Building with .NET Native tool chain causes error with missing property in dynamic object

Question

I have a piece of code that gets a JSON response and checks whether there is a .error field

dynamic jsonResponse = JsonConvert.DeserializeObject(responseString);
if (jsonResponse.error != null) { error = jsonResponse.error; }
else
{
  success = true;
}

This runs successfully when it is not compiled with .NET Native toolchain but produces an error (on jsonResponse.error) when it's built with it.

What is the reason for this? Any other similar incompatible behavior with native code?

EDIT: It turns out that even if there is an "error" key in the JSON, we still get an error. The exception is:

System.Reflection.MissingMetadataException: ''Microsoft.CSharp.RuntimeBinder.CSharpGetMemberBinder' is missing metadata. For more information, please visit http://go.microsoft.com/fwlink/?LinkID=392859'

MattWhilden · Accepted Answer · 2017-04-03 22:04:41Z

3

The subsystem that powers the dynamic keyword has various corner cases that don't run super well on .NET Native. This particular issue was reported to us in February, you can see some discussion on the CoreFX GitHub here.

The general idea is that the dynamic keyword causes a great deal of machinery to wander through APIs and some pieces of the framework don't have the proper hinting to say "This isn't a thing you need to reflect on." Because our compiler analysis says you won't need this type at runtime but this particular component does, we end up throwing this exception.

The link in the exception is trying to help build a runtime directive (think of it as a hint to the .NET Native compiler) so that we'll know you'll need type information at runtime. For this particular case it would look like:

<Type Name="Microsoft.CSharp.RuntimeBinder.CSharpGetMemberBinder" Dynamic="Required All"/>

If you add that to the the file Properties\Default.rd.xml I would expect this error to disappear. You may hit additional errors of this type but they should be able to be addressed in a similar fashion.

We've logged a bug on our side to get this addressed at some point in the future but you'll need this workaround in the meantime.

answered Apr 3, 2017 at 22:04

MattWhilden

1,69613 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

visc Over a year ago

I have Dynamic="Required All" in my project but it never works... Any time I use reflection or dynamic it always breaks down on me... perhaps this is the edge cases referred to by this thread.

Collectives™ on Stack Overflow

Building with .NET Native tool chain causes error with missing property in dynamic object

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related