From 2074b975c3d08fec2ecd47dab48132be2ec7c3cf Mon Sep 17 00:00:00 2001
From: Kim Barrett <kbarrett@openjdk.org>
Date: Wed, 7 Jan 2026 10:06:29 +0000
Subject: [PATCH] 8374623: Move DependentAlwaysFalse variable template to its
 own file

Reviewed-by: jsjolen
---
 .../metaprogramming/dependentAlwaysFalse.hpp  | 36 +++++++++++++++++++
 src/hotspot/share/runtime/atomic.hpp          |  3 +-
 .../share/utilities/globalDefinitions.hpp     | 10 +-----
 src/hotspot/share/utilities/lockFreeStack.hpp |  3 +-
 4 files changed, 41 insertions(+), 11 deletions(-)
 create mode 100644 src/hotspot/share/metaprogramming/dependentAlwaysFalse.hpp

diff --git a/src/hotspot/share/metaprogramming/dependentAlwaysFalse.hpp b/src/hotspot/share/metaprogramming/dependentAlwaysFalse.hpp
new file mode 100644
index 00000000000..b1f9d89df11
--- /dev/null
+++ b/src/hotspot/share/metaprogramming/dependentAlwaysFalse.hpp
@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2025, 2026, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#ifndef SHARE_METAPROGRAMMING_DEPENDENTALWAYSFALSE_HPP
+#define SHARE_METAPROGRAMMING_DEPENDENTALWAYSFALSE_HPP
+
+// This provides a workaround for static_assert(false) in discarded or
+// otherwise uninstantiated places.  Instead use
+//   static_assert(DependentAlwaysFalse<T>, "...")
+// See http://wg21.link/p2593r1. Some, but not all, compiler versions we're
+// using have implemented that change as a DR:
+// https://cplusplus.github.io/CWG/issues/2518.html
+template<typename T> inline constexpr bool DependentAlwaysFalse = false;
+
+#endif // SHARE_METAPROGRAMMING_DEPENDENTALWAYSFALSE_HPP
diff --git a/src/hotspot/share/runtime/atomic.hpp b/src/hotspot/share/runtime/atomic.hpp
index 0c335913b5c..02e9f82cfb6 100644
--- a/src/hotspot/share/runtime/atomic.hpp
+++ b/src/hotspot/share/runtime/atomic.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2025, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,6 +26,7 @@
 #define SHARE_RUNTIME_ATOMIC_HPP
 
 #include "cppstdlib/type_traits.hpp"
+#include "metaprogramming/dependentAlwaysFalse.hpp"
 #include "metaprogramming/primitiveConversions.hpp"
 #include "runtime/atomicAccess.hpp"
 #include "utilities/globalDefinitions.hpp"
diff --git a/src/hotspot/share/utilities/globalDefinitions.hpp b/src/hotspot/share/utilities/globalDefinitions.hpp
index 3284fd3bd15..54602297759 100644
--- a/src/hotspot/share/utilities/globalDefinitions.hpp
+++ b/src/hotspot/share/utilities/globalDefinitions.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -1374,14 +1374,6 @@ template<typename K> int primitive_compare(const K& k0, const K& k1) {
 template<typename T>
 std::add_rvalue_reference_t<T> declval() noexcept;
 
-// This provides a workaround for static_assert(false) in discarded or
-// otherwise uninstantiated places.  Instead use
-//   static_assert(DependentAlwaysFalse<T>, "...")
-// See http://wg21.link/p2593r1. Some, but not all, compiler versions we're
-// using have implemented that change as a DR:
-// https://cplusplus.github.io/CWG/issues/2518.html
-template<typename T> inline constexpr bool DependentAlwaysFalse = false;
-
 // Quickly test to make sure IEEE-754 subnormal numbers are correctly
 // handled.
 bool IEEE_subnormal_handling_OK();
diff --git a/src/hotspot/share/utilities/lockFreeStack.hpp b/src/hotspot/share/utilities/lockFreeStack.hpp
index 3f63482a268..871e697f404 100644
--- a/src/hotspot/share/utilities/lockFreeStack.hpp
+++ b/src/hotspot/share/utilities/lockFreeStack.hpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, 2025, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2019, 2026, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,6 +25,7 @@
 #ifndef SHARE_UTILITIES_LOCKFREESTACK_HPP
 #define SHARE_UTILITIES_LOCKFREESTACK_HPP
 
+#include "metaprogramming/dependentAlwaysFalse.hpp"
 #include "runtime/atomic.hpp"
 #include "runtime/atomicAccess.hpp"
 #include "utilities/debug.hpp"