[wasm] trim System.Private.Uri.dll

[pavelsavara]

In the legacy interop, we have edge case use-case: when somebody would bind_static_method("Foo") where void Foo(Uri uri) the old marshaler would marshal string as Uri instance in Net6.
This feature costs about 103KB of System.Private.Uri.dll uncompressed for all runtime/wasm users, regardles if they use it or not.

This changes the code so that ILLink would not protect Uri class and it could be trimmed out.

I think that if the user code calls methods with Uri parameter, they probably also have the Uri constructor in scope.

Even if they don't have it, they could configure ILLink to protect Uri after they enabled trimming.

My.csproj

  <ItemGroup>
    <TrimmerRootDescriptor Include="$(MSBuildThisFileDirectory)ILLink.Descriptors.xml" />
  </ItemGroup>

ILLink.Descriptors.xml

<linker>
  <assembly fullname="System.Private.Uri">
    <type fullname="System.Uri">
        <method signature="System.Void .ctor(System.String)" />
    </type>
  </assembly>
</linker>

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Issue Details

---

In the legacy interop, we have edge case use-case: when somebody would bind_static_method("Foo") where void Foo(Uri uri) the old marshaler would marshal string as Uri instance in Net6.
This feature costs about 80KB of System.Private.Uri.dll uncompressed for all runtime/wasm users, regardles if they use it or not.

This changes the code so that ILLink would not protect Uri class and it could be trimmed out.

I think that if the user code calls methods with Uri parameter, they probably also have the Uri constructor in scope.
Even if they don't have it, they could configure ILLing to protect Uri it after they enabled trimming.

Author:	pavelsavara
Assignees:	pavelsavara
Labels:	arch-wasm, area-System.Runtime.InteropServices.JavaScript
Milestone:	8.0.0

[pavelsavara]

/azp run runtime-wasm

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[radekdoulik]

Given that it is a corner case, I think it is fine. For NET8 it will make sense to add a new feature switch for the legacy JS interop as discussed on discord and hide the reflection behind it.

[radical]

/azp run runtime-wasm

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Azure Pipelines successfully started running 1 pipeline(s).

[pavelsavara]

/azp run runtime-wasm

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Azure Pipelines successfully started running 1 pipeline(s).

[pavelsavara]

Uncaught Error: System.MissingMethodException: Constructor on type 'System.Uri' not found. Please consider to protect it's constructor from trimming.
 ---> System.MissingMethodException: Constructor on type 'System.Uri' not found.
   at System.RuntimeType.CreateInstanceImpl(BindingFlags , Binder , Object[] , CultureInfo )
   at System.Activator.CreateInstance(Type , BindingFlags , Binder , Object[] , CultureInfo , Object[] )
   at System.Activator.CreateInstance(Type , Object[] )
   at System.Runtime.InteropServices.JavaScript.LegacyExports.CreateUriRef(String uri, Object& result)
   --- End of inner exception stack trace ---
   at System.Runtime.InteropServices.JavaScript.LegacyExports.CreateUriRef(String uri, Object& result)

This is how it looks like when the constructor was trimmed.
I also tested that the ILink configuration makes it work again, see top post.

[pavelsavara]

/azp run runtime-wasm

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Azure Pipelines successfully started running 1 pipeline(s).