PATCH: private ivars

[Adrian Prantl]

On Feb 18, 2013, at 4:28 PM, David Blaikie <dblaikie at gmail.com> wrote:
> On Mon, Feb 18, 2013 at 4:24 PM, Adrian Prantl <aprantl at apple.com> wrote:
> On Feb 15, 2013, at 3:59 PM, Dmitri Gribenko <gribozavr at gmail.com> wrote:
> >
> > +    ObjCInterfaceDecl* decl = cast<ObjCInterfaceType>(Ty)->getDecl();
> > +    if (decl)
> >
> > cast<> can not return null (it will either succeed or assert in
> > +Asserts mode, or just produce a wrong value in -Asserts).  Use
> > dyn_cast (that returns null on failure) or drop the check -- whatever
> > is appropriate.  And there's a dyn_cast idiom:
> >
> > if (Foo *F = dyn_cast<Foo>(Blah))
> > ... use F...
> 
> I'm actually not checking the return value from cast<>() but the the result of getDecl() [which just happens to also return an ObjCInterfaceDecl]. Do you think I should use a temporary for the result of the cast to make it clearer?
> 
> Then you're missing test cases, because dyn_cast doesn't propagate null. It should fail if you pass it null.
> 
> You  probably want cast_or_null. 

At least in my particular case I'm not so sure about this. The code fragment we are talking about looks like this:

 switch (Ty->getTypeClass()) {
  ...
  case Type::ObjCInterface: {
    ObjCInterfaceDecl* Decl = cast<ObjCInterfaceType>(Ty)->getDecl();
    if (Decl)
       ...
  }

At this point Ty should always be nonzero and since we switch over the TypeClass the cast<> should always be safe, right?

-- adrian