Start using the Regex source generator in this repo

[danmoseley]

We now have a source generator in .NET 7 SDK builds to generate regex code at compile time. We should start using it in this repo. (Not in the System.Text.RegularExpressions tests, of course - but in tests elsewhere in the repo there are some regexes.)

Up for grabs. If this works out we can open an issue in aspnetcore to do the same.

This needs main to start using the .NET 7 SDK first. @dotnet/runtime-infrastructure is that planned soon?

cc @stephentoub

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Issue Details

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We now have a source generator in .NET 7 SDK builds to generate regex code at compile time. We should start using it in this repo. (Not in the System.Text.RegularExpressions tests, of course - but in tests elsewhere in the repo there are some regexes.)

Up for grabs. If this works out we can open an issue in aspnetcore to do the same.

This needs main to start using the .NET 7 SDK first. @dotnet/runtime-infrastructure is that planned soon?

cc @stephentoub

Author:	danmoseley
Assignees:	-
Labels:	area-System.Text.RegularExpressions, up-for-grabs
Milestone:	-

[Clockwork-Muse]

It's been a while since I've done anything. I suppose I can take this on (will keep me out of trouble).

[am11]

The naming difference in [RegexGenerator] and [GeneratedDllImport] (both corresponding to upcoming .NET 7 generators) might look a bit strange when working in common configurations like the ones in eng/generators.targets. It was mentioned under Alternative names in #58880. It would be nice to align their names, but not sure if it is too late to propose name change; GeneratedDllImport to match regex one (or vice versa) before .NET 7 ships.

[stephentoub]

not sure if it is too late to propose name change; GeneratedDllImport to match regex one (or vice versa) before .NET 7 ships.

It's not too late. I agree we should be consistent between them. Can you please open a separate issue?

(Personally, I prefer RegexGeneratorAttribute / DllImportGeneratorAttribute, as it's the thing causing the generation to happen rather than being the result of the generation process.)

[danmoseley]

This needs main to start using the .NET 7 SDK first. @dotnet/runtime-infrastructure is that planned soon?

Seems that has now happened. #61472

Edit: excuse me, that's the GA SDK. We will need a newer one. @Clockwork-Muse I guess you will have to use a newer SDK locally, then before we can merge we will need main to be using a .NET 7 SDK. I suspect they would normally not do that until Preview 1 (Feb) but perhaps it can happen earlier.

[jkoritzinsky]

Why don't we use the live generator instead of the LKG one from the SDK? That way we have a better loop for fixing bugs in the generator and we don't have to update to use a nightly unsigned SDK.

[danmoseley]

If that's technically possible (sounds like build phases all over again?) then I agree that's better.

[jkoritzinsky]

That's what we're doing with the DllImport source generator. We're using the same mechanisms used to test the generator to use them in the rest of the repo itself.

[danmoseley]

Perfect, then @Clockwork-Muse you should be unblocked. thanks for offering to do this!

We will also need to solve this problem for aspnetcore, or they will, if they want to opt into this in the near term. Let's do our repo first.

[jkoritzinsky]

If the Regex generator is shipping in the .NET 7 ref pack, then ASP.NET Core should be able to consume it by the same mechanism that they consume the nightly ref packs today.

[Clockwork-Muse]

Confirm that I can use the in-repo generator.

If there are non-test projects that are using regex, should I switch them as well?