[libcxx-commits] [PATCH] D107671: [libcxx][ranges] Add `ranges::join_view`.

[Tim Song via Phabricator via libcxx-commits]

tcanens added inline comments.


================
Comment at: libcxx/include/__ranges/join_view.h:41
+    requires is_reference_v<_Tp>
+  struct __inner_cache<_Tp> { };
+
----------------
zoecarver wrote:
> I know you wanted me to do 
> ```
> static constexpr bool _UseCache = !is_reference_v<_InnerRange>;
> using _Cache = _If<_UseCache, __non_propagating_cache<remove_cv_t<_InnerRange>>, __empty_cache>;
> [[no_unique_address]] _Cache __cache_;
> ```
> which I agree would be better, but I was getting compiler errors, because `__non_propagating_cache<remove_cv_t<_InnerRange>>` is not valid when `_InnerRange` is a reference type (because `__non_propagating_cache ` requires `is_object_v`). 
> 
> There may be a creative solution to work around this. 
Just use `remove_cvref_t`? If it's not a reference, the `ref` part has no effect. If it is, then we don't care what it ends up being anyway (but it is an object type so it satisfies the constraint).


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D107671/new/

https://reviews.llvm.org/D107671