[Trimming] Enable trimming and AOT analyzers in Core

[simonrozsival]

Description of Change

This PR marks the Core project as AOT-compatible and it fixes all the warnings reported by the analyzers which are now enabled.

Issues Fixed

Contributes to #18658

/cc @jonathanpeppers @vitek-karas

[vitek-karas]

Just for future reference:
We've been burned in other projects by adding RUC (and other annotations) onto interface members. The problem is that doing so effectively marks all implementations of the interface with RUC. But RUC is a statement about the implementation, not about the interface.

For example Type.GetMembers - this has some annotation on it, but it's an abstract class. The reflection based implementation needs that annotation, but we also have MetadataLoadContext which also implements Type and that one doesn't need the annotation. But there's no way to tell that to the system and it will produce warnings and so on. Not that we will change Type.GetMembers, but it shows how the statement applies to all implementations, regardless if they are affected or not. (and also, removing the annotation from the interface member is a breaking change!)

I guess in this specific case, we basically don't care, since the methods are obsolete anyway. But it's a good rule to remember for the future: "Think hard if the annotation should be on the interface, really hard!"

[simonrozsival]

I struggled with this one. It feels wrong adding those attributes to the interface. I just couldn't figure out how else to apply the annotation in this case. I arrived at the same conclusion that we don't care too much since we already marked it obsolte and we don't know about any customer who would have their custom implementation of IImageSourceProvider at the moment.

[simonrozsival]

The analyzers reported the following issues on Windows:

D:\a\1\s\src\Core\src\obj\Release\net9.0-windows10.0.20348\XamlTypeInfo.g.cs(1749,13): error IL2059: Unrecognized value passed to the parameter 'type' of method 'System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(RuntimeTypeHandle)'. It's not possible to guarantee the availability of the target static constructor. [D:\a\1\s\src\Core\src\Core.csproj::TargetFramework=net9.0-windows10.0.20348]
D:\a\1\s\src\Core\src\Platform\Windows\FrameworkElementExtensions.cs(182,9): error IL2072: 'type' argument does not satisfy 'DynamicallyAccessedMemberTypes.All' in call to 'Microsoft.Maui.Platform.ReflectionExtensions.GetField(Type, Func<FieldInfo, Boolean>)'. The return value of method 'System.Object.GetType()' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to. [D:\a\1\s\src\Core\src\Core.csproj::TargetFramework=net9.0-windows10.0.20348]
D:\a\1\s\src\Core\src\obj\Release\net9.0-windows10.0.19041\XamlTypeInfo.g.cs(1749,13): error IL2059: Unrecognized value passed to the parameter 'type' of method 'System.Runtime.CompilerServices.RuntimeHelpers.RunClassConstructor(RuntimeTypeHandle)'. It's not possible to guarantee the availability of the target static constructor. [D:\a\1\s\src\Core\src\Core.csproj::TargetFramework=net9.0-windows10.0.19041]
D:\a\1\s\src\Core\src\Platform\Windows\FrameworkElementExtensions.cs(182,9): error IL2072: 'type' argument does not satisfy 'DynamicallyAccessedMemberTypes.All' in call to 'Microsoft.Maui.Platform.ReflectionExtensions.GetField(Type, Func<FieldInfo, Boolean>)'. The return value of method 'System.Object.GetType()' does not have matching annotations. The source value must declare at least the same requirements as those declared on the target location it is assigned to. [D:\a\1\s\src\Core\src\Core.csproj::TargetFramework=net9.0-windows10.0.19041]

We could do something about FrameworkElementExtensions.cs but since there is also a warning coming from the source generated by WinUI, I suggest we don't enable the analyzers on Windows for now.

[jonathanpeppers]

The analyzers reported the following issues on Windows:
...

My "hope" is we would soon be able to put something like this in the project template:

<!-- greenfield apps should have an easier time with this -->
<PropertyGroup Condition="'$(Configuration)' == 'Release'">
  <TrimMode>full</TrimMode>
</PropertyGroup>

Then in the iOS/Android workloads, we would do similar for the iOS/Android templates there.

But if we do this in MAUI, will there be trimming warnings from the WindowsAppSDK we can't do much about?

[vitek-karas]

I asked and apparently they're aware of it, and hopefully will fix it soon.

[jonathanpeppers]

I have sent WindowsAppSdk PRs in the past, and that seemed to move things along more quickly. So, if the changes are simple, we can consider that.

[simonrozsival]

The failing test seems unrelated