Robert Bastian

unrelated to missing locales, but I have another use case for `ExportResult`, returning the crates that a baked exporter needs. This is currently only logged.

I see `DynamicDataProvider` as a core provider type, it's the equivalent to `DataProvider` where the key is only known at runtime. In fact, `AnyProvider` and `BufferProvider` should be instantiations of...

`DynamicDataProvider` currently unifies code between `BufferProvider` aka `DynamicDataProvider`, and `ExportableProvider`, aka `DynamicDataProvider`. Ideally it would also do this for `AnyMarker`, but this doesn't currently work with yoke.

I believe this should be ```rust fn supported_requests(&self) -> Result ``` This is because after moving key attributes to the request, supported-locales is not enough to enumerate all supported requests....

I made the change from `locales` to `requests`, as the PR requires that, and from `Vec` to `HashSet`, as that gets rid of a hash-set-to-vec conversion in `icu_datagen`. I have...

> Such a struct could be a field of DataRequest, but I am not proposing that. No, because we use the fact that locale and attributes can be independently borrowed...

A struct over two borrowed values cannot be borrowed as a struct over the owned values. The pair we're currently using is basically a struct, so the problem is not...

Yes I'm using `Cow`s in #4995. This API can stay the same.

Preliminary discussion: ```rust struct DataIdentityOwned { pub locale: DataLocale, pub marker_attributes: DataMarkerAttributes } struct DataIdentityBorrowed { id: DataIdentityBorrowed

Nothing.