address review feedback

1 files changed, 34 insertions, 29 deletions

diff --git a/compiler/src/dotty/tools/dotc/typer/Namer.scala b/compiler/src/dotty/tools/dotc/typer/Namer.scala
index 7d8c5f95f..6e1c564cd 100644
--- a/compiler/src/dotty/tools/dotc/typer/Namer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Namer.scala
@@ -484,7 +484,7 @@ class Namer { typer: Typer =>
   /** Create top-level symbols for statements and enter them into symbol table */
   def index(stats: List[Tree])(implicit ctx: Context): Context = {
 
-    // module name -> (stat, moduleCls / moduleVal)
+    // module name -> (stat, moduleCls | moduleVal)
     val moduleClsDef = mutable.Map[TypeName, (Tree, TypeDef)]()
     val moduleValDef = mutable.Map[TermName, (Tree, ValDef)]()
 
@@ -512,49 +512,54 @@ class Namer { typer: Typer =>
       res
     }
 
+    /** Merge `fromCls` of `fromStat` into `toCls` of `toStat`
+     *  if the former is synthetic and the latter not.
+     *
+     *  Note:
+     *    1. `fromStat` and `toStat` could be the same stat
+     *    2. `fromCls` and `toCls` are necessarily different
+     */
+    def mergeIfSynthetic(fromStat: Tree, fromCls: TypeDef, toStat: Tree, toCls: TypeDef): Unit =
+      if (fromCls.mods.is(Synthetic) && !toCls.mods.is(Synthetic)) {
+        removeInExpanded(fromStat, fromCls)
+        val mcls = mergeModuleClass(toStat, toCls, fromCls.rhs.asInstanceOf[Template].body)
+        moduleClsDef(fromCls.name) = (toStat, mcls)
+      }
+
     /** Merge the definitions of a synthetic companion generated by a case class
      *  and the real companion, if both exist.
      */
     def mergeCompanionDefs() = {
-      def valid(mdef: MemberDef): Boolean = !mdef.mods.is(Package) && mdef.mods.is(Module)
+      def valid(mdef: MemberDef): Boolean = mdef.mods.is(Module, butNot = Package)
 
       for (stat <- stats)
         expanded(stat) match {
           case Thicket(trees) => // companion object always expands to thickets
             trees.map {
               case mcls @ TypeDef(name, impl: Template) if valid(mcls) =>
-                if (moduleClsDef.contains(name)) {
-                  val (stat1, mcls1 @ TypeDef(_, impl1: Template)) = moduleClsDef(name)
-                  if (mcls.mods.is(Synthetic) && !mcls1.mods.is(Synthetic)) { // merge synthetic into user-defined module
-                    removeInExpanded(stat, mcls)
-                    val mcls2 = mergeModuleClass(stat1, mcls1, impl.body)
-                    moduleClsDef(name) = (stat1, mcls2)
-                  }
-                  else if (!mcls.mods.is(Synthetic) && mcls1.mods.is(Synthetic)) {
-                    removeInExpanded(stat1, mcls1)
-                    val mcls2 = mergeModuleClass(stat, mcls, impl1.body)
-                    moduleClsDef(name) = (stat, mcls2)
-                  }
-                  else {
-                    // redefinition of objects or case classes, handled elsewhere
-                  }
+                moduleClsDef.get(name) match {
+                  case Some((stat1, mcls1@TypeDef(_, impl1: Template))) =>
+                    mergeIfSynthetic(stat, mcls, stat1, mcls1)
+                    mergeIfSynthetic(stat1, mcls1, stat, mcls)
+                  case None =>
+                    moduleClsDef(name) = (stat, mcls)
                 }
-                else moduleClsDef(name) = (stat, mcls)
 
               case vdef @ ValDef(name, _, _) if valid(vdef) =>
-                if (moduleValDef.contains(name)) {
-                  val (stat1, vdef1) = moduleValDef(name)
-                  if (vdef.mods.is(Synthetic) && !vdef1.mods.is(Synthetic))  // merge synthetic into user-defined module
-                    removeInExpanded(stat, vdef)
-                  else if (!vdef.mods.is(Synthetic) && vdef1.mods.is(Synthetic)) {
-                    removeInExpanded(stat1, vdef1)
+                moduleValDef.get(name) match {
+                  case Some((stat1, vdef1)) =>
+                    if (vdef.mods.is(Synthetic) && !vdef1.mods.is(Synthetic))
+                      removeInExpanded(stat, vdef)
+                    else if (!vdef.mods.is(Synthetic) && vdef1.mods.is(Synthetic)) {
+                      removeInExpanded(stat1, vdef1)
+                      moduleValDef(name) = (stat, vdef)
+                    }
+                    else {
+                      // double definition of objects or case classes, handled elsewhere
+                    }
+                  case None =>
                     moduleValDef(name) = (stat, vdef)
-                  }
-                  else {
-                    // redefinition of objects or case classes, handled elsewhere
-                  }
                 }
-                else moduleValDef(name) = (stat, vdef)
 
               case _ =>
             }