Link all in Xamarin release,failed with Autofac Assembly - xamarin

Question

When setting the Linker behaviour to "Link all" I get the following error at runtime:
Autofac.Core.DependencyResolutionException.
I've tried adding ignore assembly Autofac but without success.
Setting the Linker behavior to "Link Framework SDKs only" does work but I want to enable "Link All" if possible.
Thanks in advance.
Update :
ReflectionActivator.ActivateInstance (Autofac.IComponentContext context, System.Collections.Generic.IEnumerable`1[T] parameters)
Autofac.Core.DependencyResolutionException: No constructors on type 'Eela.Taxi.Service.RestService' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'.
No constructors on type 'Eela.Taxi.Service.RestService' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'.
An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = RestService (ReflectionActivator), Services = [Eela.Model.Xamarin.Interfaces.IRestService], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = OwnedByLifetimeScope ---> No constructors on type 'Eela.Taxi.Service.RestService' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'. (See inner exception for details.)
1
ReflectionActivator.ActivateInstance (Autofac.IComponentContext context, System.Collections.Generic.IEnumerable`1[T] parameters)
2
InstanceLookup.Activate (System.Collections.Generic.IEnumerable`1[T] parameters)
An error occurred during the activation of a particular registration. See the inner exception for details. Registration: Activator = RestService (ReflectionActivator), Services = [Eela.Model.Xamarin.Interfaces.IRestService], Lifetime = Autofac.Core.Lifetime.CurrentScopeLifetime, Sharing = None, Ownership = OwnedByLifetimeScope ---> No constructors on type 'Eela.Taxi.Service.RestService' can be found with the constructor finder 'Autofac.Core.Activators.Reflection.DefaultConstructorFinder'. (See inner exception for details.)
1
InstanceLookup.Activate (System.Collections.Generic.IEnumerable`1[T] parameters)
2
InstanceLookup.Execute ()
3
ResolveOperation.GetOrCreateInstance (Autofac.Core.ISharingLifetimeScope currentOperationScope, Autofac.Core.IComponentRegistration registration, System.Collections.Generic.IEnumerable`1[T] parameters)
4
ResolveOperation.ResolveComponent (Autofac.Core.IComponentRegistration registration, System.Collections.Generic.IEnumerable`1[T] parameters)
5
ResolveOperation.Execute (Autofac.Core.IComponentRegistration registration, System.Collections.Generic.IEnumerable`1[T] parameters)
6
LifetimeScope.ResolveComponent (Autofac.Core.IComponentRegistration registration, System.Collections.Generic.IEnumerable`1[T] parameters)
7
Container.ResolveComponent (Autofac.Core.IComponentRegistration registration, System.Collections.Generic.IEnumerable`1[T] parameters)
8
ResolutionExtensions.TryResolveService (Autofac.IComponentContext context, Autofac.Core.Service service, System.Collections.Generic.IEnumerable`1[T] parameters, System.Object& instance)
9
ResolutionExtensions.ResolveService (Autofac.IComponentContext context, Autofac.Core.Service service, System.Collections.Generic.IEnumerable`1[T] parameters)
10
ResolutionExtensions.Resolve (Autofac.IComponentContext context, System.Type serviceType, System.Collections.Generic.IEnumerable`1[T] parameters)
11
ResolutionExtensions.Resolve[TService] (Autofac.IComponentContext context, System.Collections.Generic.IEnumerable`1[T] parameters)
12
ResolutionExtensions.Resolve[TService] (Autofac.IComponentContext context)
13
App+<OnStart>d__4.MoveNext ()
14
ExceptionDispatchInfo.Throw ()
15
AsyncMethodBuilderCore+<>c.<ThrowAsync>b__6_0 (System.Object state)
16
SyncContext+<>c__DisplayClass2_0.<Post>b__0 ()
17
Thread+RunnableImplementor.Run ()
18
IRunnableInvoker.n_Run (System.IntPtr jnienv, System.IntPtr native__this)
19
(wrapper dynamic-method) System.Object:f9684b08-49ee-4f47-8b7c-c59b675c18f3 (intptr,intptr)

Answer 1

So as your Stack Trace indicates. Autofac is trying to instantiate an instance of Eela.Taxi.Service.RestService. However, it seems like the Mono Linker has removed the constructor because it is never directly invoked.
So you could do a couple of things. You could:
Add your assembly to be ignored from the linker
You could add a [Preserve] attribute on your RestService to tell the Linker not to touch it
You could similar to what MvvmCross does have a LinkerPleaseInclude.cs file which describes usage of each type that get stripped out. So for every one you discover you will need to add it here.
So 1. and 2. are fairly self explanatory. You have already used 1. for autofac, just do the same for your own assembly containing RestService. However, the downside here is that nothing in this assembly will be linked, potentially leaving you with a lot more code in it than actually needed.
For 2. you simply add [Preserve] right before declaring your class. So something like:
[Preserve]
public class RestService : IRestService { }
You may also consider using it with AllMembers = true: [Preserve(AllMembers = true)] to keep member fields too.
As for the last option. You basically create a LinkerPleaseInclude.cs in your App project. You let the linker do its job. You continue adding stuff to the class until the Linker does kill your App at runtime. So a start on LinkerPleaseInclude.cs could look like:
[Preserve(AllMembers = true)]
public class LinkerPleaseInclude
{
public void Include(IRestService service)
{
service = new RestService();
}
}
This class is never invoked, but it is enough for the linker to know that the constructor of RestService should not be linked out.