Add suppport for decimal plurals (Android cs/fr/lt/sk are missing "many" in plurals)

[eighthave]

Describe the issue

Android's lint tool is complaining about missing "many" entries in plural strings for "cs" (Czech), "fr" (French) , "lt" (Lithuanian), and "sk" (Slovak). The Weblate interface does not offer "many" as an option for those languages/strings. For example:

https://gitlab.com/grote/fdroidclient/-/jobs/2351872888

    ^
/builds/grote/fdroidclient/app/src/main/res/values-cs/strings.xml:396: Error: For locale "cs" (Czech) the following quantities should also be defined: many [MissingQuantity]
    <plurals name="details_last_update_months">
    ^
/builds/grote/fdroidclient/app/src/main/res/values-cs/strings.xml:401: Error: For locale "cs" (Czech) the following quantities should also be defined: many [MissingQuantity]
    <plurals name="details_last_update_years">
    ^
/builds/grote/fdroidclient/app/src/main/res/values-lt/strings.xml:406: Error: For locale "lt" (Lithuanian) the following quantities should also be defined: many [MissingQuantity]
    <plurals name="button_view_all_apps_in_category">
    ^
/builds/grote/fdroidclient/app/src/main/res/values-lt/strings.xml:501: Error: For locale "lt" (Lithuanian) the following quantities should also be defined: many [MissingQuantity]
    <plurals name="tts_view_all_in_category">
    ^
   Explanation for issues of type "MissingQuantity":
   Different languages have different rules for grammatical agreement with
   quantity. In English, for example, the quantity 1 is a special case. We
   write "1 book", but for any other quantity we'd write "n books". This
   distinction between singular and plural is very common, but other languages
   make finer distinctions.
   This lint check looks at each translation of a <plural> and makes sure that
   all the quantity strings considered by the given language are provided by
   this translation.
   For example, an English translation must provide a string for
   quantity="one". Similarly, a Czech translation must provide a string for
   quantity="few".
   https://developer.android.com/guide/topics/resources/string-resource.html#Plurals

This is related to #1550. This site seems to say it is a matter of conversion between the CLDR and gettext representation schemes for plurals:
https://github.com/miracle2k/android2po#plurals-support

I already tried

• I've read and searched the documentation.
• I've searched for similar issues in this repository.

Steps to reproduce the behavior

These are some of the strings:

• https://hosted.weblate.org/translate/f-droid/f-droid/lt/?offset=1&q=button_view_all_apps_in_category&sort_by=-priority%2Cposition&checksum=
• https://hosted.weblate.org/translate/f-droid/f-droid/cs/?offset=1&q=details_last_update_months&sort_by=-priority%2Cposition&checksum=

Expected behavior

Weblate should support the "many" field for Android strings.xml for cs/fr/lt/sk languages.

Screenshots

No response

Exception traceback

No response

How do you run Weblate?

weblate.org service

Weblate versions

No response

Weblate deploy checks

No response

Additional context

No response

[nijel]

This definitely was not the case in the past, what has changed in Android regarding this? Weblate uses CLDR data for Android.

The many plural is used for decimal numbers (see https://unicode-org.github.io/cldr-staging/charts/37/supplemental/language_plural_rules.html#cs) and that indeed cannot be represented in Weblate right now.

[eighthave]

I'm not sure exactly when it changed, it could have been a while ago since I haven't been too active working on Android things recently.

Here's the lint check code:
https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/PluralsDetector.kt?q=%22the%20following%20quantities%20should%20also%20be%20defined%22

[nijel]

It was introduced in https://cs.android.com/android-studio/platform/tools/base/+/97f96e70464579c01712dec78bb398d2e47582df, unfortunately the commit does not include any reasoning...

[nijel]

Weblate certainly could be changed to deal with non-integer plurals. On the other side, most of the applications don't really need this, and it would add one additional string to translate (and confuse translators because they are currently not used to this).

[eighthave]

I have no opinion of whether it is needed or not. I'm just reporting that Android is calling it a requirement, and they added a _lint_ check to enforce it.

[github-actions]

This issue has been put aside. It is currently unclear if it will ever be implemented as it seems to cover too narrow of a use case or doesn't seem to fit into Weblate.

Please try to clarify the use case or consider proposing something more generic to make it useful to more users.

[eighthave]

So here's more info on the use case: * Dev who does not know anything about ca/fr/lt/sk puts their Android app on Weblate. * Dev sets up standard Android _lint_ checks since the include important checks to prevent crashes due to incomplete translations. * Dev has no idea what "many" plurals are, and wonders why _lint_ is failing. * Dev has no idea how to fix it, so disables _lint_ or uses different translation service.

[warting]

maybe make it configurable in weblate what kind of different plurals it exists for each language?

[nijel]

The plural rules are currently detected based on the file. Some formats do explicitly include it (Gettext), for others we do guess what should be used (what turns out to be tricky, see for example translate/translate#786).

Having that user configurable would be possible, but I'm uncertain if it will address the issue - the choice here is between Android lint complains and translators having extra work which is not needed in most cases. Anyway, it's safe to assume that most people will not change the configuration :-).

[eighthave]

As far as I know, the lint rules are not configurable beyond enable/disable across the project. I don't think that Weblate should be configurable for the Android strings.xml unless Android itself is. Do you think this could be a bug in Android lint? If so, I'm happy to report it, but I don't know the details of CLDR and things like that.

[nijel]

Apparently, it was intentional change there. Knowing the reasons might help us understand that as well...

[eighthave]

Based on the info here, my guess is that they added support for many to support strings with decimal numbers in them. Seems like just an incremental improvement to their localization support. Their test example is in Czech, does it make sense?

                                        + "<plurals name=\"product_type_ch_adult_general_abonnement\">\n"
                                        + "  <item quantity=\"few\">%d dospělí (karta GA)</item>\n"
                                        + "  <item quantity=\"many\">%d dospělých (karta GA)</item>\n"
                                        + "  <item quantity=\"one\">%d Dospělý (GA travelcard)</item>\n"
                                        + "  <item quantity=\"other\">%d Dospělí/dospělých (GA travelcard)</item>\n"
                                        + "</plurals>"))

[nijel]

Yes, it makes grammatical sense when you need decimals. The problem is that you don't need them in numerous instances. In this case, you won't have two and half adults, as you usually don't cut them ;-).

Anyway, to support this in Weblate:

• the plural rules have to be expanded to handle decimals
• translate-toolkit needs to understand these as well
• translate-toolkit should be able to migrate from the old to new plurals (it currently stores them in the list, so other would become many and other would be untranslated
• additional plural rules need to be added for Android in Weblate
• migrate existing translations in the Weblate database (again, these are stored sequentially, so without migration the plurals would be offset)