Fix a newly-found false positive.

Author: hokein

clang/lib/Sema/CheckExprLifetime.cpp

@@ -367,6 +367,8 @@ static bool shouldTrackImplicitObjectArg(const CXXMethodDecl *Callee) {
   if (Callee->getReturnType()->isReferenceType()) {
     if (!Callee->getIdentifier()) {
       auto OO = Callee->getOverloadedOperator();
+      if (!Callee->getParent()->hasAttr<OwnerAttr>())
+        return false;
       return OO == OverloadedOperatorKind::OO_Subscript ||
              OO == OverloadedOperatorKind::OO_Star;
     }

clang/test/Sema/Inputs/lifetime-analysis.h

@@ -128,6 +128,11 @@ struct reference_wrapper {
 template<typename T>
 reference_wrapper<T> ref(T& t) noexcept;
 
+template <typename T>
+struct [[gsl::Pointer]] iterator {
+  T& operator*() const;
+};
+
 struct false_type {
     static constexpr bool value = false;
     constexpr operator bool() const noexcept { return value; }

clang/test/Sema/warn-lifetime-analysis-nocfg.cpp

@@ -752,4 +752,28 @@ Pointer test3(Bar bar) {
   return bar; // expected-warning {{address of stack}}
 }
 
+template<typename T>
+struct MySpan {
+  MySpan(const std::vector<T>& v);
+  using iterator = std::iterator<T>;
+  iterator begin() const [[clang::lifetimebound]];
+};
+template <typename T>
+typename MySpan<T>::iterator ReturnFirstIt(const MySpan<T>& v [[clang::lifetimebound]]);
+
+void test4() {
+  std::vector<int> v{1};
+  // MySpan<T> doesn't own any underlying T objects, the pointee object of
+  // the MySpan iterator is still alive when the whole span is destroyed, thus
+  // no diagnostic.
+  const int& t1 = *MySpan<int>(v).begin();
+  const int& t2 = *ReturnFirstIt(MySpan<int>(v));
+  // Ideally, we would diagnose the following case, but due to implementation
+  // constraints, we do not.
+  const int& t4 = *MySpan<int>(std::vector<int>{}).begin();
+  
+  auto it1 = MySpan<int>(v).begin(); // expected-warning {{temporary whose address is use}}
+  auto it2 = ReturnFirstIt(MySpan<int>(v)); // expected-warning {{temporary whose address is used}}
+}
+
 } // namespace LifetimeboundInterleave