Better Default implementation for date data

[sffc]

We should build a Default implementation for date data based on root.json.

[sffc]

Depends on #257

[sffc]

I think we should hard-code this into the source file. This is only last-resort data. We don't necessarily need to enforce that it stays up-to-date with root.json; that could be another task for later.

[Manishearth]

@sffc Which date data is being referred to here?

[sffc]

All data structures related to dates, in order to perform date formatting if locale data is unavailable

[Manishearth]

Makes sense, thanks! @samchen61661 this would be anything tagged #[data_struct] in the datetime component, e.g.

icu4x/components/datetime/src/provider/time_zones.rs

Line 45 in 26b1be1

#[icu_provider::data_struct]

You can find a lot of the root data in https://unicode-org.github.io/cldr-staging/charts/latest/summary/root.html , though it's a bit unwieldy to work with

[samchen61661]

Thanks for explaining!

In order to move forward, I might need to know what would be the default local and its metadata mapping which will be used in the date time structures.

I checked https://unicode-org.github.io/cldr-staging/charts/latest/summary/root.html, and it contains lots of information. Need to find an efficient way to figure out the value mapping.

[sffc]

Let's hold off on this until @zbraniecki's DateTime refactoring lands.

[sffc]

We should do this once all the datetime data refactoring is done.

[robertbastian]

Do we still want to do this after the decision in #1494 (comment)?

[Manishearth]

I'd say no, and we can close this. @sffc ?

[sffc]

Given the additional further discussion in #2174, we can close this.