Merge pull request #1428 from dotty-staging/fix-#1285

Fix #1285: Mutable vars are not to be considered constant

Author: odersky

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

@@ -448,7 +448,7 @@ object Flags {
   /** Flags guaranteed to be set upon symbol creation */
   final val FromStartFlags =
     AccessFlags | Module | Package | Deferred | Final | MethodOrHKCommon | Param | ParamAccessor | Scala2ExistentialCommon |
-    InSuperCall | Touched | JavaStatic | CovariantOrOuter | ContravariantOrLabel | ExpandedName | AccessorOrSealed |
+    Mutable.toCommonFlags | InSuperCall | Touched | JavaStatic | CovariantOrOuter | ContravariantOrLabel | ExpandedName | AccessorOrSealed |
     CaseAccessorOrBaseTypeArg | Fresh | Frozen | Erroneous | ImplicitCommon | Permanent | Synthetic |
     LazyOrTrait | SuperAccessorOrScala2x | SelfNameOrImplClass
 

src/dotty/tools/dotc/typer/Namer.scala

@@ -830,8 +830,8 @@ class Namer { typer: Typer =>
 
       // println(s"final inherited for $sym: ${inherited.toString}") !!!
       // println(s"owner = ${sym.owner}, decls = ${sym.owner.info.decls.show}")
-      def isInline = sym.is(Final, butNot = Method)
-
+      def isInline = sym.is(Final, butNot = Method | Mutable)
+      
       // Widen rhs type and approximate `|' but keep ConstantTypes if
       // definition is inline (i.e. final in Scala2).
       def widenRhs(tp: Type): Type = tp.widenTermRefExpr match {

tests/pos/i1285.scala

@@ -0,0 +1,4 @@
+class Test {
+  final var x = false
+  x = true
+}