Error message printed if text is piped to a script STDIN

[philwalk]

Compiler version

This is common to all versions of scala3 that I've tried.
It can be demonstrated with scala3-3.6.3-x86_64-pc-win32.
No such error occurs in scala 2.13.

Minimized code

#!/usr/bin/env -S scala
val lines = for {
  line <- scala.collection.Iterator.Iterator.continually(scala.io.StdIn.readLine()).takeWhile( _ != null )
  if line != null
} yield line
printf("%d lines\n", lines.size)

Output

# ls -l | jsrc/readStdin.sc
stty: 'standard input': Inappropriate ioctl for device
Compiling project (Scala 3.6.3, JVM (17))
Compiled project (Scala 3.6.3, JVM (17))
837 lines

Expectation

No error message

A fix is to not call stty unless there's a tty, as in this modification of scala3-3.6.3-x86_64-pc-win32/libexec/common-shared

#!/usr/bin/env bash

#/*--------------------------------------------------------------------------
# *  Credits: This script is based on the script generated by sbt-pack.
# *--------------------------------------------------------------------------*/

if [ -e /usr/bin/tty -a "`tty`" != "not a tty" -a ! -p /dev/stdin ]; then
  isterminal=1
  # save terminal settings
  saved_stty=$(stty -g 2>/dev/null)
  # clear on error so we don't later try to restore them
  if [[ ! $? ]]; then
    saved_stty=""
  fi
else
  isterminal=0
fi

# restore stty settings (echo in particular)
function restoreSttySettings() {
  [ $isterminal -eq 1 ] && stty $saved_stty
  saved_stty=""
}

It's also necessary to condition another call to stty later in the file:

      [ $isterminal -eq 1 ] && stty -icanon min 1 -echo

Making stty calls conditional fixes the problem in all my manually tested environments, including cygwin, msys64, git-bash, WSL ubuntu, Linux Ubuntu and OSX.

I can submit a PR.

[hamzaremmal]

I can't reproduce this with my MacBook, I'm undusting my old Windows machine to try to reproduce the issue; since you're using scala3-3.6.3-x86_64-pc-win32

[philwalk]

I can't reproduce this with my MacBook

I believe the fix does the right thing on a MacBook, and I assume it doesn't matter whether the problem it fixes is reproducible there.

This is a subtle test due to a variety of behaviors across different supported systems. My goal was to find an expression that does the same thing on all tested systems in both the tty context, and when running on the receiving end of a pipe.

I tested it against Linux, MaxBook, and several varieties of Window shell and console environments. Please let me know if it fails anywhere in either context.