Merge pull request #3867 from lrytz/t8708

SI-8708 Fix pickling of LOCAL_CHILD child of sealed classes

1 files changed, 10 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/symtab/classfile/Pickler.scala b/src/compiler/scala/tools/nsc/symtab/classfile/Pickler.scala
index 2fc00fe068..25e13a1314 100644
--- a/src/compiler/scala/tools/nsc/symtab/classfile/Pickler.scala
+++ b/src/compiler/scala/tools/nsc/symtab/classfile/Pickler.scala
@@ -186,7 +186,16 @@ abstract class Pickler extends SubComponent {
             val (locals, globals) = sym.children partition (_.isLocalClass)
             val children =
               if (locals.isEmpty) globals
-              else globals + sym.newClassWithInfo(tpnme.LOCAL_CHILD, List(sym.tpe), EmptyScope, pos = sym.pos)
+              else {
+                // The LOCAL_CHILD was introduced in 12a2b3b to fix Aladdin bug 1055. When a sealed
+                // class/trait has local subclasses, a single <local child> class symbol is added
+                // as pickled child (instead of a reference to the anonymous class; that was done
+                // initially, but seems not to work, as the bug shows).
+                // Adding the LOCAL_CHILD is necessary to retain exhaustivity warnings under separate
+                // compilation. See test neg/aladdin1055.
+                val parents = (if (sym.isTrait) List(definitions.ObjectTpe) else Nil) ::: List(sym.tpe)
+                globals + sym.newClassWithInfo(tpnme.LOCAL_CHILD, parents, EmptyScope, pos = sym.pos)
+              }
 
             putChildren(sym, children.toList sortBy (_.sealedSortName))
           }