Rename early command to `early(command)`

Backports #2741, Fixes #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; and keeps `--` variant for log
level for backward compatibility.

main/command/src/main/scala/sbt/BasicCommandStrings.scala

@@ -60,7 +60,7 @@ object BasicCommandStrings {
 	This will be used as the default level for logging from commands, settings, and tasks.
 	Any explicit `logLevel` configuration in a project overrides this setting.
 
-${runEarly(level.toString)}
+-$level
 
 	Sets the global logging level as described above, but does so before any other commands are executed on startup, including project loading.
 	This is useful as a startup option:
@@ -68,21 +68,23 @@ ${runEarly(level.toString)}
 		* if no other commands are passed, interactive mode is still entered
 """
 
-  def runEarly(command: String) = {
+  def runEarly(command: String) = s"$EarlyCommand($command)"
-    val sep = if (command.isEmpty || Character.isLetter(command.charAt(0))) "" else " "
-    s"$EarlyCommand$sep$command"
-  }
   private[sbt] def isEarlyCommand(s: String): Boolean = {
-    s.startsWith(EarlyCommand) && s != Compat.FailureWall && s != Compat.ClearOnFailure
+    val levelShortOptions = Level.values.toSeq map { "-" + _ }
+    val levelLongOptions = Level.values.toSeq map { "--" + _ }
+    (s.startsWith(EarlyCommand + "(") && s.endsWith(")")) ||
+      (levelShortOptions contains s) ||
+      (levelLongOptions contains s)
   }
 
-  val EarlyCommand = "--"
+  val OldEarlyCommand = "--"
-  val EarlyCommandBrief = (s"$EarlyCommand<command>", "Schedules a command to run before other commands on startup.")
+  val EarlyCommand = "early"
+  val EarlyCommandBrief = (s"$EarlyCommand(<command>)", "Schedules a command to run before other commands on startup.")
   val EarlyCommandDetailed =
-    s"""$EarlyCommand<command>
+    s"""$EarlyCommand(<command>)
 
 	Schedules an early command, which will be run before other commands on the command line.
-	The order is preserved between all early commands, so `sbt --a --b` executes `a` and `b` in order.
+	The order is preserved between all early commands, so `sbt "early(a)" "early(b)"` executes `a` and `b` in order.
 """
 
   def ReadCommand = "<"

main/command/src/main/scala/sbt/BasicCommands.scala

@@ -22,7 +22,18 @@ object BasicCommands {
   def ignore = Command.command(FailureWall)(idFun)
 
   def early = Command.arb(earlyParser, earlyHelp) { (s, other) => other :: s }
-  private[this] def earlyParser = (s: State) => token(EarlyCommand).flatMap(_ => otherCommandParser(s))
+  private[this] def levelParser: Parser[String] =
+    token(Level.Debug.toString) | token(Level.Info.toString) | token(Level.Warn.toString) | token(Level.Error.toString)
+  private[this] def earlyParser: State => Parser[String] = (s: State) =>
+    (token(EarlyCommand + "(") flatMap { _ =>
+      otherCommandParser(s) <~ token(")")
+    }) |
+      (token("-") flatMap { _ =>
+        levelParser
+      }) |
+      (token(OldEarlyCommand) flatMap { _ =>
+        levelParser
+      })
   private[this] def earlyHelp = Help(EarlyCommand, EarlyCommandBrief, EarlyCommandDetailed)
 
   def help = Command.make(HelpCommand, helpBrief, helpDetailed)(helpParser)

notes/0.13.13/early.md

@@ -0,0 +1,6 @@
+### Fixes with compatibility implications
+
+- sbt 0.13.13 renames the early command that was added in 0.13.1 to `early(<command>)`. This fixes the regression [#1041][1041]. For backward compatibility `--error`, `--warn`, `--info`, and `--debug` will continue to function during 0.13 series, but it is strongly encouraged to migrate to the single hyphen option: `-error`, `-warn`, `-info`, and `-debug`.   [@eed3si9n][@eed3si9n]
+
+  [1041]: https://github.com/sbt/sbt/issues/1041
+  [@eed3si9n]: https://github.com/eed3si9n

sbt/src/sbt-test/actions/early-command/build.sbt

@@ -0,0 +1 @@
+lazy val root = (project in file("."))

sbt/src/sbt-test/actions/early-command/test

@@ -0,0 +1,3 @@
+> early(error)
+> -error
+> --error