Merge pull request #3493 from retronym/ticket/3452-2

SI-3452 Correct Java generic signatures for mixins, static forwarders

40 files changed, 840 insertions, 263 deletions

diff --git a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
index 18ccced75e..359e5d6c29 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/BCodeHelpers.scala
@@ -583,53 +583,7 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
 
   trait BCAnnotGen extends BCInnerClassGen {
 
-    /*
-     *  can-multi-thread
-     */
-    def ubytesToCharArray(bytes: Array[Byte]): Array[Char] = {
-      val ca = new Array[Char](bytes.length)
-      var idx = 0
-      while (idx < bytes.length) {
-        val b: Byte = bytes(idx)
-        assert((b & ~0x7f) == 0)
-        ca(idx) = b.asInstanceOf[Char]
-        idx += 1
-      }
-
-      ca
-    }
-
-    /*
-     *  can-multi-thread
-     */
-    private def arrEncode(sb: ScalaSigBytes): Array[String] = {
-      var strs: List[String]  = Nil
-      val bSeven: Array[Byte] = sb.sevenBitsMayBeZero
-      // chop into slices of at most 65535 bytes, counting 0x00 as taking two bytes (as per JVMS 4.4.7 The CONSTANT_Utf8_info Structure)
-      var prevOffset = 0
-      var offset     = 0
-      var encLength  = 0
-      while (offset < bSeven.size) {
-        val deltaEncLength = (if (bSeven(offset) == 0) 2 else 1)
-        val newEncLength = encLength.toLong + deltaEncLength
-        if (newEncLength >= 65535) {
-          val ba     = bSeven.slice(prevOffset, offset)
-          strs     ::= new java.lang.String(ubytesToCharArray(ba))
-          encLength  = 0
-          prevOffset = offset
-        } else {
-          encLength += deltaEncLength
-          offset    += 1
-        }
-      }
-      if (prevOffset < offset) {
-        assert(offset == bSeven.length)
-        val ba = bSeven.slice(prevOffset, offset)
-        strs ::= new java.lang.String(ubytesToCharArray(ba))
-      }
-      assert(strs.size > 1, "encode instead as one String via strEncode()") // TODO too strict?
-      mkArrayReverse(strs)
-    }
+    import genASM.{ubytesToCharArray, arrEncode}
 
     /*
      *  can-multi-thread
@@ -676,7 +630,7 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
             av.visit(name, strEncode(sb))
           } else {
             val arrAnnotV: asm.AnnotationVisitor = av.visitArray(name)
-            for(arg <- arrEncode(sb)) { arrAnnotV.visit(name, arg) }
+            for(arg <- genASM.arrEncode(sb)) { arrAnnotV.visit(name, arg) }
             arrAnnotV.visitEnd()
           }          // for the lazy val in ScalaSigBytes to be GC'ed, the invoker of emitAnnotations() should hold the ScalaSigBytes in a method-local var that doesn't escape.
 
@@ -772,25 +726,6 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
 
   trait BCJGenSigGen {
 
-    // @M don't generate java generics sigs for (members of) implementation
-    // classes, as they are monomorphic (TODO: ok?)
-    /*
-     * must-single-thread
-     */
-    private def needsGenericSignature(sym: Symbol) = !(
-      // PP: This condition used to include sym.hasExpandedName, but this leads
-      // to the total loss of generic information if a private member is
-      // accessed from a closure: both the field and the accessor were generated
-      // without it.  This is particularly bad because the availability of
-      // generic information could disappear as a consequence of a seemingly
-      // unrelated change.
-         settings.Ynogenericsig
-      || sym.isArtifact
-      || sym.isLiftedMethod
-      || sym.isBridge
-      || (sym.ownerChain exists (_.isImplClass))
-    )
-
     def getCurrentCUnit(): CompilationUnit
 
     /* @return
@@ -799,61 +734,7 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
      *
      * must-single-thread
      */
-    def getGenericSignature(sym: Symbol, owner: Symbol): String = {
-
-      if (!needsGenericSignature(sym)) { return null }
-
-      val memberTpe = enteringErasure(owner.thisType.memberInfo(sym))
-
-      val jsOpt: Option[String] = erasure.javaSig(sym, memberTpe)
-      if (jsOpt.isEmpty) { return null }
-
-      val sig = jsOpt.get
-      log(sig) // This seems useful enough in the general case.
-
-          def wrap(op: => Unit) = {
-            try   { op; true }
-            catch { case _: Throwable => false }
-          }
-
-      if (settings.Xverify) {
-        // Run the signature parser to catch bogus signatures.
-        val isValidSignature = wrap {
-          // Alternative: scala.tools.reflect.SigParser (frontend to sun.reflect.generics.parser.SignatureParser)
-          import scala.tools.asm.util.CheckClassAdapter
-          if (sym.isMethod)    { CheckClassAdapter checkMethodSignature sig }
-          else if (sym.isTerm) { CheckClassAdapter checkFieldSignature  sig }
-          else                 { CheckClassAdapter checkClassSignature  sig }
-        }
-
-        if (!isValidSignature) {
-          getCurrentCUnit().warning(sym.pos,
-              """|compiler bug: created invalid generic signature for %s in %s
-                 |signature: %s
-                 |if this is reproducible, please report bug at https://issues.scala-lang.org/
-              """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig))
-          return null
-        }
-      }
-
-      if ((settings.check containsName phaseName)) {
-        val normalizedTpe = enteringErasure(erasure.prepareSigMap(memberTpe))
-        val bytecodeTpe = owner.thisType.memberInfo(sym)
-        if (!sym.isType && !sym.isConstructor && !(erasure.erasure(sym)(normalizedTpe) =:= bytecodeTpe)) {
-          getCurrentCUnit().warning(sym.pos,
-              """|compiler bug: created generic signature for %s in %s that does not conform to its erasure
-                 |signature: %s
-                 |original type: %s
-                 |normalized type: %s
-                 |erasure type: %s
-                 |if this is reproducible, please report bug at http://issues.scala-lang.org/
-              """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig, memberTpe, normalizedTpe, bytecodeTpe))
-           return null
-        }
-      }
-
-      sig
-    }
+    def getGenericSignature(sym: Symbol, owner: Symbol): String = genASM.getGenericSignature(sym, owner, getCurrentCUnit())
 
   } // end of trait BCJGenSigGen
 
@@ -906,7 +787,7 @@ abstract class BCodeHelpers extends BCodeTypes with BytecodeWriters {
       )
 
       // TODO needed? for(ann <- m.annotations) { ann.symbol.initialize }
-      val jgensig = if (m.isDeferred) null else getGenericSignature(m, module); // only add generic signature if method concrete; bug #1745
+      val jgensig = genASM.staticForwarderGenericSignature(m, module, getCurrentCUnit())
       addRemoteExceptionAnnot(isRemoteClass, hasPublicBitSet(flags), m)
       val (throws, others) = m.annotations partition (_.symbol == definitions.ThrowsClass)
       val thrownExceptions: List[String] = getExceptions(throws)
diff --git a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
index b03519ce7d..a389816caf 100644
--- a/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
+++ b/src/compiler/scala/tools/nsc/backend/jvm/GenASM.scala
@@ -20,7 +20,7 @@ import scala.annotation.tailrec
  *
  * Documentation at http://lamp.epfl.ch/~magarcia/ScalaCompilerCornerReloaded/2012Q2/GenASM.pdf
  */
-abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
+abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM { self =>
   import global._
   import icodes._
   import icodes.opcodes._
@@ -803,134 +803,9 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
       annot.args.isEmpty &&
       !annot.matches(DeprecatedAttr)
 
