[BUG] Index type ambiguity with InternalsVisibleTo and Microsoft.Bcl.Memory

[alastairlundy]

Describe the bug

When using a dependency that relies on Microsoft.Bcl.Memory or using Microsoft.Bcl.Memory directly, a type conflict occurs where both Polyfill and Microsoft.Bcl.Memory provide versions of Index and Polyfill forwards it's type to a package that has a dependency on Microsoft.Bcl.Memory.

I haven't tested this with the Range type but presumably this also occurs since Microsoft.Bcl.Memory also provides ```Range``.

If I may be so bold, I would suggest considering removing Index and Range from Polyfill in a future major version since it is provided by a Microsoft Bcl NuGet package for .NET Standard 2.0.

Minimal Repro

Attached a minimal repro:

MinimalReproDependent.zip

Submit a PR that fixes the bug

I've created a PR that I believe fixes this (#512) by adding a PolyIndexAndRange feature toggle that is set to true by default, and removes the Index And Range types from compilation if set to false.

[SimonCropp]

can u try 9.24.1

[alastairlundy]

can u try 9.24.1

9.24.1 only hides Index and Range if Microsoft.Bcl.Memory isn't used, but if it used by the dependant project then the dependant project with Polyfill internal type forwading sees both versions of Index.

[SimonCropp]

in your repro, isnt the correct fix to add a ref to <PackageReference Include="Microsoft.Bcl.Memory" /> in MinimalReproDependent ?

[alastairlundy]

in your repro, isnt the correct fix to add a ref to <PackageReference Include="Microsoft.Bcl.Memory" /> in MinimalReproDependent ?

I realized I miscommunicated in the minimal repro I provided and it may also not be as clear as in my actual issue. My bad for that.

Here's an example closer to the exact issue I have: Project A uses Polyfill and type forwards with InternalsVisibleTo for Project C but it doesn't itself require Microsoft.Bcl.Memory. Project B relies on Microsoft.Bcl.Memory but has no relation to Project A. Project C relies on Project A and Project B. Project C sees Project A's internal types including the Index and Range from Polyfill AND also Project B's Index and Range from Microsoft.Bcl.Memory.

It doesn't make sense to add Microsoft.Bcl.Memory as a dependency to Project A and it's not super easy to get rid of as a dependency for Project B. Adding it to Project C makes no difference, the conflict still exists. As a workaround I can try to avoid InternalsVisibleTo from Project A to Project C but it would be nice to be able to avoid this type conflict in future.

[SimonCropp]

can u share a zipped repro of that. or push it to a GH repository