[ Suggestion ] Add rollForward policy to the global.json config

[FoggyFinder]

https://docs.microsoft.com/en-us/dotnet/core/tools/global-json?tabs=netcore3x#rollforward

[kekekeks]

We have SDK version pinned because the concept of backwards compatibility seems to not apply well to the SDK. Anything newer than one in our global.json complains about a missing method in XmlSerializer

[FoggyFinder]

Anything newer than one in our global.json complains about a missing method in XmlSerializer

Are you sure ? I have only 3.1.301 so I add rollForward locally every time: without it most projects from solution are unloaded and except #4257 (which seems unrelated) I haven't saw any other issues.

[grokys]

The very next patch version after 3.1.101 (3.1.201 I think) broke Avalonia builds (see SharpGenTools/SharpGenTools#164 (comment)). This wouldn't be the first time that a .NET update broke our CI builds, so I think not having a roll-forward policy was a good idea.

[FoggyFinder]

Okay. Closing the issue then.
Though I personally think it would be better to find the actual reason and fix it ;-)

[kekekeks]

The actual reason is most likely a bug in CoreCLR

[Kryptos-FR]

I have the latest version of VS 2019 and VS 2019 preview (both with .NET Core 2.1 and 3.1 installed) and if I don't remove the specific version from global.json, not a single project can be loaded.

edit: currently building and running with 3.1.401 without any issue (after adding "rollForward": "latestFeature").