[cfe-dev] ElaboratedType, QualifiedNameType and TypenameType.

[Abramo Bagnara]

Il 22/03/2010 23:27, Douglas Gregor ha scritto:
> 
> On Mar 22, 2010, at 3:15 PM, Abramo Bagnara wrote:
> 
>> Il 22/03/2010 21:10, Douglas Gregor ha scritto:
>>> 
>>> 
>>> There is an option (C). Here's what I think each of the types
>>> should do:
>>> 
>>> ElaboratedType: Should handle all elaborated-type-specifiers in
>>> the C++0x sense, which means a type referenced via the 
>>> enum/class/struct/union keyword. This class should be extended
>>> with an optional NestedNameSpecifier to handle qualified 
>>> elaborated-type-specifiers, ideally in a implementation-detail
>>> base class so that we don't pay a size penalty for "struct X".
>>> Getting this right should make fixing PR5681 trivial.
>> 
>> Why don't have ElaboratedType of QualifiedNameType instead of
>> optional NNS?
>> 
>> It seems to me it would be more congruent:
>> 
>> 1) ElaboratedType of EnumType (for non qualified enum X) 2)
>> ElaboratedType of QualifiedNameType of EnumType (for qualified not 
>> dependent enum A::X) 3) ElaboratedType of TypenameType (for
>> qualified dependent enum A::X)
> 
> 
> The problem is that elaborated-type-specifiers in the C++ language
> have very different name-lookup semantics than
> QualifiedNameType/TypenameType (C++ [basic.lookup.elab]), so it's
> cleaner to have the *Type nodes match up with language constructs.
> That's actually what
> 
> http://llvm.org/bugs/show_bug.cgi?id=5681
> 
> is about: we're using ElaboratedType as an outer level of sugar (more
> like what you're proposing than what I'm proposing), and because of
> that we get name-lookup wrong when we instantiate the node that the
> ElaboratedType points to. Instead, we should have enough information
> in the ElaboratedType itself to perform instantiation and
> elaborated-type-specifier name lookup without having to dig deeper
> into the type that the ElaboratedType points to.

I guess I've misunderstood something...

Tell me where I'm wrong:

- non qualified enum X would be represented as ElaboratedType of
EnumType (exactly as now)

- qualified not dependent enum A::X would be represented as
ElaboratedType of EnumType using the (to be inserted) optional NNS

- qualified dependent enum A::X ???

Here I'm lost, from your previous message I believed you want to leave
it as now (ElaboratedType of TypenameType), but now I thought I've
misunderstood (as PR5681 is related to this case).

How you'd like to represent this case, exactly?