Merge pull request #4652 from retronym/ticket/9408

SI-9408 Avoid capturing outer class in local classes.

4 files changed, 16 insertions, 6 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/Constructors.scala b/src/compiler/scala/tools/nsc/transform/Constructors.scala
index 86685d46de..7c66bda46b 100644
--- a/src/compiler/scala/tools/nsc/transform/Constructors.scala
+++ b/src/compiler/scala/tools/nsc/transform/Constructors.scala
@@ -165,11 +165,19 @@ abstract class Constructors extends Statics with Transform with ast.TreeDSL {
         return
       }
 
+      // Note: elision of outer reference is based on a class-wise analysis, if a class might have subclasses,
+      //       it doesn't work. For example, `LocalParent` retains the outer reference in:
+      //
+      //   class Outer { def test = {class LocalParent; class LocalChild extends LocalParent } }
+      //
+      // See run/t9408.scala for related test cases.
+      val isEffectivelyFinal = clazz.isEffectivelyFinal
       def isParamCandidateForElision(sym: Symbol) = (sym.isParamAccessor && sym.isPrivateLocal)
-      def isOuterCandidateForElision(sym: Symbol) = (sym.isOuterAccessor && sym.owner.isEffectivelyFinal && !sym.isOverridingSymbol)
+      def isOuterCandidateForElision(sym: Symbol) = (sym.isOuterAccessor && isEffectivelyFinal && !sym.isOverridingSymbol)
 
-      val paramCandidatesForElision: Set[ /*Field*/  Symbol] = (clazz.info.decls.toSet filter isParamCandidateForElision)
-      val outerCandidatesForElision: Set[ /*Method*/ Symbol] = (clazz.info.decls.toSet filter isOuterCandidateForElision)
+      val decls = clazz.info.decls.toSet
+      val paramCandidatesForElision: Set[ /*Field*/  Symbol] = (decls filter isParamCandidateForElision)
+      val outerCandidatesForElision: Set[ /*Method*/ Symbol] = (decls filter isOuterCandidateForElision)
 
       omittables ++= paramCandidatesForElision
       omittables ++= outerCandidatesForElision
diff --git a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
index a11906ace1..00de77a8d4 100644
--- a/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
+++ b/src/compiler/scala/tools/nsc/transform/patmat/MatchAnalysis.scala
@@ -138,7 +138,7 @@ trait TreeAndTypeAnalysis extends Debugging {
 
           if(grouped) {
             def enumerateChildren(sym: Symbol) = {
-              sym.children.toList
+              sym.sealedChildren.toList
                 .sortBy(_.sealedSortName)
                 .filterNot(x => x.isSealed && x.isAbstractClass && !isPrimitiveValueClass(x))
             }
diff --git a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
index fc632e0d0d..8bcd5e6f12 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Checkable.scala
@@ -212,8 +212,8 @@ trait Checkable {
     )
     /** Are all children of these symbols pairwise irreconcilable? */
     def allChildrenAreIrreconcilable(sym1: Symbol, sym2: Symbol) = (
-      sym1.children.toList forall (c1 =>
-        sym2.children.toList forall (c2 =>
+      sym1.sealedChildren.toList forall (c1 =>
+        sym2.sealedChildren.toList forall (c2 =>
           areIrreconcilableAsParents(c1, c2)
         )
       )
diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 777ff388b6..cc15a2485f 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1694,6 +1694,8 @@ trait Typers extends Adaptations with Tags with TypersTracking with PatternTyper
               psym addChild context.owner
             else
               pending += ParentSealedInheritanceError(parent, psym)
+          if (psym.isLocalToBlock && !phase.erasedTypes)
+            psym addChild context.owner
           val parentTypeOfThis = parent.tpe.dealias.typeOfThis
 
           if (!(selfType <:< parentTypeOfThis) &&