Source line + carat for errors should work for Scala CLI Example

[jackkoenig]

Type of issue: Bug Report

Please provide the steps to reproduce the problem:

Consider the following example built from the Scala CLI template chisel-example.scala:

//> using scala "2.13.12"
//> using dep "org.chipsalliance::chisel:6.4.0"
//> using plugin "org.chipsalliance:::chisel-plugin:6.4.0"
//> using options "-unchecked", "-deprecation", "-language:reflectiveCalls", "-feature", "-Xcheckinit", "-Xfatal-warnings", "-Ywarn-dead-code", "-Ywarn-unused", "-Ymacro-annotations"

import chisel3._
import chisel3.probe._
// _root_ disambiguates from package chisel3.util.circt if user imports chisel3.util._
import _root_.circt.stage.ChiselStage

class Foo extends Module {
  val out = IO(Output(Probe(UInt(8.W))))

  val w = Wire(UInt(8.W))
  define(out, w)

}

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

What is the current behavior?

This prints the following error:

[error] Users/koenig/work/t/define/chisel-example.scala 15:9: Expected source to be a probe expression.
[error] There were 1 error(s) during hardware elaboration.
Exception in thread "main" chisel3.internal.Errors: Fatal errors during hardware elaboration. Look above for error list. Rerun with --throw-on-first-error if you wish to see a stack trace.

What is the expected behavior?

If you emit CHIRRTL from a working build, you'll see that when using Scala-CLI, the source locators are absolute but missing the root /, e.g.:

input clock : Clock @[Users/koenig/work/t/define/chisel-example.scala 11:7]

It seems that Scala-CLI compiles in the root directory but then runs in .. The leading / is stripped here:

chisel/core/src/main/scala/chisel3/internal/SourceInfoFileResolver.scala

Line 22 in 6c708b1

val pathNoStartingSlash = if (path(0) == '/') path.tail else path

I'm not sure why we're stripping it, but I think we can stop doing that and this will work.

Please tell us about your environment:

Other Information

What is the use case for changing the behavior?