-    // @M don't generate java generics sigs for (members of) implementation
-    // classes, as they are monomorphic (TODO: ok?)
-    private def needsGenericSignature(sym: Symbol) = !(
-      // PP: This condition used to include sym.hasExpandedName, but this leads
-      // to the total loss of generic information if a private member is
-      // accessed from a closure: both the field and the accessor were generated
-      // without it.  This is particularly bad because the availability of
-      // generic information could disappear as a consequence of a seemingly
-      // unrelated change.
-         settings.Ynogenericsig
-      || sym.isArtifact
-      || sym.isLiftedMethod
-      || sym.isBridge
-      || (sym.ownerChain exists (_.isImplClass))
-    )
-
     def getCurrentCUnit(): CompilationUnit
 
-    /** @return
-     *   - `null` if no Java signature is to be added (`null` is what ASM expects in these cases).
-     *   - otherwise the signature in question
-     */
-    def getGenericSignature(sym: Symbol, owner: Symbol): String = {
-
-      if (!needsGenericSignature(sym)) { return null }
-
-      val memberTpe = enteringErasure(owner.thisType.memberInfo(sym))
-
-      val jsOpt: Option[String] = erasure.javaSig(sym, memberTpe)
-      if (jsOpt.isEmpty) { return null }
-
-      val sig = jsOpt.get
-      log(sig) // This seems useful enough in the general case.
-
-          def wrap(op: => Unit) = {
-            try   { op; true }
-            catch { case _: Throwable => false }
-          }
-
-      if (settings.Xverify) {
-        // Run the signature parser to catch bogus signatures.
-        val isValidSignature = wrap {
-          // Alternative: scala.tools.reflect.SigParser (frontend to sun.reflect.generics.parser.SignatureParser)
-          import scala.tools.asm.util.CheckClassAdapter
-          if (sym.isMethod)    { CheckClassAdapter checkMethodSignature sig } // requires asm-util.jar
-          else if (sym.isTerm) { CheckClassAdapter checkFieldSignature  sig }
-          else                 { CheckClassAdapter checkClassSignature  sig }
-        }
-
-        if(!isValidSignature) {
-          getCurrentCUnit().warning(sym.pos,
-              """|compiler bug: created invalid generic signature for %s in %s
-                 |signature: %s
-                 |if this is reproducible, please report bug at https://issues.scala-lang.org/
-              """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig))
-          return null
-        }
-      }
-
-      if ((settings.check containsName phaseName)) {
-        val normalizedTpe = enteringErasure(erasure.prepareSigMap(memberTpe))
-        val bytecodeTpe = owner.thisType.memberInfo(sym)
-        if (!sym.isType && !sym.isConstructor && !(erasure.erasure(sym)(normalizedTpe) =:= bytecodeTpe)) {
-          getCurrentCUnit().warning(sym.pos,
-              """|compiler bug: created generic signature for %s in %s that does not conform to its erasure
-                 |signature: %s
-                 |original type: %s
-                 |normalized type: %s
-                 |erasure type: %s
-                 |if this is reproducible, please report bug at http://issues.scala-lang.org/
-              """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig, memberTpe, normalizedTpe, bytecodeTpe))
-           return null
-        }
-      }
-
-      sig
-    }
-
-    def ubytesToCharArray(bytes: Array[Byte]): Array[Char] = {
-      val ca = new Array[Char](bytes.length)
-      var idx = 0
-      while(idx < bytes.length) {
-        val b: Byte = bytes(idx)
-        assert((b & ~0x7f) == 0)
-        ca(idx) = b.asInstanceOf[Char]
-        idx += 1
-      }
-
-      ca
-    }
-
-    private def arrEncode(sb: ScalaSigBytes): Array[String] = {
-      var strs: List[String]  = Nil
-      val bSeven: Array[Byte] = sb.sevenBitsMayBeZero
-      // chop into slices of at most 65535 bytes, counting 0x00 as taking two bytes (as per JVMS 4.4.7 The CONSTANT_Utf8_info Structure)
-      var prevOffset = 0
-      var offset     = 0
-      var encLength  = 0
-      while(offset < bSeven.length) {
-        val deltaEncLength = (if(bSeven(offset) == 0) 2 else 1)
-        val newEncLength = encLength.toLong + deltaEncLength
-        if(newEncLength >= 65535) {
-          val ba     = bSeven.slice(prevOffset, offset)
-          strs     ::= new java.lang.String(ubytesToCharArray(ba))
-          encLength  = 0
-          prevOffset = offset
-        } else {
-          encLength += deltaEncLength
-          offset    += 1
-        }
-      }
-      if(prevOffset < offset) {
-        assert(offset == bSeven.length)
-        val ba = bSeven.slice(prevOffset, offset)
-        strs ::= new java.lang.String(ubytesToCharArray(ba))
-      }
-      assert(strs.size > 1, "encode instead as one String via strEncode()") // TODO too strict?
-      strs.reverse.toArray
-    }
-
-    private def strEncode(sb: ScalaSigBytes): String = {
-      val ca = ubytesToCharArray(sb.sevenBitsMayBeZero)
-      new java.lang.String(ca)
-      // debug val bvA = new asm.ByteVector; bvA.putUTF8(s)
-      // debug val enc: Array[Byte] = scala.reflect.internal.pickling.ByteCodecs.encode(bytes)
-      // debug assert(enc(idx) == bvA.getByte(idx + 2))
-      // debug assert(bvA.getLength == enc.size + 2)
-    }
+    def getGenericSignature(sym: Symbol, owner: Symbol) = self.getGenericSignature(sym, owner, getCurrentCUnit())
 
     def emitArgument(av:   asm.AnnotationVisitor,
                      name: String,
@@ -1064,7 +939,7 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
       )
 
       // TODO needed? for(ann <- m.annotations) { ann.symbol.initialize }
-      val jgensig = if (m.isDeferred) null else getGenericSignature(m, module); // only add generic signature if method concrete; bug #1745
+      val jgensig = staticForwarderGenericSignature(m, module, getCurrentCUnit())
       addRemoteExceptionAnnot(isRemoteClass, hasPublicBitSet(flags), m)
       val (throws, others) = m.annotations partition (_.symbol == ThrowsClass)
       val thrownExceptions: List[String] = getExceptions(throws)
@@ -3303,4 +3178,147 @@ abstract class GenASM extends SubComponent with BytecodeWriters with GenJVMASM {
 
