--- build/rust/allocator/alias.h.orig	2025-05-20 09:16:26 UTC
+++ build/rust/allocator/alias.h
@@ -0,0 +1,37 @@
+// Copyright 2023 The Chromium Authors
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// This file has been copied from //base/debug/alias.h (and then trimmed to just
+// the APIs / macros needed by //build/rust/std;  additionally the APIs were
+// moved into the `build_rust_std` namespace).
+//
+// TODO(crbug.com/40279749): Avoid code duplication / reuse code.
+
+#ifndef BUILD_RUST_ALLOCATOR_ALIAS_H_
+#define BUILD_RUST_ALLOCATOR_ALIAS_H_
+
+#include <stddef.h>
+
+namespace build_rust_std {
+namespace debug {
+
+// Make the optimizer think that |var| is aliased. This can be used to prevent a
+// local variable from being optimized out (which is something that
+// `NO_CODE_FOLDING` macro definition below depends on).  See
+// //base/debug/alias.h for more details.
+void Alias(const void* var);
+
+}  // namespace debug
+
+}  // namespace build_rust_std
+
+// Prevent code folding (where a linker identifies functions that are
+// bit-identical and overlays them, which saves space but it leads to confusing
+// call stacks because multiple symbols are at the same address).  See
+// //base/debug/alias.h for more details.
+#define NO_CODE_FOLDING()           \
+  const int line_number = __LINE__; \
+  build_rust_std::debug::Alias(&line_number)
+
+#endif  // BUILD_RUST_ALLOCATOR_ALIAS_H_