On 2013-11-10 10:38, Adam Butcher wrote:
> On 2013-11-10 6:10, Jason Merrill wrote:
>>
>> Hmm, actually I think messing with the non-pack's decl is dangerous,
>> and we should come up with a new decl for the pack instead.  I think
>> you can use reduce_template_parm_level with a "levels" argument of 0
>> to build a new decl and parm index.
>>
> I actually did this in one of my experiments and it worked fine.
> Although I also had to update the template parm list with new decl:
>
>   TREE_VALUE (TREE_VEC_ELT (current, i)) = TREE_CHAIN (t);
>
> At that point I had the convert function in pt.c an operating 
> directly
> on current_template_parms (also having direct access to the two 
> statics
> required; reduce_template_parm_level and canonical_type_parameter).
>
> I can't think of a case where we'd want to make this substitution in
> anything but the current_template_parms so maybe moving the convert
> function back into to pt.c and removing the 'current' parm from it
> might be best?
>
>> And if we're doing that, setting TYPE_STUB_DECL and TYPE_NAME is
>> indeed necessary.
>>
>>> Only for the sake of not exposing this (currently static) function 
>>> from
>>> pt.c (or moving the pack convert function into pt.c).  My original 
>>> impl
>>> did extern canonical_type_parameter and use that and I think it 
>>> worked
>>> as expected.  Would that be preferred?
>>
>> Yes.  Please declare it in cp-tree.h rather than within the 
>> function.
>>
> Will do.  Unless, as suggested above, we go for moving
> convert_generic_types_to_packs into pt.c in which case exposing these
> internals won't be necessary.
>

With the convert function in pt.c, PATCH 2/3 now looks as follows: