net40 target has compability issues with .NET 4.5+ frameworks

[jklawrence]

I'm using Lambda2Js.Signed as a transitive dependency of RavenDb.Client in a .NET Framework 4.7.2 application.

Lambda2Js.Signed's NuGet package has a net40 lib and a netstandard1.0 lib. Since I'm using .NET Framework, NuGet package manager picks the latest .NET Framework version of the package, net40. This would be fine, except the net40 package has some compatbility definitions of types that exist in mscorlib in .NET 4.5 and later, such as System.Threading.Interlocked. Because of this, my application is full of warnings like warning CS1685: The predefined type 'System.Threading.Interlocked' is defined in multiple assemblies in the global alias; using definition from 'c:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.7.2\mscorlib.dll'

I am able to manually edit my csproj to use the netstandard1.0 lib instead of net40, which resolves the issue. But any updates through NuGet package manager will reverse this, making this dependency fragile.

Would it be possible to add a new net45 lib to the NuGet package that doesn't contain the net40 compatibility types? This would help anyone on .NET Framework 4.5 or later.