   }
 
+  // @M don't generate java generics sigs for (members of) implementation
+  // classes, as they are monomorphic (TODO: ok?)
+  private def needsGenericSignature(sym: Symbol) = !(
+    // PP: This condition used to include sym.hasExpandedName, but this leads
+    // to the total loss of generic information if a private member is
+    // accessed from a closure: both the field and the accessor were generated
+    // without it.  This is particularly bad because the availability of
+    // generic information could disappear as a consequence of a seemingly
+    // unrelated change.
+       settings.Ynogenericsig
+    || sym.isArtifact
+    || sym.isLiftedMethod
+    || sym.isBridge
+    || (sym.ownerChain exists (_.isImplClass))
+  )
+
+  final def staticForwarderGenericSignature(sym: Symbol, moduleClass: Symbol, unit: CompilationUnit): String = {
+    if (sym.isDeferred) null // only add generic signature if method concrete; bug #1745
+    else {
+      // SI-3452 Static forwarder generation uses the same erased signature as the method if forwards to.
+      // By rights, it should use the signature as-seen-from the module class, and add suitable
+      // primitive and value-class boxing/unboxing.
+      // But for now, just like we did in mixin, we just avoid writing a wrong generic signature
+      // (one that doesn't erase to the actual signature). See run/t3452b for a test case.
+      val memberTpe = enteringErasure(moduleClass.thisType.memberInfo(sym))
+      val erasedMemberType = erasure.erasure(sym)(memberTpe)
+      if (erasedMemberType =:= sym.info)
+        getGenericSignature(sym, moduleClass, memberTpe, unit)
+      else null
+    }
+  }
+
+  /** @return
+   *   - `null` if no Java signature is to be added (`null` is what ASM expects in these cases).
+   *   - otherwise the signature in question
+   */
+  def getGenericSignature(sym: Symbol, owner: Symbol, unit: CompilationUnit): String = {
+    val memberTpe = enteringErasure(owner.thisType.memberInfo(sym))
+    getGenericSignature(sym, owner, memberTpe, unit)
+  }
+  def getGenericSignature(sym: Symbol, owner: Symbol, memberTpe: Type, unit: CompilationUnit): String = {
+    if (!needsGenericSignature(sym)) { return null }
+
+    val jsOpt: Option[String] = erasure.javaSig(sym, memberTpe)
+    if (jsOpt.isEmpty) { return null }
+
+    val sig = jsOpt.get
+    log(sig) // This seems useful enough in the general case.
+
+        def wrap(op: => Unit) = {
+          try   { op; true }
+          catch { case _: Throwable => false }
+        }
+
+    if (settings.Xverify) {
+      // Run the signature parser to catch bogus signatures.
+      val isValidSignature = wrap {
+        // Alternative: scala.tools.reflect.SigParser (frontend to sun.reflect.generics.parser.SignatureParser)
+        import scala.tools.asm.util.CheckClassAdapter
+        if (sym.isMethod)    { CheckClassAdapter checkMethodSignature sig } // requires asm-util.jar
+        else if (sym.isTerm) { CheckClassAdapter checkFieldSignature  sig }
+        else                 { CheckClassAdapter checkClassSignature  sig }
+      }
+
+      if(!isValidSignature) {
+        unit.warning(sym.pos,
+            """|compiler bug: created invalid generic signature for %s in %s
+               |signature: %s
+               |if this is reproducible, please report bug at https://issues.scala-lang.org/
+            """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig))
+        return null
+      }
+    }
+
+    if ((settings.check containsName phaseName)) {
+      val normalizedTpe = enteringErasure(erasure.prepareSigMap(memberTpe))
+      val bytecodeTpe = owner.thisType.memberInfo(sym)
+      if (!sym.isType && !sym.isConstructor && !(erasure.erasure(sym)(normalizedTpe) =:= bytecodeTpe)) {
+        unit.warning(sym.pos,
+            """|compiler bug: created generic signature for %s in %s that does not conform to its erasure
+               |signature: %s
+               |original type: %s
+               |normalized type: %s
+               |erasure type: %s
+               |if this is reproducible, please report bug at http://issues.scala-lang.org/
+            """.trim.stripMargin.format(sym, sym.owner.skipPackageObject.fullName, sig, memberTpe, normalizedTpe, bytecodeTpe))
+         return null
+      }
+    }
+
+    sig
+  }
+
+  def ubytesToCharArray(bytes: Array[Byte]): Array[Char] = {
+    val ca = new Array[Char](bytes.length)
+    var idx = 0
+    while(idx < bytes.length) {
+      val b: Byte = bytes(idx)
+      assert((b & ~0x7f) == 0)
+      ca(idx) = b.asInstanceOf[Char]
+      idx += 1
+    }
+
+    ca
+  }
+
+  final def arrEncode(sb: ScalaSigBytes): Array[String] = {
+    var strs: List[String]  = Nil
+    val bSeven: Array[Byte] = sb.sevenBitsMayBeZero
+    // chop into slices of at most 65535 bytes, counting 0x00 as taking two bytes (as per JVMS 4.4.7 The CONSTANT_Utf8_info Structure)
+    var prevOffset = 0
+    var offset     = 0
+    var encLength  = 0
+    while(offset < bSeven.length) {
+      val deltaEncLength = (if(bSeven(offset) == 0) 2 else 1)
+      val newEncLength = encLength.toLong + deltaEncLength
+      if(newEncLength >= 65535) {
+        val ba     = bSeven.slice(prevOffset, offset)
+        strs     ::= new java.lang.String(ubytesToCharArray(ba))
+        encLength  = 0
+        prevOffset = offset
+      } else {
+        encLength += deltaEncLength
+        offset    += 1
+      }
+    }
+    if(prevOffset < offset) {
+      assert(offset == bSeven.length)
+      val ba = bSeven.slice(prevOffset, offset)
+      strs ::= new java.lang.String(ubytesToCharArray(ba))
+    }
+    assert(strs.size > 1, "encode instead as one String via strEncode()") // TODO too strict?
+    strs.reverse.toArray
+  }
+
+  private def strEncode(sb: ScalaSigBytes): String = {
+    val ca = ubytesToCharArray(sb.sevenBitsMayBeZero)
+    new java.lang.String(ca)
+    // debug val bvA = new asm.ByteVector; bvA.putUTF8(s)
+    // debug val enc: Array[Byte] = scala.reflect.internal.pickling.ByteCodecs.encode(bytes)
+    // debug assert(enc(idx) == bvA.getByte(idx + 2))
+    // debug assert(bvA.getLength == enc.size + 2)
+  }
 }
diff --git a/src/compiler/scala/tools/nsc/transform/Mixin.scala b/src/compiler/scala/tools/nsc/transform/Mixin.scala
index 89f9cb4b06..673bc04bd9 100644
--- a/src/compiler/scala/tools/nsc/transform/Mixin.scala
+++ b/src/compiler/scala/tools/nsc/transform/Mixin.scala
@@ -172,18 +172,23 @@ abstract class Mixin extends InfoTransform with ast.TreeDSL {
       // info) as they are seen from the class.  We can't use the member that we get from the
       // implementation class, as it's a clone that was made after erasure, and thus it does not
       // know its info at the beginning of erasure anymore.
-      //   Optimize: no need if mixinClass has no typeparams.
-      mixinMember cloneSymbol clazz modifyInfo (info =>
-        if (mixinClass.typeParams.isEmpty) info
-        else (clazz.thisType baseType mixinClass) memberInfo mixinMember
-      )
+      val sym = mixinMember cloneSymbol clazz
+
+      val erasureMap = erasure.erasure(mixinMember)
+      val erasedInterfaceInfo: Type = erasureMap(mixinMember.info)
+      val specificForwardInfo       = (clazz.thisType baseType mixinClass) memberInfo mixinMember
+      val forwarderInfo =
+        if (erasureMap(specificForwardInfo) =:= erasedInterfaceInfo)
+          specificForwardInfo
+        else {
+          erasedInterfaceInfo
+        }
+      // Optimize: no need if mixinClass has no typeparams.
+      // !!! JZ Really? What about the effect of abstract types, prefix?
+      if (mixinClass.typeParams.isEmpty) sym
+      else sym modifyInfo (_ => forwarderInfo)
     }
-    // clone before erasure got rid of type info we'll need to generate a javaSig
-    // now we'll have the type info at (the beginning of) erasure in our history,
-    // and now newSym has the info that's been transformed to fit this period
-    // (no need for asSeenFrom as phase.erasedTypes)
-    // TODO: verify we need the updateInfo and document why
-    newSym updateInfo (mixinMember.info cloneInfo newSym)
+    newSym
   }
 
