Fenix: [Bug] changing language does not work if Fenix theme !== device theme

[cadeyrn]

Steps to reproduce

1. open menu > Settings > Language
2. change the language

Expected behavior

The language of the app changes.

Actual behavior

The language of the app does not change. Even after removing Fenix from the Android recent apps and starting Fenix again Fenix still has the original language.

I also noted that after going to the language settings again no language has a checkmark.

Device information

• Android device: OnePlus 7T Pro McLaren Edition / Android 10
• Fenix version: master branch revision 95d4de416dbf00b860e60ccb30fa5e68b6e63793

[Amejia481]

On my device, I'm able to change the language but the selected language doesn't have a check-mark,after you go leave the language screen and re-enter. I'm using a pixel 3 with Android 10

Nightly 200109 06:02 (Build #20090616)
28.0.0, 11219297f
GV: 74.0a1-20200107215758
Thursday 1/9 @ 6:15 AM

[Amejia481]

cc @BranescuMihai

[cadeyrn]

I tested again and it's not true that it's not working _at all_ - a few strings are changed but most strings are not.

Some observations:

• The language list itself updates the language.
• The label of the search widget on the Android home screen changes the language.
• In the settings overview screen the active value of the "Theme" and the "Toolbar" category change the language.
• But the active value of "Enhanced Tracking Protection" and "Delete browsing data on quit" on the same screen does not change the language.
• If you open the "Theme" or the "Toolbar" category there is still the device language used - even if another language was selected in the Fenix settings.
• All other strings does not change (as far as I can tell)
• But: Changing the language in the Android settings works: all strings are in the correct language.

[cadeyrn]

Some new observations:

• using dark system theme and light Fenix theme: it does not work
• using dark system theme and dark Fenix theme: it does work
• using light system theme and light Fenix theme: it does work
• using light system theme and dark Fenix theme: it does not work

=> So it only works when the system and Fenix theme both use the light or dark theme. It does not work if system and Fenix theme are different.

Also note that _when_ it's work the opposite of the following is true:

In the settings overview screen the active value of the "Theme" and the "Toolbar" category change the language.

In this case these strings have the wrong translation.

[cadeyrn]

This works now on my device.

[AndiAJ]

Hi, verified as fixed on the latest Nightly Build #20350605 from 2/4 using the following devices:

• Google Pixel 3a XL (Android 10)
• Google Pixel 3 XL (Android 9)
• Samsung Galaxy Note 8 (Android 9)
• LG G7 fit (Android 8.1.0)
• Samsung Galaxy S9 (Android 8.0.0)
• Motorola Moto G6 (Android 8.0.0)
• Samsung Galaxy S7 (Android 7.0.0)
• OnePlus A3 (Android 6.0.1)
• LG Nexus 4 (Android 5.1.1)

[ekager]

@boek should we retest the changes we reverted as part of the crash investigation to see if we can keep these around for this bug fix?

[cadeyrn]

@boek gentle ping: Did you forget this issue? The issue is known since two months, the language switcher is one of the advertised features of Fenix 4.0 (https://github.com/mozilla-mobile/fenix/releases/tag/v4.0.0) and does not work at all in Fenix 4.0 for all users with dark Android theme and light Fenix theme or light Android theme and dark Fenix theme since your backout of the previous patch…

It's related to #7988 and release quality - it's not a regression from the user's POV because it's a new feature but it's still really bad to ship broken features in stable releases. /cc @liuche

[softvision-miralobontiu]

I was able to reproduce this issue on HTC Desire 820 (Android 6.0.1), and Xiaomi Mi4i (Android 5.0.2), on the latest Nightly build from 3/10.

[liuche]

Closing this because this seems fixed, as commented in #9413.