Implement new C++ intrinsics __is_assignable and __is_constructible.

c-family/

Implement new C++ intrinsics __is_assignable and __is_constructible.
* c-common.c (__is_assignable, __is_constructible): New.
* c-common.h (RID_IS_ASSIGNABLE, RID_IS_CONSTRUCTIBLE): Likewise.

cp/

PR c++/80654
PR c++/80682
Implement new C++ intrinsics __is_assignable and __is_constructible.
* cp-tree.h (CPTK_IS_ASSIGNABLE, CPTK_IS_CONSTRUCTIBLE): New.
(is_xible): New.
* cxx-pretty-print.c (pp_cxx_trait_expression): Handle
CPTK_IS_ASSIGNABLE and CPTK_IS_CONSTRUCTIBLE.
* method.c (constructible_expr): Set cp_unevaluated.
(is_xible_helper): New.
(is_trivially_xible): Adjust.
(is_xible): New.
* parser.c (cp_parser_primary_expression): Handle
RID_IS_ASSIGNABLE and RID_IS_CONSTRUCTIBLE.
(cp_parser_trait_expr): Likewise.
* semantics.c (trait_expr_value): Handle
CPTK_IS_ASSIGNABLE and CPTK_IS_CONSTRUCTIBLE.

testsuite/

* g++.dg/ext/80654.C: New.

libstdc++-v3/

Implement new C++ intrinsics __is_assignable and __is_constructible.
* include/std/type_traits (__do_is_static_castable_impl): Remove.
(__is_static_castable_impl, __is_static_castable_safe): Likewise.
(__is_static_castable, __do_is_direct_constructible_impl): Likewise.
(__is_direct_constructible_impl): Likewise.
(__is_direct_constructible_new_safe): Likewise.
(__is_base_to_derived_ref, __is_lvalue_to_rvalue_ref): Likewise.
(__is_direct_constructible_ref_cast): Likewise.
(__is_direct_constructible_new, __is_direct_constructible): Likewise.
(__do_is_nary_constructible_impl): Likewise.
(__is_nary_constructible_impl, __is_nary_constructible): Likewise.
(__is_constructible_impl): Likewise.
(is_constructible): Call the intrinsic.
(__is_assignable_helper): Remove.
(is_assignable): Call the intrinsic.
(is_trivially_constructible): Likewise.
(__is_trivially_copy_constructible_impl): New.
(is_trivially_copy_constructible): Use it.
(__is_trivially_move_constructible_impl): New.
(is_trivially_move_constructible): Use it.
(is_trivially_assignable): Call the intrinsic.
(__is_trivially_copy_assignable_impl): New.
(is_trivially_copy_assignable): Use it.
(__is_trivially_move_assignable_impl): New.
(is_trivially_move_assignable): Use it.
(testsuite/20_util/declval/requirements/1_neg.cc): Adjust.
(testsuite/20_util/is_trivially_copy_assignable/value.cc):
Add test for void.
(testsuite/20_util/is_trivially_copy_constructible/value.cc): Likewise.
(testsuite/20_util/is_trivially_move_assignable/value.cc): Likewise.
(testsuite/20_util/is_trivially_move_constructible/value.cc): Likewise.
(testsuite/20_util/make_signed/requirements/typedefs_neg.cc): Adjust.
(testsuite/20_util/make_unsigned/requirements/typedefs_neg.cc):
Likewise.

From-SVN: r248153

1 files changed, 60 insertions, 230 deletions

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index aac7cff6cf6..390b6f40af5 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -924,213 +924,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public __is_default_constructible_safe<_Tp>::type
     { };
 
