From 48aa2e14a2bd35820a40e3ebe0d447be15219389 Mon Sep 17 00:00:00 2001
From: Eric Fiselier <eric@efcs.ca>
Date: Fri, 14 Oct 2016 07:19:52 +0000
Subject: [PATCH] Add void_t and invoke feature test macros

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@284209 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/functional                            |  2 +
 include/type_traits                           |  2 +
 .../invoke_feature_test_macro.pass.cpp        | 39 +++++++++++++++++++
 .../void_t_feature_test_macro.pass.cpp        | 36 +++++++++++++++++
 4 files changed, 79 insertions(+)
 create mode 100644 test/std/utilities/function.objects/func.invoke/invoke_feature_test_macro.pass.cpp
 create mode 100644 test/std/utilities/meta/meta.unary.prop.query/void_t_feature_test_macro.pass.cpp

diff --git a/include/functional b/include/functional
index 4adb8c92a..088be05ca 100644
--- a/include/functional
+++ b/include/functional
@@ -2635,6 +2635,8 @@ struct _LIBCPP_TYPE_VIS_ONLY hash : public __enum_hash<_Tp>
 
 #if _LIBCPP_STD_VER > 14
 
+#define __cpp_lib_invoke 201411
+
 template <class _Fn, class ..._Args>
 result_of_t<_Fn&&(_Args&&...)>
 invoke(_Fn&& __f, _Args&&... __args)
diff --git a/include/type_traits b/include/type_traits
index 43687a7c6..0f158fdb8 100644
--- a/include/type_traits
+++ b/include/type_traits
@@ -4599,6 +4599,8 @@ struct __has_operator_addressof
 #endif  // _LIBCPP_CXX03_LANG
 
 #if _LIBCPP_STD_VER > 14
+
+#define __cpp_lib_void_t 201411
 template <class...> using void_t = void;
 
 # ifndef _LIBCPP_HAS_NO_VARIADICS
diff --git a/test/std/utilities/function.objects/func.invoke/invoke_feature_test_macro.pass.cpp b/test/std/utilities/function.objects/func.invoke/invoke_feature_test_macro.pass.cpp
new file mode 100644
index 000000000..aaac98474
--- /dev/null
+++ b/test/std/utilities/function.objects/func.invoke/invoke_feature_test_macro.pass.cpp
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// template <class F, class ...Args>
+// result_of_t<F&&(Args&&...)> invoke(F&&, Args&&...);
+
+#include <functional>
+#include <cassert>
+
+#include "test_macros.h"
+
+#if TEST_STD_VER <= 14
+# ifdef __cpp_lib_invoke
+#   error Feature test macro should be defined
+# endif
+#else
+# ifndef __cpp_lib_invoke
+#   error Feature test macro not defined
+# endif
+# if __cpp_lib_invoke != 201411
+#   error __cpp_lib_invoke has the wrong value
+# endif
+#endif
+
+int foo(int) { return 42; }
+
+int main() {
+#if defined(__cpp_lib_invoke)
+  assert(std::invoke(foo, 101) == 42);
+#endif
+}
\ No newline at end of file
diff --git a/test/std/utilities/meta/meta.unary.prop.query/void_t_feature_test_macro.pass.cpp b/test/std/utilities/meta/meta.unary.prop.query/void_t_feature_test_macro.pass.cpp
new file mode 100644
index 000000000..f188c098c
--- /dev/null
+++ b/test/std/utilities/meta/meta.unary.prop.query/void_t_feature_test_macro.pass.cpp
@@ -0,0 +1,36 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// type_traits
+
+// void_t
+
+#include <type_traits>
+
+#include "test_macros.h"
+
+#if TEST_STD_VER <= 14
+# ifdef __cpp_lib_void_t
+#   error Feature test macro should not be defined!
+# endif
+#else
+# ifndef __cpp_lib_void_t
+#   error Feature test macro is not defined
+# endif
+# if __cpp_lib_void_t != 201411
+#   error Feature test macro has the wrong value
+# endif
+#endif
+
+int main()
+{
+#if defined(__cpp_lib_void_t)
+  static_assert(std::is_same_v<std::void_t<int>, void>, "");
+#endif
+}