Implement is_error_code_v and is_error_condition_v for c++17. Rework the tests for is_error_code and is_error_condition, since they were really lacking. Thanks to Alisdair for the heads-up that we were missing these.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@282331 91177308-0d34-0410-b5e6-96231b3b80d8

include/system_error

@@ -46,6 +46,12 @@ template <class T> struct is_error_code_enum
 template <class T> struct is_error_condition_enum
     : public false_type {};
 
+template <class _Tp>
+constexpr size_t is_error_condition_enum_v = is_error_condition_enum<_Tp>::value; // C++17
+
+template <class _Tp>
+constexpr size_t is_error_code_enum_v = is_error_code_enum<_Tp>::value; // C++17
+
 class error_code
 {
 public:
@@ -236,12 +242,22 @@ template <class _Tp>
 struct _LIBCPP_TYPE_VIS_ONLY is_error_code_enum
     : public false_type {};
 
+#if _LIBCPP_STD_VER > 14
+template <class _Tp>
+constexpr size_t is_error_code_enum_v = is_error_code_enum<_Tp>::value;
+#endif
+
 // is_error_condition_enum
 
 template <class _Tp>
 struct _LIBCPP_TYPE_VIS_ONLY is_error_condition_enum
     : public false_type {};
 
+#if _LIBCPP_STD_VER > 14
+template <class _Tp>
+constexpr size_t is_error_condition_enum_v = is_error_condition_enum<_Tp>::value;
+#endif
+
 // Some error codes are not present on all platforms, so we provide equivalents
 // for them:
 

test/std/diagnostics/syserr/is_error_code_enum.pass.cpp

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+//
+// UNSUPPORTED: c++03
+
+// <future>
+
+// template <> struct is_error_code_enum<> : public false_type {};
+
+#include <future>
+#include <string>
+#include "test_macros.h"
+
+template <bool Expected, class T>
+void
+test()
+{
+    static_assert((std::is_error_code_enum<T>::value == Expected), "");
+#if TEST_STD_VER > 14
+    static_assert((std::is_error_code_enum_v<T>      == Expected), "");
+#endif
+}
+
+class A {
+	A();
+	operator std::error_code () const { return std::error_code(); }
+};
+
+// Specialize the template for my class
+namespace std
+{
+  template <>
+  struct is_error_code_enum<A> : public std::true_type {};
+}
+
+	
+int main()
+{
+    test<false, void>();
+    test<false, int>();
+    test<false, std::nullptr_t>();
+    test<false, std::string>();
+
+    test<true, A>();
+}

test/std/diagnostics/syserr/is_error_condition_enum.pass.cpp

@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// <system_error>
+
+// template <class T> constexpr bool is_error_condition_enum_v;
+
+#include <system_error>
+#include <type_traits>
+#include "test_macros.h"
+
+template <bool Expected, class T>
+void
+test()
+{
+    static_assert((std::is_error_condition_enum<T>::value == Expected), "");
+#if TEST_STD_VER > 14
+    static_assert((std::is_error_condition_enum_v<T>        == Expected), "");
+#endif
+}
+
+class A {
+	A();
+	operator std::error_condition () const { return std::error_condition(); }
+};
+
+// Specialize the template for my class
+namespace std
+{
+  template <>
+  struct is_error_condition_enum<A> : public std::true_type {};
+}
+
+	
+int main()
+{
+    test<false, void>();
+    test<false, int>();
+    test<false, std::nullptr_t>();
+    test<false, std::string>();
+    
+    test<true, A>();
+}

test/std/input.output/iostreams.base/is_error_code_enum_io_errc.pass.cpp

@@ -0,0 +1,25 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+//
+// UNSUPPORTED: c++03
+
+// <ios>
+
+// template <> struct is_error_code_enum<io_errc> : public true_type {};
+
+#include <ios>
+#include "test_macros.h"
+
+int main()
+{
+    static_assert(std::is_error_code_enum  <std::io_errc>::value, "");
+#if TEST_STD_VER > 14
+    static_assert(std::is_error_code_enum_v<std::io_errc>, "");
+#endif
+}

test/std/thread/futures/futures.overview/is_error_code_enum_future_errc.pass.cpp

@@ -14,8 +14,12 @@
 // template <> struct is_error_code_enum<future_errc> : public true_type {};
 
 #include <future>
+#include "test_macros.h"
 
 int main()
 {
-    static_assert(std::is_error_code_enum<std::future_errc>::value, "");
+    static_assert(std::is_error_code_enum  <std::future_errc>::value, "");
+#if TEST_STD_VER > 14
+    static_assert(std::is_error_code_enum_v<std::future_errc>, "");
+#endif
 }