[cfe-dev] Template parameters for out-of-line definitions of class template methods.

[Abramo Bagnara]

Il 03/06/2010 08:52, Enea Zaffanella ha scritto:
> Douglas Gregor wrote:
>> On Apr 21, 2010, at 12:20 PM, Enea Zaffanella wrote:
>>
>>> Hello.
>>>
>>> We have a somewhat naive question regarding the AST generated for the 
>>> following program fragment:
>>> ======================================
>>> template <typename T>
>>> struct S {
>>>   void foo();
>>> };
>>>
>>> template <class W>
>>> void S<W>::foo() {}
>>> ======================================
>>>
>>> We would like to retrieve the template parameter list for the 
>>> out-of-line definition of method foo(), that is
>>>   template <class W>
>>> but we cannot see if and how this could be achieved.
>>
>> Clang's AST doesn't actually store the template parameter list that was used in the out-of-line definition. It should.
> 
> Hello.
> 
> Reconsidering the point above, we would like to propose a solution.
> 
> The template parameter lists we are interested in are simply thrown away 
> after calls to method
> 
>    TemplateParameterList*
>    Sema::MatchTemplateParametersToScopeSpecifier
>      (SourceLocation DeclStartLoc, const CXXScopeSpec &SS,
>       TemplateParameterList **ParamLists, unsigned NumParamLists,
>       bool IsFriend, bool &IsExplicitSpecialization);
> 
> Hence, we simply have to store somewhere the lists of parameters that 
> have been matched against the CXXScopeSpec: either all of the lists in 
> ParamLists, or all but the last one (which would be the one returned as 
> result).
> 
> As far as we can see, the best place for this info is in the ExtInfo 
> struct inside DeclaratorDecl, so that the space overhead will be paid 
> only in the uncommon case of an out-of-line declaration:
> 
> 00369 class DeclaratorDecl : public ValueDecl {
> 00370   // A struct representing both a TInfo and a syntactic qualifier,
> 00371   // to be used for the (uncommon) case of out-of-line declarations.
> 00372   struct ExtInfo {
> 00373     TypeSourceInfo *TInfo;
> 00374     NestedNameSpecifier *NNS;
> 00375     SourceRange NNSRange;
> 00376   };
> 
> A similar chnage will be done for the ExtInfo struct inside TagDecl nodes.
> 
> Would this be OK?

The attached patch shows better and implement the proposal of Enea for
your review/approval.
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