[PATCH v2 4/4] libstdc++: Optimize std::remove_extent compilation performance

[Ken Matsui <kmatsui@gcc.gnu.org>]

This patch optimizes the compilation performance of std::remove_extent
by dispatching to the new __remove_extent built-in trait.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (remove_extent): Use __remove_extent
	built-in trait.

Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
---
 libstdc++-v3/include/std/type_traits | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index 3bde7cb8ba3..0fb1762186c 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -2064,6 +2064,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // Array modifications.
 
   /// remove_extent
+#if _GLIBCXX_USE_BUILTIN_TRAIT(__remove_extent)
+  template<typename _Tp>
+    struct remove_extent
+    { using type = __remove_extent(_Tp); };
+#else
   template<typename _Tp>
     struct remove_extent
     { using type = _Tp; };
@@ -2075,6 +2080,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _Tp>
     struct remove_extent<_Tp[]>
     { using type = _Tp; };
+#endif
 
   /// remove_all_extents
   template<typename _Tp>
-- 
2.43.0