Fix #3471: Avoid wrong flag kind when desugaring module definitions

Author: odersky

compiler/src/dotty/tools/dotc/ast/Desugar.scala

@@ -578,7 +578,7 @@ object desugar {
       val clsName = moduleName.moduleClassName
       val clsRef = Ident(clsName)
       val modul = ValDef(moduleName, clsRef, New(clsRef, Nil))
-        .withMods(mods | ModuleCreationFlags | mods.flags & AccessFlags)
+        .withMods(mods.toTermFlags & RetainedModuleValFlags | ModuleValCreationFlags)
         .withPos(mdef.pos.startPos)
       val ValDef(selfName, selfTpt, _) = impl.self
       val selfMods = impl.self.mods

compiler/src/dotty/tools/dotc/core/Flags.scala

@@ -472,7 +472,7 @@ object Flags {
   final val RetainedTypeArgFlags = VarianceFlags | Protected | Local
 
   /** Modules always have these flags set */
-  final val ModuleCreationFlags = ModuleVal | Lazy | Final | Stable
+  final val ModuleValCreationFlags = ModuleVal | Lazy | Final | Stable
 
   /** Module classes always have these flags set */
   final val ModuleClassCreationFlags = ModuleClass | Final

compiler/src/dotty/tools/dotc/core/Symbols.scala

@@ -153,7 +153,7 @@ trait Symbols { this: Context =>
         modcls, owner, modclsName, modclsFlags,
         infoFn(module, modcls), privateWithin)
     val mdenot = SymDenotation(
-        module, owner, name, modFlags | ModuleCreationFlags,
+        module, owner, name, modFlags | ModuleValCreationFlags,
         if (cdenot.isCompleted) TypeRef.withSym(owner.thisType, modcls, modclsName)
         else new ModuleCompleter(modcls))
     module.denot = mdenot

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -382,7 +382,7 @@ class TreeUnpickler(reader: TastyReader, nameAtRef: NameRef => TermName, posUnpi
       if (lacksDefinition && tag != PARAM) flags |= Deferred
       if (tag == DEFDEF) flags |= Method
       if (givenFlags is Module)
-        flags = flags | (if (tag == VALDEF) ModuleCreationFlags else ModuleClassCreationFlags)
+        flags = flags | (if (tag == VALDEF) ModuleValCreationFlags else ModuleClassCreationFlags)
       if (ctx.owner.isClass) {
         if (tag == TYPEPARAM) flags |= Param
         else if (tag == PARAM) flags |= ParamAccessor

tests/pos/i3471.scala

@@ -0,0 +1 @@
+sealed object Fun // error