Are netstandard2.1 or netcoreapp3.1 supported for source generator projects?

[sid-6581]

I've just started to use this project for some basic source generation tasks, and after a lot of trial and error I have it set up and working. All my projects that will consume the source generators are netcoreapp3.1 projects, but the source generator project itself doesn't seem to want to play ball if I set the target framework to netstandard2.1 or netcoreapp3.1. net48 and netstandard2.0 work, and I settled on netstandard2.0 for now.

I don't technically need anything higher since the source generator project is fairly small and simple, but it would be nice to have some of the newer .NET Core 3.x features. Is this not currently possible, or am I missing something? I've searched through the issues, looked at the source code, looked at other projects, and I can't find any indication as to whether this is supported or not.

[jeromelaban]

Thanks for your interest in the project!

At this point, Uno.SourceGeneration supports both the .NET Framework and .NET Core user projects, and the best option for generators is to use netstandard2.0 to be compatible.

For netstandard 2.1 to be supported, the underlying runtime hosting msbuild must also support it, and Visual Studio 2019, when running from the IDE, builds .NET core projects using the .NET framework. This might change in the future, but until then, both netcoreapp and netstandard 2.1 won't be available to generators.

My guess is that it will change in the .NET 5 timeframe.

[sid-6581]

Thanks for the quick reply! That makes sense. I figured it might be a limitation, in which case it's no big deal. I just didn't want to miss out if I was doing something wrong, but netstandard2.0 works great.

Speaking of limitations, I'm having a hard time getting VS to recognize my generated code. The build works fine, but IntelliSense seems to have no clue about the generated code until I clean, rebuild, restart VS, wait, and do it all again a time or two. I'm not sure what my expectations should be in this area, either. Is that also something that is just a limitation of the environment it's running in, or should it not behave like that? Apologies if this question is unrelated to my original one, or if it is too vague.

[jeromelaban]

This is a Visual Studio limitation at this point, where the Intellisense engine is not recognizing the generated files.

My guess is that it will be fixed somehow with the introduction of C# 9.0, but in the meantime, unloading/reloading the solution or project that uses the generator, or to change the build action of any file in the project can do for Intellisense to reevaluate compile items.

[sid-6581]

I noticed there was a VSIX earlier that was supposed to flush/refresh the Intellisense, but that was removed in favor of I assume similar functionality in the msbuild task. If I'm having issues getting Intellisense to update (short of cleaning the solution and deleting the .vs directory), do you think it's worthwhile for me to go back and try to use the VSIX? Or was that not any more effective than the current method?

[carldebilly]

That VSIX was causing a lot of problems. A lot. When a file was saved, it was forcing VisualStudio to reload it by removing and re-adding the file on the project. It was working most of the time, but destroying any customization in the .csproj. So this approach has been abandonned.

[sid-6581]

Do you think it would work if the VSIX was modified not to remove/re-add the file, but instead change the build action for the current file to None and then back to what it was? I've tried a couple of approaches, and that seems like the least intrusive. I haven't seen any side effects yet from doing it manually, but I can't say for sure whether it would have any unintended side effects.

Edit: I take that back, it doesn't always seem to trigger an Intellisense refresh. Sometimes it works, sometimes it doesn't. I've found unloading and reloading the project to work reliably, so I just have that mapped to a keyboard shortcut. In the absence of anything cleaner, that should tide me over until the IDE experience catches up.