[cfe-commits] [PATCH][MS][Review request] - Microsoft function specialization at scope scope

[Francois Pichet]

On Thu, Jun 16, 2011 at 9:52 PM, John McCall <rjmccall at apple.com> wrote:
>
> On Jun 16, 2011, at 6:26 PM, Francois Pichet wrote:
>
>> I struggled getting this patch right and I am not confident enough to
>> submit it directly without review so here it is:
>> Template function specialization at class scope for -fms-extensions
>>
>> Example:
>> template <class T>
>> class B {
>> public:
>>   template <class U>
>>   void f(U p) {   }
>>
>>   template <>
>>    void f(int p) {    }  // <= not standard C++, Microsoft extension
>> };
>>
>> As Doug suggested to me on the IRC chat, I created a new Decl node:
>> ClassScopeFunctionSpecializationDecl
>> This node hold a temporary CXXMethodDecl and it will use it to create
>> an explicit specialization during class instantiation.
>
> Can you explain the need to do this rather than simply making this
> a FunctionTemplateSpecializationDecl, like it would be at global
> scope?  There's already code in SemaTemplateInstantiateDecl for
> instantiating such things;  I'm sure it would need to be changed,
> but...
>
> John.
>

What is a FunctionTemplateSpecializationDecl? I can't find it.
I suppose you mean a FunctionDecl whose TemplateOrSpecialization
member is a FunctionTemplateSpecializationInfo?

The problem is that you cannot call
CheckFunctionTemplateSpecialization inside a dependent context
otherwise you'll assert somewhere inside DeduceTemplateArguments.

As such, the idea is to postpone CheckFunctionTemplateSpecialization
until you are no longer inside a dependent context. I tried many
approaches that failed until dgregor suggested to me to create that
ClassScopeFunctionSpecializationDecl node and to spawn the
specialization during class instantiation.

does that answer your question?