   /** Add getters and setters for all non-module fields of an implementation
diff --git a/test/files/neg/t4749.check b/test/files/neg/t4749.check
index 63d5c21532..3539140954 100644
--- a/test/files/neg/t4749.check
+++ b/test/files/neg/t4749.check
@@ -25,6 +25,10 @@ t4749.scala:26: warning: Fail6 has a main method with parameter type Array[Strin
 
   object Fail6 {
          ^
+t4749.scala:42: warning: Win3 has a main method with parameter type Array[String], but bippy.Win3 will not be a runnable program.
+  Reason: main method must have exact signature (Array[String])Unit
+  object Win3 extends WinBippy[Unit] { }
+         ^
 error: No warnings can be incurred under -Xfatal-warnings.
-6 warnings found
+7 warnings found
 one error found
diff --git a/test/files/pos/t3452f.scala b/test/files/pos/t3452f.scala
new file mode 100644
index 0000000000..efe25a62fc
--- /dev/null
+++ b/test/files/pos/t3452f.scala
@@ -0,0 +1,10 @@
+class Base[Coll] {
+  trait Transformed[S] {
+    lazy val underlying: Coll = ???
+  }
+}
+
+class Derived extends Base[String] {
+  class C extends Transformed[Any]
+}
+
diff --git a/test/files/run/mixin-signatures.check b/test/files/run/mixin-signatures.check
new file mode 100644
index 0000000000..3031fe75af
--- /dev/null
+++ b/test/files/run/mixin-signatures.check
@@ -0,0 +1,59 @@
+class Test$bar1$ {
+  public java.lang.String Test$bar1$.f(java.lang.Object)
+  public java.lang.Object Test$bar1$.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar1$.g(java.lang.String)
+  public java.lang.Object Test$bar1$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar1$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar1$.h(java.lang.Object)
+}
+
+class Test$bar2$ {
+  public java.lang.Object Test$bar2$.f(java.lang.String)
+  public java.lang.Object Test$bar2$.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar2$.g(java.lang.String)
+  public java.lang.Object Test$bar2$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar2$.g(java.lang.String) <bridge> <synthetic>
+  public java.lang.Object Test$bar2$.h(java.lang.Object)
+}
+
+class Test$bar3$ {
+  public java.lang.String Foo3.f(java.lang.Object)
+    generic: public java.lang.String Foo3.f(T)
+  public java.lang.Object Foo3.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar3$.g(java.lang.String)
+  public java.lang.Object Test$bar3$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar3$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Foo3.h(java.lang.Object)
+}
+
+class Test$bar4$ {
+  public java.lang.Object Foo4.f(java.lang.String)
+    generic: public R Foo4.f(java.lang.String)
+  public java.lang.Object Foo4.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar4$.g(java.lang.String)
+  public java.lang.Object Test$bar4$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar4$.g(java.lang.String) <bridge> <synthetic>
+  public java.lang.Object Foo4.h(java.lang.Object)
+}
+
+class Test$bar5$ {
+  public java.lang.String Test$bar5$.f(java.lang.String)
+  public java.lang.Object Test$bar5$.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar5$.f(java.lang.String) <bridge> <synthetic>
+  public java.lang.String Test$bar5$.f(java.lang.Object) <bridge> <synthetic>
+  public java.lang.String Test$bar5$.g(java.lang.String)
+  public java.lang.Object Test$bar5$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar5$.g(java.lang.String) <bridge> <synthetic>
+  public java.lang.String Test$bar5$.g(java.lang.Object) <bridge> <synthetic>
+  public java.lang.Object Test$bar5$.h(java.lang.Object)
+}
+
+class Foo1$class {
+  public static java.lang.String Foo1$class.f(Foo1,java.lang.Object)
+}
+
+class Foo2$class {
+  public static java.lang.Object Foo2$class.f(Foo2,java.lang.String)
+}
+
+000000000000000000000000000000000000
diff --git a/test/files/run/mixin-signatures.scala b/test/files/run/mixin-signatures.scala
new file mode 100644
index 0000000000..afd3fad877
--- /dev/null
+++ b/test/files/run/mixin-signatures.scala
@@ -0,0 +1,105 @@
+trait Base[T, R] {
+  def f(x: T): R
+  def g(x: T): R
+  def h(x: T): R = null.asInstanceOf[R]
+}
+
+trait Foo1[T] extends Base[T, String] {
+  def f(x: T): String = null
+  def g(x: T): String
+}
+trait Foo2[R] extends Base[String, R] {
+  def f(x: String): R = { print(x.length) ; null.asInstanceOf[R] }
+  def g(x: String): R
+}
+abstract class Foo3[T] extends Base[T, String] {
+  def f(x: T): String = ""
+  def g(x: T): String
+}
+abstract class Foo4[R] extends Base[String, R] {
+  def f(x: String): R = { print(x.length) ; null.asInstanceOf[R] }
+  def g(x: String): R
+}
+
+object Test {
+  object bar1 extends Foo1[String] { def g(x: String): String = { print(x.length) ; "" } }
+  object bar2 extends Foo2[String] { def g(x: String): String = { print(x.length) ; "" } }
+  object bar3 extends Foo3[String] { def g(x: String): String = { print(x.length) ; "" } }
+  object bar4 extends Foo4[String] { def g(x: String): String = { print(x.length) ; "" } }
+
+  // Notice that in bar5, f and g require THREE bridges, because the final
+  // implementation is (String)String, but:
+  //
+  //   inherited abstract signatures: T(R), (T)String, and (String)R
+  //   which erase to: (Object)Object, (Object)String, and (String)Object
+  //
+  // each of which must be bridged to the actual (String)String implementation.
+  //
+  // public java.lang.String Test$bar5$.g(java.lang.String)
+  // public java.lang.Object Test$bar5$.g(java.lang.String) <bridge> <synthetic>
+  // public java.lang.Object Test$bar5$.g(java.lang.Object) <bridge> <synthetic>
+  // public java.lang.String Test$bar5$.g(java.lang.Object) <bridge> <synthetic>
+  object bar5 extends Foo1[String] with Foo2[String] {
+    override def f(x: String): String = { print(x.length) ; x }
+    def g(x: String): String = { print(x.length) ; x }
+  }
+
+  final def m1[T, R](x: Base[T, R], y: T)   = { x.f(y) ; x.g(y) ; x.h(y) }
+  final def m2[T](x: Base[T, String], y: T) = { x.f(y) ; x.g(y) ; x.h(y) }
