[cfe-dev] Getting the FieldDecl of a template class from a MemberExpr

[Douglas Gregor]

On May 27, 2011, at 2:32 PM, Johannes Schaub (litb) wrote:

> Douglas Gregor wrote:
> 
>> 
>> On May 27, 2011, at 10:02 AM, Adrien Chauve wrote:
>> 
>>> Hi,
>>> 
>>> Using a RecursiveASTVisitor, I've been trying to rename field names
>>> against some conventions.
>>> 
>>> Let's say I would like to rename Foo::bar into Foo::m_bar in the
>>> following code:
>>> 
>>> template<typename T>
>>> struct Foo
>>> {
>>>    int bar;
>>> };
>>> 
>>> int main()
>>> {
>>>    Foo<double> foo;
>>>    foo.bar = 2;
>>> 
>>>    return 1;
>>> }
>>> 
>>> 
>>> In my custom visitor, I implement the following method:
>>> 
>>> bool VisitMemberExpr(MemberExpr* member)
>>> {
>>>    ValueDecl* v = member->getMemberDecl(); // FieldDecl or CXXMethodDecl
>>>    ...
>>> }
>>> 
>>> But the FieldDecl I get when visiting the statement corresponding to
>>> "foo.bar=2;" is Foo<double>::bar, but not Foo::bar.
>>> 
>>> So my question is: is it possible to get the FieldDecl of Foo<T>::bar
>>> from the FieldDecl of Foo<double>::bar ? at least when the struct is not
>>> specialized? What happens when the struct is specialized?
>> 
>> For fields, this is a pain. You'll actually have to look at the type that
>> owns the field (a ClassTemplateSpecializationDecl), check whether it was
>> instantiated vs. specialized (using getSpecializationKind()) and, if it
>> was instantiated, retrieve the class template from which is was
>> instantiated (getSpecializedTemplate()).
>> 
> 
> I was looking into the doxygen documentations, and I couldn't find how to 
> proceed from that.
> 
> How to get the correct field decl of the class template that correspond to 
> the field decl of the instantiated specialization? Can one just take the 
> std::distance of the field decl iterator for the specialization, and with 
> that, index into the field decl iterator of the class template?

That works, or you can use name lookup.

	- Doug