[PATCH] D32385: [libcxx] Implement LWG 2900 "The copy and move constructors of optional are not constexpr"
CaseyCarter updated this revision to Diff 96644.
CaseyCarter added a comment.
Assigning an empty optional to a non-empty optional needs to destroy the
contained value, so we need to also require `is_trivially_destructible` to
implement trivial assignments.
https://reviews.llvm.org/D32385
Files:
include/optional
test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
Index: test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
===
--- test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
+++ test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
@@ -10,7 +10,10 @@
// UNSUPPORTED: c++98, c++03, c++11, c++14
//
-// optional(optional&& rhs);
+// constexpr optional(const optional&& rhs);
+// If is_trivially_move_constructible_v is true,
+//this constructor shall be a constexpr constructor.
+
#include
#include
@@ -131,6 +134,31 @@
#endif
}
+constexpr bool test_constexpr()
+{
+{
+using T = int;
+optional o1{};
+optional o2 = std::move(o1);
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = std::move(o3);
+static_cast(o4);
+}
+{
+struct T {
+constexpr T(int) {}
+T(T&&) = default;
+};
+optional o1{};
+optional o2 = std::move(o1);
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = std::move(o3);
+static_cast(o4);
+}
+return true;
+}
int main()
{
@@ -198,4 +226,7 @@
{
test_reference_extension();
}
+{
+static_assert(test_constexpr(), "");
+}
}
Index: test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
===
--- test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
+++ test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
@@ -10,7 +10,9 @@
// UNSUPPORTED: c++98, c++03, c++11, c++14
//
-// optional(const optional& rhs);
+// constexpr optional(const optional& rhs);
+// If is_trivially_copy_constructible_v is true,
+//this constructor shall be a constexpr constructor.
#include
#include
@@ -104,6 +106,31 @@
#endif
}
+constexpr bool test_constexpr()
+{
+{
+using T = int;
+optional o1{};
+optional o2 = o1;
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = o3;
+static_cast(o4);
+}
+{
+struct T {
+constexpr T(int) {}
+};
+optional o1{};
+optional o2 = o1;
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = o3;
+static_cast(o4);
+}
+return true;
+}
+
int main()
{
test();
@@ -152,4 +179,7 @@
{
test_reference_extension();
}
+{
+static_assert(test_constexpr(), "");
+}
}
Index: include/optional
===
--- include/optional
+++ include/optional
@@ -436,46 +436,122 @@
}
};
-template ::value>
-struct __optional_storage;
-
-template
-struct __optional_storage<_Tp, true> : __optional_storage_base<_Tp>
+template ::value>
+struct __optional_copy_base : __optional_storage_base<_Tp>
{
using __optional_storage_base<_Tp>::__optional_storage_base;
};
template
-struct __optional_storage<_Tp, false> : __optional_storage_base<_Tp>
+struct __optional_copy_base<_Tp, false> : __optional_storage_base<_Tp>
{
-using value_type = _Tp;
using __optional_storage_base<_Tp>::__optional_storage_base;
_LIBCPP_INLINE_VISIBILITY
-__optional_storage() = default;
+__optional_copy_base() = default;
_LIBCPP_INLINE_VISIBILITY
-__optional_storage(const __optional_storage& __opt)
+__optional_copy_base(const __optional_copy_base& __opt)
{
this->__construct_from(__opt);
}
_LIBCPP_INLINE_VISIBILITY
-__optional_storage(__optional_storage&& __opt)
+__optional_copy_base(__optional_copy_base&&) = default;
+_LIBCPP_INLINE_VISIBILITY
+__optional_copy_base& operator=(const __optional_copy_base&) = default;
+_LIBCPP_INLINE_VISIBILITY
+__optional_copy_base& operator=(__optional_copy_base&&) = default;
+};
+
+template ::value>
+struct __optional_move_base : __optional_copy_base<_Tp>
+{
+using __optional_copy_base<_Tp>::__optional_copy_base;
+};
+
+template
+struct __optional_move_base<_Tp, false> : __optional_copy_base<_Tp>
+{
+using value_type = _Tp;
+using __optional_copy_base<_Tp>::__optional_copy_base;
+
+_LIBCPP_INLINE_VISIBILITY
+__optional_move_base() = default;
+_LIBCPP_INLINE_VISIBILITY
+__optional_move_base(const __optional_move_base&) = default;
+
[PATCH] D32385: [libcxx] Implement LWG 2900 "The copy and move constructors of optional are not constexpr"
CaseyCarter created this revision.
