Remove unsafe.Tag based type resolution for CFuncPtr.{fromScalaFunction,apply}

[tanishiking]

Fix #3220

This pull request refacts the handling of CFuncPtr.{fromscalaFunction,apply} by preserving the exact type information during the type erasure phase and referencing it in the NIR generation phase. This is the same approach as sizeOf[T] and alignmentOf[T] #3198.

Previously, we restored the type information based on the `unsafe.Tag' proof types, which is a bit buggy.

This PR includes the following changes

• Addition of special attachments to the AST for CFuncPtr#apply and CFuncPtr.fromScalaFunction whose values are their type information (parameter types and return type).
• At the NIR generation phase (NIRGenExpr.scala), get the attached exact type information and use it to generate external forwarder methods (previously we used the type information restored based on unsafe.Tag).
• Remove the dead code for tag parsing in NirGenUtil.unwrap{ClassTag,Tag} and Tags related code in NirDefinitions.
• Update nativelib/src/main/scala/scalanative/unsafe.CFuncPtr.scala.gyb to remove unsed evidences types.

finished todo

TODOs

• Remove unsafe.Tag from CFuncPtrX and remove unwrapTag from NirGenUtil`
• Migrate scalalib-patch-tool to scala-cli
  • It required to re-generate patch files to publish locally during development, but it turned out we don't need re-creation now 🤔 Maybe we can separate f86daba to another PR.
• Testing
  • tests2_13 / Test
  • test3 / Test
  • test2_12 / Test
    • auxlib failed to build with this patch nevermind, it seems like it my local environment probem.
• manual testing (testing on https://github.com/tanishiking/scala-native-sbt)
  • ++3.2.2 publishLocal ok
  • ++2.12.17 publishLocal
  • ++2.13.10 publishLocal~ it seems like nativeLink always fail with the following error while tests pass.~ it's also my local environment problem. nevermind

[info] ZipFile invalid LOC header (bad signature)
[error] Found 2 missing definitions while linking
[error] Not found Top(Main)
[error] Not found Member(Top(Main),D4mainLAL16java.lang.String_uEo)
[error] Undefined definitions found in reachability phase
[error] (Compile / nativeLink) Undefined definitions found in reachability phase
[error] Total time: 1 s, completed May 5, 2023, 10:11:12 PM

[WojciechMazur]

Looks good so far, I've left some comments how we can simplify it a bit.

Regarding to problems with local publishing, it is probably due to usage of nativeLink task in root project. I'm not sure where does it comes from, probably we could inspect the build and override it. Due to complexity of the build (we don't have typical crossVersion but use project duplicates for each Scala binary version), and the fact that there are cases where we need to either always depend on Scala 2.12 (sbtPlugin) or Scala 2.13 (scalalib for Scala 3) running tasks in root project is not recommended. To target a single project you can use one of dedicated subprojects, eg. tests2_13, tests3, etc.
If you want to publish all projects locally you can use a custom command publish-local-dev <scala-version>

[WojciechMazur]

It looks like this attachment is not used anywhere (at least in Scala2), we use only attachment for CFuncPtrApply. It means to can safely remove handling fromScalaFunction and it's erased variant _fromScalaFunction.

It made me think about how we can achiv the same in Scala 3. I'll describe below how to get rid of this attachment for Scala3 version of this method

[WojciechMazur]

We can add attachment to outer Apply without transformation of inner TypeApply. This combined with the fact that on Scala 2 it's not needed as well, would allow to eliminate additional _fromScalaFunction method.
In Scala2 this transformation was unused, but in Scala3 we need to get original type and save it in attachment, because the target of a lambda might get replaced with adapted (boxed and erased) variant of a function. https://github.com/lampepfl/dotty/blob/abf9a25d5f27a41c11c11c11cf671ed3cb33d10d/compiler/src/dotty/tools/dotc/transform/Erasure.scala#L409-L439

Suggested change

	case Apply(TypeApply(fun, tArgs), args) if defnNir.CFuncPtr_fromScalaFunction.contains(fun.symbol) =>
	val idx = defnNir.CFuncPtr_fromScalaFunction.indexOf(fun.symbol)
	val transformed = defnNir._CFuncPtr_fromScalaFunction(idx)
	val cls = defnNir.CFuncPtrNClass(idx)
	val tys = tArgs.map(t => dealiasTypeMapper(t.typeOpt))
	cpy
	.Apply(tree)(
	ref(transformed),
	args
	)
	.withAttachment(NirDefinitions.NonErasedTypes, tys)
	case appy @ Apply(TypeApply(fun, tArgs), _) if defnNir.CFuncPtr_fromScalaFunction.contains(fun.symbol) =>
	val tys = tArgs.map(t => dealiasTypeMapper(t.typeOpt))
	app
	.withAttachment(NirDefinitions.NonErasedTypes, tys)

[tanishiking]

Thanks! _fromScalaFunction was a thing I don't like in this change and I'm glad we can get rid of that!
done cc62ca2

but in Scala3 we need to get original type and save it in attachment, because the target of a lambda might get replaced with adapted (boxed and erased) variant of a function.

Oh, that's why we didn't need this in Scala2, while Scala3 does. That makes sense, thank you for the explanation!

[WojciechMazur]

We can get rid of these, see comments below

[tanishiking]

Regarding to problems with local publishing, it is probably due to usage of nativeLink task in root project. I'm not sure where does it comes from, probably we could inspect the build and override it

If you want to publish all projects locally you can use a custom command publish-local-dev <scala-version>

Regarding the auxlib, it seems like the same problem as #3265 and I do workaround by publishing locally for another version of scala 2.12

It seems like the linking problems are caused by my contaminated local environment (by ++x.x.x publishLocal 😅), removing the local cache, and republish by publish-local-dev x.x.x fixed the problem. Thanks!