[cfe-dev] Declaration for TemplateTypeParmType

[Abramo Bagnara]

Il 14/06/2010 18:21, Douglas Gregor ha scritto:
> 
> On Jun 13, 2010, at 1:22 AM, John McCall wrote:
> 
>> On Jun 13, 2010, at 12:16 AM, Abramo Bagnara wrote:
>>> We have not found any way to get declaration from TemplateTypeParmType
>>> (while this is feasibile for UnresolvedUsingType, TypedefType,
>>> RecordType, EnumType, InjectedClassNameType).
>>>
>>> What is the proper way to associate TemplateTypeParmType to its
>>> TemplateTypeParmDecl?
>>
>> By finding the template parameters from the appropriate enclosing context.
>> That's... not really a satisfying answer.
>>
>> Doug, is there a good reason the optional IdentifierInfo isn't an optional
>> TemplateTypeParmDecl?  Just to save a very small amount of memory
>> when there are lots of out-of-line template member declarations?
> 
> 
> The intent is to reduce memory usage, since I'd imagined that there were many depth-0, index-0 template parameters named 'T' or '_Tp' in any given translation unit. Frankly, I doubt that it's that big a deal, and storing a TemplateTypeParmDecl* would be more consistent with the rest of the type system.
> 
> I see that we could actually make TemplateTypeParmType itself smaller, by storing a single uintptr_t that is either (1) a TemplateTypeParmDecl*, or (2) a bit-field containing Depth/Index/ParameterPack.

I've attached the patch for your review/approval.
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