.. by injecting base classes that differentiate between trivial/non-trivial
implementation of each copy/move constructor/assignment. This actually goes a
bit beyond the PR by also making the copy/move assignment operators trivial
when the base type has corresponding trivial construction and assignment.
https://reviews.llvm.org/D32385
Files:
include/optional
test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
Index: test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
===
--- test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
+++ test/std/utilities/optional/optional.object/optional.object.ctor/move.pass.cpp
@@ -10,7 +10,10 @@
// UNSUPPORTED: c++98, c++03, c++11, c++14
//
-// optional(optional&& rhs);
+// constexpr optional(const optional&& rhs);
+// If is_trivially_move_constructible_v is true,
+//this constructor shall be a constexpr constructor.
+
#include
#include
@@ -131,6 +134,31 @@
#endif
}
+constexpr bool test_constexpr()
+{
+{
+using T = int;
+optional o1{};
+optional o2 = std::move(o1);
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = std::move(o3);
+static_cast(o4);
+}
+{
+struct T {
+constexpr T(int) {}
+T(T&&) = default;
+};
+optional o1{};
+optional o2 = std::move(o1);
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = std::move(o3);
+static_cast(o4);
+}
+return true;
+}
int main()
{
@@ -198,4 +226,7 @@
{
test_reference_extension();
}
+{
+static_assert(test_constexpr(), "");
+}
}
Index: test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
===
--- test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
+++ test/std/utilities/optional/optional.object/optional.object.ctor/copy.pass.cpp
@@ -10,7 +10,9 @@
// UNSUPPORTED: c++98, c++03, c++11, c++14
//
-// optional(const optional& rhs);
+// constexpr optional(const optional& rhs);
+// If is_trivially_copy_constructible_v is true,
+//this constructor shall be a constexpr constructor.
#include
#include
@@ -104,6 +106,31 @@
#endif
}
+constexpr bool test_constexpr()
+{
+{
+using T = int;
+optional o1{};
+optional o2 = o1;
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = o3;
+static_cast(o4);
+}
+{
+struct T {
+constexpr T(int) {}
+};
+optional o1{};
+optional o2 = o1;
+static_cast(o2);
+optional o3{T{42}};
+optional o4 = o3;
+static_cast(o4);
+}
+return true;
+}
+
int main()
{
test();
@@ -152,4 +179,7 @@
{
test_reference_extension();
}
+{
+static_assert(test_constexpr(), "");
+}
}
Index: include/optional
===
--- include/optional
+++ include/optional
@@ -436,46 +436,118 @@
}
};
-template ::value>
-struct __optional_storage;
-
-template
-struct __optional_storage<_Tp, true> : __optional_storage_base<_Tp>
+template ::value>
+struct __optional_copy_base : __optional_storage_base<_Tp>
{
using __optional_storage_base<_Tp>::__optional_storage_base;
};
template
-struct __optional_storage<_Tp, false> : __optional_storage_base<_Tp>
+struct __optional_copy_base<_Tp, false> : __optional_storage_base<_Tp>
{
-using value_type = _Tp;
using __optional_storage_base<_Tp>::__optional_storage_base;
_LIBCPP_INLINE_VISIBILITY
-__optional_storage() = default;
+__optional_copy_base() = default;
_LIBCPP_INLINE_VISIBILITY
-__optional_storage(const __optional_storage& __opt)
+__optional_copy_base(const __optional_copy_base& __opt)
{
this->__construct_from(__opt);
}
_LIBCPP_INLINE_VISIBILITY
-__optional_storage(__optional_storage&& __opt)
+__optional_copy_base(__optional_copy_base&&) = default;
+_LIBCPP_INLINE_VISIBILITY
+__optional_copy_base& operator=(const __optional_copy_base&) = default;
+_LIBCPP_INLINE_VISIBILITY
+__optional_copy_base& operator=(__optional_copy_base&&) = default;
+};
+
+template ::value>
+struct __optional_move_base : __optional_copy_base<_Tp>
+{
+using __optional_copy_base<_Tp>::__optional_copy_base;
+};
+
+template
+struct __optional_move_base<_Tp, false> : __optional_copy_base<_Tp>
+{
+using value_type = _Tp;
+using __optional_copy_base<_Tp>::__optional_copy_base;
+
+_LIBCPP_INLINE_VISIBILITY
+__optional_move_base() = default;
+_LIBCPP_IN
