It is illegal to reflect on the custom attributes of a Type loaded via ReflectionOnlyGetType

[fizxmike]

Environment

• Pythonnet version: 2.5.1
• Python version: 3.8 (anaconda)
• Operating System: Windows 10

Details

• Describe what you were trying to get done.

  View C# object members in jupyter notebook (via dot tab). C# app crashes.

• What commands did you run to trigger this issue?

    csharpObjectWithCustomAttributes.  # +tab in jupyter notebook should list members, but instead crashes

The c# library I am using is not publicly available. I assume it could be reproduced with some effort (creating an example C# library having an object with custom attributes).

However, I have found a related stack overflow issue (and solution): https://stackoverflow.com/a/42540881

And I see the potential "illegal use" in the code base here: https://github.com/pythonnet/pythonnet/search?q=GetCustomAttributes&unscoped_q=GetCustomAttributes

The fix might be to convert calls to GetCustomAttributes to what is mentioned in the stack overflow answer.

• If there was a crash, please include the traceback here.

Traceback happens inside loaded DLL and application crashes. All I get is this: TBH, that is one of the best error messages I've seen in a long time.

[lostmsu]

@fizxmike is this a regression from a previous version?

[fizxmike]

@lostmsu I'm not sure what you mean. Yes, I have had previous versions of PythonNet work with the C# library I'm using. However, the library has also been updated...

[lostmsu]

@fizxmike did this code work on 2.4.0 and/or below, and you used it, or is this something you started doing just now?

[lostmsu]

Basically, I think, Python.NET always assumes, that loaded assemblies are loaded in the full context, meaning reflection only is not currently supported.

BTW, it would be more helpful to have full stack trace.

[fizxmike]

Ah, so must be library I'm using is loading things "reflection only" ... I don't get stack trace with library I'm using. App crashes and I get that error message. So It's not clear which call in your code is the culprit; there are only 8 or so calls to GetFunctionAttributes(...). But I should confirm that the stack overflow solution is indeed the fix to my issue.

[fizxmike]

I can confirm this is not a regression. Something changed in the C# library I'm accessing I believe. Bump support for reflection only!