From 90782b1cd045c84bb82c7d5ba655540c3870cbd7 Mon Sep 17 00:00:00 2001
From: jvican <jorgevc@fastmail.es>
Date: Wed, 19 Apr 2017 08:32:45 +0200
Subject: [PATCH] Fix implementation of `LoadBuildConfiguration`

It mainly does three things:

* Clean up the implementation, removing unused values like
  `globalPluginDefs`.
* Make the implementation more readable.
* And the big one: Remove the creation of a classloader that we were
  instantiating but whose value we were throwing away. This has an impact
  in performance, but I'm yet to benchmark how much it is.
---
 main/src/main/scala/sbt/EvaluateTask.scala  |  5 ++++
 main/src/main/scala/sbt/internal/Load.scala | 32 ++++++++++++---------
 2 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/main/src/main/scala/sbt/EvaluateTask.scala b/main/src/main/scala/sbt/EvaluateTask.scala
index bed9ee8ee..3b3fc8524 100644
--- a/main/src/main/scala/sbt/EvaluateTask.scala
+++ b/main/src/main/scala/sbt/EvaluateTask.scala
@@ -138,6 +138,11 @@ final case class PluginData(
   val classpath: Seq[Attributed[File]] = definitionClasspath ++ dependencyClasspath
 }
 
+object PluginData {
+  private[sbt] def apply(dependencyClasspath: Def.Classpath): PluginData =
+    PluginData(dependencyClasspath, Nil, None, None, Nil)
+}
+
 object EvaluateTask {
   import std.Transform
   import Keys.state
diff --git a/main/src/main/scala/sbt/internal/Load.scala b/main/src/main/scala/sbt/internal/Load.scala
index fdeae3667..453b37618 100755
--- a/main/src/main/scala/sbt/internal/Load.scala
+++ b/main/src/main/scala/sbt/internal/Load.scala
@@ -34,7 +34,7 @@ import Keys.{
   thisProjectRef,
   update
 }
-import tools.nsc.reporters.ConsoleReporter
+import scala.tools.nsc.reporters.ConsoleReporter
 import sbt.internal.util.{ Attributed, Settings, ~> }
 import sbt.util.{ Eval => Ev, Show }
 import sbt.internal.util.Attributed.data
@@ -909,13 +909,15 @@ private[sbt] object Load {
   def pluginDefinitionLoader(config: LoadBuildConfiguration, pluginData: PluginData): (Seq[Attributed[File]], ClassLoader) =
     pluginDefinitionLoader(config, pluginData.dependencyClasspath, pluginData.definitionClasspath)
 
+  def buildPluginClasspath(config: LoadBuildConfiguration,
+                           depcp: Seq[Attributed[File]]): Def.Classpath = {
+    if (depcp.isEmpty) config.classpath
+    else (depcp ++ config.classpath).distinct
+  }
+
   def pluginDefinitionLoader(config: LoadBuildConfiguration, depcp: Seq[Attributed[File]], defcp: Seq[Attributed[File]]): (Seq[Attributed[File]], ClassLoader) =
     {
-      val definitionClasspath =
-        if (depcp.isEmpty)
-          config.classpath
-        else
-          (depcp ++ config.classpath).distinct
+      val definitionClasspath = buildPluginClasspath(config, depcp)
       val pm = config.pluginManagement
       // only the dependencyClasspath goes in the common plugin class loader ...
       def addToLoader() = pm.loader add Path.toURLs(data(depcp))
@@ -1000,7 +1002,7 @@ private[sbt] object Load {
 
 final case class LoadBuildConfiguration(
     stagingDirectory: File,
-    classpath: Seq[Attributed[File]],
+    classpath: Def.Classpath,
     loader: ClassLoader,
     compilers: Compilers,
     evalPluginDef: (BuildStructure, State) => PluginData,
@@ -1012,21 +1014,23 @@ final case class LoadBuildConfiguration(
     extraBuilds: Seq[URI],
     log: Logger
 ) {
-  lazy val (globalPluginClasspath, _) = Load.pluginDefinitionLoader(this, Load.globalPluginClasspath(globalPlugin))
+  lazy val globalPluginClasspath: Def.Classpath =
+    Load.buildPluginClasspath(this, Load.globalPluginClasspath(globalPlugin))
 
-  private[sbt] lazy val globalPluginDefs = {
+  lazy val detectedGlobalPlugins: DetectedPlugins = {
     val pluginData = globalPlugin match {
-      case Some(x) => PluginData(x.data.fullClasspath, x.data.internalClasspath, Some(x.data.resolvers), Some(x.data.updateReport), Nil)
-      case None    => PluginData(globalPluginClasspath, Nil, None, None, Nil)
+      case Some(info) =>
+        val data = info.data
+        PluginData(data.fullClasspath, data.internalClasspath, Some(data.resolvers), Some(data.updateReport), Nil)
+      case None    => PluginData(globalPluginClasspath)
     }
     val baseDir = globalPlugin match {
       case Some(x) => x.base
       case _       => stagingDirectory
     }
-    Load.loadPluginDefinition(baseDir, this, pluginData)
+    val globalPlugins = Load.loadPluginDefinition(baseDir, this, pluginData)
+    globalPlugins.detected
   }
-
-  lazy val detectedGlobalPlugins = globalPluginDefs.detected
 }
 
 final class IncompatiblePluginsException(msg: String, cause: Throwable) extends Exception(msg, cause)