Consider making Scala CLI backwards compatible with current scala commands

[romanowski]

A list of incompatible options that makes a lot of sense:

• -classpath does not work even if prefixed with -O (how to pass agrs in such case?)
• -d conflicts with Scala CLI dependencies - do we really need to emit classes from REPL?
• -color - we have it on by default if I am not mistaken
• -encoding
• -explain, -explain-types (-explaintypes from Scala 2)
• -feature
• -help - conflicts with our help
• -language (-language:<features> from Scala 2)
• -nowarn
• -print-lines
• -release (-target from Scala 2)
• -source
• -sourcepath and -sourceroot (-rootdir from Scala 2) but I have mixed feeling about those
• -unchecked
• @<file> - provide a file with arguments and options

A list of options that I can see some usage but proabaly are not critical (so we can just fallback to require -O prefix)

• -old-syntax
• -new-syntax
• -no-indent
• -from-tasty
• -javabootclasspath, -bootclasspath (-nobootcp and -toolcp from Scala 2)- not sure if we can support both
• -scalajs, -scalajs-genStaticForwardersForNonTopLevelObjects, -scalajs-mapSourceURI - I was under impression that REPL does not support Scala JS but even if so I think --js and related flags has superior UX
• -uniqid, -verbose - debugging REPL is instead for powerusers and I think we can expect them to prefix these options with -O
• -dependencyfile - not supported in Scala 3
• -no-specialization- not supported in Scala 3
• -opt:<optimizations>, -opt-inline-from:<patterns>, -opt-warnings:<warnings> - not supported in Scala 3
• -print - not supported in Scala 3
• -usemanifestcp - not supported in Scala 3

A list of options that I do not see a use case in REPL:

• -indent - do not print indent based version of the provided code also when running
• -print-tasty - do not print TASTY from provided code
• -project-url
• -rewrite - no effect also when running code from file
• -semanticdb-target - does not seem to have any effect

A list of options I have no idea what they do:

• -extdirs
• -javaextdirs

[Gedochao]

relevant: https://github.com/VirtusLab/scala-cli/pull/1313

[julienrf]

Thank you for going over the list :) There is one thing that I am not sure to understand: you assessed the relevance of every option in the context of the REPL, but I think these options in the old scala command were also active when running a program, not just in the REPL mode?

[romanowski]

I tried to assest them also in the contested of running the program and in many cases I was surprised that given option has no effect (e.g. -print-tasty).

Also, I changed the issue a bit to consider what should be added and not to just add 100% of the options listed (even from the main category).

[Gedochao]

This has mostly been addressed already, so I'm closing the ticket. Most popular scalac options which make sense in the context of scala-cli are already available without -O. Aliases have been added where clashes with native scala-cli options happened. Documentation has been added in #1503 Other relevant PRs: #1501, #1413, #1369, #1340, #1313