Merge pull request #1666 from dotty-staging/fix-#1653

Fix #1653: Check "no inherit from final" earlier.

2 files changed, 12 insertions, 10 deletions

diff --git a/src/dotty/tools/dotc/typer/Namer.scala b/src/dotty/tools/dotc/typer/Namer.scala
index dd7326fae..687de1e7a 100644
--- a/src/dotty/tools/dotc/typer/Namer.scala
+++ b/src/dotty/tools/dotc/typer/Namer.scala
@@ -656,6 +656,8 @@ class Namer { typer: Typer =>
        * (1) It must be a class type with a stable prefix (@see checkClassTypeWithStablePrefix)
        * (2) If may not derive from itself
        * (3) Overriding type parameters must be correctly forwarded. (@see checkTypeParamOverride)
+       * (4) The class is not final
+       * (5) If the class is sealed, it is defined in the same compilation unit as the current class
        */
       def checkedParentType(parent: untpd.Tree, paramAccessors: List[Symbol]): Type = {
         val ptype = parentType(parent)(ctx.superCallContext)
@@ -674,7 +676,14 @@ class Namer { typer: Typer =>
           }
           else if (!paramAccessors.forall(checkTypeParamOverride(pt, _)))
             defn.ObjectType
-          else pt
+          else {
+            val pclazz = pt.typeSymbol
+            if (pclazz.is(Final))
+              ctx.error(em"cannot extend final $pclazz", cls.pos)
+            if (pclazz.is(Sealed) && pclazz.associatedFile != cls.associatedFile)
+              ctx.error(em"cannot extend sealed $pclazz in different compilation unit", cls.pos)
+            pt
+          }
         }
       }
 
diff --git a/src/dotty/tools/dotc/typer/RefChecks.scala b/src/dotty/tools/dotc/typer/RefChecks.scala
index 026015d1d..46bdbf3b3 100644
--- a/src/dotty/tools/dotc/typer/RefChecks.scala
+++ b/src/dotty/tools/dotc/typer/RefChecks.scala
@@ -72,8 +72,7 @@ object RefChecks {
     }
   }
 
-  /** Check that final and sealed restrictions on class parents
-   *  and that self type of this class conforms to self types of parents.
+  /** Check that self type of this class conforms to self types of parents.
    *  and required classes.
    */
   private def checkParents(cls: Symbol)(implicit ctx: Context): Unit = cls.info match {
@@ -83,14 +82,8 @@ object RefChecks {
         if (otherSelf.exists && !(cinfo.selfType <:< otherSelf))
           ctx.error(ex"$category: self type ${cinfo.selfType} of $cls does not conform to self type $otherSelf of $relation ${other.classSymbol}", cls.pos)
       }
-      for (parent <- cinfo.classParents) {
-        val pclazz = parent.classSymbol
-        if (pclazz.is(Final))
-          ctx.error(em"cannot extend final $pclazz", cls.pos)
-        if (pclazz.is(Sealed) && pclazz.associatedFile != cls.associatedFile)
-          ctx.error(em"cannot extend sealed $pclazz in different compilation unit", cls.pos)
+      for (parent <- cinfo.classParents)
         checkSelfConforms(parent, "illegal inheritance", "parent")
-      }
       for (reqd <- cinfo.givenSelfType.classSymbols)
         checkSelfConforms(reqd.typeRef, "missing requirement", "required")
     case _ =>