Unclear error report when using uninitialized variable in a local function: "Use of possibly unassigned field '_dummyPrimitive'"

[ForNeVeR]

Version Used:

dotnet --info
.NET SDK:
 Version:           9.0.101
 Commit:            eedb237549
 Workload version:  9.0.100-manifests.3068a692
 MSBuild version:   17.12.12+1cce77968

Steps to Reproduce:

Write the following program (dotnet new classlib, <TargetFramework>net9.0</TargetFramework>).

namespace ClassLibrary2;

public class Class1
{
    public static void Foo()
    {
        var my = DoSmth();

        var guid = Guid.NewGuid();
        int DoSmth() => guid.GetHashCode();
    }
}

Diagnostic Id:

CS0170: Use of possibly unassigned field '_dummyPrimitive'

Expected Behavior:
Roslyn should report that it's impossible to use DoSmth() local function before initializing guid local variable. Without referring to any of private fields in the Guid type.

Actual Behavior:

Class1.cs(7,18): error CS0170: Use of possibly unassigned field '_dummyPrimitive'

So, not only it doesn't reference the actual variable that's not initialized, it also mentions _dummyPrimitive, a name of the synthetic field in the corresponding reference assembly and not a real field from System.Guid (I assume).

Imagine what will happen if you are working in a function with a dozen of variables, and Roslyn tells you that some of them are not initialized, using an unfamiliar field name when telling that. The error is quite confusing.

[jhinder]

Probably a duplicate of #67212.

[ForNeVeR]

I saw that issue but not sure honestly.

#67212 seems to describe a more complex situation involving pattern matching and async, while this one is much simpler.

There's an identical example in the last comment, though. But I am not sure if all the same arguments apply to this particular case.

So, whether you wish to close this as a duplicate is up to you, folks.