Noticeable changes:
- use `in` at declaration of "in" parameters, not `ref readonly`
- `ref` comes before `partial` when declaring partial ref structs.
- unboxing conversions for ref-like types are statically rejected as impossible to succeed
The corresponding VSIX to match these compiler bits with IDE experience is -
https://dotnet.myget.org/F/roslyn/vsix/0b48e25b-9903-4d8b-ad39-d4cca196e3c7-2.6.0.6221102.vsix
This was a "special" build, so there is no public VSIX for this.
The old one should be ok, for most scenarios.
When VS 15.5 preview1 is available it will match this compiler feature-wise by default.
PackageLineup is a way to manage PackageReference versions across large projects. It removes the version information from the repository and instead pulls the information from an external "lineup" file.