+  final def m3[R](x: Base[String, R])       = { x.f("") ; x.g("") ; x.h("") }
+  final def m4(x: Base[String, String])     = { x.f("") ; x.g("") ; x.h("") }
+
+  final def m11[T](x: Foo1[T], y: T) = { x.f(y) ; x.g(y) ; x.h(y) }
+  final def m12(x: Foo1[String])     = { x.f("") ; x.g("") ; x.h("") }
+  final def m21[T](x: Foo2[T], y: T) = { x.f("") ; x.g("") ; x.h("") }
+  final def m22(x: Foo2[String])     = { x.f("") ; x.g("") ; x.h("") }
+  final def m31[T](x: Foo3[T], y: T) = { x.f(y) ; x.g(y) ; x.h(y) }
+  final def m32(x: Foo3[String])     = { x.f("") ; x.g("") ; x.h("") }
+  final def m41[T](x: Foo4[T], y: T) = { x.f("") ; x.g("") ; x.h("") }
+  final def m42(x: Foo4[String])     = { x.f("") ; x.g("") ; x.h("") }
+
+  def go = {
+    m1(bar1, "") ; m2(bar1, "") ; m3(bar1) ; m4(bar1)
+    m1(bar2, "") ; m2(bar2, "") ; m3(bar2) ; m4(bar2)
+    m1(bar3, "") ; m2(bar3, "") ; m3(bar3) ; m4(bar3)
+    m1(bar4, "") ; m2(bar4, "") ; m3(bar4) ; m4(bar4)
+
+    m11(bar1, "") ; m12(bar1)
+    m21(bar2, "") ; m22(bar2)
+    m31(bar3, "") ; m32(bar3)
+    m41(bar4, "") ; m42(bar4)
+    ""
+  }
+
+  def flagsString(m: java.lang.reflect.Method) = {
+    val str = List(
+      if (m.isBridge) "<bridge>" else "",
+      if (m.isSynthetic) "<synthetic>" else ""
+    ) filterNot (_ == "") mkString " "
+
+    if (str == "") "" else " " + str
+    //
+    // val flags = scala.reflect.internal.ClassfileConstants.toScalaMethodFlags(m.getModifiers())
+    // scala.tools.nsc.symtab.Flags.flagsToString(flags)
+  }
+
+  def show(clazz: Class[_]) {
+    print(clazz + " {")
+    clazz.getMethods.sortBy(x => (x.getName, x.isBridge, x.toString)) filter (_.getName.length == 1) foreach { m =>
+      print("\n  " + m + flagsString(m))
+      if ("" + m != "" + m.toGenericString) {
+        print("\n    generic: " + m.toGenericString)
+      }
+    }
+    println("\n}")
+    println("")
+  }
+  def show(x: AnyRef) { show(x.getClass) }
+  def show(x: String) { show(Class.forName(x)) }
+
+  def main(args: Array[String]): Unit = {
+    List(bar1, bar2, bar3, bar4, bar5) foreach show
+    List("Foo1$class", "Foo2$class") foreach show
+    println(go)
+  }
+}
\ No newline at end of file
diff --git a/test/files/run/t3452.check b/test/files/run/t3452.check
new file mode 100644
index 0000000000..b8626c4cff
--- /dev/null
+++ b/test/files/run/t3452.check
@@ -0,0 +1 @@
+4
diff --git a/test/files/run/t3452.scala b/test/files/run/t3452.scala
new file mode 100644
index 0000000000..253fc93cfa
--- /dev/null
+++ b/test/files/run/t3452.scala
@@ -0,0 +1,21 @@
+trait IStringPair[T] {
+  def a : String
+  def b : String
+  def build(a : String, b : String) : T
+  def cat(that : IStringPair[T]) = build(this.a + that.a, this.b + that.b)
+  override def toString = a + b
+}
+
+class StringPair(val a : String, val b : String) extends IStringPair[StringPair] {
+  def build(a : String, b : String) = new StringPair(a, b)
+  def len = a.length + b.length
+}
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    val a = new StringPair("A", "B")
+    val b = new StringPair("1", "2")
+    val c = a cat b
+    println(c.len)
+  }
+}
diff --git a/test/files/run/t3452a.check b/test/files/run/t3452a.check
new file mode 100644
index 0000000000..9ff787eb86
--- /dev/null
+++ b/test/files/run/t3452a.check
@@ -0,0 +1 @@
+BulkSearch.searchFor called.
diff --git a/test/files/run/t3452a/J_2.java b/test/files/run/t3452a/J_2.java
new file mode 100644
index 0000000000..62057ffe61
--- /dev/null
+++ b/test/files/run/t3452a/J_2.java
@@ -0,0 +1,5 @@
+public class J_2 {
+       public static void main(String[] args) {
+               BulkSearchInstance.searchFor(new UpRelation());
+       }
+}
diff --git a/test/files/run/t3452a/S_1.scala b/test/files/run/t3452a/S_1.scala
new file mode 100644
index 0000000000..791faf42fa
--- /dev/null
+++ b/test/files/run/t3452a/S_1.scala
@@ -0,0 +1,24 @@
+abstract class BulkSearch {
+       type R   <: Row
+       type Rel <: Relation [R]
+       type Corr <: Correspondence[R]
+
+       def searchFor(input: Rel): Mapping[Corr] = { println("BulkSearch.searchFor called.") ; null }
+}
+
+object BulkSearchInstance extends BulkSearch {
+       type R   = UpRow
+       type Rel = UpRelation
+       type Corr = UpCorrespondence
+}
+
+class Row
+class UpRow extends Row
+
+class Relation [R <: Row]
+class UpRelation extends Relation [UpRow]
+
+class Correspondence [R <: Row]
+class UpCorrespondence extends Correspondence [UpRow]
+
+class Mapping[MC <: Correspondence[_]]
diff --git a/test/files/run/t3452a/S_3.scala b/test/files/run/t3452a/S_3.scala
new file mode 100644
index 0000000000..aaa898dcde
--- /dev/null
+++ b/test/files/run/t3452a/S_3.scala
@@ -0,0 +1,5 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    J_2.main(args)
+  }
+}
diff --git a/test/files/run/t3452b-bcode.check b/test/files/run/t3452b-bcode.check
new file mode 100644
index 0000000000..204c3d0437
--- /dev/null
+++ b/test/files/run/t3452b-bcode.check
@@ -0,0 +1,2 @@
+Search received: test
+SearchC received: test
diff --git a/test/files/run/t3452b-bcode.flags b/test/files/run/t3452b-bcode.flags
new file mode 100644
index 0000000000..c30091d3de
--- /dev/null
+++ b/test/files/run/t3452b-bcode.flags
@@ -0,0 +1 @@
+-Ybackend:GenBCode
diff --git a/test/files/run/t3452b-bcode/J_2.java b/test/files/run/t3452b-bcode/J_2.java
new file mode 100644
index 0000000000..839f334508
--- /dev/null
+++ b/test/files/run/t3452b-bcode/J_2.java
@@ -0,0 +1,6 @@
+public class J_2 {
+  public static void j() {
+    StringSearch.search("test");
+    StringSearch.searchC("test");
+  }
+}
diff --git a/test/files/run/t3452b-bcode/S_1.scala b/test/files/run/t3452b-bcode/S_1.scala
new file mode 100644
index 0000000000..a209f12035
--- /dev/null
+++ b/test/files/run/t3452b-bcode/S_1.scala
@@ -0,0 +1,17 @@
+trait Search[M] {
+  def search(input: M): C[Int] = {
+    println("Search received: " + input)
+    null
+  }
+}
+
+class SearchC[M] {
