2.12.12 regression in Bash: fscbad option: '-Ytrack-dependencies'

[mb73]

reproduction steps

using Scala 2.12.12, running the following file

#!/bin/bash
echo "in Bash"
exec scala "$0" "$@"
!#
object Example {
  def main(args: Array[String]) {
    println("in Scala")
  }
}

problem

should output

in Bash
in Scala

(as it did with Scala 2.12.11 and before) but outputs

in Bash
fscbad option: '-Ytrack-dependencies'
  fsc -help  gives more information
error: IO error while decoding /home/marcus/-Ytrack-dependencies with UTF-8: /home/marcus/-Ytrack-dependencies (No such file or directory)
Please try specifying another one using the -encoding option
error: IO error while decoding /home/marcus/-Xscript with UTF-8: /home/marcus/-Xscript (No such file or directory)
Please try specifying another one using the -encoding option
error: IO error while decoding /home/marcus/Main with UTF-8: /home/marcus/Main (No such file or directory)
Please try specifying another one using the -encoding option
three errors found

[josephw]

git log v2.12.11..v2.12.12 -S track-dependencies only turns up scala/scala#8861.

[som-snytt]

The long-standing tradition that boolean flags default to false means that defaulting the new flag to true makes it show up in the fsc command via unparse. Other settings test value != default, but a boolean setting only tests for true.

In any case, it's necessary to exit the background resident compiler when switching foreground runners.

➜  snips scala -version                         
Scala code runner version 2.12.11 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.
➜  snips ./huh.sh                               
in Bash
in Scala
➜  snips PATH=~/scala-2.12.12/bin:$PATH ./huh.sh
in Bash
fscbad option: '-Ytrack-dependencies'
  fsc -help  gives more information
error: IO error while decoding...
three errors found
➜  snips fsc -shutdown                          
[Compile server exited]
➜  snips PATH=~/scala-2.12.12/bin:$PATH ./huh.sh
in Bash
in Scala

You can tell in this simple test whether the script is actually getting re-compiled, because there will be a delay in output.

[SethTisue]

Note that starting with Scala 2.13.0, -nocompdaemon is the default: scala/scala#6747. And https://github.com/scala/scala/releases/tag/v2.13.0 says "The daemon was not reliable and will likely be removed entirely from a future release"

On 2.12.x, I would suggest explicitly using -nocompdaemon in all scripts.

[som-snytt]

Another option is to be less scripty and use scalac -d mytool.jar to stick it into a jar, then scala mytool.jar.

[som-snytt]

We forgot say fixed in ammonite.

[mb73]

Thanks. However, I wonder why the daemon is not stopped on uninstalling scala. Sounds like a bug to me.

[SethTisue]

Yeah, it's a bug. The "fix" is to increasingly disable and discourage use of the daemon at all.