[sbt 1.0] Rename early command to early(command)

[eed3si9n]

Fixes #2734, Ref #1041

e93c445 added a feature called early command, which uses -- as a prefix to denote some commands that runs ahead of session loading. While the feature might be useful especially for logging, -- is too useful just for this purpose.

In addition, this adds log level commands with single -, such as -error to treat them as early commands.

/review @dwijnand, @Duhemm

[dwijnand]

Why not keep these as --debug/--warn/--error? -debug/-warn/-error is less UNIX-y that that.

This way we remove -- from making everything early to just special cases.

[eed3si9n]

It's true that general Unix convention would be to use double hyphen for long options, but java, scala, and sbt have been using single hyphen for options. See https://github.com/sbt/sbt-launcher-package/blob/master/src/universal/bin/sbt

  -d | -debug        set sbt log level to debug

[dwijnand]

That is true.. But what's wrong with keeping it as --error? It conveys the right meaning, it doesn't clash with anything, and most importantly it's backwards compatible.

[eed3si9n]

I'd keep it for 0.13 for compat but I don't really see strong reason to keep it for 1.0.
early(command) is the generic handler, and -error would be a new option that's consistent with every other options. The reason for removal is the same reason for removing <<=, which is reducing the surface area.

[dwijnand]

Ok. I think it's much better if we don't do these breaking changes in point releases, but instead documented in the upgrade/migration notes. Thanks

[dwijnand]

For clarity, I think we should add notes here.

[eed3si9n]

Added migration notes - 9783ab1

[retronym]

Over in scala/scala#6256, we found that:

$ sbt '--warn' 'eval ???'; echo $?
[warn] The `-` command is deprecated in favor of `onFailure` and will be removed in a later version
[error] scala.NotImplementedError: an implementation is missing
[error] 	at scala.Predef$.$qmark$qmark$qmark(Predef.scala:284)
[error] 	at $b7f279a4d8e441649156$.$sbtdef(<eval>:1)
[error] 	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[error] 	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
[error] 	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
[error] 	at java.lang.reflect.Method.invoke(Method.java:498)
[error] 	at sbt.compiler.Eval$.getValue(Eval.scala:551)
[error] 	at sbt.compiler.Eval.$anonfun$eval$1(Eval.scala:121)
[error] 	at sbt.BuiltinCommands$.$anonfun$loadedEval$1(Main.scala:383)
[error] 	at sbt.internal.util.ManagedLogger.log(ManagedLogger.scala:24)
[error] 	at sbt.util.Logger.info(Logger.scala:22)
[error] 	at sbt.BuiltinCommands$.loadedEval(Main.scala:383)
[error] 	at sbt.BuiltinCommands$.$anonfun$eval$1(Main.scala:374)
[error] 	at sbt.Command$.$anonfun$apply1$2(Command.scala:146)
[error] 	at sbt.MainLoop$.processCommand(MainLoop.scala:154)
[error] 	at sbt.MainLoop$.$anonfun$next$2(MainLoop.scala:137)
[error] 	at sbt.State$$anon$1.runCmd$1(State.scala:242)
[error] 	at sbt.State$$anon$1.process(State.scala:248)
[error] 	at sbt.MainLoop$.$anonfun$next$1(MainLoop.scala:137)
[error] 	at sbt.internal.util.ErrorHandling$.wideConvert(ErrorHandling.scala:16)
[error] 	at sbt.MainLoop$.next(MainLoop.scala:137)
[error] 	at sbt.MainLoop$.run(MainLoop.scala:130)
[error] 	at sbt.MainLoop$.$anonfun$runWithNewLog$1(MainLoop.scala:108)
[error] 	at sbt.io.Using.apply(Using.scala:22)
[error] 	at sbt.MainLoop$.runWithNewLog(MainLoop.scala:102)
[error] 	at sbt.MainLoop$.runAndClearLast(MainLoop.scala:58)
[error] 	at sbt.MainLoop$.runLoggedLoop(MainLoop.scala:43)
[error] 	at sbt.MainLoop$.runLogged(MainLoop.scala:35)
[error] 	at sbt.StandardMain$.runManaged(Main.scala:113)
[error] 	at sbt.xMain.run(Main.scala:76)
[error] 	at xsbt.boot.Launch$$anonfun$run$1.apply(Launch.scala:109)
[error] 	at xsbt.boot.Launch$.withContextLoader(Launch.scala:128)
[error] 	at xsbt.boot.Launch$.run(Launch.scala:109)
[error] 	at xsbt.boot.Launch$$anonfun$apply$1.apply(Launch.scala:35)
[error] 	at xsbt.boot.Launch$.launch(Launch.scala:117)
[error] 	at xsbt.boot.Launch$.apply(Launch.scala:18)
[error] 	at xsbt.boot.Boot$.runImpl(Boot.scala:41)
[error] 	at xsbt.boot.Boot$.main(Boot.scala:17)
[error] 	at xsbt.boot.Boot.main(Boot.scala)
[error] scala.NotImplementedError: an implementation is missing
[error] Use 'last' for the full log.
0

gives a zero error code, because this is now the same as sbt 'onFailure -warn' ....

I'll assume that this was unintentional. This is quite dangerous, as sbt-extra lists -w in its help which it translates to --warn. Both sbt-extras and the official sbt launcher passes through --warn, which is was our scripts have been using.

It is quite easy to miss or ignore the warning, and then run into the trap of having build scripts pass when a test fails.

Thoughts? I'd recommend adding --warn etc as aliases, possibly deprecated.

[eed3si9n]

onFailure kicking in was unintentional. Maybe it's time to remove - command too.
For compat (and also for JEP 293), I'd be happy to bring back --warn as special case of early(warn).

[eed3si9n]

Opened an issue for this #4088