[cfe-dev] Name lookup in ObjC methods

[Ted Kremenek]

Argiris,

I've been very impressed with the work you have been doing on all of  
this.  It's quite impressive, and will make a great contribution to  
clang.  Comments inline.

On Apr 2, 2008, at 8:30 AM, Argiris Kirtzidis wrote:

> Chris Lattner wrote:
>>> -Decl class has a ContextDecl member
>>
>> Should this be in Decl, or in ScopedDecl?  It doesn't make much sense
>> for struct fields (for example) to have this context pointer.

Chris: Why is that the case?  For example, I can imagine cases in the  
static analyzer where knowing the RecordDecl for a given structure  
field could potentially be very useful, and clean some things up  
nicely.  Is it the cost of the extra pointer that you are worried about?

>>
>>
>>> -All Decl subclasses receive a ContextDecl at their constructors
>>
>> Sounds good, but only scopedecl if possible.
> Isn't this a bit restricting ? When NamespaceDecl is added,
> non-ScopedDecls could be under TranslationUnitDecl or a
> specific NamespaceDecl. NamespaceDecl itself makes little sense to  
> be a
> ScopedDecl, but it makes sense to give it
> a context pointer to its enclosing namespace.
> Most of the non-ScopedDecls are ObjC specific but for Objective C++  
> they
> will be able to use NamespaceDecl
> context pointers to, for example, get their fully qualified name.

All of this makes a lot of sense to me.  I like the unifying concept  
of context here, from the TranslationUnit level and down, and I like  
having NamespaceDecls having an enclosing context, etc., so that one  
can easily traverse the namespace hierarchy.  I'm curious, how would  
the following be handled:

   namespace foo {
     class F {  public:  void foo(); };
   }

   using namespace foo;

   void F::foo() {}

What would the "ContextDecl" be for the decl representing the  
definition of foo?  Would it be a NamespaceDecl, or a  
TranslationUnitDecl?  If it is a NamespaceDecl, is it the same  
NamespaceDecl as the one enclosing the class definition?  I'm sorry if  
this has already been discussed; I'm trying to wrap my mind around  
what exactly a ContextDecl is, as it seems to represents both a  
syntactic construct and a language concept.

> And if RecordDecl is made a ContextDecl (mostly useful for C++), a
> context pointer for FieldDecl would point at
> the struct/class that defined it.

This makes sense to me, and I think it would be very useful.