[libcxx-commits] [PATCH] D58879: Implement uses-allocator (P0591R4)

[Zoe Carver via Phabricator via libcxx-commits]

zoecarver added a comment.

As I have worked through fixing all the issues around this patch, I think I have come to the two root problems. First, using `forward_as_tuple` makes it so that the tuple cannot be copied (rightfully so) and are therefore useless in `make_from_tuple`. Here is an example <https://gist.github.com/zoecarver/d95320d274dfbb4bbd5a307a98c487af>. This should probably be fixed with an LWG issue (either to change what tuples can be copied or update `make_from_tuple`). Second, and more important, the expression `forward_as_tuple(move(p).second)` is unable to preserve `rvalue`ness of a type. Here is an example <https://gist.github.com/zoecarver/eac87b03aadaf5d70ffdf9925062569e>. I think the paper either needs to be updated or an issue needs to be presented to fix this (I am happy to write that issue). What are your thoughts @mclow.lists, @EricWF, and @Quuxplusone?


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https://reviews.llvm.org/D58879