Refactor std::optional SFINAE constraints

	* include/std/optional (_Optional_payload): Use variable templates
	for conditions in default template arguments and exception
	specifications.
	(optional): Likewise. Adjust indentation.
	(optional::__not_self, optional::__not_tag, optional::_Requires): New
	SFINAE helpers.
	(optional::optional): Use new helpers in constructor constraints.
	* include/std/type_traits (__or_v, __and_v): New variable templates.
	* testsuite/20_util/optional/cons/value_neg.cc: Change dg-error to
	dg-prune-output. Remove unused header.

From-SVN: r263657

libstdc++-v3/ChangeLog

+2018-08-20  Jonathan Wakely  <jwakely@redhat.com>
+
+	* include/std/optional (_Optional_payload): Use variable templates
+	for conditions in default template arguments and exception
+	specifications.
+	(optional): Likewise. Adjust indentation.
+	(optional::__not_self, optional::__not_tag, optional::_Requires): New
+	SFINAE helpers.
+	(optional::optional): Use new helpers in constructor constraints.
+	* include/std/type_traits (__or_v, __and_v): New variable templates.
+	* testsuite/20_util/optional/cons/value_neg.cc: Change dg-error to
+	dg-prune-output. Remove unused header.
+
 2018-08-18  François Dumont  <fdumont@gcc.gnu.org>
 
 	* testsuite/25_algorithms/copy/86658.cc: Use dg-options to define

libstdc++-v3/include/std/type_traits

@@ -144,6 +144,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus >= 201703L
 
+  template<typename... _Bn>
+    inline constexpr bool __or_v = __or_<_Bn...>::value;
+  template<typename... _Bn>
+    inline constexpr bool __and_v = __and_<_Bn...>::value;
+
 #define __cpp_lib_logical_traits 201510
 
   template<typename... _Bn>

libstdc++-v3/testsuite/20_util/optional/cons/value_neg.cc

@@ -19,8 +19,6 @@
 // <http://www.gnu.org/licenses/>.
 
 #include <optional>
-#include <testsuite_hooks.h>
-
 #include <string>
 #include <memory>
 
@@ -37,8 +35,6 @@ int main()
     std::optional<std::unique_ptr<int>> oup2 = new int;  // { dg-error "conversion" }
     struct U { explicit U(std::in_place_t); };
     std::optional<U> ou(std::in_place); // { dg-error "no matching" }
-    // { dg-error "no type" "" { target { *-*-* } } 1020 }
-    // { dg-error "no type" "" { target { *-*-* } } 1030 }
-    // { dg-error "no type" "" { target { *-*-* } } 1087 }
   }
 }
+// { dg-prune-output "no type .*enable_if" }