Fixes #3297 and #3531

Add commandName as an extension method in Command

main-command/src/main/scala/sbt/Command.scala

@@ -187,6 +187,13 @@ object Command {
 
   def spacedC(name: String, c: Parser[Char]): Parser[String] =
     ((c & opOrIDSpaced(name)) ~ c.+) map { case (f, rem) => (f +: rem).mkString }
+
+  implicit class CommandWithName(cmd: Command) {
+    def commandName: Option[String] = cmd match {
+      case sc: SimpleCommand => Some(sc.name)
+      case _                 => None
+    }
+  }
 }
 
 trait Help {

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

@@ -0,0 +1,5 @@
+val command = Command.command("noop") { s => s }
+
+TaskKey[Unit]("check") := {
+  assert(command.commandName == Some("noop"), """command.commandName should be "noop"""")
+}

sbt/src/sbt-test/actions/command-name/test

@@ -0,0 +1 @@
+> check