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

[Abramo Bagnara]

Il 12/06/2010 04:08, John McCall ha scritto:
> 
> On Jun 3, 2010, at 11:32 PM, Abramo Bagnara wrote:
> 
>> 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.
> 
> If NNSInfo is going to be used in multiple places, which I think is the intent, please
> lift it out of DeclaratorDecl and give it a better name.  QualifierInfo, maybe?
> OutOfLineInfo?
> 
> +  unsigned getNumTemplateParameterLists() const {
> +    return hasExtInfo() ? DeclInfo.get<ExtInfo*>()->NumTemplParamLists : 0;
> +  }
> 
> Please use getExtInfo() consistently.
> 
> Otherwise looks good!

Commited with suggested changes in r105882.