From 8908d0e93b9c1ec1d0cc7d791b78af59c8f5d9fc Mon Sep 17 00:00:00 2001
From: Mark Harrah <dmharrah@gmail.com>
Date: Sat, 16 Jun 2012 23:40:52 -0400
Subject: [PATCH] attempt at better error message for linkage errors in
 plugins. fixes #483

Only catches linkage errors during static initialization of the plugin module,
but these are likely to be the most common.
---
 main/EvaluateTask.scala |  2 +-
 main/Load.scala         | 21 +++++++++++++++++----
 2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/main/EvaluateTask.scala b/main/EvaluateTask.scala
index 087fec19d..247f27f5c 100644
--- a/main/EvaluateTask.scala
+++ b/main/EvaluateTask.scala
@@ -12,7 +12,7 @@ package sbt
 	import scala.Console.RED
 
 final case class EvaluateConfig(cancelable: Boolean, restrictions: Seq[Tags.Rule], checkCycles: Boolean = false)
-final case class PluginData(classpath: Seq[Attributed[File]], resolvers: Option[Seq[Resolver]])
+final case class PluginData(classpath: Seq[Attributed[File]], resolvers: Option[Seq[Resolver]], report: Option[UpdateReport])
 object EvaluateTask
 {
 	import Load.BuildStructure
diff --git a/main/Load.scala b/main/Load.scala
index d547c0069..ed7a800e2 100755
--- a/main/Load.scala
+++ b/main/Load.scala
@@ -14,7 +14,7 @@ package sbt
 	import Compiler.{Compilers,Inputs}
 	import inc.{FileValueCache, Locate}
 	import Project.{inScope, ScopedKey, ScopeLocal, Setting}
-	import Keys.{appConfiguration, baseDirectory, configuration, fullResolvers, fullClasspath, pluginData, streams, Streams, thisProject, thisProjectRef}
+	import Keys.{appConfiguration, baseDirectory, configuration, fullResolvers, fullClasspath, pluginData, streams, Streams, thisProject, thisProjectRef, update}
 	import Keys.{isDummy, loadedBuild, parseResult, resolvedScoped, taskDefinitionKey}
 	import tools.nsc.reporters.ConsoleReporter
 	import Build.{analyzed, data}
@@ -446,7 +446,7 @@ object Load
 		}
 	val autoPluginSettings: Seq[Setting[_]] = inScope(GlobalScope in LocalRootProject)(Seq(
 		Keys.sbtPlugin :== true,
-		pluginData <<= (fullClasspath in Configurations.Runtime, fullResolvers) map ( (cp, rs) => PluginData(cp, Some(rs)) ),
+		pluginData <<= (fullClasspath in Configurations.Runtime, update, fullResolvers) map ( (cp, rep, rs) => PluginData(cp, Some(rs), Some(rep)) ),
 		Keys.onLoadMessage <<= Keys.baseDirectory("Loading project definition from " + _)
 	))
 	def enableSbtPlugin(config: LoadBuildConfiguration): LoadBuildConfiguration =
@@ -472,7 +472,7 @@ object Load
 		!(dir * -GlobFilter(DefaultTargetName)).get.isEmpty
 	}
 	def noPlugins(dir: File, config: LoadBuildConfiguration): LoadedPlugins =
-		loadPluginDefinition(dir, config, PluginData(config.globalPluginClasspath, None))
+		loadPluginDefinition(dir, config, PluginData(config.globalPluginClasspath, None, None))
 	def buildPlugins(dir: File, s: State, config: LoadBuildConfiguration): LoadedPlugins =
 		loadPluginDefinition(dir, config, buildPluginDefinition(dir, s, config))
 
@@ -523,10 +523,22 @@ object Load
 	{
 		val (pluginNames, plugins) = if(data.classpath.isEmpty) (Nil, Nil) else {
 			val names = getPluginNames(data.classpath, loader)
-			(names, loadPlugins(loader, names) )
+			val loaded =
+				try loadPlugins(loader, names)
+				catch { case e: LinkageError => incompatiblePlugins(data, e) }
+			(names, loaded)
 		}
 		new LoadedPlugins(dir, data, loader, plugins, pluginNames)
 	}
+	private[this] def incompatiblePlugins(data: PluginData, t: LinkageError): Nothing =
+	{
+		val evicted = data.report.toList.flatMap(_.configurations.flatMap(_.evicted))
+		val evictedModules = evicted map { id => (id.organization, id.name) } distinct ;
+		val evictedStrings = evictedModules map { case (o,n) => o + ":" + n }
+		val msgBase = "Binary incompatibility in plugins detected."
+		val msgExtra = if(evictedStrings.isEmpty) "" else "\nNote that conflicts were resolved for some dependencies:\n\t" + evictedStrings.mkString("\n\t")
+		throw new IncompatiblePluginsException(msgBase + msgExtra, t)
+	}
 	def getPluginNames(classpath: Seq[Attributed[File]], loader: ClassLoader): Seq[String] =
 		 ( binaryPlugins(Build.data(classpath), loader) ++ (analyzed(classpath) flatMap findPlugins) ).distinct
 
@@ -675,3 +687,4 @@ object Load
 		val aggregateKeyIndex: KeyIndex
 	)
 }
+final class IncompatiblePluginsException(msg: String, cause: Throwable) extends Exception(msg, cause)
\ No newline at end of file