feat: generate Locale type based on configuration

[BobbieGoede]

🔗 Linked issue

• Narrow typed locale identifiers #2857

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This changes type generation to narrow the Locale type to the configured locales, this way functions that accept a locale parameter (such as our composables) will have proper autocompletion for all configured locales.

@kazupon
There's still an issue/quirk with the type, I'm don't know how to narrow the locale property on the Composer type in the same way, so currently the following would cause a type error:

const { locale } = useI18n()
const switchLocalePath = useSwitchLocalePath()

switchLocalePath(locale.value) // Argument of type 'string' is not assignable to parameter of type 'Locale'.

Maybe you know how to resolve this? I don't think this should be merged while this issue is present 😅

Also working on this BobbieGoede#49.

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

[kazupon]

@BobbieGoede
Hmm, 🤔
The locale of the current Compose is resolved by the type parameter as locale: WritableComputedRef<Locales>.

https://github.com/intlify/vue-i18n/blob/c03fec09f9c3f9f16f8773295523a8d693e9ce0b/packages/vue-i18n-core/src/composer.ts#L1268-L1296

To support nuxt-i18n use cases, this could be extended more on the Vue I18n side.

e.g. locale: IsNever<CustomLocales> extends true ? WritableComputedRef<Locales> : WritableComputedRef<CustomLocale> .

It may be possible to dynamically extend the locale.

[BobbieGoede]

@kazupon
I have a possible solution here intlify/vue-i18n#1890, I have updated this PR to make use of that solution. Let me know if this works for you locally or if a different approach is preferred.

[kazupon]

Okay, I could work it with vue-i18n v10 latest version!