Linker

[bgavrilMS]

tracking bug: #1586
Things that don't work now: json exception.

[bgavrilMS]

Please use if ANDROID as we not hiding anything here.

[bgavrilMS]

This is probably the reason why the fix isn't working.

[trwalke]

We tried doing this with #if ANDROID but that did not seem to work. The only thing that did work was adding preserve to each of the classes. We can remove this from the AssemblyInfo

[bgavrilMS]

Context: the linker works by removing code that isn't used by your app. For example, if the customer uses the system webview, then all the code related to embedded webview will be removed.

The root cause for json exceptions:

1. The LINKER looks at objects like ClientInfo and thinks - their constructors are are not used anywhere, so I can remove them! This is because MSAL doesn't use those constructors directly, but Newtonsoft invokes them thorough reflection. But Newtonsoft can't deserialize if constructors are removed :)
2. I bet that the Linker knows about the old [DataContract] attributes but doesn't know about the new [JsonObject] attributes.

So the solution is either:

1. to add the #if ANDROID || IOS [Preserve] attribute to ALL classes that we deserlialize, i.e. all classes that are decorated with  [JsonObject].
   OR
2. Alternatively, we can add [assembly: LinkerSafe] to tell the linker to leave the entire assembly alone.

If we want to play nice with Xamarin, we should go with [Preserve] attributes. This will allow Xamarin to remove unused code form MSAL and produce a smaller apk. If we want to be more future proof, [assembly: LinkerSafe] is the answer - this will tell Xamarin to leave MSAL alone and if we add a new object that we deserialize, then we wouldn't have to add the [Preseve] attribute as well. But the size of APK will be larger, and customers may complain.

CC @henrik-me @trwalke @jennyf19

[bgavrilMS]

LGTM

[bgavrilMS]

You don't need all those else clauses because you are either returning or throwing, which breaks the flow anyway.

[hig-dev]

I would not use something like:

#if iOS
using Foundation;
#endif
#if ANDROID
using Android.Runtime;
#endif

Instead declare a PreserveAttribute class and use that in the code:

public sealed class PreserveAttribute : System.Attribute {
    public bool AllMembers;
    public bool Conditional;
}

Then you can use it like:

    [PreserveAttribute(AllMembers = true)]
    public class ExampleClassToPreserve
    {
     ....
    }

This is a much cleaner solution.
Source: https://docs.microsoft.com/en-us/xamarin/ios/deploy-test/linker?tabs=macos#controlling-the-linker

[bgavrilMS]

If you just replace the entire block with

Console.WriteLine(exception);

it will be enough. The exception.ToString() method takes care of outputting the message, the stack trace and the inner exception details