Improved error messages for certain illegal ove...

Improved error messages for certain illegal overriding situations, plus
test cases. Resolves bug #276.

3 files changed, 17 insertions, 0 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index 745979790b..bcc1a1686e 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -208,6 +208,11 @@ abstract class RefChecks extends InfoTransform {
             (ob == RootClass || ob == NoSymbol || !ob.hasTransOwner(mb) ||
              (other hasFlag PROTECTED) && !(member hasFlag PROTECTED))) {
           overrideAccessError()
+        }
+        else if (other.isClass || other.isModule) {
+          overrideError("cannot be used here - classes and objects cannot be overridden");
+        } else if (!other.isDeferred && (member.isClass || member.isModule)) {
+          overrideError("cannot be used here - classes and objects can only override abstract types");
         } else if (other hasFlag FINAL) { // (1.2)
           overrideError("cannot override final member");
         } else if (!other.isDeferred && !(member hasFlag (OVERRIDE | ABSOVERRIDE | SYNTHETIC))) { // (1.3), SYNTHETIC because of DEVIRTUALIZE
diff --git a/test/files/neg/bug276.check b/test/files/neg/bug276.check
new file mode 100644
index 0000000000..edc4ec568f
--- /dev/null
+++ b/test/files/neg/bug276.check
@@ -0,0 +1,5 @@
+bug276.scala:6: error: overriding type Bar in class Foo, which equals (Int, Int);
+ class Bar cannot be used here - classes and objects can only override abstract types
+  class Bar
+        ^
+one error found
diff --git a/test/files/neg/bug276.scala b/test/files/neg/bug276.scala
new file mode 100644
index 0000000000..e083e21705
--- /dev/null
+++ b/test/files/neg/bug276.scala
@@ -0,0 +1,7 @@
+class Foo {
+  type Bar = (Int, Int)
+}
+
+class FooFoo extends Foo {
+  class Bar
+}
\ No newline at end of file