+  def searchC(input: M): C[Int] = {
+    println("SearchC received: " + input)
+    null
+  }
+}
+
+object StringSearch extends SearchC[String] with Search[String]
+
+trait C[T]
diff --git a/test/files/run/t3452b-bcode/S_3.scala b/test/files/run/t3452b-bcode/S_3.scala
new file mode 100644
index 0000000000..102b433f47
--- /dev/null
+++ b/test/files/run/t3452b-bcode/S_3.scala
@@ -0,0 +1,5 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    J_2.j()
+  }
+}
diff --git a/test/files/run/t3452b.check b/test/files/run/t3452b.check
new file mode 100644
index 0000000000..204c3d0437
--- /dev/null
+++ b/test/files/run/t3452b.check
@@ -0,0 +1,2 @@
+Search received: test
+SearchC received: test
diff --git a/test/files/run/t3452b/J_2.java b/test/files/run/t3452b/J_2.java
new file mode 100644
index 0000000000..839f334508
--- /dev/null
+++ b/test/files/run/t3452b/J_2.java
@@ -0,0 +1,6 @@
+public class J_2 {
+  public static void j() {
+    StringSearch.search("test");
+    StringSearch.searchC("test");
+  }
+}
diff --git a/test/files/run/t3452b/S_1.scala b/test/files/run/t3452b/S_1.scala
new file mode 100644
index 0000000000..a209f12035
--- /dev/null
+++ b/test/files/run/t3452b/S_1.scala
@@ -0,0 +1,17 @@
+trait Search[M] {
+  def search(input: M): C[Int] = {
+    println("Search received: " + input)
+    null
+  }
+}
+
+class SearchC[M] {
+  def searchC(input: M): C[Int] = {
+    println("SearchC received: " + input)
+    null
+  }
+}
+
+object StringSearch extends SearchC[String] with Search[String]
+
+trait C[T]
diff --git a/test/files/run/t3452b/S_3.scala b/test/files/run/t3452b/S_3.scala
new file mode 100644
index 0000000000..102b433f47
--- /dev/null
+++ b/test/files/run/t3452b/S_3.scala
@@ -0,0 +1,5 @@
+object Test {
+  def main(args: Array[String]): Unit = {
+    J_2.j()
+  }
+}
diff --git a/test/files/run/t3452c.check b/test/files/run/t3452c.check
new file mode 100644
index 0000000000..ab47181198
--- /dev/null
+++ b/test/files/run/t3452c.check
@@ -0,0 +1,8 @@
+3
+3
+3
+3
+3
+3
+3
+3
diff --git a/test/files/run/t3452c.scala b/test/files/run/t3452c.scala
new file mode 100644
index 0000000000..2c55767abc
--- /dev/null
+++ b/test/files/run/t3452c.scala
@@ -0,0 +1,113 @@
+trait Base[A, B, C] {
+  def f(x: A, y: B, z: C): Unit
+  def g(x: A, y: B, z: C) = f(x, y, z)
+  def h(x: A, y: B, z: C) = g(x, y, z)
+}
+
+trait D1[B, C] extends Base[String, B, C]
+trait D2[A, B] extends Base[A, B, String]
+trait D3[A, C] extends Base[A, String, C]
+trait D4[A] extends Base[A, String, String]
+trait D5[B] extends Base[String, B, String]
+trait D6[C] extends Base[String, String, C]
+trait D7 extends Base[String, String, String]
+
+trait E1[B, C] extends Base[String, B, C] { def f(x: String, y: B, z: C): Unit ; override def h(x: String, y: B, z: C) = g(x, y, z) }
+trait E2[A, B] extends Base[A, B, String] { def f(x: A, y: B, z: String): Unit ; override def h(x: A, y: B, z: String) = g(x, y, z) }
+trait E3[A, C] extends Base[A, String, C] { def f(x: A, y: String, z: C): Unit ; override def h(x: A, y: String, z: C) = g(x, y, z) }
+trait E4[A] extends Base[A, String, String] { def f(x: A, y: String, z: String): Unit ; override def h(x: A, y: String, z: String) = g(x, y, z) }
+trait E5[B] extends Base[String, B, String] { def f(x: String, y: B, z: String): Unit ; override def h(x: String, y: B, z: String) = g(x, y, z) }
+trait E6[C] extends Base[String, String, C] { def f(x: String, y: String, z: C): Unit ; override def h(x: String, y: String, z: C) = g(x, y, z) }
+trait E7 extends Base[String, String, String] { def f(x: String, y: String, z: String): Unit ; override def h(x: String, y: String, z: String) = g(x, y, z) }
+
+trait F1[B, C] extends Base[String, B, C] { def f(x: String, y: B, z: C): Unit = println(x.length) }
+trait F2[A, B] extends Base[A, B, String] { def f(x: A, y: B, z: String): Unit = println(z.length) }
+trait F3[A, C] extends Base[A, String, C] { def f(x: A, y: String, z: C): Unit  = println(y.length) }
+trait F4[A] extends Base[A, String, String] { def f(x: A, y: String, z: String): Unit = println(y.length) }
+trait F5[B] extends Base[String, B, String] { def f(x: String, y: B, z: String): Unit = println(x.length) }
+trait F6[C] extends Base[String, String, C] { def f(x: String, y: String, z: C): Unit = println(x.length) }
+trait F7 extends Base[String, String, String] { def f(x: String, y: String, z: String): Unit = println(x.length) }
+
+abstract class DBag extends D1[String, String] with D2[String, String] with D3[String, String] with D4[String] with D5[String] with D6[String] with D7 {
+  def f(x: String, y: String, z: String) = println(x.length + y.length + z.length)
+}
+abstract class EBag extends E1[String, String] with E2[String, String] with E3[String, String] with E4[String] with E5[String] with E6[String] with E7 {
+  def f(x: String, y: String, z: String) = println(x.length + y.length + z.length)
+}
+abstract class FBag extends F1[String, String] with F2[String, String] with F3[String, String] with F4[String] with F5[String] with F6[String] with F7 {
+  override def f(x: String, y: String, z: String) = println(x.length + y.length + z.length)
+}
+
+abstract class GBag1[A, B] extends Base[A, B, String] with D2[A, B] {
+  def f(x: A, y: B, z: String) = println(z.length)
+}
+abstract class GBag2[A] extends GBag1[A, String] with D4[A] {
+  override def f(x: A, y: String, z: String) = println(z.length)
+}
+abstract class GBag3 extends GBag2[String] with D7 {
+  override def f(x: String, y: String, z: String) = println(z.length)
+}
+class GBag extends GBag3 with D2[String, String] with D3[String, String] with D4[String] with D5[String] with D6[String] with D7 {
+}
+
+object Test {
+  def f0(x: Base[String, String, String]) = x.f("a", "b", "c")
+  def f1(x: D1[String, String])           = x.f("a", "b", "c")
+  def f2(x: D2[String, String])           = x.f("a", "b", "c")
+  def f3(x: D3[String, String])           = x.f("a", "b", "c")
+  def f4(x: D4[String])                   = x.f("a", "b", "c")
