`with_locales_no_fallback` does fallback about icu4x HOT 14 OPEN

Context: I'm trying to replace https://github.com/robertbastian/icu4x/blob/ec32ad4a79707b1ddb7852ed1653ac2d86c27f3f/provider/datagen/src/baked_exporter.rs#L25 by a version that doesn't use the network (the current test does). However I cannot figure out an invocation for baked that doesn't use fallback.

from icu4x.

_no_fallback only means no runtime fallback. It still does datagen-time fallback.

You can avoid the datagen-time fallback by using LocaleFamily::FULL. But, hmm, it's not possible to pass a LocaleFamily into .with_locales_no_fallback.

from icu4x.

The invocation I've used in a number of other places to avoid this problem is

.with_locales_and_fallback([LocaleFamily::FULL], Default::default())

from icu4x.

It's not a bug, so unassigning myself.

from icu4x.

The function docs say: "Sets this driver to generate the given locales assuming no runtime fallback."

It's totally reasonable that the driver needs datagen-time fallback in order to generate data that requires no runtime fallback. That's the only way to ensure that the input list of langids can all be fully resolved at datagen time.

We may have previously avoided loading the fallbacker if the explicit langid had an exact match with the supported locales, but now we always load the fallbacker in order to pick up any aux keys and locale extensions from the parent locales, which was a bug before.

from icu4x.

This invocation works with HelloWorldProvider:

It uses implicit exporter-derived defaults - what's the equivalent invocation for a baked provider?

from icu4x.

I guess it's .with_all_locales().with_fallback_mode(FallbackMode::Hybrid), which doesn't exist on the new API?

from icu4x.

.with_all_locales().with_fallback_mode(FallbackMode::Hybrid)

is the same as

.with_locales_and_fallback([LocaleFamily::FULL], FallbackOptions {
    deduplication_strategy: Some(DeduplicationStrategy::None),
    runtime_fallback_location: Some(RuntimeFallbackLocation::External),
})

from icu4x.

This transformation is implemented in code

            (_, Some(legacy_locales), FallbackMode::Hybrid) => {
                LocalesWithOrWithoutFallback::WithFallback {
                    families: map_legacy_locales_to_locales_with_expansion(legacy_locales),
                    options: FallbackOptions {
                        runtime_fallback_location: Some(RuntimeFallbackLocation::External),
                        deduplication_strategy: Some(DeduplicationStrategy::None),
                    },
                }
            }

from icu4x.

• [LocaleFamily::FULL] disables locale selection fallback (it forwards all supported locales to the output)
• DeduplicationStrategy::None disables the deduplicator, which requires fallback
• RuntimeFallbackLocation::External disables runtime fallback and asserts that LocaleFallbackProvider will be supplied at runtime, so the exporter can proceed with that assumption

I think you should be good if you set all three of those.

from icu4x.

So what's the difference between with_locales_and_fallback with ::None and ::External, and with_locales_no_fallback?

from icu4x.

So what's the difference between with_locales_and_fallback with ::None and ::External, and with_locales_no_fallback?

with_locales_no_fallback is preresolved...

It might be mechanically the same as with_locales_and_fallback with ::None and ::External if all of the locale families are ::single. However, with_locales_and_fallback carries with it the assertion that a LocaleFallbackAdapter will be provided at runtime.

from icu4x.

Does this issue change your position on flattening these options to DatagenDriver?

impl DatagenDriver {
  pub fn with_locale_families(...)
  pub fn with_deduplication(...)
  pub fn with_runtime_fallback_location(...)
}

And perhaps change RuntimeFallbackLocation::External to RuntimeFallbackLocation::ExternalOrDisabled. Hmm.

from icu4x.

I think I'm fine flattening it.

from icu4x.