[NativeAOT] GenericCompositionNode issue when Instantiation type name ends with _0, _1 or _2

[tomcashman]

I'm currently getting a Duplicate node name emitted to file on a project. After debugging, it comes from ObjectWriter for the following auto-generated types:

Com.Alchemiccutie.Scripting.Compiled.Npc.Martha.Martha_breed_jelly_tutorial_2
Com.Alchemiccutie.Scripting.Compiled.Npc.Martha.Martha_breed_jelly_tutorial

I've traced the issue to GenericCompositionNode.AppendMangledName where it suffixes a number based on the variance.

I've had trouble making a simple reproduction of this outside of our project. However, I've pinpointed the steps causing the issue:

• Martha_breed_jelly_tutorial_2 is added first to _previouslyWrittenNodeNames in ObjectWriter
• Martha_breed_jelly_tutorial is attempted to be added but due to how GenericCompositionNode generates the mangled name (result is Martha_breed_jelly_tutorial_2), it thinks there is a conflict.

[MichalStrehovsky]

Thanks for reporting this and root causing! Simplified repro:

_ = typeof(IFoo<GenXXX>).ToString();
_ = typeof(Foo<GenXXX_2>).ToString();

class GenXXX { }
class GenXXX_2 { }

interface IFoo<in T> { }
class Foo<T> { }

[MichalStrehovsky]

It will take a couple days for package with the fix to come out. We're still publishing packages from this repo, but the fix is in the runtime repo. I'm waiting for fixes to dotnet/runtime#63778 and dotnet/runtime#63906 before integration because NativeAOT is currently a bit broken.

[tomcashman]

No problem thank you for quickly resolving the issue 🙂