-
-  // Implementation of is_constructible.
-
-  // The hardest part of this trait is the binary direct-initialization
-  // case, because we hit into a functional cast of the form T(arg).
-  // This implementation uses different strategies depending on the
-  // target type to reduce the test overhead as much as possible:
-  //
-  // a) For a reference target type, we use a static_cast expression
-  //    modulo its extra cases.
-  //
-  // b) For a non-reference target type we use a ::new expression.
-  struct __do_is_static_castable_impl
-  {
-    template<typename _From, typename _To, typename
-             = decltype(static_cast<_To>(declval<_From>()))>
-      static true_type __test(int);
-
-    template<typename, typename>
-      static false_type __test(...);
-  };
-
-  template<typename _From, typename _To>
-    struct __is_static_castable_impl
-    : public __do_is_static_castable_impl
-    {
-      typedef decltype(__test<_From, _To>(0)) type;
-    };
-
-  template<typename _From, typename _To>
-    struct __is_static_castable_safe
-    : public __is_static_castable_impl<_From, _To>::type
-    { };
-
-  // __is_static_castable
-  template<typename _From, typename _To>
-    struct __is_static_castable
-    : public integral_constant<bool, (__is_static_castable_safe<
-				      _From, _To>::value)>
-    { };
-
-  // Implementation for non-reference types. To meet the proper
-  // variable definition semantics, we also need to test for
-  // is_destructible in this case.
-  // This form should be simplified by a single expression:
-  // ::delete ::new _Tp(declval<_Arg>()), see c++/51222.
-  struct __do_is_direct_constructible_impl
-  {
-    template<typename _Tp, typename _Arg, typename
-	     = decltype(::new _Tp(declval<_Arg>()))>
-      static true_type __test(int);
-
-    template<typename, typename>
-      static false_type __test(...);
-  };
-
-  template<typename _Tp, typename _Arg>
-    struct __is_direct_constructible_impl
-    : public __do_is_direct_constructible_impl
-    {
-      typedef decltype(__test<_Tp, _Arg>(0)) type;
-    };
-
-  template<typename _Tp, typename _Arg>
-    struct __is_direct_constructible_new_safe
-    : public __and_<is_destructible<_Tp>,
-                    __is_direct_constructible_impl<_Tp, _Arg>>
-    { };
-
-  template<typename, typename>
-    struct is_same;
-
-  template<typename, typename>
-    struct is_base_of;
-
-  template<typename>
-    struct remove_reference;
-
-  template<typename _From, typename _To, bool
-           = __not_<__or_<is_void<_From>,
-                          is_function<_From>>>::value>
-    struct __is_base_to_derived_ref;
-
-  template<typename _Tp, typename... _Args>
-    struct is_constructible;
-
-  // Detect whether we have a downcast situation during
-  // reference binding.
-  template<typename _From, typename _To>
-    struct __is_base_to_derived_ref<_From, _To, true>
-    {
-      typedef typename remove_cv<typename remove_reference<_From
-        >::type>::type __src_t;
-      typedef typename remove_cv<typename remove_reference<_To
-        >::type>::type __dst_t;
-      typedef __and_<__not_<is_same<__src_t, __dst_t>>,
-		     is_base_of<__src_t, __dst_t>,
-		     __not_<is_constructible<__dst_t, _From>>> type;
-      static constexpr bool value = type::value;
-    };
-
-  template<typename _From, typename _To>
-    struct __is_base_to_derived_ref<_From, _To, false>
-    : public false_type
-    { };
-
-  template<typename _From, typename _To, bool
-           = __and_<is_lvalue_reference<_From>,
-                    is_rvalue_reference<_To>>::value>
-    struct __is_lvalue_to_rvalue_ref;
-
-  // Detect whether we have an lvalue of non-function type
-  // bound to a reference-compatible rvalue-reference.
-  template<typename _From, typename _To>
-    struct __is_lvalue_to_rvalue_ref<_From, _To, true>
-    {
-      typedef typename remove_cv<typename remove_reference<
-        _From>::type>::type __src_t;
-      typedef typename remove_cv<typename remove_reference<
-        _To>::type>::type __dst_t;
-      typedef __and_<__not_<is_function<__src_t>>,
-        __or_<is_same<__src_t, __dst_t>,
-		    is_base_of<__dst_t, __src_t>>> type;
-      static constexpr bool value = type::value;
-    };
-
-  template<typename _From, typename _To>
-    struct __is_lvalue_to_rvalue_ref<_From, _To, false>
-    : public false_type
-    { };
-
-  // Here we handle direct-initialization to a reference type as
-  // equivalent to a static_cast modulo overshooting conversions.
-  // These are restricted to the following conversions:
-  //    a) A base class value to a derived class reference
-  //    b) An lvalue to an rvalue-reference of reference-compatible
-  //       types that are not functions
-  template<typename _Tp, typename _Arg>
-    struct __is_direct_constructible_ref_cast
-    : public __and_<__is_static_castable<_Arg, _Tp>,
-                    __not_<__or_<__is_base_to_derived_ref<_Arg, _Tp>,
-                                 __is_lvalue_to_rvalue_ref<_Arg, _Tp>
-                   >>>
-    { };
-
-  template<typename _Tp, typename _Arg>
-    struct __is_direct_constructible_new
-    : public conditional<is_reference<_Tp>::value,
-			 __is_direct_constructible_ref_cast<_Tp, _Arg>,
-			 __is_direct_constructible_new_safe<_Tp, _Arg>
-			 >::type
-    { };
-
-  template<typename _Tp, typename _Arg>
-    struct __is_direct_constructible
-    : public __is_direct_constructible_new<_Tp, _Arg>::type
-    { };
-
-  // Since default-construction and binary direct-initialization have
-  // been handled separately, the implementation of the remaining
-  // n-ary construction cases is rather straightforward. We can use
-  // here a functional cast, because array types are excluded anyway
-  // and this form is never interpreted as a C cast.
-  struct __do_is_nary_constructible_impl
-  {
-    template<typename _Tp, typename... _Args, typename
-             = decltype(_Tp(declval<_Args>()...))>
-      static true_type __test(int);
-
-    template<typename, typename...>
-      static false_type __test(...);
-  };
-
-  template<typename _Tp, typename... _Args>
-    struct __is_nary_constructible_impl
-    : public __do_is_nary_constructible_impl
-    {
-      typedef decltype(__test<_Tp, _Args...>(0)) type;
-    };
-
-  template<typename _Tp, typename... _Args>
-    struct __is_nary_constructible
-    : public __is_nary_constructible_impl<_Tp, _Args...>::type
-    {
-      static_assert(sizeof...(_Args) > 1,
-                    "Only useful for > 1 arguments");
-    };
-
-  template<typename _Tp, typename... _Args>
-    struct __is_constructible_impl
-    : public __is_nary_constructible<_Tp, _Args...>
-    { };
-
-  template<typename _Tp, typename _Arg>
-    struct __is_constructible_impl<_Tp, _Arg>
-    : public __is_direct_constructible<_Tp, _Arg>
-    { };
-
-  template<typename _Tp>
-    struct __is_constructible_impl<_Tp>
-    : public is_default_constructible<_Tp>
-    { };
-
   /// is_constructible
   template<typename _Tp, typename... _Args>
     struct is_constructible
-    : public __is_constructible_impl<_Tp, _Args...>::type
+      : public __bool_constant<__is_constructible(_Tp, _Args...)>
     { };
 
