONSTEXPR20_DYNALLOC auto construct_at(_Ty* const _Location, _Types&&... _Args) noexcept(
-    noexcept(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...))) // strengthened
-    -> decltype(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...)) {
+template <class _Ty, class... _Types,
+    class = void_t<decltype(::new (_STD declval<void*>()) _Ty(_STD declval<_Types>()...))>>
+_CONSTEXPR20_DYNALLOC _Ty* construct_at(_Ty* const _Location, _Types&&... _Args) noexcept(
+    noexcept(::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...))) /* strengthened */ {
     return ::new (_Voidify_iter(_Location)) _Ty(_STD forward<_Types>(_Args)...);
 }
 #endif // _HAS_CXX20
 
 // FUNCTION TEMPLATE _Construct_in_place
 template <class _Ty, class... _Types>
-void _Construct_in_place(_Ty& _Obj, _Types&&... _Args) noexcept(is_nothrow_constructible_v<_Ty, _Types...>) {
-    ::new (_Voidify_iter(_STD addressof(_Obj))) _Ty(_STD forward<_Types>(_Args)...);
+_CONSTEXPR20_DYNALLOC void _Construct_in_place(_Ty& _Obj, _Types&&... _Args) noexcept(
+    is_nothrow_constructible_v<_Ty, _Types...>) {
+#ifdef __cpp_lib_constexpr_dynamic_alloc
+    if (_STD is_constant_evaluated()) {
+        _STD construct_at(_STD addressof(_Obj), _STD forward<_Types>(_Args)...);
+    } else
+#endif // __cpp_lib_constexpr_dynamic_alloc
+    {
+        ::new (_Voidify_iter(_STD addressof(_Obj))) _Ty(_STD forward<_Types>(_Args)...);
+    }
 }
 
 // FUNCTION TEMPLATE _Default_construct_in_place

stl/inc/yvals_core.h

@@ -1190,10 +1190,9 @@
 #define __cpp_lib_constexpr_algorithms 201806L
 #define __cpp_lib_constexpr_complex    201711L
 
-#if defined(__cpp_constexpr_dynamic_alloc) \
-    && defined(__clang__) // TRANSITION, MSVC support for constexpr dynamic allocation
+#ifdef __cpp_constexpr_dynamic_alloc
 #define __cpp_lib_constexpr_dynamic_alloc 201907L
-#endif // defined(__cpp_constexpr_dynamic_alloc) && defined(__clang__)
+#endif // __cpp_constexpr_dynamic_alloc
 
 #define __cpp_lib_constexpr_functional  201907L
 #define __cpp_lib_constexpr_iterator    201811L
@@ -1284,6 +1283,13 @@
 #define _CONSTEXPR20_DYNALLOC inline
 #endif
 
+// Functions that became constexpr in C++20 via P0980R1 or P1004R2
+#if defined(__cpp_lib_constexpr_dynamic_alloc) && !defined(__clang__) // TRANSITION:LLVM-48606
+#define _CONSTEXPR20_CONTAINER constexpr
+#else
+#define _CONSTEXPR20_CONTAINER inline
+#endif
+
 #ifdef _RTC_CONVERSION_CHECKS_ENABLED
 #ifndef _ALLOW_RTCc_IN_STL
 #error /RTCc rejects conformant code, so it is not supported by the C++ Standard Library. Either remove this \

tests/libcxx/expected_results.txt

@@ -310,18 +310,9 @@ std/language.support/support.limits/support.limits.general/format.version.pass.c
 std/utilities/format/format.error/format.error.pass.cpp FAIL
 
 # C++20 P0784R7 "More constexpr containers"
-std/utilities/memory/allocator.traits/allocator.traits.members/allocate.pass.cpp:0 FAIL
-std/utilities/memory/allocator.traits/allocator.traits.members/allocate_hint.pass.cpp:0 FAIL
 std/utilities/memory/allocator.traits/allocator.traits.members/construct.pass.cpp FAIL
-std/utilities/memory/allocator.traits/allocator.traits.members/deallocate.pass.cpp:0 FAIL
 std/utilities/memory/allocator.traits/allocator.traits.members/destroy.pass.cpp FAIL
-std/utilities/memory/allocator.traits/allocator.traits.members/max_size.pass.cpp:0 FAIL
-std/utilities/memory/allocator.traits/allocator.traits.members/select_on_container_copy_construction.pass.cpp:0 FAIL
-std/utilities/memory/default.allocator/allocator.globals/eq.pass.cpp:0 FAIL
 std/utilities/memory/specialized.algorithms/specialized.construct/construct_at.pass.cpp FAIL
-std/utilities/memory/specialized.algorithms/specialized.destroy/destroy.pass.cpp:0 FAIL
-std/utilities/memory/specialized.algorithms/specialized.destroy/destroy_at.pass.cpp:0 FAIL
-std/utilities/memory/specialized.algorithms/specialized.destroy/destroy_n.pass.cpp:0 FAIL
 
