From b0758e99c8380acf1acff47eccfe4e9f0b6995b1 Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Mon, 23 Dec 2019 14:31:15 -0800
Subject: [PATCH] Fix cross multi command performance

In 53788ba3561a4e79bc9c36c329f43540ad48814e, I changed the cross multi
parser to issue all of the commands sequentially. This caused a
performance regression for many use cases:
https://github.com/sbt/sbt/issues/5321. This commit restores the old
behavior of `+` if the command to run has no arguments.
---
 main/src/main/scala/sbt/Cross.scala | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/main/src/main/scala/sbt/Cross.scala b/main/src/main/scala/sbt/Cross.scala
index ca2e8974a..2bdde84dd 100644
--- a/main/src/main/scala/sbt/Cross.scala
+++ b/main/src/main/scala/sbt/Cross.scala
@@ -194,7 +194,13 @@ object Cross {
           .sortBy(_._1)
         commandsByVersion.flatMap {
           case (v, commands) =>
-            Seq(s"$SwitchCommand $verbose $v!") ++ commands
+            commands match {
+              case Seq(c) => Seq(s"$SwitchCommand $verbose $v! $c")
+              case Seq()  => Nil // should be unreachable
+              case multi if fullArgs.isEmpty =>
+                Seq(s"$SwitchCommand $verbose $v! all ${multi.mkString(" ")}")
+              case multi => Seq(s"$SwitchCommand $verbose $v!") ++ multi
+            }
         }
     }
     allCommands.toList ::: CrossRestoreSessionCommand :: captureCurrentSession(state, extracted)