[net9-pre3] Enabling ILLink causes the build to fail on Application attribute

[tranb3r]

Android application type

.NET Android (net7.0-android, net8.0-android, etc.)

Affected platform version

VS 17.10.0-pre5 / net9-pre3 / xamarin-android 34.99.0-pre3

Description

When building with TrimMode=full, the build fails with the following error:

ILLink : error IL1012: IL Trimmer has encountered an unexpected error. Please report the issue at https://aka.ms/report-illink 
  Fatal error in IL Linker
  Unhandled exception. System.InvalidOperationException: Sequence contains no matching element
     at System.Linq.ThrowHelper.ThrowNoMatchException()
     at System.Linq.Enumerable.First[TSource](IEnumerable`1 source, Func`2 predicate)
     at MonoDroid.Tuner.PreserveApplications.PreserveTypeProperty(CustomAttribute attribute, String property) in /Users/runner/work/1/s/xamarin-android/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs:line 69
     at MonoDroid.Tuner.PreserveApplications.PreserveApplicationAttribute(CustomAttribute attribute) in /Users/runner/work/1/s/xamarin-android/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs:line 60
     at MonoDroid.Tuner.PreserveApplications.ProcessAttributeProvider(ICustomAttributeProvider provider) in /Users/runner/work/1/s/xamarin-android/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs:line 55
     at MonoDroid.Tuner.PreserveApplications.ProcessType(TypeDefinition type) in /Users/runner/work/1/s/xamarin-android/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs:line 43
     at MonoDroid.Tuner.PreserveApplications.<Initialize>b__0_1(TypeDefinition type) in /Users/runner/work/1/s/xamarin-android/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs:line 21
     at Mono.Linker.Steps.MarkStep.MarkType(TypeReference reference, DependencyInfo reason, Nullable`1 origin)
     at Mono.Linker.Steps.MarkStep.MarkTypeVisibleToReflection(TypeReference type, TypeDefinition definition, DependencyInfo& reason, MessageOrigin& origin)
     at Mono.Linker.Steps.MarkStep.MarkEntireType(TypeDefinition type, DependencyInfo& reason)
     at Mono.Linker.Steps.MarkStep.MarkEntireAssembly(AssemblyDefinition assembly)
     at Mono.Linker.Steps.MarkStep.MarkAssembly(AssemblyDefinition assembly, DependencyInfo reason)
     at Mono.Linker.Steps.MarkStep.MarkModule(ModuleDefinition module, DependencyInfo reason)
     at Mono.Linker.Steps.MarkStep.ProcessMarkedPending()
     at Mono.Linker.Steps.MarkStep.Initialize()
     at Mono.Linker.Steps.MarkStep.Process(LinkContext context)
     at Mono.Linker.Pipeline.ProcessStep(LinkContext context, IStep step)
     at Mono.Linker.Pipeline.Process(LinkContext context)
     at Mono.Linker.Driver.Run(ILogger customLogger)
     at Mono.Linker.Driver.Main(String[] args)
     at Mono.Linker.Driver.Main(String[] args)
c:\Nuget\microsoft.net.illink.tasks\9.0.0-preview.3.24172.9\build\Microsoft.NET.ILLink.targets(91,5): error NETSDK1144: Optimizing assemblies for size failed. 

Also, if I add null parameters to the Application attribute...

[global::Android.App.ApplicationAttribute(
        ...
        BackupAgent = null,
        ManageSpaceActivity = null
    )]

...it fails later on:

