Do not generate `SupportedOSPlatformAttribute` type on net6?

[radekdoulik]

Commit da12df4 added support for using SupportedOSPlatformAttribute.

In XA it breaks CI builds as we are getting this warning in DotNetBuild test and the test fails when we get any warning:

/Users/runner/work/1/s/bin/TestRelease/temp/DotNetBuildandroid.21-armandroid.21-arm64android.21-x86android.21-x64False/obj/Debug/net6.0-android/UnnamedProject.AssemblyInfo.cs(21,38): warning CS0436: The type 'SupportedOSPlatformAttribute' in '/Users/runner/work/1/s/bin/TestRelease/temp/DotNetBuildandroid.21-armandroid.21-arm64android.21-x86android.21-x64False/obj/Debug/net6.0-android/generated/src/__NamespaceMapping__.cs' conflicts with the imported type 'SupportedOSPlatformAttribute' in 'System.Runtime, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'. Using the type defined in '/Users/runner/work/1/s/bin/TestRelease/temp/DotNetBuildandroid.21-armandroid.21-arm64android.21-x86android.21-x64False/obj/Debug/net6.0-android/generated/src/__NamespaceMapping__.cs'. [/Users/runner/work/1/s/bin/TestRelease/temp/DotNetBuildandroid.21-armandroid.21-arm64android.21-x86android.21-x64False/UnnamedProject.csproj]

Complete build.log from dotnet/android#5444 CI build

Looks like we should not be generating own SupportedOSPlatformAttribute type on net6?

[radekdoulik]

It is probably caused by this line? https://github.com/xamarin/java.interop/blob/da12df4535422f2aaf3a7570326336b30cd50b55/tools/generator/Java.Interop.Tools.Generator.ObjectModel/NamespaceMapping.cs#L38

We should probably use #if !NETCOREAPP instead? As we still build our libraries and tools with netcoreapp3.1.

[jpobst]

We definitely need to have it for netcoreapp3.1 as the type does not exist until net5.0.

I am trying to understand this test, is it building with netcoreapp3.1 but referencing net5.0 BCL? That would be a problem.

https://github.com/xamarin/xamarin-android/blob/master/src/Xamarin.Android.Build.Tasks/Tests/Xamarin.Android.Build.Tests/XASdkTests.cs#L338

cc: @jonathanpeppers

[jonathanpeppers]

@jpobst MSBuild in these tests run out of process. This test build the actual project with ~\android-toolchain\dotnet\dotnet.exe build, but the C# code in this test is netcoreapp3.1.

We could change this now if we need to.

[radekdoulik]

The test already uses net6.0-android TFM. So maybe there is an issue with NET5_0_OR_GREATER define missing.

From the log I see these defines when compiling the test:

/define:TRACE;DEBUG;NET;NET6_0;NETCOREAPP;__XAMARIN_ANDROID_v1_0__;__MOBILE__;__ANDROID__;__ANDROID_1__;__ANDROID_2__;__ANDROID_3__;__ANDROID_4__;__ANDROID_5__;__ANDROID_6__;__ANDROID_7__;__ANDROID_8__;__ANDROID_9__;__ANDROID_10__;__ANDROID_11__;__ANDROID_12__;__ANDROID_13__;__ANDROID_14__;__ANDROID_15__;__ANDROID_16__;__ANDROID_17__;__ANDROID_18__;__ANDROID_19__;__ANDROID_20__;__ANDROID_21__;__ANDROID_22__;__ANDROID_23__;__ANDROID_24__;__ANDROID_25__;__ANDROID_26__;__ANDROID_27__;__ANDROID_28__;__ANDROID_29__;__ANDROID_30__;ANDROID

[radekdoulik]

It looks like the define might still be only in design phase? https://github.com/dotnet/designs/blob/main/accepted/2020/or-greater-defines/or-greater-defines.md

I think we can use NET instead and change this and other places which use NETCOREAPP once that the define is available.

[radekdoulik]

Ah, I missed the last line of the design:

Due to a lot of confusion and concern we ended up not shipping this design.

So that's why the define is missing.