Debug issues with implicit usage for CompileSetup.

* Force CompileSetup Equiv typeclass to use Equiv relations defined locally.
* Add toString methods on many of the incremental compiler datatypes.
* Remove remaining binary compatibility issues in Defaults.scala.

compile/inc/src/main/scala/sbt/CompileSetup.scala

@@ -10,24 +10,41 @@ import java.io.File
 //  We cannot require an implicit parameter Equiv[Seq[String]] to construct Equiv[CompileSetup]
 //    because complexity(Equiv[Seq[String]]) > complexity(Equiv[CompileSetup])
 //     (6 > 4)
-final class CompileOptions(val options: Seq[String], val javacOptions: Seq[String])
+final class CompileOptions(val options: Seq[String], val javacOptions: Seq[String]) {
+  override def toString = s"CompileOptions(scalac=$options, javac=$javacOptions)"
+}
 final class CompileSetup(val output: APIOutput, val options: CompileOptions, val compilerVersion: String,
     val order: CompileOrder, val nameHashing: Boolean) {
   @deprecated("Use the other overloaded variant of the constructor that takes `nameHashing` value, instead.", "0.13.2")
   def this(output: APIOutput, options: CompileOptions, compilerVersion: String, order: CompileOrder) = {
     this(output, options, compilerVersion, order, false)
   }
+  override def toString = s"""CompileSetup(
+       |  options = $options
+       |  compilerVersion = $compilerVersion
+       |  order = $order
+       |  nameHashing = $nameHashing
+       |  output = $output
+       |)""".stripMargin
 }
 
 object CompileSetup {
   // Equiv[CompileOrder.Value] dominates Equiv[CompileSetup]
   implicit def equivCompileSetup(implicit equivOutput: Equiv[APIOutput], equivOpts: Equiv[CompileOptions], equivComp: Equiv[String] /*, equivOrder: Equiv[CompileOrder]*/ ): Equiv[CompileSetup] = new Equiv[CompileSetup] {
-    def equiv(a: CompileSetup, b: CompileSetup) =
-      equivOutput.equiv(a.output, b.output) &&
-        equivOpts.equiv(a.options, b.options) &&
-        equivComp.equiv(a.compilerVersion, b.compilerVersion) &&
-        a.order == b.order && // equivOrder.equiv(a.order, b.order)
-        a.nameHashing == b.nameHashing
+    def equiv(a: CompileSetup, b: CompileSetup) = {
+      // For some reason, an Equiv[Nothing] or some such is getting injected into here now, and borking all our results.
+      // We hardcode these to use the Equiv defined in this class.
+      def sameOutput = CompileSetup.equivOutput.equiv(a.output, b.output)
+      def sameOptions = CompileSetup.equivOpts.equiv(a.options, b.options)
+      def sameCompiler = equivComp.equiv(a.compilerVersion, b.compilerVersion)
+      def sameOrder = a.order == b.order
+      def sameNameHasher = a.nameHashing == b.nameHashing
+      sameOutput &&
+        sameOptions &&
+        sameCompiler &&
+        sameOrder && // equivOrder.equiv(a.order, b.order)
+        sameNameHasher
+    }
   }
   implicit val equivFile: Equiv[File] = new Equiv[File] {
     def equiv(a: File, b: File) = a.getAbsoluteFile == b.getAbsoluteFile
@@ -41,14 +58,17 @@ object CompileSetup {
             case (a, b) =>
               equivFile.equiv(a.sourceDirectory, b.sourceDirectory) && equivFile.equiv(a.outputDirectory, b.outputDirectory)
           })
-      case (s1: SingleOutput, s2: SingleOutput) => equivFile.equiv(s1.outputDirectory, s2.outputDirectory)
-      case _                                    => false
+      case (s1: SingleOutput, s2: SingleOutput) =>
+        equivFile.equiv(s1.outputDirectory, s2.outputDirectory)
+      case _ =>
+        false
     }
   }
   implicit val equivOpts: Equiv[CompileOptions] = new Equiv[CompileOptions] {
-    def equiv(a: CompileOptions, b: CompileOptions) =
+    def equiv(a: CompileOptions, b: CompileOptions) = {
       (a.options sameElements b.options) &&
         (a.javacOptions sameElements b.javacOptions)
+    }
   }
   implicit val equivCompilerVersion: Equiv[String] = new Equiv[String] {
     def equiv(a: String, b: String) = a == b

