[PATCH] D128113: Clang: fix AST representation of expanded template arguments.

Sat Aug 27 10:50:44 PDT 2022

davrec added a comment.

In D128113#3753656 <https://reviews.llvm.org/D128113#3753656>, @davrec wrote:

> In D128113#3753640 <https://reviews.llvm.org/D128113#3753640>, @mizvekov wrote:
>
>> In D128113#3753624 <https://reviews.llvm.org/D128113#3753624>, @davrec wrote:
>>
>>> Or just `SubstTemplateTypeParmType` could store this number in addition to its `TemplateTypeParmType`?  (E.g. the first Ts in an expansion is 0, the second Ts in the same expansion is 1, etc. - but it resets for the next expansion.)
>>
>> Well that number is just the pack_index, as implemented in this current patch :)

Disregard my previous comment, you're right, that would be identical.  I'm mixing up my STTPTs and TTPTs :).  So the proposed solution would be to make the TTPTs unique, and map from the TTPTs to their current pack indices in the Resugarer.  But, that is probably identical in terms of memory usage as your proposal to introduce a new sugar type representing unique expansion instances, and the latter is probably clearer/less disruptive.

Thanks for your work on this, and for explaining these complexities.

Repository:
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  https://reviews.llvm.org/D128113/new/

https://reviews.llvm.org/D128113