Chisel Hierarchy API not working after Scala 2.13 update

[tymcauley]

Background Work

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• Yes, I searched prior issues
• Yes, I searched the documentation

Chipyard Version and Hash

Release: main
Hash: c8764d6

OS Setup

macOS 13.2.1

Other Setup

Check out fresh Chipyard, run ./scripts/init-submodules-no-riscv-tools.sh

Current Behavior

It looks like the recent update to Scala 2.13 (#1303) broke the Chisel Hierarchy API. It looks like we'll need an extra scalac option to fix the issue.

To reproduce, take this code snippet from the Chisel Hierarchy Cookbook, and place it at the end of generators/chipyard/src/main/scala/example/GCD.scala:

import chisel3.experimental.hierarchy.{Definition, Instance, instantiable, public}

@instantiable
class AddOne(width: Int) extends Module {
  @public val in  = IO(Input(UInt(width.W)))
  @public val out = IO(Output(UInt(width.W)))
  out := in + 1.U
}

class AddTwo(width: Int) extends Module {
  val in  = IO(Input(UInt(width.W)))
  val out = IO(Output(UInt(width.W)))
  val addOneDef = Definition(new AddOne(width))
  val i0 = Instance(addOneDef)
  val i1 = Instance(addOneDef)
  i0.in := in
  i1.in := i0.out
  out   := i1.out
}

Try to compile, and you should see these errors:

[info] compiling 1 Scala source to /path/to/chipyard/generators/chipyard/target/scala-2.13/classes ...
[error] /path/to/chipyard/generators/chipyard/src/main/scala/example/GCD.scala:224:6: value in is not a member of chisel3.experimental.hierarchy.Instance[chipyard.example.AddOne]
[error] did you mean isA?
[error]   i0.in := in
[error]      ^
[error] /path/to/chipyard/generators/chipyard/src/main/scala/example/GCD.scala:225:6: value in is not a member of chisel3.experimental.hierarchy.Instance[chipyard.example.AddOne]
[error] did you mean isA?
[error]   i1.in := i0.out
[error]      ^
[error] /path/to/chipyard/generators/chipyard/src/main/scala/example/GCD.scala:225:15: value out is not a member of chisel3.experimental.hierarchy.Instance[chipyard.example.AddOne]
[error]   i1.in := i0.out
[error]               ^
[error] /path/to/chipyard/generators/chipyard/src/main/scala/example/GCD.scala:226:15: value out is not a member of chisel3.experimental.hierarchy.Instance[chipyard.example.AddOne]
[error]   out   := i1.out
[error]               ^
[error] four errors found
[error] (Compile / compileIncremental) Compilation failed

Expected Behavior

I would expect the above code to compile without error. In fact, if you add "-Ymacro-annotations" to scalacOptions in build.sbt, the build works. I'm not sure if there are other Scala compiler options that we're missing, but that one certainly seems necessary.

Other Information

No response