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[committed] libstdc++: Simplify constraints for std::any construction

Message ID YVxn+QG4OV4lPi43@redhat.com
State New
Headers show
Series [committed] libstdc++: Simplify constraints for std::any construction | expand

Commit Message

Jonathan Wakely Oct. 5, 2021, 2:58 p.m. UTC 
libstdc++-v3/ChangeLog:

	* include/bits/utility.h (__is_in_place_type_v): Define
	variable template to detect in_place_type_t specializations.
	(__is_in_place_type): Replace class template with alias
	template using __is_in_place_type_v.
	* include/std/any (any(T&&)): Check __is_in_place_type first and
	avoid instantiating is_copy_constructible unnecessarily.

Tested powerpc64le-linux. Committed to trunk.
commit 6da36b7d0e43b6f9281c65c19a025d4888a25b2d
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Oct 4 23:14:30 2021

    libstdc++: Simplify constraints for std::any construction
    
    libstdc++-v3/ChangeLog:
    
            * include/bits/utility.h (__is_in_place_type_v): Define
            variable template to detect in_place_type_t specializations.
            (__is_in_place_type): Replace class template with alias
            template using __is_in_place_type_v.
            * include/std/any (any(T&&)): Check __is_in_place_type first and
            avoid instantiating is_copy_constructible unnecessarily.
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Patch

diff --git a/libstdc++-v3/include/bits/utility.h b/libstdc++-v3/include/bits/utility.h
index 96d350874d9..fce52a4530d 100644
--- a/libstdc++-v3/include/bits/utility.h
+++ b/libstdc++-v3/include/bits/utility.h
@@ -184,17 +184,14 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     inline constexpr in_place_index_t<_Idx> in_place_index{};
 
   template<typename>
-    struct __is_in_place_type_impl : false_type
-    { };
+    inline constexpr bool __is_in_place_type_v = false;
 
   template<typename _Tp>
-    struct __is_in_place_type_impl<in_place_type_t<_Tp>> : true_type
-    { };
+    inline constexpr bool __is_in_place_type_v<in_place_type_t<_Tp>> = true;
 
   template<typename _Tp>
-    struct __is_in_place_type
-      : public __is_in_place_type_impl<_Tp>
-    { };
+    using __is_in_place_type = bool_constant<__is_in_place_type_v<_Tp>>;
+
 #endif // C++17
 #endif // C++14
 
diff --git a/libstdc++-v3/include/std/any b/libstdc++-v3/include/std/any
index 625cac619f0..e3d9d774de4 100644
--- a/libstdc++-v3/include/std/any
+++ b/libstdc++-v3/include/std/any
@@ -183,8 +183,8 @@  _GLIBCXX_BEGIN_NAMESPACE_VERSION
     /// Construct with a copy of @p __value as the contained object.
     template <typename _Tp, typename _VTp = _Decay_if_not_any<_Tp>,
 	      typename _Mgr = _Manager<_VTp>,
-	      enable_if_t<is_copy_constructible<_VTp>::value
-			  && !__is_in_place_type<_VTp>::value, bool> = true>
+	      typename = _Require<__not_<__is_in_place_type<_VTp>>,
+				  is_copy_constructible<_VTp>>>
       any(_Tp&& __value)
       : _M_manager(&_Mgr::_S_manage)
       {