[cfe-dev] Normalizing the AST across languages

[Chris Lattner]

On Oct 30, 2008, at 12:52 PM, Doug Gregor wrote:
>>> The intent of CXXRecordDecl is clear: since C++ requires us to keep
>>> additional information about classes in the AST (which isn't  
>>> needed in
>>> C), all that extra information goes into CXXRecordDecl so that we
>>> don't bloat the C compilation with unused data.  This means that
>>> compiling a C program as C++ uses different ASTs and requires more
>>> memory.
>>
>> Right, this is something I asked Argiris to do.  The intent was for  
>> "C like"
>> struct definitions in C++ to use the lighter weight RecordDecl when  
>> possible
>> (which is what the fixme is about).
>
> I don't see how it can work. The problem is that we need to allocate
> the RecordDecl as soon as we see the "struct Blah". After we've done
> that, we can't go back and make it into a CXXRecordDecl if we then
> find out that it has friend declarations.

Yep, this is a very good point.  Perhaps Argiris' suggestion of making  
*all* instance variables be a separate allocation from the decl would  
help?

-Chris