// is_scalar
+template <class _Tp> struct __is_block : false_type {};
+#if defined(_LIBCPP_HAS_EXTENSION_BLOCKS)
+template <class _Rp, class ..._Args> struct __is_block<_Rp (^)(_Args...)> : true_type {};
+#endif
+
template <class _Tp> struct _LIBCPP_TEMPLATE_VIS is_scalar
: public integral_constant<bool, is_arithmetic<_Tp>::value ||
is_member_pointer<_Tp>::value ||
is_pointer<_Tp>::value ||
__is_nullptr_t<_Tp>::value ||
+ __is_block<_Tp>::value ||
is_enum<_Tp>::value > {};
template <> struct _LIBCPP_TEMPLATE_VIS is_scalar<nullptr_t> : public true_type {};
--- /dev/null
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// UNSUPPORTED: c++98, c++03
+
+// <type_traits>
+
+// std::is_scalar
+
+// Make sure we report that blocks are scalar types.
+
+#include <type_traits>
+#include <optional>
+
+struct Foo { };
+template <int> struct Arg { };
+
+static_assert(std::is_scalar<void (^)(void)>::value, "");
+static_assert(std::is_scalar<void (^)()>::value, "");
+static_assert(std::is_scalar<void (^)(Arg<0>)>::value, "");
+static_assert(std::is_scalar<void (^)(Arg<0>, Arg<1>)>::value, "");
+static_assert(std::is_scalar<void (^)(Arg<0>, Arg<1>, Arg<2>)>::value, "");
+static_assert(std::is_scalar<Foo (^)(void)>::value, "");
+static_assert(std::is_scalar<Foo (^)()>::value, "");
+static_assert(std::is_scalar<Foo (^)(Arg<0>)>::value, "");
+static_assert(std::is_scalar<Foo (^)(Arg<0>, Arg<1>)>::value, "");
+static_assert(std::is_scalar<Foo (^)(Arg<0>, Arg<1>, Arg<2>)>::value, "");
+
+
+int main(int, char**) {
+ std::optional<Foo (^)(Arg<0>)> opt; (void)opt;
+ return 0;
+}
--- /dev/null
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <optional>
+
+// This test makes sure that we can create a `std::optional` containing
+// an Objective-C++ block.
+
+#include <optional>
+#include <cassert>
+
+int main(int, char**)
+{
+ using Block = void (^)(void);
+ std::optional<Block> block;
+ assert(!block);
+
+ return 0;
+}