SingleTargetAnnotations will report java.lang.NumberFormatException when indexing a Vec chisel type

[davine47]

Type of issue: Bug Report

Please provide the steps to reproduce the problem:
Run the following code:

package sandbox

import chisel3.{UInt, _}
import chisel3.util.{Fill, Pipe}
import freechips.rocketchip.diplomacy.{LazyModule, LazyModuleImp, LazyModuleImpLike}
import org.chipsalliance.cde.config.Parameters
import chisel3.experimental.Trace._

class TestAggregate extends Bundle {
  val flag = Bool()
  val value = UInt(3.W)
}

class TestAggregate2 extends Bundle {
  val flag = Bool()
  val value = UInt(3.W)
}

class Hello()(implicit p:Parameters) extends LazyModule {
  lazy val  module = new Impl
  class Impl extends LazyModuleImp(this) {

    val io = IO(new Bundle {
      val in = Input(UInt(8.W))
      val out = Output(UInt(3.W))
    })
    val pipe = Module(new Pipe(UInt(8.W), 40))
    val foo = Wire(Vec(8, new TestAggregate))
    val debug_microOp = Reg(Vec(4, new TestAggregate2))
    foo.foreach(ptr => {
      ptr.flag := 0.B
      ptr.value := 0.U
    })
    val index = foo(0).value
    val tt = debug_microOp(index).value
    pipe.io.enq.bits := io.in
    pipe.io.enq.valid := true.B
    io.out := pipe.io.deq.bits
    traceName(tt) // java.lang.NumberFormatException: For input string: "_tt_T"
  }
}

What is the current behavior?
Java exceptions

[269] java.lang.NumberFormatException: For input string: "_tt_T"
[269] emat java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
[269] 72at java.base/java.lang.Integer.parseInt(Integer.java:652)
[269] emat java.base/java.lang.Integer.parseInt(Integer.java:770)
[269] 72at scala.collection.StringOps$.toInt$extension(StringOps.scala:908)
[269] emat firrtl.annotations.Target$.$anonfun$toTargetTokens$1(Target.scala:155)
[269] 	at scala.collection.immutable.List.foreach(List.scala:333)
[269] 	at firrtl.annotations.Target$.toTargetTokens(Target.scala:153)
[269] 	at chisel3.internal.NamedComponent.toTarget(Builder.scala:381)
[269] 	at chisel3.internal.NamedComponent.toTarget$(Builder.scala:372)
[269] 	at chisel3.Data.toTarget(Data.scala:286)
[269] 	at chisel3.internal.NamedComponent.toAbsoluteTarget(Builder.scala:389)
[269] 	at chisel3.internal.NamedComponent.toAbsoluteTarget$(Builder.scala:388)
[269] 	at chisel3.Data.toAbsoluteTarget(Data.scala:286)
[269] 	at chisel3.experimental.Trace$$anon$3.toFirrtl(Trace.scala:40)
[269] 72at chisel3.internal.firrtl.Circuit.$anonfun$firrtlAnnotations$1(IR.scala:484)
[269] emat scala.collection.immutable.List.flatMap(List.scala:293)
[269] 	at scala.collection.immutable.List.flatMap(List.scala:79)
[269] 	at chisel3.internal.firrtl.Circuit.firrtlAnnotations(IR.scala:484)
[269] 	at chisel3.stage.phases.Convert.$anonfun$transform$1(Convert.scala:33)
[269] 	at scala.collection.immutable.List.flatMap(List.scala:293)
[269] 	at scala.collection.immutable.List.flatMap(List.scala:79)
[269] 	at chisel3.stage.phases.Convert.transform(Convert.scala:26)
[269] 	at chisel3.stage.phases.Convert.transform(Convert.scala:18)
[269] 	at generators.DiplomacyGenerator$.$anonfun$elaborate$4(DiplomacyGenerator.scala:40)
[269] 	at scala.collection.LinearSeqOps.foldLeft(LinearSeq.scala:183)
[269] 	at scala.collection.LinearSeqOps.foldLeft$(LinearSeq.scala:179)
[269] 72at scala.collection.immutable.List.foldLeft(List.scala:79)
[269] emat generators.DiplomacyGenerator$.elaborate(DiplomacyGenerator.scala:40)
[269] 	at generators.DiplomacyGenerator$.$anonfun$main$1(DiplomacyGenerator.scala:54)
[269] 	at generators.DiplomacyGenerator$.$anonfun$main$1$adapted(DiplomacyGenerator.scala:54)
[269] 	at mainargs.Invoker$.$anonfun$invoke0$2(Invoker.scala:68)
[269] 	at mainargs.Result.flatMap(Result.scala:13)
[269] 	at mainargs.Result.flatMap$(Result.scala:12)
[269] 	at mainargs.Result$Success.flatMap(Result.scala:23)
[269] 	at mainargs.Invoker$.invoke0(Invoker.scala:67)
[269] 	at mainargs.Invoker$.invoke(Invoker.scala:77)
[269] 	at mainargs.Invoker$.invokeLocal$1(Invoker.scala:89)
[269] 	at mainargs.Invoker$.$anonfun$runMains$2(Invoker.scala:103)
[269] 	at mainargs.Result.flatMap(Result.scala:13)
[269] 	at mainargs.Result.flatMap$(Result.scala:12)
[269] 72at mainargs.Result$Success.flatMap(Result.scala:23)
[269] emat mainargs.Invoker$.groupArgs$1(Invoker.scala:103)
[269] 	at mainargs.Invoker$.runMains(Invoker.scala:108)
[269] 	at mainargs.ParserForMethods.runRaw0(Parser.scala:170)
[269] 	at mainargs.ParserForMethods.runEither(Parser.scala:108)
[269] 	at mainargs.ParserForMethods.runEither(Parser.scala:151)
[269] 	at mainargs.ParserForMethods.runOrExit(Parser.scala:56)
[269] 	at generators.DiplomacyGenerator$.main(DiplomacyGenerator.scala:54)
[269] 	at generators.DiplomacyGenerator.main(DiplomacyGenerator.scala)
[269] 

What is the expected behavior?
It seems like lacking assertions or match patterns in function:
Target.scala -> toTargetTokens

Please tell us about your environment:
- version: org.chipsalliance::chisel:6.0.0-RC1
- scala: 2.13.10

[light-ly]

dontTouch(tt) also has exception