C:\Program Files\dotnet\packs\Microsoft.Android.Sdk.Windows\34.99.0-preview.3.231\tools\Xamarin.Android.Common.targets(1460,3): error XAGJS7001: System.NullReferenceException: Object reference not set to an instance of an object.
   at Xamarin.Android.Manifest.ManifestDocumentElement.ResolveType(String type, ICustomAttributeProvider provider, IAssemblyResolver resolver)
   at Android.App.ApplicationAttribute.<>c.<.cctor>b__114_7(ApplicationAttribute self, ICustomAttributeProvider p, IAssemblyResolver r, TypeDefinitionCache cache)
   at Xamarin.Android.Manifest.ManifestDocumentElement`1.ToAttributeValue(String name, T value, ICustomAttributeProvider provider, IAssemblyResolver resolver, TypeDefinitionCache cache, Int32 targetSdkVersion)
   at Xamarin.Android.Manifest.ManifestDocumentElement`1.ToAttribute(String name, T value, String packageName, ICustomAttributeProvider provider, IAssemblyResolver resolver, TypeDefinitionCache cache, Int32 targetSdkVersion)
   at Xamarin.Android.Manifest.ManifestDocumentElement`1.<>c__DisplayClass8_0.<ToElement>b__1(String e)
   at System.Linq.Enumerable.IteratorSelectIterator`2.MoveNext()
   at System.Linq.Enumerable.IEnumerableWhereIterator`1.MoveNext()
   at System.Xml.Linq.XContainer.AddContentSkipNotify(Object content)
   at Xamarin.Android.Manifest.ManifestDocumentElement`1.ToElement(T value, ICollection`1 specified, String packageName, TypeDefinitionCache cache, ICustomAttributeProvider provider, IAssemblyResolver resolver, Int32 targetSdkVersion)
   at Android.App.ApplicationAttribute.ToElement(IAssemblyResolver resolver, String packageName, TypeDefinitionCache cache)
   at Xamarin.Android.Tasks.ManifestDocument.CreateApplicationElement(XElement manifest, String applicationClass, List`1 subclasses, TypeDefinitionCache cache)
   at Xamarin.Android.Tasks.ManifestDocument.Merge(TaskLoggingHelper log, TypeDefinitionCache cache, List`1 subclasses, String applicationClass, Boolean embed, String bundledWearApplicationName, IEnumerable`1 mergedManifestDocuments)
   at Xamarin.Android.Tasks.GenerateJavaStubs.MergeManifest(NativeCodeGenState codeGenState, Dictionary`2 userAssemblies)
   at Xamarin.Android.Tasks.GenerateJavaStubs.Run(Boolean useMarshalMethods)
   at Xamarin.Android.Tasks.GenerateJavaStubs.RunTask()
   at Microsoft.Android.Build.Tasks.AndroidTask.Execute() in /Users/runner/work/1/s/xamarin-android/external/xamarin-android-tools/src/Microsoft.Android.Build.BaseTasks/AndroidTask.cs:line 25

No issue with the same csproj configuration, when using net8.

This similar to a net6 issue: #7301

Here are the binlog for both errors:
binlog.zip

Steps to Reproduce

Have a look at binlogs.

Did you find any workaround?

No response

Relevant log output

No response

[jonathanpeppers]

Looking at the code here:
https://github.com/xamarin/xamarin-android/blob/74a90be5b3654173582b8ef455236de9b06508dd/src/Microsoft.Android.Sdk.ILLink/PreserveApplications.cs#L58-L62

What did your original [global::Android.App.ApplicationAttribute] look like? Just an empty attribute?

[tranb3r]

No, it's not empty, it has several properties:

    [Application(
        Icon = "@mipmap/appicon",
        RoundIcon = "@mipmap/appicon_round",
        NetworkSecurityConfig = "@xml/network_security_config",
        AllowBackup = true
#if DEBUG
        , Debuggable = true
#endif
    )]

As explained, adding BackupAgent=null and ManageSpaceActivity=null will get rid of the first error, but then it fails with the second error.

[jonathanpeppers]

@tranb3r I have a fix (which will probably be .NET 9 Preview 5) at this point.

It looks like setting these to null:

BackupAgent = null,
ManageSpaceActivity = null

Is actually not valid if it can't find these types:
https://github.com/xamarin/xamarin-android/blob/ce5bbd0f43fd8bf60fade283773932429894d0c5/src/Xamarin.Android.Build.Tasks/Utilities/ManifestDocumentElement.cs#L60-L61
(But would be nice if it didn't throw NRE)

If you put a valid Type, does this workaround for now:

BackupAgent = typeof(Android.App.Backup.BackupAgent),
ManageSpaceActivity = typeof(object)

[tranb3r]

Thank you @jonathanpeppers , the workaround seems to work.