[P1004] Implement constexpr vector

Fixes microsoft#45

stl/inc/xmemory

@@ -2249,7 +2249,8 @@ _NODISCARD _CONSTEXPR20 _FwdIt remove_if(_FwdIt _First, const _FwdIt _Last, _Pr
 
 // FUNCTION TEMPLATE _Erase_remove
 template <class _Container, class _Uty>
-typename _Container::size_type _Erase_remove(_Container& _Cont, const _Uty& _Val) { // erase each element matching _Val
+_CONSTEXPR20_DYNALLOC typename _Container::size_type _Erase_remove(_Container& _Cont, const _Uty& _Val) {
+    // erase each element matching _Val
     auto _First          = _Cont.begin();
     const auto _Last     = _Cont.end();
     const auto _Old_size = _Cont.size();
@@ -2260,7 +2261,8 @@ typename _Container::size_type _Erase_remove(_Container& _Cont, const _Uty& _Val
 
 // FUNCTION TEMPLATE _Erase_remove_if
 template <class _Container, class _Pr>
-typename _Container::size_type _Erase_remove_if(_Container& _Cont, _Pr _Pred) { // erase each element satisfying _Pred
+_CONSTEXPR20_DYNALLOC typename _Container::size_type _Erase_remove_if(_Container& _Cont, _Pr _Pred) {
+    // erase each element satisfying _Pred
     auto _First          = _Cont.begin();
     const auto _Last     = _Cont.end();
     const auto _Old_size = _Cont.size();

stl/inc/yvals_core.h

@@ -176,6 +176,7 @@
 // P0919R3 Heterogeneous Lookup For Unordered Containers
 // P0966R1 string::reserve() Should Not Shrink
 // P1001R2 execution::unseq
+// P1004R2 constexpr std::vector
 // P1006R1 constexpr For pointer_traits<T*>::pointer_to()
 // P1007R3 assume_aligned()
 // P1020R1 Smart Pointer Creation With Default Initialization
@@ -1204,6 +1205,10 @@
 #define __cpp_lib_constexpr_tuple       201811L
 #define __cpp_lib_constexpr_utility     201811L
 
+#if defined(__cpp_constexpr_dynamic_alloc) && defined(__clang__) // TRANSITION, ADO1256891, ADO1256895
+#define __cpp_lib_constexpr_vector 201907L
+#endif // __cpp_constexpr_dynamic_alloc && __clang__
+
 #ifdef __cpp_impl_coroutine // TRANSITION, Clang coroutine support
 #define __cpp_lib_coroutine 201902L
 #endif // __cpp_impl_coroutine

tests/std/test.lst

@@ -252,6 +252,7 @@ tests\P0758R1_is_nothrow_convertible
 tests\P0768R1_spaceship_cpos
 tests\P0768R1_spaceship_operator
 tests\P0769R2_shift_left_shift_right
+tests\P0784R7_library_machinery
 tests\P0784R7_library_support_for_more_constexpr_containers
 tests\P0811R3_midpoint_lerp
 tests\P0896R4_common_iterator
@@ -368,6 +369,8 @@ tests\P0898R3_identity
 tests\P0912R5_coroutine
 tests\P0919R3_heterogeneous_unordered_lookup
 tests\P0966R1_string_reserve_should_not_shrink
+tests\P1004R2_constexpr_vector
+tests\P1004R2_constexpr_vector_bool
 tests\P1007R3_assume_aligned
 tests\P1020R1_smart_pointer_for_overwrite
 tests\P1023R0_constexpr_for_array_comparisons

