Revert Linq Version change 4.1.2.0 → 4.2.0.0 *no merge*

[JonHanna]

This is failing for me locally, but a comment by @ericstj leads me to suspect maybe that is to be expected. It certainly shouldn't be merged until CI is definitely cleared though.

[justinvp]

This line was added in #13726. Maybe removing will fix the failures?

[justinvp]

This line was also added in #13726. Maybe removing will fix the failure?

[justinvp]

I'm guessing pkg/Microsoft.Private.PackageBaseline/packageIndex.json needs to be changed back too.

[JonHanna]

It did.

I can build locally if I change the reference in System.Linq.Tets.csproj from referencing ..\pkg\System.Linq.pkgproj to referencing ..\src\System.Linq.csproj.

What further implications there?

[justinvp]

Have you tried reverting the change to packageIndex.json? I didn't see it in the diff here.

https://github.com/dotnet/corefx/blob/master/pkg/Microsoft.Private.PackageBaseline/packageIndex.json#L1607

[JonHanna]

Oh for goodness sake. I did, but then committed from too deep a directory and it didn't get included 😊

[JonHanna]

It would seem some change to layout/Microsoft.Private.CoreFx.NETCoreApp/Microsoft.Private.CoreFx.NETCoreApp.pkgproj or rather something(s) it pulls in needs to be changed.

@ericstj ?

[ericstj]

None of these are related to the index.

D:\j\workspace\windows_nt_de---4526f5ff\layout\Microsoft.Private.CoreFx.NETCoreApp\Microsoft.Private.CoreFx.NETCoreApp.pkgproj(63,5): error : Assembly 'System.Linq.Expressions' has insufficient version for dependency 'System.Linq' : 4.1.2.0 < 4.2.0.0.
D:\j\workspace\windows_nt_de---4526f5ff\layout\Microsoft.Private.CoreFx.NETCoreApp\Microsoft.Private.CoreFx.NETCoreApp.pkgproj(63,5): error : Assembly 'Microsoft.CSharp' has insufficient version for dependency 'System.Linq' : 4.1.2.0 < 4.2.0.0.
D:\j\workspace\windows_nt_de---4526f5ff\layout\Microsoft.Private.CoreFx.NETCoreApp\Microsoft.Private.CoreFx.NETCoreApp.pkgproj(63,5): error : Assembly 'System.Security.Cryptography.Encoding' has insufficient version for dependency 'System.Linq' : 4.1.2.0 < 4.2.0.0.
D:\j\workspace\windows_nt_de---4526f5ff\layout\Microsoft.Private.CoreFx.NETCoreApp\Microsoft.Private.CoreFx.NETCoreApp.pkgproj(63,5): error : Assembly 'System.ComponentModel.TypeConverter' has insufficient version for dependency 'System.Linq' : 4.1.2.0 < 4.2.0.0.

These are all problematic. Those errors are occurring when I do a closure walk of the final output.

These are ref-def mismatches in the final package set that will cause runtime issues. They're happening because each of these libraries is building against the old packages.

We could fix them all by adding p2p references but that is going to be painful.

I'm tempted to leave this as it is. If we want to make this change that will be much easier once dev/eng work is done.