IronLanguages / IronLanguages/ironpython3
FirstOrDefault returns lambda function on empty collections from .NET 6 and forward
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Description
If you run
List[Object]().FirstOrDefault(lambda x: x)
after the appropriate imports the result will be something like this
<function <lambda$172> at 0x000000000000002B>
when it should be None
It does work as expected if you instead of object use another type like this
List[DateTime]().FirstOrDefault(lambda x: x)
I reproduced this in the IronPythonConsole by changing target framework to .NET 6 (same issue in .NET 7 and .NET 8)
Tested on
IronPython 3.4.1 DEBUG (3.4.1.1000)
[.NETCoreApp,Version=v6.0 on .NET 6.0.25 (64-bit)] on win32
It seems like there is an explicit cast to PythonFunction when it should still be an Object
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Research direction
Reproduce the expression in the IronPythonConsole on .NET 6 or later, comparing ListObject.FirstOrDefault(lambda x: x) with the working DateTime case. Trace the FirstOrDefault entry point and the handling of the lambda result; done means the empty Object collection returns None rather than a Python function.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp, python
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100