From: Patrick Palka <ppalka@redhat.com>
Date: Wed, 7 Sep 2022 14:21:51 +0000 (-0400)
Subject: libstdc++: Optimize is_reference
X-Git-Tag: basepoints/gcc-14~4684
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=cdcc27c1ca9c485c66ac1914e352c79e5048b6b5;p=thirdparty%2Fgcc.git

libstdc++: Optimize is_reference

Instead of defining is_reference in terms of is_[lr]value_reference,
just define it directly.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_reference): Make the primary
	template derive from false_type.  Define two partial
	specializations that derive from true_type.
---

diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
index b83e7257a9f3..94e73eafd2fb 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -611,8 +611,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// is_reference
   template<typename _Tp>
     struct is_reference
-    : public __or_<is_lvalue_reference<_Tp>,
-                   is_rvalue_reference<_Tp>>::type
+    : public false_type
+    { };
+
+  template<typename _Tp>
+    struct is_reference<_Tp&>
+    : public true_type
+    { };
+
+  template<typename _Tp>
+    struct is_reference<_Tp&&>
+    : public true_type
     { };
 
   /// is_arithmetic