[cfe-dev] Declaration for TemplateTypeParmType

[Douglas Gregor]

Hello Abramo,

On Jun 16, 2010, at 7:39 AM, Abramo Bagnara wrote:

> 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.
> <TTPT_getDecl.patch>

Looks good, thanks!

	- Doug