Merge pull request #5633 from adriaanm/ticket/9331

SI-9331 Fix canEqual for case classes with HK type params

3 files changed, 11 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
index 99e61d2482..9b73f203e0 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala
@@ -676,10 +676,9 @@ abstract class ClassfileParser {
               // so have to check unsafeTypeParams.isEmpty before worrying about raw type case below,
               // or we'll create a boatload of needless existentials.
               else if (classSym.isMonomorphicType || classSym.unsafeTypeParams.isEmpty) tp
-              else debuglogResult(s"raw type from $classSym"){
+              else debuglogResult(s"raw type from $classSym") {
                 // raw type - existentially quantify all type parameters
-                val eparams = typeParamsToExistentials(classSym, classSym.unsafeTypeParams)
-                newExistentialType(eparams, typeRef(pre, classSym, eparams.map(_.tpeHK)))
+                classExistentialType(pre, classSym)
               }
             case tp =>
               assert(sig.charAt(index) != '<', s"sig=$sig, index=$index, tp=$tp")
diff --git a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
index 1b3f066fc1..9cc0fc4c59 100644
--- a/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/SyntheticMethods.scala
@@ -143,8 +143,9 @@ trait SyntheticMethods extends ast.TreeDSL {
      */
     def canEqualMethod: Tree = {
       syntheticCanEqual = true
-      createMethod(nme.canEqual_, List(AnyTpe), BooleanTpe)(m =>
-        Ident(m.firstParam) IS_OBJ classExistentialType(clazz))
+      createMethod(nme.canEqual_, List(AnyTpe), BooleanTpe) { m =>
+        Ident(m.firstParam) IS_OBJ classExistentialType(context.prefix, clazz)
+      }
     }
 
     /* that match { case _: this.C => true ; case _ => false }
diff --git a/src/reflect/scala/reflect/internal/Definitions.scala b/src/reflect/scala/reflect/internal/Definitions.scala
index 0bdf5b4647..69cdf5f04e 100644
--- a/src/reflect/scala/reflect/internal/Definitions.scala
+++ b/src/reflect/scala/reflect/internal/Definitions.scala
@@ -646,8 +646,8 @@ trait Definitions extends api.StandardDefinitions {
       isBundle && isBlackbox
     }
 
-    def isListType(tp: Type)     = tp <:< classExistentialType(ListClass)
-    def isIterableType(tp: Type) = tp <:< classExistentialType(IterableClass)
+    def isListType(tp: Type)     = tp.typeSymbol.isNonBottomSubClass(ListClass)
+    def isIterableType(tp: Type) = tp.typeSymbol.isNonBottomSubClass(IterableClass)
 
     // These "direct" calls perform no dealiasing. They are most needed when
     // printing types when one wants to preserve the true nature of the type.
@@ -925,14 +925,10 @@ trait Definitions extends api.StandardDefinitions {
      *
      *    C[E1, ..., En] forSome { E1 >: LB1 <: UB1 ... en >: LBn <: UBn }.
      */
-    // TODO Review the way this is used. I see two potential problems:
-    //  1. `existentialAbstraction` here doesn't create fresh existential type symbols, it just
-    //     uses the class type parameter symbols directly as the list of quantified symbols.
-    //     See SI-8244 for the trouble that this can cause.
-    //     Compare with callers of `typeParamsToExistentials` (used in Java raw type handling)
-    //  2. Why don't we require a prefix? Could its omission lead to wrong results in CheckabilityChecker?
-    def classExistentialType(clazz: Symbol): Type =
-      existentialAbstraction(clazz.typeParams, clazz.tpe_*)
+    def classExistentialType(prefix: Type, clazz: Symbol): Type = {
+      val eparams = typeParamsToExistentials(clazz, clazz.unsafeTypeParams)
+      newExistentialType(eparams, typeRef(prefix, clazz, eparams.map(_.tpeHK)))
+    }
 
     // members of class scala.Any