From db072f75e5ade3b9f1f2ff76fcdfda0d3bf028d1 Mon Sep 17 00:00:00 2001
From: Jonathan Wakely <jwakely@redhat.com>
Date: Thu, 12 Feb 2026 18:52:12 +0000
Subject: [PATCH] libstdc++: Fix fallback definitions of
 std::is_member_*_pointer

When the builtins aren't used we need a declaration of std::is_function
for the fallback definitions of std::is_member_function_pointer and
std::is_member_object_pointer.

libstdc++-v3/ChangeLog:

	* include/std/type_traits (is_function): Declare before first
	use.
---
 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 d533dc0ef09..ea700d1ed97 100644
--- a/libstdc++-v3/include/std/type_traits
+++ b/libstdc++-v3/include/std/type_traits
@@ -674,6 +674,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public __bool_constant<__is_member_object_pointer(_Tp)>
     { };
 #else
+  template<typename _Tp>
+    struct is_function;
+
   template<typename>
     struct __is_member_object_pointer_helper
     : public false_type { };
@@ -696,6 +699,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public __bool_constant<__is_member_function_pointer(_Tp)>
     { };
 #else
+  template<typename _Tp>
+    struct is_function;
+
   template<typename>
     struct __is_member_function_pointer_helper
     : public false_type { };
-- 
2.47.3