[PATCH 15/18] move REAL_IDENTIFIER_TYPE_VALUE to be a field of lang_identifier

[Jason Merrill]

On 03/11/2011 09:19 AM, Nathan Froyd wrote:
> On Fri, Mar 11, 2011 at 06:04:45AM -0800, Nathan Froyd wrote:
>> On Fri, Mar 11, 2011 at 08:40:24AM -0500, Jason Merrill wrote:
>>> On 03/10/2011 11:23 PM, Nathan Froyd wrote:
>>> The C++ FE expects that we can check the TREE_TYPE of anything that
>>> appears as an expression, and uses IDENTIFIER_NODE to indicate a
>>> dependent name within templates.  If you want to break TREE_TYPE on
>>> IDENTIFIER_NODE, you need to change the representation of dependent
>>> names so that we can continue to use TREE_TYPE on all expressions.
>>
>> I'm confused.  Isn't this what the switching on IDENTIFIER_NODE in a
>> number of places is doing?  (And any future places that g++/libstdc++
>> didn't catch will be an ICE.)  Or are you saying that you don't want the
>> switching and IDENTIFIER_NODEs should retain TREE_TYPE unless and until
>> somebody comes forth with a better design?

The latter.

> Or, alternatively, are you saying that blindly replacing TREE_TYPE with
> REAL_IDENTIFIER_TYPE_VALUE is wrong, semantically speaking, as TREE_TYPE
> and REAL_IDENTIFIER_TYPE_VALUE mean different things and should be kept
> separate, even if they happen to share the same storage?

This too.  I'm surprised that them sharing the same storage hasn't 
broken anything yet.

> And if so,
> would moving that storage into lang_identifier be OK

Moving the uses of REAL_IDENTIFIER_TYPE_VALUE into lang_identifier or 
even a separate hash table would be OK.

> so long as the
> requisite occurrences of TREE_TYPE are audited and the appropriate name
> (REAL_IDENTIFIER_TYPE_VALUE vs. ...I don't know, EXPR_LIKE_TYPE) is
> used?

No, I want to keep using TREE_TYPE.  I was thinking of something more 
like the DEPENDENT_NAME_EXPR that Joseph mentioned.

Jason