Adds withIncludeSynthToNameHashing. Ref #2537

Provides a workaround flag `incOptions :=
incOptions.value.withIncludeSynthToNameHashing(true)` for name hashing
not including synthetic methods. This will not be enabled by default in
sbt 0.13. It can also enabled by passing `sbt.inc.include_synth=true`
to JVM.

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

@@ -206,6 +206,7 @@ private final class AnalysisCallback(internalMap: File => Option[File], external
   def usedName(sourceFile: File, name: String) = add(usedNames, sourceFile, name)
 
   def nameHashing: Boolean = options.nameHashing
+  def includeSynthToNameHashing: Boolean = options.includeSynthToNameHashing
 
   def get: Analysis = addUsedNames(addCompilation(addProductsAndDeps(Analysis.empty(nameHashing = nameHashing))))
 

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

@@ -80,7 +80,11 @@ final class IncOptions(
      * Once Scala compiler sources are refactored to work well with name hashing algorithm this option will be
      * deleted immediately.
      */
-    val antStyle: Boolean) extends Product with Serializable {
+    val antStyle: Boolean,
+    /**
+     * Include synthetic methods into the dependency tracking by name hashing.
+     */
+    val includeSynthToNameHashing: Boolean) extends Product with Serializable {
 
   /**
    * Secondary constructor introduced to make IncOptions to be binary compatible with version that didn't have
@@ -90,59 +94,72 @@ final class IncOptions(
     apiDiffContextSize: Int, apiDumpDirectory: Option[java.io.File], newClassfileManager: () => ClassfileManager) = {
     this(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
       apiDumpDirectory, newClassfileManager, IncOptions.recompileOnMacroDefDefault, IncOptions.nameHashingDefault,
-      IncOptions.antStyleDefault)
+      IncOptions.antStyleDefault, IncOptions.includeSynthToNameHashingDefault)
+  }
+
+  def this(transitiveStep: Int, recompileAllFraction: Double, relationsDebug: Boolean, apiDebug: Boolean,
+    apiDiffContextSize: Int, apiDumpDirectory: Option[java.io.File], newClassfileManager: () => ClassfileManager,
+    recompileOnMacroDef: Boolean, nameHashing: Boolean, antStyle: Boolean) = {
+    this(transitiveStep, recompileAllFraction, relationsDebug, apiDebug,
+      apiDiffContextSize, apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing,
+      antStyle, IncOptions.includeSynthToNameHashingDefault)
   }
 
   assert(!(antStyle && nameHashing), "Name hashing and Ant-style cannot be enabled at the same time.")
 
   def withTransitiveStep(transitiveStep: Int): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withRecompileAllFraction(recompileAllFraction: Double): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withRelationsDebug(relationsDebug: Boolean): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withApiDebug(apiDebug: Boolean): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withApiDiffContextSize(apiDiffContextSize: Int): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withApiDumpDirectory(apiDumpDirectory: Option[File]): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withNewClassfileManager(newClassfileManager: () => ClassfileManager): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withRecompileOnMacroDef(recompileOnMacroDef: Boolean): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withNameHashing(nameHashing: Boolean): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
+  }
+
+  def withIncludeSynthToNameHashing(includeSynthToNameHashing: Boolean): IncOptions = {
+    new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   def withAntStyle(antStyle: Boolean): IncOptions = {
     new IncOptions(transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize,
-      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle)
+      apiDumpDirectory, newClassfileManager, recompileOnMacroDef, nameHashing, antStyle, includeSynthToNameHashing)
   }
 
   //- EXPANDED CASE CLASS METHOD BEGIN -//
@@ -219,6 +236,8 @@ object IncOptions extends Serializable {
   private val recompileOnMacroDefDefault: Boolean = true
   private[sbt] val nameHashingDefault: Boolean = true
   private val antStyleDefault: Boolean = false
+  // This should default to false
+  private[sbt] val includeSynthToNameHashingDefault = java.lang.Boolean.getBoolean("sbt.inc.include_synth")
   val Default = IncOptions(
     //    1. recompile changed sources
     // 2(3). recompile direct dependencies and transitive public inheritance dependencies of sources with API changes in 1(2).

compile/interface/src/main/scala/xsbt/ExtractUsedNames.scala

@@ -41,6 +41,8 @@ import scala.tools.nsc._
 class ExtractUsedNames[GlobalType <: CallbackGlobal](val global: GlobalType) extends Compat {
   import global._
 
+  @inline def debug(msg: => String) = if (settings.verbose.value) inform(msg)
+
   def extract(unit: CompilationUnit): Set[String] = {
     val tree = unit.body
     val extractedByTreeWalk = extractByTreeWalk(tree)
@@ -122,7 +124,7 @@ class ExtractUsedNames[GlobalType <: CallbackGlobal](val global: GlobalType) ext
     }
 
     (symbol != NoSymbol) &&
-      !symbol.isSynthetic &&
+      (callback.includeSynthToNameHashing || !symbol.isSynthetic) &&
       !emptyName(symbol.name)
   }
 }

interface/src/main/java/xsbti/AnalysisCallback.java

@@ -59,4 +59,8 @@ public interface AnalysisCallback
 	 *       Do not depend on it, please.
 	 */
 	boolean nameHashing();
+	/**
+	 * Include synthetic methods into the dependency tracking by name hashing.
+	 */
+	boolean includeSynthToNameHashing();
 }

notes/0.13.12/include_synth.markdown

@@ -0,0 +1,10 @@
+  [@eed3si9n]: https://github.com/eed3si9n
+  [@jsuereth]: https://github.com/jsuereth
+  [@dwijnand]: http://github.com/dwijnand
+  [@Duhemm]: http://github.com/Duhemm
+  [@gkossakowski]: https://github.com/gkossakowski
+  [2573]: https://github.com/sbt/sbt/issues/2537
+
+### Bug fixes
+
+- Provides a workaround flag `incOptions := incOptions.value.withIncludeSynthToNameHashing(true)` for name hashing not including synthetic methods. This will not be enabled by default in sbt 0.13. It can also enabled by passing `sbt.inc.include_synth=true` to JVM. [#2537][2573] by [@eed3si9h][@eed3si9h]

sbt/src/sbt-test/source-dependencies/naha-synthetic/A.scala

@@ -0,0 +1 @@
+case class A(a: Int)

sbt/src/sbt-test/source-dependencies/naha-synthetic/B.scala

@@ -0,0 +1 @@
+class B { def test(a: A) = a.copy() }

sbt/src/sbt-test/source-dependencies/naha-synthetic/build.sbt

@@ -0,0 +1,5 @@
+lazy val root = (project in file(".")).
+  settings(
+    scalaVersion := "2.11.7",
+    incOptions := incOptions.value.withIncludeSynthToNameHashing(true)
+  )

sbt/src/sbt-test/source-dependencies/naha-synthetic/changes/A.scala

@@ -0,0 +1 @@
+case class A(a: Int) { private def copy = ??? }

sbt/src/sbt-test/source-dependencies/naha-synthetic/test

@@ -0,0 +1,5 @@
+> compile
+
+$ copy-file changes/A.scala A.scala
+
+-> compile