[cxx-interop] Treat C++ structs that store iterators as unsafe

C++ types that store pointers as fields are treated as unsafe in Swift. Types that store other types that in turn store pointers are also treated as unsafe.

Types that store raw C++ iterators are also treated as unsafe in Swift. However, a type that stores another type that stores a raw iterator was previously imported as safe. This change fixes that.

rdar://105493479

Author: egorzhdan

lib/ClangImporter/ClangImporter.cpp

@@ -6274,6 +6274,9 @@ static bool hasPointerInSubobjects(const clang::CXXRecordDecl *decl) {
             hasUnsafeAPIAttr(cxxRecord))
           return false;
 
+        if (hasIteratorAPIAttr(cxxRecord) || isIterator(cxxRecord))
+          return true;
+
         if (hasPointerInSubobjects(cxxRecord))
           return true;
       }

test/Interop/Cxx/class/Inputs/type-classification.h

@@ -197,4 +197,20 @@ struct HasUnsupportedUsingShadow : DependentParent<int> {
   using typename DependentParent<int>::Child;
 };
 
+struct __attribute__((swift_attr("import_iterator"))) Iterator {
+  int idx;
+};
+
+struct HasMethodThatReturnsIterator {
+  Iterator getIterator() const;
+};
+
+struct IteratorBox {
+  Iterator it;
+};
+
+struct HasMethodThatReturnsIteratorBox {
+  IteratorBox getIteratorBox() const;
+};
+
 #endif // TEST_INTEROP_CXX_CLASS_INPUTS_TYPE_CLASSIFICATION_H

test/Interop/Cxx/class/type-classification-module-interface.swift

@@ -18,3 +18,17 @@
 // CHECK-NOT: StructWithDeletedDestructor
 // CHECK-NOT: StructWithInheritedDeletedDestructor
 // CHECK-NOT: StructWithSubobjectDeletedDestructor
+
+// CHECK: struct Iterator {
+// CHECK: }
+
+// CHECK: struct HasMethodThatReturnsIterator {
+// CHECK:   func __getIteratorUnsafe() -> Iterator
+// CHECK: }
+
+// CHECK: struct IteratorBox {
+// CHECK: }
+
+// CHECK: struct HasMethodThatReturnsIteratorBox {
+// CHECK:   func __getIteratorBoxUnsafe() -> IteratorBox
+// CHECK: }