SD-256 enable colored output by default on unix

[gourlaysama]

This enables -Dscala.color by default when running via the shell
script and when stdout is a terminal.

Can be overriden on the CLI or via JAVA_OPTS:

$ qbin/scala -nc -e 'println(util.Properties.propOrFalse("scala.color"))'
true
$ qbin/scala -nc -e 'println(util.Properties.propOrFalse("scala.color"))' | cat
false
$ qbin/scala -nc -Dscala.color=false -e 'println(util.Properties.propOrFalse("scala.color"))'
false
$ JAVA_OPTS="-Dscala.color=false" qbin/scala -nc -e 'println(util.Properties.propOrFalse("scala.color"))'
false

[adriaanm]

Sweet! Thanks! Anyone out there familiar with unix gotchas like this? I'm not qualified to review, but would love to get this in!

[dwijnand]

Rather than mess directly with JAVA_OPTS I would follow the precendence set by -Dscala.usejavacp/OVERRIDE_USEJAVACP

[gourlaysama]

I originally didn't want to clutter the command line to run with one more variable, but you're right, it's cleaner that way. Done.

[smarter]

That only solves part of the problem, it would also be nice to get colors when running sbt console for example, for this the default value of scala.color should be auto which would behave like grep --color=auto and many other tools, but this means that the terminal detection must be done on the JVM.

[smarter]

System.console seems to be the way to do that: https://stackoverflow.com/questions/1403772/how-can-i-check-if-a-java-programs-input-output-streams-are-connected-to-a-term

[gourlaysama]

The original reason I did it in the bash script was that we only want to activate it by default on unix-like things.

Hmm, having an auto mode that tests System.console would indeed make it work all on its own in sbt and with the bash runner. Then I can add a -Dscala.color=false default in the bat runner for windows.
Maybe that's a better solution?

[smarter]

I think the Windows console supports color now, though I have no idea how to test for that: https://blogs.msdn.microsoft.com/commandline/2016/09/22/24-bit-color-in-the-windows-console/ Simply disabling color in the batch script might be enough.

[smarter]

Or always disable if the platform is windows: http://www.scala-lang.org/api/2.12.0/scala-compiler/scala/tools/nsc/Properties$.html#isWin:Boolean

[gourlaysama]

Or always disable if the platform is windows

Oh, right, I'll just do that.

I think the Windows console supports color now, though I have no idea how to test for that

After a bit of digging: it is enabled by default when used from the Windows Subsystem for Linux, but not for normal windows console programs run directly or from cmd or powershell. cmd.exe does enable it for itself, so it works within a .bat script, but java.exe doesn't, and that property isn't inherited by child processes for compatibility reasons. So no color out of the box for the normal usecase. We could enable it, but it is a native API, so JNI and all that... let's just keep it disabled on Windows.

[gourlaysama]

@smarter done. Now it works in SBT too :)

I moved the property somewhere more central since it is already used in two places. The next step would be to use it for a few more things, like the default ConsoleReporter, and maybe more things in the repl.

[gourlaysama]

library/mima failed: java.lang.RuntimeException: MiMa failed with exit code 2

😦

[adriaanm]

Awesome! Yeah, scala's package-private can't be represented in byte code. Will need whitelisting :-/

[lrytz]

LGTM - needs a rebase unfortunately

[gourlaysama]

Rebased.

[lrytz]

/rebuild - interesting failure

Caused by: sbt.ForkMain$ForkError: java.lang.ArrayIndexOutOfBoundsException: 15
	at java.util.ArrayList.add(ArrayList.java:459)
	at sbt.ForkMain$Run$2$1.handle(ForkMain.java:294)
	at scala.tools.partest.sbt.SBTRunner$$anon$1.onFinishTest(SBTRunner.scala:70)
	at scala.tools.partest.nest.SuiteRunner.runTest(Runner.scala:781)
	at scala.tools.partest.nest.SuiteRunner.$anonfun$runTestsForFiles$2(Runner.scala:788)
	at scala.tools.partest.package$$anon$2.call(package.scala:135)

[adriaanm]

🎉

[SethTisue]

Now it works in SBT too

confirmed. 🙌

[som-snytt]

Just noticed my scripts with -Dscala.color stopped working. That is, it's no longer taken as -Dscala.color=true or even auto.