+  def f5(x: D5[String])                   = x.f("a", "b", "c")
+  def f6(x: D6[String])                   = x.f("a", "b", "c")
+  def f7(x: D7)                           = x.f("a", "b", "c")
+
+  def main(args: Array[String]): Unit = {
+    val x = new DBag { }
+    f0(x)
+    f1(x)
+    f2(x)
+    f3(x)
+    f4(x)
+    f5(x)
+    f6(x)
+    f7(x)
+  }
+}
+
+object TestE {
+  def f0(x: Base[String, String, String]) = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f1(x: E1[String, String])           = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f2(x: E2[String, String])           = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f3(x: E3[String, String])           = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f4(x: E4[String])                   = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f5(x: E5[String])                   = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f6(x: E6[String])                   = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f7(x: E7)                           = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+
+  def main(args: Array[String]): Unit = {
+    val x = new EBag { }
+    f0(x)
+    f1(x)
+    f2(x)
+    f3(x)
+    f4(x)
+    f5(x)
+    f6(x)
+    f7(x)
+  }
+}
+
+
+object TestG {
+  def f0(x: Base[String, String, String]) = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f1(x: GBag1[String, String])        = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f2(x: GBag2[String])                = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+  def f3(x: GBag3)                        = { x.f("a", "b", "c") ; x.g("a", "b", "c") ; x.h("a", "b", "c") }
+
+  def main(args: Array[String]): Unit = {
+    val x = new GBag { }
+    f0(x)
+    f1(x)
+    f2(x)
+    f3(x)
+  }
+}
diff --git a/test/files/run/t3452d/A.scala b/test/files/run/t3452d/A.scala
new file mode 100644
index 0000000000..67a2080d27
--- /dev/null
+++ b/test/files/run/t3452d/A.scala
@@ -0,0 +1,7 @@
+trait TraversableLike[A, Repr] {
+  def tail: Repr = null.asInstanceOf[Repr]
+}
+
+abstract class AbstractTrav[A] extends TraversableLike[A, Traversable[A]]
+
+class C[A] extends AbstractTrav[A]
diff --git a/test/files/run/t3452d/Test.java b/test/files/run/t3452d/Test.java
new file mode 100644
index 0000000000..875be6176c
--- /dev/null
+++ b/test/files/run/t3452d/Test.java
@@ -0,0 +1,12 @@
+import scala.collection.immutable.Nil;
+import scala.collection.immutable.List;
+import scala.collection.Traversable;
+
+public class Test {
+	public static void main(String[] args) {
+		C<String> c = new C<String>();
+		// TODO add a bridge during mixin so we can expose
+		// sharper generic signature for `tail`.
+		/*Traversable<String>*/ Object ls = c.tail();
+	}
+}
diff --git a/test/files/run/t3452e/A.scala b/test/files/run/t3452e/A.scala
new file mode 100644
index 0000000000..939172f401
--- /dev/null
+++ b/test/files/run/t3452e/A.scala
@@ -0,0 +1,4 @@
+trait F1[T, R] {
+  def andThen[A](g: R => A): Int = 0
+}
+class C1[TT, RR] extends F1[TT, RR]
diff --git a/test/files/run/t3452e/B.java b/test/files/run/t3452e/B.java
new file mode 100644
index 0000000000..0268af9987
--- /dev/null
+++ b/test/files/run/t3452e/B.java
@@ -0,0 +1,2 @@
+class B extends C1<String, String> {
+}
diff --git a/test/files/run/t3452e/Test.scala b/test/files/run/t3452e/Test.scala
new file mode 100644
index 0000000000..fc175bf94a
--- /dev/null
+++ b/test/files/run/t3452e/Test.scala
@@ -0,0 +1,3 @@
+object Test extends App {
+	new B
+}
diff --git a/test/files/run/t3452f.scala b/test/files/run/t3452f.scala
new file mode 100644
index 0000000000..af64f5c042
--- /dev/null
+++ b/test/files/run/t3452f.scala
@@ -0,0 +1,19 @@
+import language.higherKinds
+
+trait GenSet[A]
+
+trait GenSetTemplate[A, +CC[X] <: GenSet[X]] {
+  def empty: CC[A] = ???
+}
+
+trait SetLike[A, +This <: SetLike[A, This] with Set[A]] {
+  def empty: This
+}
+
+abstract class Set[A] extends GenSet[A] with SetLike[A,Set[A]] with GenSetTemplate[A,Set]
+
+object Test {
+  def main(args: Array[String]): Unit = {
+    locally(classOf[Set[_]]) // trigger classloading to verify class
+  }
+}
diff --git a/test/files/run/t3452g/A.scala b/test/files/run/t3452g/A.scala
new file mode 100644
index 0000000000..a3f74c1e1e
--- /dev/null
+++ b/test/files/run/t3452g/A.scala
@@ -0,0 +1,9 @@
+trait TraversableLike[A, Repr] {
+  def tail: Repr = null.asInstanceOf[Repr]
+}
+
+abstract class AbstractTrav[A] extends TraversableLike[A, AbstractTrav[A]]
+
+object O extends AbstractTrav[String]
+
+class C[A] extends AbstractTrav[A]
diff --git a/test/files/run/t3452g/Test.java b/test/files/run/t3452g/Test.java
new file mode 100644
index 0000000000..c3b4222d16
--- /dev/null
+++ b/test/files/run/t3452g/Test.java
@@ -0,0 +1,14 @@
+
+public class Test {
+	public static void main(String[] args) {
+		// To get better types here, we would need to
+		// add bridge during mixin so we can expose
+		// a generic return type of Traversable<A>, because the erasure
+		// of this (Traversable) differs from the erasure of the mixed
+		// method (erasure(Repr) = Object)
+
+		Object lsSharp = O.tail();
+
+		Object lsSharp2 = new C<String>().tail();
+	}
+}
diff --git a/test/files/run/t3452h.scala b/test/files/run/t3452h.scala
new file mode 100644
index 0000000000..6237d3ea64
--- /dev/null
+++ b/test/files/run/t3452h.scala
@@ -0,0 +1,8 @@
+class Mix___eFoo_I_wBar__f extends Foo_I_ with Bar__f { f; }
+trait T
+abstract class Foo_I_ { class I extends T    ; def f: I         ; f; }
+trait Bar__f          { type  I>:Null<:T;      def f: I = {null}; f; def gobble: I = {null}}
+
+object Test extends App {
+  new Mix___eFoo_I_wBar__f
+}
diff --git a/test/files/run/t6554.check b/test/files/run/t6554.check
new file mode 100644
index 0000000000..6e0af7b474
--- /dev/null
+++ b/test/files/run/t6554.check
@@ -0,0 +1 @@
+public java.lang.Object Bar.minBy(java.lang.Object) / public java.lang.Object Bar.minBy(java.lang.Object)