tests/std/tests/P0784R7_library_machinery/env.lst

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

tests/std/tests/P0784R7_library_machinery/test.cpp

@@ -0,0 +1,147 @@
+// Copyright (c) Microsoft Corporation.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+#include <algorithm>
+#include <assert.h>
+#include <memory>
+
+#pragma warning(disable : 4582) // '%s': constructor is not implicitly called
+#pragma warning(disable : 4583) // '%s': destructor is not implicitly called
+
+using namespace std;
+
+struct int_wrapper_copy {
+    constexpr int_wrapper_copy() = default;
+    constexpr int_wrapper_copy(const int v) : _val(v){};
+
+    constexpr int_wrapper_copy(const int_wrapper_copy& other) : _val(other._val) {}
+    constexpr int_wrapper_copy& operator=(const int_wrapper_copy& other) {
+        _val = other._val;
+        return *this;
+    }
+
+    constexpr int_wrapper_copy(int_wrapper_copy&&) = delete;
+    constexpr int_wrapper_copy& operator=(int_wrapper_copy&&) = delete;
+
+    constexpr bool operator==(const int_wrapper_copy&) const = default;
+
+    int _val = 0;
+};
+
+struct int_wrapper_move {
+    constexpr int_wrapper_move() = default;
+    constexpr int_wrapper_move(const int v) : _val(v){};
+
+    constexpr int_wrapper_move(const int_wrapper_move&) = delete;
+    constexpr int_wrapper_move& operator=(const int_wrapper_move&) = delete;
+
+    constexpr int_wrapper_move(int_wrapper_move&& other) : _val(exchange(other._val, -1)) {}
+    constexpr int_wrapper_move& operator=(int_wrapper_move&& other) {
+        _val = exchange(other._val, -1);
+        return *this;
+    }
+
+    constexpr bool operator==(const int_wrapper_move&) const = default;
+
+    int _val = 0;
+};
+
+static constexpr int_wrapper_copy expected_copy[]       = {1, 2, 3, 4};
+static constexpr int_wrapper_move expected_move[]       = {1, 2, 3, 4};
+static constexpr int_wrapper_move expected_after_move[] = {-1, -1, -1, -1};
+
+constexpr bool test() {
+    { // _Copy_unchecked
+        int_wrapper_copy input[]   = {1, 2, 3, 4};
+        int_wrapper_copy output[4] = {5, 6, 7, 8};
+
+        const auto result = _Copy_unchecked(begin(input), end(input), begin(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_copy*>);
+        assert(result == end(output));
+        assert(equal(begin(expected_copy), end(expected_copy), begin(output), end(output)));
+    }
+
+    { // _Copy_backward_unchecked
+        int_wrapper_copy input[]   = {1, 2, 3, 4};
+        int_wrapper_copy output[4] = {5, 6, 7, 8};
+
+        const auto result = _Copy_backward_unchecked(begin(input), end(input), end(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_copy*>);
+        assert(result == begin(output));
+        assert(equal(begin(expected_copy), end(expected_copy), begin(output), end(output)));
+    }
+
+#if _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc) && defined(__clang__)
+    { // _Uninitialized_copy_unchecked
+        int_wrapper_copy input[] = {1, 2, 3, 4};
+        int_wrapper_copy output[4];
+
+        const auto result = _Uninitialized_copy_unchecked(begin(input), end(input), begin(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_copy*>);
+        assert(result == end(output));
+        assert(equal(begin(expected_copy), end(expected_copy), begin(output), end(output)));
+    }
+#endif // _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc)
+
+    { // _Move_unchecked
+        int_wrapper_move input[]   = {1, 2, 3, 4};
+        int_wrapper_move output[4] = {5, 6, 7, 8};
+
+        const auto result = _Move_unchecked(begin(input), end(input), begin(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_move*>);
+        assert(result == end(output));
+        assert(equal(begin(expected_move), end(expected_move), begin(output), end(output)));
+        if (is_constant_evaluated()) {
+            assert(equal(begin(input), end(input), begin(expected_after_move), end(expected_after_move)));
+        }
+    }
+
+    { // _Move_backward_unchecked
+        int_wrapper_move input[]   = {1, 2, 3, 4};
+        int_wrapper_move output[4] = {5, 6, 7, 8};
+
+        const auto result = _Move_backward_unchecked(begin(input), end(input), end(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_move*>);
+        assert(result == begin(output));
+        assert(equal(begin(expected_move), end(expected_move), begin(output), end(output)));
+        if (is_constant_evaluated()) {
+            assert(equal(begin(input), end(input), begin(expected_after_move), end(expected_after_move)));
+        }
+    }
+
+#ifdef __cpp_lib_concepts
+    { // _Move_backward_common
+        int_wrapper_move input[]   = {1, 2, 3, 4};
+        int_wrapper_move output[4] = {5, 6, 7, 8};
+
+        const auto result = ranges::_Move_backward_common(begin(input), end(input), end(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_move*>);
+        assert(result == begin(output));
+        assert(equal(begin(expected_move), end(expected_move), begin(output), end(output)));
+        if (is_constant_evaluated()) {
+            assert(equal(begin(input), end(input), begin(expected_after_move), end(expected_after_move)));
+        }
+    }
+#endif // __cpp_lib_concepts
+
+#if _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc) && defined(__clang__)
+    { // _Uninitialized_move_unchecked
+        int_wrapper_move input[] = {1, 2, 3, 4};
+        int_wrapper_move output[4];
+
+        const auto result = _Uninitialized_move_unchecked(begin(input), end(input), begin(output));
+        static_assert(is_same_v<remove_const_t<decltype(result)>, int_wrapper_move*>);
+        assert(result == end(output));
+        assert(equal(begin(expected_move), end(expected_move), begin(output), end(output)));
+        if (is_constant_evaluated()) {
+            assert(equal(begin(input), end(input), begin(expected_after_move), end(expected_after_move)));
+        }
+    }
+#endif // _HAS_CXX20 && defined(__cpp_constexpr_dynamic_alloc)
+    return true;
+}
+
+int main() {
+    test();
+    static_assert(test());
+}

tests/std/tests/P1004R2_constexpr_vector/env.lst

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