Revert "[cxx-interop] Treat un-instantiated templated types as unsafe"

This reverts commit c813254.

This caused #65446

Author: hyp

lib/ClangImporter/ClangImporter.cpp

@@ -6396,9 +6396,7 @@ static bool hasIteratorAPIAttr(const clang::Decl *decl) {
 static bool hasPointerInSubobjects(const clang::CXXRecordDecl *decl) {
   // Probably a class template that has not yet been specialized:
   if (!decl->getDefinition())
-    // If the definition is unknown, there is no way to determine if the type
-    // stores pointers. Stay on the safe side and assume that it does.
-    return true;
+    return false;
 
   auto checkType = [](clang::QualType t) {
     if (t->isPointerType())
@@ -6693,10 +6691,9 @@ bool IsSafeUseOfCxxDecl::evaluate(Evaluator &evaluator,
           return false;
         }
 
+        // Mark this as safe to help our diganostics down the road.
         if (!cxxRecordReturnType->getDefinition()) {
-          // This is a templated type that has not been instantiated yet. We do
-          // not know if it is safe. Assume that it isn't.
-          return false;
+          return true;
         }
 
         if (!cxxRecordReturnType->hasUserDeclaredCopyConstructor() &&

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

@@ -213,32 +213,4 @@ struct HasMethodThatReturnsIteratorBox {
   IteratorBox getIteratorBox() const;
 };
 
-template <typename T>
-struct TemplatedPointerBox {
-  T *ptr;
-};
-
-struct HasMethodThatReturnsTemplatedPointerBox {
-  TemplatedPointerBox<int> getTemplatedPointerBox() const;
-};
-
-template <typename T>
-struct TemplatedBox {
-  T value;
-};
-
-struct HasMethodThatReturnsTemplatedBox {
-  TemplatedBox<int> getIntBox() const;
-  TemplatedBox<int *> getIntPtrBox() const;
-};
-
-template <typename T>
-struct __attribute__((swift_attr("import_iterator"))) TemplatedIterator {
-  T idx;
-};
-
-struct HasMethodThatReturnsTemplatedIterator {
-  TemplatedIterator<int *> getIterator() const;
-};
-
 #endif // TEST_INTEROP_CXX_CLASS_INPUTS_TYPE_CLASSIFICATION_H

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

@@ -35,18 +35,3 @@
 // CHECK:   func __getIteratorBoxUnsafe() -> IteratorBox
 // CHECK-SKIP-UNSAFE-NOT: func __getIteratorBoxUnsafe() -> IteratorBox
 // CHECK: }
-
-// CHECK: struct HasMethodThatReturnsTemplatedPointerBox {
-// CHECK:   func __getTemplatedPointerBoxUnsafe() -> TemplatedPointerBox<Int32>
-// CHECK-SKIP-UNSAFE-NOT: func __getTemplatedPointerBoxUnsafe() -> TemplatedPointerBox<Int32>
-// CHECK: }
-
-// CHECK: struct HasMethodThatReturnsTemplatedBox {
-// FIXME: This is unfortunate, we should be able to recognize that TemplatedBox<Int32> does not store any pointers as fields.
-// CHECK:   func __getIntBoxUnsafe() -> TemplatedBox<Int32>
-// CHECK:   func __getIntPtrBoxUnsafe()
-// CHECK: }
-
-// CHECK: struct HasMethodThatReturnsTemplatedIterator {
-// CHECK:   func __getIteratorUnsafe()
-// CHECK: }

test/Interop/Cxx/templates/Inputs/large-class-templates.h

@@ -28,17 +28,17 @@ struct ValExpr {
   using type = typename E::type;
   E expr;
 
-  ValExpr<SliceExpr<E, 1>> test1() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 1>{expr}}; }
-  ValExpr<SliceExpr<E, 2>> test2() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 2>{expr}}; }
-  ValExpr<SliceExpr<E, 3>> test3() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 3>{expr}}; }
-  ValExpr<SliceExpr<E, 4>> test4() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 4>{expr}}; }
-  ValExpr<SliceExpr<E, 5>> test5() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 5>{expr}}; }
-  ValExpr<SliceExpr<E, 6>> test6() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 6>{expr}}; }
-  ValExpr<SliceExpr<E, 7>> test7() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 7>{expr}}; }
-  ValExpr<SliceExpr<E, 8>> test8() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 8>{expr}}; }
-  ValExpr<SliceExpr<E, 9>> test9() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 8>{expr}}; }
-  ValExpr<SliceExpr<E, 11>> test11() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 11>{expr}}; }
-  ValExpr<SliceExpr<E, 12>> test12() __attribute__((swift_attr("import_unsafe"))) { return {SliceExpr<E, 12>{expr}}; }
+  ValExpr<SliceExpr<E, 1>> test1() { return {SliceExpr<E, 1>{expr}}; }
+  ValExpr<SliceExpr<E, 2>> test2() { return {SliceExpr<E, 2>{expr}}; }
+  ValExpr<SliceExpr<E, 3>> test3() { return {SliceExpr<E, 3>{expr}}; }
+  ValExpr<SliceExpr<E, 4>> test4() { return {SliceExpr<E, 4>{expr}}; }
+  ValExpr<SliceExpr<E, 5>> test5() { return {SliceExpr<E, 5>{expr}}; }
+  ValExpr<SliceExpr<E, 6>> test6() { return {SliceExpr<E, 6>{expr}}; }
+  ValExpr<SliceExpr<E, 7>> test7() { return {SliceExpr<E, 7>{expr}}; }
+  ValExpr<SliceExpr<E, 8>> test8() { return {SliceExpr<E, 8>{expr}}; }
+  ValExpr<SliceExpr<E, 9>> test9() { return {SliceExpr<E, 8>{expr}}; }
+  ValExpr<SliceExpr<E, 11>> test11() { return {SliceExpr<E, 11>{expr}}; }
+  ValExpr<SliceExpr<E, 12>> test12() { return {SliceExpr<E, 12>{expr}}; }
 };
 
 // This class template is exponentially slow to *fully* instantiate (and the