[Lifetimes] Fix false positive warning from BUG 49342

[xazax.hun]

Summary

After some interaction between the statement local lifetime analysis and some newly introduced warnings (https://github.com/llvm/llvm-project/commit/2177e4555ab84771c611a3295ab1149af7f79c29), a new false positive pattern appeared. This patch updates the logic that is responsible to make sure we only warn for a returned GslPointer when it was initialized from a value with a local owner.

clang/lib/Sema/SemaInit.cpp

 }
 
 static bool pathOnlyInitializesGslPointer(IndirectLocalPath &Path) {
   for (auto It = Path.rbegin(), End = Path.rend(); It != End; ++It) {
     if (It->Kind == IndirectLocalPathEntry::VarInit)
       continue;
     if (It->Kind == IndirectLocalPathEntry::AddressOf)
       continue;
+    if (It->Kind == IndirectLocalPathEntry::LifetimeBoundCall)
+      continue;
     return It->Kind == IndirectLocalPathEntry::GslPointerInit ||
            It->Kind == IndirectLocalPathEntry::GslReferenceInit;
   }
   return false;
 }
 
 void Sema::checkInitializerLifetime(const InitializedEntity &Entity,
                                     Expr *Init) {

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

 };
 
 template<typename T>
 struct basic_string_view {
   basic_string_view(const T *);
   const T *begin() const;
 };
 
+template<class _Mystr> struct iter {
+    iter& operator-=(int);
+
+    iter operator-(int _Off) const {
+        iter _Tmp = *this;
+        return _Tmp -= _Off;
+    }
+};
+
 template<typename T>
 struct basic_string {
   basic_string();
   basic_string(const T *);
   const T *c_str() const;
   operator basic_string_view<T> () const;
+  using const_iterator = iter<T>;
 };
 
 
 template<typename T>
 struct unique_ptr {
   T &operator*();
   T *get() const;
 };

 MyIntPointer handleDerivedToBaseCast2(MyOwnerIntPointer ptr) {
   return ptr; // expected-warning {{address of stack memory associated with parameter 'ptr' returned}}
 }
 
 std::vector<int>::iterator noFalsePositiveWithVectorOfPointers() {
   std::vector<std::vector<int>::iterator> iters;
   return iters.at(0);
 }
+
+void testForBug49342()
+{
+  auto it = std::iter<char>{} - 2; // Used to be false positive.
+}