Android crashes on startup when linker links SDK Assemblies with a SplashActivity

[rezamohamed]

Description

When there is a splash activity and the Linker settings are set to link SDK Assemblies only or SDK and User Assemblies, Xamarin Android crashes on startup.

Splash screen docs to create splash screen - https://docs.microsoft.com/en-us/xamarin/android/user-interface/splash-screen

Steps to Reproduce

1. Create a new project, upgrade nugets
2. Add a splashactivity.cs to the android package, set MainLauncher to true, change MainActivity MainLauncher to false
3. Add the splash screen xml file to drawable folder
4. Add the splash screen to the styles.xml in the values folder
5. Change Debug settings (to mimic release settings): bundle package, Dex: d8, Code Shrinker: Proguard, Linking: SDK Assemblies only, uncheck Use Shared Runtime
6. Debug to an actual device

Expected Behavior

Show the startup splash screen and start the project

Actual Behavior

Crash on startup with the following error message:

Java.Lang.RuntimeException: 'Unable to start activity ComponentInfo{com.companyname.splashscreenfails/crc64d70e5fbbedc622a2.SplashActivity}: android.view.InflateException: Binary XML file line #17: Error inflating class android.support.v7.widget.FitWindowsLinearLayout'

Basic Information

• Version with issue: Visual Studio 2019 16.5.4 Xamarin Forms 4.5.0.617, also tested with 4.6.0.616-pre4 Debugging to a device: Motorola XT1029 (Android 5.1 - API 22)

Screenshots

Crash message:

Reproduction Link

Attaching project SplashScreenFails.zip

Workaround

Tried the workarounds mentioned here but nothing has worked

faking the linker

    class LinkerPleaseLink
    {

        static bool falseflag = false;
        static LinkerPleaseLink()
        {
            if (falseflag)
            {
                var ignore = new FitWindowsFrameLayout(Application.Context);
            }
        }
    }

as well as adding a proguard.cfg file with the following statements

-keep class android.support.v7.widget.** { *; }
-dontwarn android.support.v7.widget.**

[rezamohamed]

Update to workaround I was able to get it to work - it was something related to ProGuard. I created a proguard.cfg file, set it as a proguard config file in the properties, and added the following line:

-keep class android.support.v7.** { *; }

I don't understand why something as simple as SplashAcitivity would not work out of the box tho, this workaround took me almost a day to find/figure out.

[PureWeen]

it's a bit odd that you have to add anything. We have a proguard file setup that takes this stuff into account

https://github.com/xamarin/Xamarin.Forms/blob/master/.nuspec/proguard.cfg#L1

if you use r8 instead of proguard do you still need your proguard file?

[rezamohamed]

yes, with r8 I am seeing the same crash. if you notice in my op I had mentioned I had also tried adding

-keep class android.support.v7.widget.** { *; }

the only difference was this time around I went one namespace shallower and it worked:

-keep class android.support.v7.** { *; }

There was a post from 2018 on this https://forums.xamarin.com/discussion/comment/346206/#Comment_346206

[holecekp]

I have encountered the same problem. My app started crashing when I have added a splash screen. The problem was with Proguard. The splash activity was shown for some time, but the crash happened when the app tried to switch to the main activity.

I have added the file with Proguard rules from https://github.com/xamarin/Xamarin.Forms/blob/master/.nuspec/proguard.cfg#L1. But I had to add one more rule to this file so that the app would not crash:

-keep class android.support.v7.widget.FitWindowsLinearLayout { *; }
-dontwarn android.support.v7.widget.FitWindowsLinearLayout

Note that in the file, there is rule for "FitWindowsFrameLayout", but "FitWindowsLinearLayout" was also required to prevent the crash.