[net6][android] SupportedOSPlatformVersion vs minSdkVersion

[spouliot]

Current behavior

For net6.0-android the templates (both UWP and WinUI) sets the SupportedOSPlatformVersion property to 21

https://github.com/unoplatform/uno/blob/197533bd2e74c9ada52d82cf47830b87f6e94707/src/SolutionTemplate/UnoSolutionTemplate.net6/Mobile/UnoQuickStart.Mobile.csproj#L22

However the AndroidManifest.xml file sets the minSdkVersion to 16 for UWP projects

https://github.com/unoplatform/uno/blob/197533bd2e74c9ada52d82cf47830b87f6e94707/src/SolutionTemplate/UnoSolutionTemplate.net6/Mobile/Android/AndroidManifest.xml#L3

and to 21 (same as .csproj) for WinUI projects

https://github.com/unoplatform/uno/blob/197533bd2e74c9ada52d82cf47830b87f6e94707/src/SolutionTemplate/UnoSolutionTemplate.WinUI.net6/Mobile/Android/AndroidManifest.xml#L3

This leads to problems

1. 16 is too low and and fails with

DebugMyApp.Mobile/Android/AndroidManifest.xml(0,0): Error: AndroidManifest.xml //uses-sdk/@android:minSdkVersion '16' is less than API-19, this configuration is not supported.

Should it be set to 19 (which is closest to the current value) ? or 21 which match WinUI ?

2. Who wins when the values are different ?

aapt d xmltree /Users/poupou/git/uno/uno-debug-test/DebugMyApp/DebugMyApp.Mobile/obj/Debug/net6.0-android/android-arm64/android/bin/DebugMyApp.DebugMyApp.apk AndroidManifest.xml
N: android=http://schemas.android.com/apk/res/android
  E: manifest (line=8)
    A: android:versionCode(0x0101021b)=(type 0x10)0x1
    A: android:versionName(0x0101021c)="1.0" (Raw: "1.0")
    A: android:compileSdkVersion(0x01010572)=(type 0x10)0x1f
    A: android:compileSdkVersionCodename(0x01010573)="12" (Raw: "12")
    A: package="DebugMyApp.DebugMyApp" (Raw: "DebugMyApp.DebugMyApp")
    A: platformBuildVersionCode=(type 0x10)0x1f
    A: platformBuildVersionName=(type 0x10)0xc
    E: uses-sdk (line=9)
      A: android:minSdkVersion(0x0101020c)=(type 0x10)0x13
      A: android:targetSdkVersion(0x01010270)=(type 0x10)0x1f
    E: uses-permission (line=10)
      A: android:name(0x01010003)="android.permission.INTERNET" (Raw: "android.permission.INTERNET")
    E: queries (line=11)
      E: intent (line=12)
        E: action (line=13)
          A: android:name(0x01010003)="android.media.browse.MediaBrowserService" (Raw: "android.media.browse.MediaBrowserService")
    E: application (line=16)
      A: android:theme(0x01010000)=@0x7f0f0008
      A: android:label(0x01010001)=@0x7f0e0000
      A: android:icon(0x01010002)=@0x7f0c0000
      A: android:name(0x01010003)="crc64eb2734f1e0c2babe.Application" (Raw: "crc64eb2734f1e0c2babe.Application")
      A: android:debuggable(0x0101000f)=(type 0x12)0xffffffff
      A: android:allowBackup(0x01010280)=(type 0x12)0xffffffff
      A: android:hardwareAccelerated(0x010102d3)=(type 0x12)0xffffffff
      A: android:largeHeap(0x0101035a)=(type 0x12)0xffffffff
      A: android:extractNativeLibs(0x010104ea)=(type 0x12)0xffffffff
      A: android:appComponentFactory(0x0101057a)="androidx.core.app.CoreComponentFactory" (Raw: "androidx.core.app.CoreComponentFactory")
      E: activity (line=17)
        A: android:name(0x01010003)="crc647c90b8909228a8dc.MainActivity" (Raw: "crc647c90b8909228a8dc.MainActivity")
        A: android:exported(0x01010010)=(type 0x12)0xffffffff
        A: android:configChanges(0x0101001f)=(type 0x11)0x40002fff
        A: android:windowSoftInputMode(0x0101022b)=(type 0x11)0x22
        E: intent-filter (line=18)

where the 0x13 in A: android:compileSdkVersion(0x01010572)=(type 0x10)0x1f turns out to be decimal 19, which is the value I used inside AndroidManifest.xml to stop the error.

IOW the winner is the AndroidManifest.xml value

Expected behavior

1. Ideally the template would not duplicate settings for the same value.
2. If it cannot be avoided they should be identical.
3. If possible a warning should tell the developer of any mismatch.

How to reproduce it (as minimally and precisely as possible)

1. Create an UWP app for net6 mobile.
2. Double check that the .csproj set the SupportedOSPlatformVersion to 21 for Android.
3. Inside the AndroidManifest.xml set minSdkVersion to 19 (to avoid build error)
4. Build app for net6.0-android
5. Check the minSdkVersion inside the .apk

Workaround

No response

Works on UWP/WinUI

No response

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia

NuGet package version(s)

4.5.9

Affected platforms

Android

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

Might be related to https://github.com/xamarin/xamarin-android/issues/6739

[jeromelaban]

Interesting, we should indeed at least align both, but it may automatically be generated now in net6? Some of the other parts of the manifest are, if I'm not mistaken.

[spouliot]

I have not checked what is generated (in the manifest) with a MAUI project/template. Ideally we would only have the net6+ configuration (that was the goal) but it could be a bug too.

Also the SDK (android) does not seem to detect the different values :(