Apply NETSDK1130 error only if reference to CSWinRT nuget is missing

[AdamBraden]

With the removal of built-in support for WinRT, net5 now gives an error when building a project that references a *.winmd file. This prevents cswinrt from improving the tooling experience to build the projection. The error should only show if there is no reference to cswinrt.

[stevenbrix]

Also see #13131 related to this error as well

[stevenbrix]

I think a better overall approach is to have the C#/WinRT nuget have a target that runs before _BlockWinMDsOnUnsupportedTFMs that does the projection generation and then removes the winmd files from ReferencePath

[Scottj1s]

I don't have a problem with the cswinrt nuget modifying references, etc. But relying on it to resolve this problem is not correct. Not all projects that experience the NETSDK1130 have any need for cswinrt.

see also:
New winmd reference enforcement takes down unit test host
New winmd reference enforcement targets wrong items

[stevenbrix]

Not all projects that experience the NETSDK1130 have any need for cswinrt.

Right, I think what you are referring to is #13131?

What I'm saying is for those that do need cswinrt, cswinrt should be the one to ensure that the _BlockWinMDsOnSupportedTFMs doesn't error. Adding a condition to _BlockWinMDsOnSupportedTFMs that says "don't error if I notice a PackageReference to cswinrt even though there may or may not be winmds" seems incorrect.

[Scottj1s]

@stevenbrix actually, in my case it was neither a need for cswinrt nuget, nor use of the Windows contract metadata. There are many potential scenarios for referencing winmd files.

[stevenbrix]

@Scottj1s what scenario is this? it seems then that this error shouldn't recommend to install the cswinrt nuget?