diff --git a/test/files/run/t6554.scala b/test/files/run/t6554.scala
new file mode 100644
index 0000000000..5d29d16666
--- /dev/null
+++ b/test/files/run/t6554.scala
@@ -0,0 +1,11 @@
+trait Foo[A] {
+  def minBy[B](b: B): A = ???
+}
+ 
+class Bar extends Foo[Int]
+
+object Test extends App {
+   val sigs = classOf[Bar].getDeclaredMethods.map(m => s"${m.toString} / ${m.toGenericString}").sorted
+   println(sigs.mkString("\n"))
+}
+// Was public java.lang.Object Bar.minBy(java.lang.Object) / public <B> int Bar.minBy(B)
diff --git a/test/files/run/t7374.check b/test/files/run/t7374.check
new file mode 100644
index 0000000000..4efa6f7af3
--- /dev/null
+++ b/test/files/run/t7374.check
@@ -0,0 +1,3 @@
+List(2, 3)
+ParVector(1, 2, 3)
+List(1, 2)
diff --git a/test/files/run/t7374/Some.scala b/test/files/run/t7374/Some.scala
new file mode 100644
index 0000000000..3266a5642e
--- /dev/null
+++ b/test/files/run/t7374/Some.scala
@@ -0,0 +1,3 @@
+object SomeScala {
+  def list = List(1, 2, 3) 
+}
diff --git a/test/files/run/t7374/Test.java b/test/files/run/t7374/Test.java
new file mode 100644
index 0000000000..02f86146ca
--- /dev/null
+++ b/test/files/run/t7374/Test.java
@@ -0,0 +1,7 @@
+public class Test {
+    public static void main(String[] args) {
+        System.out.println(SomeScala.list().tail());
+        System.out.println(SomeScala.list().par());
+        System.out.println(SomeScala.list().init());
+    }
+}
diff --git a/test/support/java-tests.txt b/test/support/java-tests.txt
new file mode 100644
index 0000000000..e0a3fddab3
--- /dev/null
+++ b/test/support/java-tests.txt
@@ -0,0 +1,97 @@
+test/files/buildmanager/t2280
+test/files/buildmanager/t3045
+test/files/buildmanager/t3133
+test/files/jvm/deprecation
+test/files/jvm/t1143-2
+test/files/jvm/t1342
+test/files/jvm/t1464
+test/files/jvm/t2470
+test/files/jvm/t2570
+test/files/jvm/t2585
+test/files/jvm/t3003
+test/files/jvm/t3415
+test/files/jvm/ticket2163
+test/files/jvm/ticket4283
+test/files/jvm/varargs
+test/files/neg/abstract-class-error
+test/files/neg/java-access-neg
+test/files/neg/primitive-sigs-1
+test/files/neg/protected-static-fail
+test/files/neg/t0673
+test/files/neg/t1548
+test/files/neg/t3663
+test/files/neg/t3757
+test/files/neg/t4851
+test/files/pos/chang
+test/files/pos/ilya
+test/files/pos/ilya2
+test/files/pos/java-access-pos
+test/files/pos/javaReadsSigs
+test/files/pos/protected-static
+test/files/pos/raw-map
+test/files/pos/signatures
+test/files/pos/super
+test/files/pos/t0288
+test/files/pos/t0695
+test/files/pos/t1101
+test/files/pos/t1102
+test/files/pos/t1150
+test/files/pos/t1152
+test/files/pos/t1176
+test/files/pos/t1186
+test/files/pos/t1196
+test/files/pos/t1197
+test/files/pos/t1203
+test/files/pos/t1230
+test/files/pos/t1231
+test/files/pos/t1232
+test/files/pos/t1235
+test/files/pos/t1254
+test/files/pos/t1263
+test/files/pos/t1409
+test/files/pos/t1459
+test/files/pos/t1642
+test/files/pos/t1711
+test/files/pos/t1745
+test/files/pos/t1751
+test/files/pos/t1782
+test/files/pos/t1836
+test/files/pos/t1840
+test/files/pos/t1937
+test/files/pos/t2377
+test/files/pos/t2409
+test/files/pos/t2413
+test/files/pos/t2433
+test/files/pos/t2464
+test/files/pos/t2569
+test/files/pos/t2868
+test/files/pos/t294
+test/files/pos/t2940
+test/files/pos/t2956
+test/files/pos/t3249
+test/files/pos/t3349
+test/files/pos/t3404
+test/files/pos/t3429
+test/files/pos/t3486
+test/files/pos/t3521
+test/files/pos/t3567
+test/files/pos/t3622
+test/files/pos/t3642
+test/files/pos/t3938
+test/files/pos/t3946
+test/files/pos/t4402
+test/files/pos/t4603
+test/files/pos/t4737
+test/files/pos/t5644
+test/files/pos/t5703
+test/files/run/inner-parse
+test/files/run/t1430
+test/files/run/t2296a
+test/files/run/t2296b
+test/files/run/t3452a
+test/files/run/t3452b
+test/files/run/t3897
+test/files/run/t4119
+test/files/run/t4238
+test/files/run/t4317
+test/files/run/t4891
diff --git a/tools/compare-java-sigs b/tools/compare-java-sigs
new file mode 100644
index 0000000000..99ab775437
--- /dev/null
+++ b/tools/compare-java-sigs
@@ -0,0 +1,56 @@
+#!/bin/sh
+#
+# Compare javac -Xprint (i.e. see signatures from java point of view)
+# for the given classes.
+#
+# Sample:
+#
+# % SCALA_HOME=/scala/inst/29 SCALA_BUILD=/scala/inst/3 tools/compare-java-sigs 'scala.Predef$'
+#
+# Comparing javac -Xprint for scala.Predef$ based on '/scala/inst/29' and '/scala/inst/3'
+# 3c3
+# < public final class Predef$ extends scala.LowPriorityImplicits implements scala.ScalaObject {
+# ---
+# > public final class Predef$ extends scala.LowPriorityImplicits {
+# 7d6
+# <   private final scala.SpecializableCompanion AnyRef;
+# 21,22d19
+# <   public scala.SpecializableCompanion AnyRef();
+# <
+# 68a66,67
+# >   public scala.runtime.Nothing$ $qmark$qmark$qmark();
+# >
+# 225c224,226
+# <   public scala.collection.immutable.StringOps augmentString(java.lang.String x);
+# ---
+# >   public scala.runtime.StringFormat any2stringfmt(java.lang.Object x);
+# >
+# >   public java.lang.String augmentString(java.lang.String x);
+# 227c228
+# <   public java.lang.String unaugmentString(scala.collection.immutable.StringOps x);
+# ---
+# >   public java.lang.String unaugmentString(java.lang.String x);
+#
+
+set -e
+
+[[ $# -gt 0 ]] || {
+  echo "Usage: $(basename $0) <class> <class> ..."
+  echo ""
+  echo "# Example usage"
+  echo "SCALA_HOME=/scala/inst/29 SCALA_BUILD=/scala/inst/3 \\"
+  echo "  $(basename $0) scala.Function1 scala.runtime.AbstractFunction1"
+  exit 0
+}
+
+home1=$(cd ${SCALA_HOME:-/scala/inst/3} && pwd)
+home2=$(cd ${SCALA_BUILD:-$(dirname $BASH_SOURCE)/../build/pack} && pwd)
+
+echo "Comparing javac -Xprint for $@ based on '$home1' and '$home2'"
+tmpdir=$(mktemp -dt $(basename $BASH_SOURCE))
+
+cd $tmpdir
+javac -Xprint -cp $home1:$home1/lib/'*' "$@" > before.txt
+javac -Xprint -cp $home2:$home2/lib/'*' "$@" > after.txt
+
+diff before.txt after.txt && echo "No differences in javac -Xprint output."