[PATCH] D128750: [c++20] Implement P2113R0: Changes to the Partial Ordering of Constrained Functions

[Roy Jacobson via Phabricator via cfe-commits]

royjacobson added a comment.

In D128750#3661576 <https://reviews.llvm.org/D128750#3661576>, @ychen wrote:

> ...
> There is *no* way to reorder the template parameters list again (to get two or more reordering) and the resulted template still works, because of the *positionally correspond* requirement. If this reasoning is sound, I think the current approach of deducing order to compare constraints for rewritten candidates is correct. I wouldn't say I'm 100% confident. But it still makes sense to me at this moment.

I'm not sure I follow your reasoning here. I agree we can't reorder the function parameters, but in your example with T/U/V we have 3 template parameters that we could reorder in 6 different ways. According to how I read 6.2.1.2 we'd need to check there's only one way to order them equivalently, which (I think) reduces to every template parameter appears only once.


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