Index: clang/lib/Analysis/UnsafeBufferUsage.cpp
===================================================================
--- clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -660,8 +660,20 @@
   return {std::move(CB.FixableGadgets), std::move(CB.WarningGadgets), std::move(CB.Tracker)};
 }
 
+// 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();
+  }
+};
+
 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:
+           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;