[cfe-dev] [Patch] IDNS_NoLookup?

[Douglas Gregor]

On Jan 18, 2009, at 8:00 PM, Douglas Gregor wrote:
> On Jan 18, 2009, at 5:58 PM, Chris Lattner wrote:
>
>> On Jan 18, 2009, at 5:02 PM, Douglas Gregor wrote:
>>> Ah, so that's the issue... the ObjCImplementationDecls need to have
>>> an
>>> identifier namespace, because they have  name, but they aren't
>>> supposed to be found by name lookup (rather, we see them through the
>>> ObjCInterfaceDecl).
>>
>> Ah, very interesting.  I think the right fix is that
>> ObjCImplementationDecl should not be scope decls and maybe not even
>> NamedDecls.  They should never ever be "looked up".
>
> I think we should swap ScopedDecl and NamedDecl in the inheritance
> hierarchy. Things without names---like, perhaps,
> ObjCImplementationDecl---should still be ScopedDecls and live inside
> DeclContexts (so we know where they occur, lexically, in the program,
> and who their owners are) but they don't need any storage for names.

For everyone who doesn't watch commits: we've gone slightly further  
this with, removing ScopedDecl entirely and collapsing its fields into  
Decl so that *every* declaration lives within a DeclContext. That way,  
traversing through the various DeclContexts in a program will  
(eventually) visit every declaration in the program.

Many *Decl nodes inherit from NamedDecl, meaning that they can have a  
name and therefore can be found by name lookup. To address the problem  
that Piotr found, we've taken some *Decl nodes that used to be  
NamedDecls (ObjCImplementationDecl and LinkageSpecDecl, for example)  
and made them inherit directly from Decl so that they don't ever have  
names and can't ever be inserted for name lookup to find.

   - Doug