Roslyn compiler updates are not flowing into Arcade and consuming repositories

[ViktorHofer]

• This issue is blocking
• This issue is causing unreasonable pain

The compiler package version hasn't been updated in Arcade for more than 2 months now:

arcade/eng/Versions.props

Line 38 in afd54cd

<MicrosoftNetCompilersToolsetVersion>3.8.0-5.20604.10</MicrosoftNetCompilersToolsetVersion>

Is that intentional or is a dependency not set-up correctly?

cc @mmitche @jaredpar

[jaredpar]

I'm not aware of any issues on our side, my expectation is that this should be flowing.

@JoeRobich, @RikkiGibson FYI

[ViktorHofer]

My assumption is that the wrong channel is associated with arcade (VS 16.8 vs something else):

PS C:\git\runtime3> darc get-subscriptions --target-repo arcade --source-repo roslyn
https://github.com/dotnet/roslyn (VS 16.8) ==> 'https://github.com/dotnet/arcade' ('master')
  - Id: c4ba476b-52c5-4bcf-e67a-08d808024d62
  - Update Frequency: EveryWeek
  - Enabled: True
  - Batchable: True
  - Merge Policies:
    Standard

[ViktorHofer]

@jaredpar @JoeRobich @RikkiGibson any update? The fix should be straightforward but I don't think I'm the right person to update the subscription. Also can we please write this down somewhere / educate folks to prevent this from happening again when your branch/channel changes again?

[JoeRobich]

@jaredpar I wasn't aware we were updating the subscriptions for Arcade. Should this be part of the Tiger duties?

[RikkiGibson]

I think in a previous snap some of the necessary darc updates may have slipped under the radar. I can try to address it now.

[RikkiGibson]

I went ahead and updated the subscription to use 16.9 channel and triggered the subscription. This automated PR was just updated to reflect that: #6894

However, I found that all the darc-related steps we have documented appear to have been followed properly. Looking at the scenario a bit, though, it feels like the consuming repo should be the ones to decide when they are ready to start consuming dependencies from a new channel, and to make the config change to do so. Does that seem right to you?

[ViktorHofer]

it feels like the consuming repo should be the ones to decide when they are ready to start consuming dependencies from a new channel, and to make the config change to do so. Does that seem right to you?

I disagree. How would Arcade know that roslyn changed their default channel? The goal of the subscription from Arcade to roslyn is to have a centralized up-to-date version of the compiler package. Handing that duty off to Arcade would mean that they would need to check every day or so if the subscription still points to the latest channel.

[RikkiGibson]

If the goal is to have Arcade always receive the most up-to-date possible compiler version, it might make sense to maintain a perpetual subscription to the "VS Master" channel.

Otherwise: The channels we use are tightly bound to VS releases. We only introduce a new default channel when we snap the first preview for a new VS release. That's the only time you should need to check.

For an example, here are some of the Roslyn subscriptions used by the SDK repo. I don't have evidence that Roslyn team manages these subscriptions, but I could be wrong. Tagging @JoeRobich @Cosifne to check my knowledge here.

https://github.com/dotnet/roslyn (VS 16.8) ==> 'https://github.com/dotnet/sdk' ('release/5.0.1xx')
  - Id: fe6e5bc9-bc04-4376-6b6a-08d85e7136ee
  - Update Frequency: EveryBuild
  - Enabled: True
  - Batchable: False
  - Merge Policies:
    Standard
  - Last Build: 20201204.10 (9ed4b774d20940880de8df1ca8b07508aa01c8cd)
https://github.com/dotnet/roslyn (VS 16.9) ==> 'https://github.com/dotnet/sdk' ('release/5.0.2xx')
  - Id: 549f64c9-69c5-4918-bc89-08d87076189d
  - Update Frequency: EveryBuild
  - Enabled: True
  - Batchable: False
  - Merge Policies:
    Standard
  - Last Build: 20210130.10 (3f54551d64817ec41c571b60cd512bd4e5902431)
https://github.com/dotnet/roslyn (VS Master) ==> 'https://github.com/dotnet/sdk' ('release/6.0.1xx-preview1')
  - Id: 15ea2541-5b90-4526-02d6-08d8b80548e4
  - Update Frequency: EveryBuild
  - Enabled: True
  - Batchable: False
  - Merge Policies:
    Standard
  - Last Build: 20210202.4 (c99c6fb04e72e0acc9d516533b17c5e1f72026f0)

This OneNote doc includes the only darc-related steps we expect the Roslyn infra team to perform when snapping a new minor VS version (e.g. dev16.8-preview1, or dev16.9-preview1).

[jaredpar]

If the goal is to have Arcade always receive the most up-to-date possible compiler version, it might make sense to maintain a perpetual subscription to the "VS Master" channel.

This matches my mental model. The compiler we are shipping to the logical "VS master" is the one that we are pushing into Arcade.

[ViktorHofer]

@RikkiGibson, based on Jared's response, should we change the subscription to always target the latest from roslyn?

[RikkiGibson]

I don't see why not :) if it builds and only arcade itself is impacted by the decision, then I have no objection.

[garath]

@mmitche As I recall, the guidance is to use the latest publicly released compiler (including previews). Is that what you rememeber?

[mmitche]

Yeah that's the general guidance for tooling.

[markwilkie]

Sounds like this is sorted, so closing. Pls reopen if I'm wrong.... :)