Address review comments

Author: sam-mccall

clang/include/clang/Basic/AttrDocs.td

@@ -4152,10 +4152,11 @@ non-underscored keywords. For example:
       @property (readonly, nonnull) NSArray *subviews;
     @end
 
-As well as built-in pointer types, ithe nullability attributes can be attached
-to nullable types from the C++ standard library such as ``std::unique_ptr`` and
-``std::function``, as well as C++ classes marked with the ``_Nullable``
-attribute.
+As well as built-in pointer types, the nullability attributes can be attached
+to C++ classes marked with the ``_Nullable`` attribute, as well as the C++
+standard library types ``unique_ptr``, ``shared_ptr``, ``auto_ptr``,
+``exception_ptr``, ``function``, ``move_only_function`` and
+``coroutine_handle``.
   }];
 }
 

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5981,7 +5981,7 @@ static void handleNullableTypeAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
     return;
 
   if (auto *CRD = dyn_cast<CXXRecordDecl>(D);
-      !D || !(CRD->isClass() || CRD->isStruct())) {
+      !CRD || !(CRD->isClass() || CRD->isStruct())) {
     S.Diag(AL.getRange().getBegin(), diag::err_attribute_wrong_decl_type_str)
         << AL << AL.isRegularKeywordAttribute() << "classes";
     return;

clang/test/Sema/nullability.c

@@ -248,3 +248,5 @@ void arraysInBlocks(void) {
   void (^withTypedefBad)(INTS _Nonnull [2]) = // expected-error {{nullability specifier '_Nonnull' cannot be applied to non-pointer type 'INTS' (aka 'int[4]')}}
       ^(INTS _Nonnull x[2]) {}; // expected-error {{nullability specifier '_Nonnull' cannot be applied to non-pointer type 'INTS' (aka 'int[4]')}}
 }
+
+struct _Nullable NotCplusplusClass {}; // expected-error {{'_Nullable' attribute only applies to classes}}

clang/test/SemaCXX/nullability.cpp

@@ -155,7 +155,7 @@ void AssignAndInitNonNullFromFn() {
   SmartPtr _Nonnull s_nonnull;
   s_nonnull = ReturnSmartNullable(); // expected-warning{{implicit conversion from nullable pointer 'SmartPtr _Nullable' to non-nullable pointer type 'SmartPtr _Nonnull'}}
   s_nonnull = {ReturnSmartNullable()};
-  TakeSmartNonnull(ReturnSmartNullable()); //expected-warning{{implicit conversion from nullable pointer 'SmartPtr _Nullable' to non-nullable pointer type 'SmartPtr _Nonnull}}
+  TakeSmartNonnull(ReturnSmartNullable()); // expected-warning{{implicit conversion from nullable pointer 'SmartPtr _Nullable' to non-nullable pointer type 'SmartPtr _Nonnull'}}
 }
 
 void ConditionalExpr(bool c) {