Index: clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
===================================================================
--- clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
+++ clang/include/clang/Analysis/Analyses/UnsafeBufferUsage.h
@@ -61,6 +61,14 @@
 // conflict if they have overlapping source ranges.
 bool anyConflict(const llvm::SmallVectorImpl<FixItHint> &FixIts,
                  const SourceManager &SM);
+
+// Compares AST nodes by source locations.
+template <typename NodeTy> struct CompareNode {
+  bool operator()(const NodeTy *N1, const NodeTy *N2) const {
+    return N1->getBeginLoc().getRawEncoding() <
+           N2->getBeginLoc().getRawEncoding();
+  }
+};
 } // namespace internal
 } // end namespace clang
 
Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -661,7 +661,11 @@
 }
 
 struct WarningGadgetSets {
-  std::map<const VarDecl *, std::set<std::unique_ptr<WarningGadget>>> byVar;
+  std::map<const VarDecl *, std::set<std::unique_ptr<WarningGadget>>,
+           // To keep keys sorted by their locations in the map so that the
+           // order is deterministic:
+           clang::internal::CompareNode<VarDecl>>
+      byVar;
   // These Gadgets are not related to pointer variables (e. g. temporaries).
   llvm::SmallVector<std::unique_ptr<WarningGadget>, 16> noVar;
 };
Index: clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
===================================================================
--- clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
+++ clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-local-var-span.cpp
@@ -1,4 +1,3 @@
-// REQUIRES: !system-windows
 // RUN: %clang_cc1 -std=c++20 -Wunsafe-buffer-usage -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
 typedef int * Int_ptr_t;
 typedef int Int_t;