New dependency resolver does not properly detect a cycle with a transitive dependency with the same name as the root project

[JohanLarsson]

NuGet Product Used

dotnet.exe

Product Version

9.0.0

Worked before?

Assume no

Impact

It's more difficult to complete my work

Repro Steps & Context

1. Name a project LightGbm
2. Try to install https://www.nuget.org/packages/Microsoft.ML.LightGbm

It fails with message 'the given key was not present in the dictionary'

This is happening because a transitive dependency has the same name as the root project and the new dependency resolver tries to replace the root project with it instead of just ignoring it for later since it needs to be detected as a cycle instead.

Verbose Logs

[jeffkl]

Thank you for reporting this issue. This is caused by a bug in the new dependency resolver. It should be informing you of a cycle and if you use the legacy dependency resolver you get the proper error message:

error NU1108: Cycle detected.
error NU1108:   LightGbm -> Microsoft.ML.LightGbm 4.0.1 -> LightGBM (>= 3.3.5)

You would not be able to install a package with a transitive dependency with the same name as your project so you'll need to rename your project. To workaround the issue, you can also enable the legacy dependency resolver: https://learn.microsoft.com/en-us/nuget/consume-packages/package-references-in-project-files#nuget-dependency-resolver

[jeffkl]

This was technically fixed in NuGet/NuGet.Client#6231 but only by accident. I might still need to fix it intentionally.