Emit host outputs

[jjonescz]

Making the source generator emit design-time C# and HTML via host outputs.

Based on

• Consolidate roslyn versions #8103.

Blocked by

• Process host outputs by GeneratorDriver roslyn#66570—until that's published, this PR needs to use manually published Roslyn version 4.5.0-2.23107.1,
• Add net6.0 TFM to ExternalAccess.Razor roslyn#66846.

[ryanbrandenburg]

One question about the NuGet.config, probably want someone with more compiler knowledge for the important bits.

[chsienki]

This is an elegant approach, but it's not going to work for us unfortunately. We need to be able to produce both the design time and runtime documents for hot reload at the same time. Instead, we should fork the graph before emitting and produce both designtime for the host outputs, and runtime for the regular source.

That's obviously going to be doing more work, so lets switch it to ImplementationOnlyOutput. Then we can hook that up on the IDE side so that, effectively, the design time only runs in the IDE, the runtime only run in the command line compiler, and both run in hot reload scenarios.

Note also this isn't actually going to do anything until we enable it on the IDE side.

[chsienki]

Need both design time and runtime

[jjonescz]

@chsienki @dotnet/razor-compiler feedback addressed, CI is green. However, we might want to first merge

• Consolidate roslyn versions #8103 (then diff of this PR will get smaller) and
• Perf/generator #8212 (I will need to resolve conflicts after this).

[adrianwright109]

@chsienki @dotnet/razor-compiler feedback addressed, CI is green. However, we might want to first merge

• Consolidate roslyn versions #8103 (then diff of this PR will get smaller) and
• Perf/generator #8212 (I will need to resolve conflicts after this).

@jjonescz Perf/generator #8212 is targeting release/dev17.6 not main like this and the other associated PRs.

[jjonescz]

@adrianwright109

Perf/generator #8212 is targeting release/dev17.6 not main like this and the other associated PRs.

True, but release/dev17.6 is periodically merged back into main, I think.

[333fred]

Test insertion link (internal only): https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/460368

[jjonescz]

@chsienki for another look

[chsienki]

New test insertion link (internal only) https://dev.azure.com/devdiv/DevDiv/_git/VS/pullrequest/467451

[chsienki]

@jjonescz We discussed in the working group about if we want to put this work in a branch or in main behind a flag. I think this work is good for main-behind-a-flag. Can we do something similar to how we suppress the whole generator with the .razorencconfig to make this opt-in?

Basically cut out early and do no host output work unless an option in the config is present? That way it'll be off by default but we can opt-in individually for testing?

[chsienki]

Latest changes LGTM

[chsienki]

🥳