Question: Need to store ObjC-specific info in type nodes.

[Ziemowit Laski]

Currently, ObjC does some rather ghastly things with accessors such as 
TYPE_CONTEXT, TREE_PUBLIC and TYPE_MAIN_VARIANT, which are used for its 
own merry purposes in RECORD_TYPEs.  This is a horrible state of 
affairs, and so I'd like to clean up the way ObjC stores its own 
information so that it plays nice(r) with what C and C++ expect.  (This 
work is part of the ongoing ObjC++ integration, BTW, so a prompt 
response would be appreciated.)

There seem to be several ways of attacking this, but I'd like to ask 
the powers that be for the preferred approach before actually 
undertaking it:
(1)  The additional info required for ObjC RECORD_TYPEs is stored as 
attributes, which peacefully co-exist with C/C++ attributes in the
      TYPE_ATTRIBUTES accessor.
(2)  In addition to a 'struct lang_type *lang_specific' field, each 
type node also gets a 'struct objc_lang_type *objc_lang_specific' field 
(set to NULL in plain C and C++ modes).
(3)  A variation of (2) in which 'struct lang_type' itself (both in C 
and C++) gets 'struct objc_lang_type *objc_lang_specific' field.

Which of these would be preferable and/or have I left out other 
possibilities?  It seems that (1) would require least (if any!) changes 
to existing GCC infrastructure, but the resulting ObjC/ObjC++ 
compile-time performance would be less than stellar.  Personally, I 
favor (3).

Please advise,

--Zem