Index: clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
+++ clang-tools-extra/clang-tidy/readability/ContainerSizeEmptyCheck.cpp
@@ -194,7 +194,13 @@
   if (isBinaryOrTernary(E) || isa<UnaryOperator>(E)) {
     ReplacementText = "(" + ReplacementText + ")";
   }
-  if (E->getType()->isPointerType())
+  const auto *OpCallExpr = dyn_cast<CXXOperatorCallExpr>(E);
+  if (OpCallExpr &&
+      OpCallExpr->getOperator() == OverloadedOperatorKind::OO_Arrow) {
+    // This can happen if the object is a smart pointer. Don't add anything
+    // because a '->' is already there (PR#51776), just call the method.
+    ReplacementText += "empty()";
+  } else if (E->getType()->isPointerType())
     ReplacementText += "->empty()";
   else
     ReplacementText += ".empty()";
Index: clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/readability-container-size-empty.cpp
@@ -696,3 +696,17 @@
   instantiatedTemplateWithSizeCall<TypeWithSize>();
   instantiatedTemplateWithSizeCall<std::vector<int>>();
 }
+
+namespace std {
+template <typename T>
+struct unique_ptr {
+  T *operator->() const;
+};
+} // namespace std
+
+bool call_through_unique_ptr(const std::unique_ptr<std::vector<int>> &ptr) {
+  return ptr->size() > 0;
+  // CHECK-MESSAGES: :[[@LINE-1]]:10: warning: the 'empty' method should be used
+  // CHECK-MESSAGES: :9:8: note: method 'vector'::empty() defined here
+  // CHECK-FIXES: {{^  }}return !ptr->empty();
+}