From f3817ad64f3018163689fec6cb9b823538c64695 Mon Sep 17 00:00:00 2001
From: Eugene Yokota <eed3si9n@gmail.com>
Date: Fri, 5 Aug 2016 01:21:06 -0400
Subject: [PATCH] Fixes #2686 by resetting scalaVersion for
 updateSbtClassifiers

Ref #2634

updateSbtClassifiers uses an artificially created dependency graph set
in classifiersModule. The problem is that ivyScala instance is reused
from the outer scope that has the user project's scalaVersion as
demonstrated as follows:

    scala> val is = (ivyScala in updateSbtClassifiers).eval
    is: Option[sbt.IvyScala] =
Some(IvyScala(2.9.3,2.9.3,List(),true,false,true,org.scala-lang))

This change fixes #2686 by redefining ivyScala with scalaVersion and
scalaBinaryVersion scoped to updateSbtClassifiers task. The existing
scripted test was modified to reproduce the bug.
---
 main/src/main/scala/sbt/Defaults.scala                    | 8 ++++++++
 .../update-sbt-classifiers/build.sbt                      | 1 +
 2 files changed, 9 insertions(+)
 create mode 100644 sbt/src/sbt-test/dependency-management/update-sbt-classifiers/build.sbt

diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 11b8b4726..866cfbf23 100755
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -1413,6 +1413,14 @@ object Classpaths {
       val pluginIDs: Vector[ModuleID] = pluginJars.flatMap(_ get moduleID.key)
       GetClassifiersModule(pid, sbtDep +: pluginIDs, Vector(Configurations.Default), classifiers.toVector)
     }).value,
+    // Redefine scalaVersion and scalaBinaryVersion specifically for the dependency graph used for updateSbtClassifiers task.
+    // to fix https://github.com/sbt/sbt/issues/2686
+    scalaVersion := appConfiguration.value.provider.scalaProvider.version,
+    scalaBinaryVersion := binaryScalaVersion(scalaVersion.value),
+    ivyScala := {
+      Some(IvyScala(scalaVersion.value, scalaBinaryVersion.value, Vector(), checkExplicit = false, filterImplicit = false,
+        overrideScalaVersion = true).withScalaOrganization(scalaOrganization.value))
+    },
     updateSbtClassifiers in TaskGlobal := (Def.task {
       val s = streams.value
       val is = ivySbt.value
diff --git a/sbt/src/sbt-test/dependency-management/update-sbt-classifiers/build.sbt b/sbt/src/sbt-test/dependency-management/update-sbt-classifiers/build.sbt
new file mode 100644
index 000000000..77e00de55
--- /dev/null
+++ b/sbt/src/sbt-test/dependency-management/update-sbt-classifiers/build.sbt
@@ -0,0 +1 @@
+scalaVersion := "2.9.2"