   template<typename _Tp, bool = __is_referenceable<_Tp>::value>
@@ -1255,26 +1052,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public __is_nothrow_move_constructible_impl<_Tp>
     { };
 
-  template<typename _Tp, typename _Up>
-    class __is_assignable_helper
-    {
-      template<typename _Tp1, typename _Up1,
-	       typename = decltype(declval<_Tp1>() = declval<_Up1>())>
-	static true_type
-	__test(int);
-
-      template<typename, typename>
-	static false_type
-	__test(...);
-
-    public:
-      typedef decltype(__test<_Tp, _Up>(0)) type;
-    };
-
   /// is_assignable
   template<typename _Tp, typename _Up>
     struct is_assignable
-      : public __is_assignable_helper<_Tp, _Up>::type
+      : public __bool_constant<__is_assignable(_Tp, _Up)>
     { };
 
   template<typename _Tp, bool = __is_referenceable<_Tp>::value>
@@ -1364,8 +1145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// is_trivially_constructible
   template<typename _Tp, typename... _Args>
     struct is_trivially_constructible
-    : public __and_<is_constructible<_Tp, _Args...>, integral_constant<bool,
-			__is_trivially_constructible(_Tp, _Args...)>>
+    : public __bool_constant<__is_trivially_constructible(_Tp, _Args...)>
     { };
 