 # C++20 P0896R4 "<ranges>"
 std/language.support/support.limits/support.limits.general/algorithm.version.pass.cpp FAIL

tests/libcxx/skipped_tests.txt

@@ -310,18 +310,9 @@ language.support\support.limits\support.limits.general\format.version.pass.cpp
 utilities\format\format.error\format.error.pass.cpp
 
 # C++20 P0784R7 "More constexpr containers"
-utilities\memory\allocator.traits\allocator.traits.members\allocate.pass.cpp
-utilities\memory\allocator.traits\allocator.traits.members\allocate_hint.pass.cpp
 utilities\memory\allocator.traits\allocator.traits.members\construct.pass.cpp
-utilities\memory\allocator.traits\allocator.traits.members\deallocate.pass.cpp
 utilities\memory\allocator.traits\allocator.traits.members\destroy.pass.cpp
-utilities\memory\allocator.traits\allocator.traits.members\max_size.pass.cpp
-utilities\memory\allocator.traits\allocator.traits.members\select_on_container_copy_construction.pass.cpp
-utilities\memory\default.allocator\allocator.globals\eq.pass.cpp
 utilities\memory\specialized.algorithms\specialized.construct\construct_at.pass.cpp
-utilities\memory\specialized.algorithms\specialized.destroy\destroy.pass.cpp
-utilities\memory\specialized.algorithms\specialized.destroy\destroy_at.pass.cpp
-utilities\memory\specialized.algorithms\specialized.destroy\destroy_n.pass.cpp
 
 # C++20 P0896R4 "<ranges>"
 language.support\support.limits\support.limits.general\algorithm.version.pass.cpp

tests/std/tests/P0784R7_library_support_for_more_constexpr_containers/test.cpp

@@ -227,6 +227,7 @@ void test_array(const T& val) {
 }
 
 #ifdef __cpp_lib_constexpr_dynamic_alloc
+#ifndef __EDG__ // TRANSITION, VSO-1269976
 template <class T>
 struct storage_for {
     union {
@@ -244,9 +245,11 @@ constexpr void test_compiletime() {
         assert(s.object == 42);
         destroy_at(&s.object);
 
+#ifdef __cpp_lib_concepts
         ranges::construct_at(&s.object, 1729);
         assert(s.object == 1729);
         ranges::destroy_at(&s.object);
+#endif // __cpp_lib_concepts
     }
 
     struct nontrivial {
@@ -262,12 +265,15 @@ constexpr void test_compiletime() {
         assert(s.object.x == 42);
         destroy_at(&s.object);
 
+#ifdef __cpp_lib_concepts
         ranges::construct_at(&s.object, 1729);
         assert(s.object.x == 1729);
         ranges::destroy_at(&s.object);
+#endif // __cpp_lib_concepts
     }
 }
 static_assert((test_compiletime(), true));
+#endif // __EDG__
 
 template <class T>
 struct A {
@@ -286,6 +292,7 @@ struct nontrivial_A {
 };
 
 constexpr void test_compiletime_destroy_variants() {
+#ifndef __EDG__ // TRANSITION, VSO-1270011
     {
         allocator<A<int>> alloc{};
         A<int>* a = alloc.allocate(10);
@@ -304,6 +311,7 @@ constexpr void test_compiletime_destroy_variants() {
         destroy(a, a + 10);
         alloc.deallocate(a, 10);
     }
+#endif // __EDG__
 #ifdef __cpp_lib_concepts
     {
         allocator<A<int>> alloc{};
@@ -385,6 +393,7 @@ constexpr void test_compiletime_destroy_variants() {
 }
 static_assert((test_compiletime_destroy_variants(), true));
 
+#ifndef __EDG__ // TRANSITION, VSO-1269976
 template <class T, bool Construct = false, bool Destroy = false>
 struct Alloc {
     using value_type = T;
@@ -498,6 +507,7 @@ constexpr void test_compiletime_allocator_traits() {
     }
 }
 static_assert((test_compiletime_allocator_traits(), true));
+#endif // __EDG__
 
 constexpr void test_compiletime_allocator() {
     {

tests/std/tests/VSO_0157762_feature_test_macros/test.compile.pass.cpp

@@ -411,8 +411,7 @@ STATIC_ASSERT(__cpp_lib_constexpr_complex == 201711L);
 #endif
 #endif
 
-#if _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc) \
-    && defined(__clang__) // TRANSITION, MSVC support for constexpr dynamic allocation
+#if _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc)
 #ifndef __cpp_lib_constexpr_dynamic_alloc
 #error __cpp_lib_constexpr_dynamic_alloc is not defined
 #elif __cpp_lib_constexpr_dynamic_alloc != 201907L