compile/integration/src/main/scala/sbt/compiler/MixedAnalyzingCompiler.scala

@@ -17,6 +17,9 @@ import xsbti.compile._
 /**
  * This is a compiler that mixes the `sbt.compiler.AnalyzingCompiler` for Scala incremental compilation
  * with a `xsbti.JavaCompiler`, allowing cross-compilation of mixed Java/Scala projects with analysis output.
+ *
+ *
+ * NOTE: this is actually the core logic of the incremental compiler for sbt.
  */
 object MixedAnalyzingCompiler {
   /** The result of running the compilation. */
@@ -90,6 +93,7 @@ object MixedAnalyzingCompiler {
     cache: GlobalsCache,
     incrementalCompilerOptions: IncOptions)(implicit log: Logger): (Analysis, Boolean) =
     {
+      import CompileSetup._
       if (skip)
         (previousAnalysis, false)
       else {

compile/interface/src/test/scala/xsbt/ScalaCompilerForUnitTesting.scala

@@ -149,6 +149,7 @@ class ScalaCompilerForUnitTesting(nameHashing: Boolean = false) {
     val args = Array.empty[String]
     object output extends SingleOutput {
       def outputDirectory: File = outputDir
+      override def toString = s"SingleOutput($outputDirectory)"
     }
     val weakLog = new WeakLog(ConsoleLogger(), ConsoleReporter)
     val cachedCompiler = new CachedCompiler0(args, output, weakLog, false)

compile/persist/src/main/scala/sbt/inc/AnalysisFormats.scala

@@ -76,7 +76,13 @@ object AnalysisFormats {
   implicit val multipleOutputFormat: Format[MultipleOutput] =
     wrap[MultipleOutput, Array[OutputGroup]](
       (_.outputGroups),
-      { groups => new MultipleOutput { def outputGroups = groups } }
+      {
+        groups =>
+          new MultipleOutput {
+            def outputGroups = groups
+            override def toString = s"MultipleOutput($outputGroups)"
+          }
+      }
     )
   implicit val singleOutputFormat: Format[SingleOutput] =
     wrap[SingleOutput, File](

compile/persist/src/main/scala/sbt/inc/TextAnalysisFormat.scala

@@ -308,8 +308,10 @@ object TextAnalysisFormat {
               case (src: File, out: File) => new MultipleOutput.OutputGroup {
                 val sourceDirectory = src
                 val outputDirectory = out
+                override def toString = s"OutputGroup($src -> $out)"
               }
             }
+            override def toString = s"MultipleOuput($outputGroups)"
           }
           case str: String => throw new ReadException("Unrecognized output mode: " + str)
         }

compile/src/main/scala/sbt/compiler/CompilerOutput.scala

@@ -8,9 +8,11 @@ package compiler
 import xsbti.compile.{ Output, SingleOutput, MultipleOutput }
 import java.io.File
 
+/** Constructor for the `Output` ADT for incremental compiler.  Can either take groups (src -> out) or a single output. */
 object CompileOutput {
   def apply(dir: File): Output = new SingleOutput {
     def outputDirectory = dir
+    override def toString = s"SingleOutput($outputDirectory)"
   }
 
   def apply(groups: (File, File)*): Output = new MultipleOutput {
@@ -18,7 +20,9 @@ object CompileOutput {
       case (src, out) => new MultipleOutput.OutputGroup {
         def sourceDirectory = src
         def outputDirectory = out
+        override def toString = s"OutputGroup($src -> $out)"
       }
     }
+    override def toString = s"MultiOutput($outputGroups)"
   }
 }

main/src/main/scala/sbt/Defaults.scala

@@ -783,7 +783,8 @@ object Defaults extends BuildCommon {
 
   def compileTask: Initialize[Task[inc.Analysis]] = Def.task { saveAnalysis.value }
   def compileIncrementalTask = Def.task {
-    compileIncrementalTaskImpl(streams.value, (compileInputs in compile).value, (readAnalysis in compile).value, (compilerReporter in compile).value)
+    // TODO - Should readAnalysis + saveAnalysis be scoped by the compile task too?
+    compileIncrementalTaskImpl(streams.value, (compileInputs in compile).value, readAnalysis.value, (compilerReporter in compile).value)
   }
   private[this] def compileIncrementalTaskImpl(s: TaskStreams, ci: Compiler.Inputs, previous: Compiler.PreviousAnalysis, reporter: Option[xsbti.Reporter]): Compiler.CompileResult =
     {