Path values do not work with multiple instantiation

[jackkoenig]

Type of issue: Bug Report

Please provide the steps to reproduce the problem:

Consider the following Chisel:

//> using repository "sonatype-s01:snapshots"
//> using scala "2.13.14"
//> using dep "org.chipsalliance::chisel:7.0.0-M2+66-a1c35ad8-SNAPSHOT"
//> using plugin "org.chipsalliance:::chisel-plugin:7.0.0-M2+66-a1c35ad8-SNAPSHOT"
//> using options "-unchecked", "-deprecation", "-language:reflectiveCalls", "-feature", "-Xcheckinit", "-Xfatal-warnings", "-Ywarn-dead-code", "-Ywarn-unused", "-Ymacro-annotations"

import chisel3._
import chisel3.util.experimental.InlineInstance
import chisel3.experimental.hierarchy._
import chisel3.properties._
// _root_ disambiguates from package chisel3.util.circt if user imports chisel3.util._
import _root_.circt.stage.ChiselStage

class Intf extends Bundle {
  val in = Input(UInt(8.W))
  val out = Output(UInt(8.W))
  val path = Output(Property[Path]())
}

@instantiable
class Child extends Module with InlineInstance {
  @public val intf = IO(new Intf)

  val r = RegInit(0.U)
  r := intf.in
  intf.out := r

  intf.path := Property(Path(r))
}

class Top extends Module {
  val intfs = IO(Vec(2, new Intf))
  val c0 = Instantiate(new Child)
  val c1 = Instantiate(new Child)

  intfs(0) :<>= c0.intf
  intfs(1) :<>= c1.intf
}

object Main extends App {
  println(
    ChiselStage.emitSystemVerilog(
      gen = new Top,
      firtoolOpts = Array("-disable-all-randomization", "-strip-debug-info", "-default-layer-specialization=enable")
    )
  )
}

What is the current behavior?

This errors in firtool with:

.../chisel-example.scala:24:18: error: duplicate identifier found
.../chisel-example.scala:24:18: note: other identifier here

Note that this requires both the Inlining and the D/I Instantiate to manifest.

What is the expected behavior?

This should work, the path should be materialized in Child and threaded through to the top.

What is the use case for changing the behavior?

It should be possible to create Path values.