   /// is_trivially_default_constructible
@@ -1405,45 +1185,95 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   { };
 
   /// is_trivially_copy_constructible
+
+  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
+    struct __is_trivially_copy_constructible_impl;
+
   template<typename _Tp>
-    struct is_trivially_copy_constructible
+    struct __is_trivially_copy_constructible_impl<_Tp, false>
+    : public false_type { };
+
+  template<typename _Tp>
+    struct __is_trivially_copy_constructible_impl<_Tp, true>
     : public __and_<is_copy_constructible<_Tp>,
 		    integral_constant<bool,
 			__is_trivially_constructible(_Tp, const _Tp&)>>
     { };
 
+  template<typename _Tp>
+    struct is_trivially_copy_constructible
+    : public __is_trivially_copy_constructible_impl<_Tp>
+    { };
+
   /// is_trivially_move_constructible
+
+  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
+    struct __is_trivially_move_constructible_impl;
+
   template<typename _Tp>
-    struct is_trivially_move_constructible
+    struct __is_trivially_move_constructible_impl<_Tp, false>
+    : public false_type { };
+
+  template<typename _Tp>
+    struct __is_trivially_move_constructible_impl<_Tp, true>
     : public __and_<is_move_constructible<_Tp>,
 		    integral_constant<bool,
 			__is_trivially_constructible(_Tp, _Tp&&)>>
     { };
 
+  template<typename _Tp>
+    struct is_trivially_move_constructible
+    : public __is_trivially_move_constructible_impl<_Tp>
+    { };
+
   /// is_trivially_assignable
   template<typename _Tp, typename _Up>
     struct is_trivially_assignable
-    : public __and_<is_assignable<_Tp, _Up>,
-		    integral_constant<bool,
-			__is_trivially_assignable(_Tp, _Up)>>
+    : public __bool_constant<__is_trivially_assignable(_Tp, _Up)>
     { };
 
   /// is_trivially_copy_assignable
+
+  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
+    struct __is_trivially_copy_assignable_impl;
+
   template<typename _Tp>
-    struct is_trivially_copy_assignable
+    struct __is_trivially_copy_assignable_impl<_Tp, false>
+    : public false_type { };
+
+  template<typename _Tp>
+    struct __is_trivially_copy_assignable_impl<_Tp, true>
     : public __and_<is_copy_assignable<_Tp>,
 		    integral_constant<bool,
 			__is_trivially_assignable(_Tp&, const _Tp&)>>
     { };
 
+  template<typename _Tp>
+    struct is_trivially_copy_assignable
+    : public __is_trivially_copy_assignable_impl<_Tp>
+    { };
+
   /// is_trivially_move_assignable
+
+  template<typename _Tp, bool = __is_referenceable<_Tp>::value>
+    struct __is_trivially_move_assignable_impl;
+
   template<typename _Tp>
-    struct is_trivially_move_assignable
+    struct __is_trivially_move_assignable_impl<_Tp, false>
+    : public false_type { };
+
+  template<typename _Tp>
+    struct __is_trivially_move_assignable_impl<_Tp, true>
     : public __and_<is_move_assignable<_Tp>,
 		    integral_constant<bool,
 			__is_trivially_assignable(_Tp&, _Tp&&)>>
     { };
 
+  template<typename _Tp>
+    struct is_trivially_move_assignable
+    : public __is_trivially_move_assignable_impl<_Tp>
+    { };
+
   /// is_trivially_destructible
   template<typename _Tp>
     struct is_trivially_destructible