Cannot run a script in the root directory

[DavidPerezIngeniero]

Version(s)
Scala-cli vesion 1.3.2

Describe the bug
Run a script with these contents:

//> using dep com.lihaoyi::requests:0.8.3
//> using dep com.lihaoyi::os-lib:0.10.2
//> using dep com.lihaoyi::upickle:3.3.1
//> using dep org.scala-lang.modules::scala-parallel-collections:1.0.4
println("Descargadas dependencias mas usadas")

localted in the root folder with:

scala-cli /myscript.sc

It complains like:

Error: os.PathError$LastOnEmptyPath: empty path has no last segment

When run in any other directory, it works ok as expected.

[philwalk]

The error message is printed by os.Path, and might be a bug there.

[Gedochao]

Any additional details on how to reproduce the problem?
I tried reproducing locally on MacOS (aarch64), but seems to work correctly.

@DavidPerezIngeniero Is it just this particular script, or did you try anything else?
Would a hello world script run into the same issue?

println("Hello")

if not, how about this:

//> using toolkit default
println(os.pwd)

[philwalk]

I was able to reproduce the problem in WSL ubuntu and in Windows. I'm surprised that you don't get the same thing in MacOS.

My hunch (not yet confirmed) is that it's a bug in os-lib, the result of trying to access the last segment of the root Path.

Here's my script. The shebang line is triggering the crash, so it shouldn't matter what the script does (according to my hunch).

#!/usr/bin/env -S scala-cli shebang
println("hello")

Here's the stackdump:

os.PathError$LastOnEmptyPath: empty path has no last segment
  os.PathError$LastOnEmptyPath$.apply(Path.scala:228)
  os.BasePathImpl.last$$anonfun$1(Path.scala:210)
  scala.Option.getOrElse(Option.scala:201)
  os.BasePathImpl.last(Path.scala:210)
  os.BasePathImpl.last$(Path.scala:190)
  os.Path.last(Path.scala:483)
  os.BasePathImpl.baseName(Path.scala:205)
  os.BasePathImpl.baseName$(Path.scala:190)
  os.Path.baseName(Path.scala:483)
  scala.build.input.Inputs$.forValidatedElems(Inputs.scala:155)
  scala.build.input.Inputs$.forNonEmptyArgs(Inputs.scala:414)
  scala.build.input.Inputs$.apply(Inputs.scala:459)
  scala.cli.commands.shared.SharedOptions$.inputs(SharedOptions.scala:697)
  scala.cli.commands.shared.SharedOptions.inputs(SharedOptions.scala:617)
  scala.cli.commands.run.Run$.runCommand(Run.scala:140)
  scala.cli.commands.shebang.Shebang$.runCommand(Shebang.scala:33)
  scala.cli.commands.shebang.Shebang$.runCommand(Shebang.scala:26)
  scala.cli.commands.ScalaCommand.run(ScalaCommand.scala:379)
  scala.cli.commands.ScalaCommand.run(ScalaCommand.scala:361)
  caseapp.core.app.CaseApp.main(CaseApp.scala:157)
  scala.cli.commands.ScalaCommand.main(ScalaCommand.scala:346)
  caseapp.core.app.CommandsEntryPoint.main(CommandsEntryPoint.scala:166)
  scala.cli.ScalaCliCommands.main(ScalaCliCommands.scala:125)
  scala.cli.ScalaCli$.main0(ScalaCli.scala:286)
  scala.cli.ScalaCli$.main(ScalaCli.scala:116)
  scala.cli.ScalaCli.main(ScalaCli.scala)

My hunch: the call to os.Path.baseName fails if the os.Path is root, because "/" has an empty segments array.
I will see if I can verify this.

[philwalk]

Submitted an os-lib PR: com-lihaoyi/os-lib#277

submitted #2988