Fix exception-specifications for std::_Not_fn

	* include/std/functional (_Not_fn): Make exception specifications
	depend on whether negating the result can throw.
	* testsuite/20_util/not_fn/1.cc: Move to ...
	* testsuite/20_util/function_objects/not_fn/1.cc: ... here. Add tests
	for types that can throw when negated and that cannot be negated.

From-SVN: r241091

libstdc++-v3/ChangeLog

 2016-10-13  Jonathan Wakely  <jwakely@redhat.com>
 
+	* include/std/functional (_Not_fn): Make exception specifications
+	depend on whether negating the result can throw.
+	* testsuite/20_util/not_fn/1.cc: Move to ...
+	* testsuite/20_util/function_objects/not_fn/1.cc: ... here. Add tests
+	for types that can throw when negated and that cannot be negated.
+
 	* include/bits/invoke.h (__invoke): Fix exception-specification.
 	* include/std/functional (invoke): Likewise.
 	* testsuite/20_util/function_objects/invoke/1.cc: New test.

libstdc++-v3/include/std/functional

@@ -2140,6 +2140,16 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
   template<typename _Fn>
     class _Not_fn
     {
+      template<typename _Tp>
+	using __is_nothrow_negatable
+	  = __bool_constant<noexcept(!std::declval<_Tp>())>;
+
+      template<typename _Fn2, typename... _Args>
+	using __noexcept_cond = __and_<
+	  __is_nothrow_callable<_Fn2(_Args&&...)>,
+	  __is_nothrow_negatable<result_of_t<_Fn2(_Args&&...)>>
+	>;
+
     public:
       template<typename _Fn2>
 	_Not_fn(_Fn2&& __fn, int)
@@ -2152,21 +2162,21 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
       template<typename... _Args>
 	auto
 	operator()(_Args&&... __args) &
-	noexcept(__is_nothrow_callable<_Fn&(_Args&&...)>::value)
+	noexcept(__noexcept_cond<_Fn&, _Args&&...>::value)
 	-> decltype(!std::declval<result_of_t<_Fn&(_Args&&...)>>())
 	{ return !std::__invoke(_M_fn, std::forward<_Args>(__args)...); }
 
       template<typename... _Args>
 	auto
 	operator()(_Args&&... __args) const &
-	noexcept(__is_nothrow_callable<const _Fn&(_Args&&...)>::value)
+	noexcept(__noexcept_cond<const _Fn&, _Args&&...>::value)
 	-> decltype(!std::declval<result_of_t<const _Fn&(_Args&&...)>>())
 	{ return !std::__invoke(_M_fn, std::forward<_Args>(__args)...); }
 
       template<typename... _Args>
 	auto
 	operator()(_Args&&... __args) &&
-	noexcept(__is_nothrow_callable<_Fn&&(_Args&&...)>::value)
+	noexcept(__noexcept_cond<_Fn&&, _Args&&...>::value)
 	-> decltype(!std::declval<result_of_t<_Fn&&(_Args&&...)>>())
 	{
 	  return !std::__invoke(std::move(_M_fn),
@@ -2176,7 +2186,7 @@ _GLIBCXX_MEM_FN_TRAITS(&&, false_type, true_type)
       template<typename... _Args>
 	auto
 	operator()(_Args&&... __args) const &&
-	noexcept(__is_nothrow_callable<const _Fn&&(_Args&&...)>::value)
+	noexcept(__noexcept_cond<const _Fn&&, _Args&&...>::value)
 	-> decltype(!std::declval<result_of_t<const _Fn&&(_Args&&...)>>())
 	{
 	  return !std::__invoke(std::move(_M_fn),

libstdc++-v3/testsuite/20_util/not_fn/1.cc → libstdc++-v3/testsuite/20_util/function_objects/not_fn/1.cc

@@ -91,6 +91,35 @@ test05()
   auto copy(nf); // PR libstdc++/70564
 }
 
+void
+test06()
+{
+  struct Boolean {
+    Boolean operator!() noexcept(false) { return *this; }
+  };
+  struct F {
+    Boolean operator()() { return {}; }
+  };
+  F f;
+  auto notf = std::not_fn(f);
+  using NotF = decltype(notf);
+  static_assert( std::is_callable<NotF()>::value, "cannot negate" );
+  static_assert( !noexcept(notf()), "conversion to bool affects noexcept" );
+}
+
+void
+test07()
+{
+  struct NonNegatable { };
+  struct F {
+    NonNegatable operator()() { return {}; }
+  };
+  F f;
+  auto notf = std::not_fn(f);
+  using NotF = decltype(notf);
+  static_assert( !std::is_callable<NotF()>::value, "cannot negate" );
+}
+
 int
 main()
 {
@@ -99,4 +128,6 @@ main()
   test03();
   test04();
   test05();
+  test06();
+  test07();
 }