8 files changed, 119 insertions, 1 deletions
diff --git a/test/files/neg/override-object-flag.check b/test/files/neg/override-object-flag.check
new file mode 100644
index 0000000000..152d31ff8a
--- /dev/null
+++ b/test/files/neg/override-object-flag.check
@@ -0,0 +1,5 @@
+override-object-flag.scala:3: error: overriding object Foo in trait A of type object B.this.Foo;
+ object Foo cannot override final member
+trait B extends A  { override object Foo }
+                                     ^
+one error found
diff --git a/test/files/neg/override-object-flag.scala b/test/files/neg/override-object-flag.scala
new file mode 100644
index 0000000000..74d00dd445
--- /dev/null
+++ b/test/files/neg/override-object-flag.scala
@@ -0,0 +1,3 @@
+// no flag enabling it, fail
+trait A { object Foo }
+trait B extends A  { override object Foo }
diff --git a/test/files/neg/override-object-no.check b/test/files/neg/override-object-no.check
new file mode 100644
index 0000000000..c509634b3f
--- /dev/null
+++ b/test/files/neg/override-object-no.check
@@ -0,0 +1,23 @@
+override-object-no.scala:14: error: overriding object Bar in trait Foo with object Bar in trait Foo2:
+an overriding object must conform to the overridden object's class bound;
+ found   : case1.Bippy with ScalaObject
+ required: case1.Bippy with case1.Bippo with ScalaObject
+    override object Bar extends Bippy {  // err
+                    ^
+override-object-no.scala:21: error: overriding object Bar in trait Quux1 with object Bar in trait Quux2:
+an overriding object must conform to the overridden object's class bound;
+ found   : java.lang.Object with ScalaObject{def g: java.lang.String}
+ required: java.lang.Object with ScalaObject{def g: Int}
+  trait Quux2 extends Quux1 { override object Bar { def g = "abc" } } // err
+                                              ^
+override-object-no.scala:25: error: overriding object Bar in trait Quux3 of type object Quux4.this.Bar;
+ object Bar cannot override final member
+  trait Quux4 extends Quux3 { override object Bar  } // err
+                                              ^
+override-object-no.scala:43: error: overriding object A in class Foo with object A in class P2:
+an overriding object must conform to the overridden object's class bound;
+ found   : case2.Bar[List[String]] with ScalaObject
+ required: case2.Bar[Traversable[String]] with ScalaObject
+    override object A extends Bar[List[String]]  // err
+                    ^
+four errors found
diff --git a/test/files/neg/override-object-no.flags b/test/files/neg/override-object-no.flags
new file mode 100644
index 0000000000..22e9a95c4f
--- /dev/null
+++ b/test/files/neg/override-object-no.flags
@@ -0,0 +1 @@
+-Yoverride-objects
+\ No newline at end of file
diff --git a/test/files/neg/override-object-no.scala b/test/files/neg/override-object-no.scala
new file mode 100644
index 0000000000..745cdb2332
--- /dev/null
+++ b/test/files/neg/override-object-no.scala
@@ -0,0 +1,45 @@
+// See also pos/override-object-yes.scala
+
+package case1 {
+  // Missing interface in overriding object
+  class Bippy { def f = 1 }
+  trait Bippo
+
+  trait Foo {
+    object Bar extends Bippy with Bippo { override def f = 2 }
+    def f(x: Bippo)
+    def g = f(Bar)
+  }
+  trait Foo2 extends Foo {
+    override object Bar extends Bippy {  // err
+      override def f = 3
+    }
+  }
+
+  // type mismatch in member
+  trait Quux1 { object Bar { def g = 55 } }
+  trait Quux2 extends Quux1 { override object Bar { def g = "abc" } } // err
+
+  // still can't override final objects!
+  trait Quux3 { final object Bar { } }
+  trait Quux4 extends Quux3 { override object Bar  } // err
+}
+
+// type parameter as-seen-from business
+package case2 {
+  // invariance (see pos for the covariant case)
+  class Bar[T]
+
+  class Foo[T] {
+    object A extends Bar[T]
+  }
+
+  class Baz[S] extends Foo[S] {
+    override object A extends Bar[S]
+  }
+
+  class P1 extends Foo[Traversable[String]]
+  class P2 extends P1 {
+    override object A extends Bar[List[String]]  // err
+  }
+}
diff --git a/test/files/neg/t276.check b/test/files/neg/t276.check
index 7d37f5cfa1..b241953a22 100644
--- a/test/files/neg/t276.check
+++ b/test/files/neg/t276.check
@@ -1,5 +1,5 @@
 t276.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 cannot be used here - classes can only override abstract types
   class Bar
         ^
 one error found
diff --git a/test/files/pos/override-object-yes.flags b/test/files/pos/override-object-yes.flags
new file mode 100644
index 0000000000..22e9a95c4f
--- /dev/null
+++ b/test/files/pos/override-object-yes.flags
@@ -0,0 +1 @@
+-Yoverride-objects
+\ No newline at end of file
diff --git a/test/files/pos/override-object-yes.scala b/test/files/pos/override-object-yes.scala
new file mode 100644
index 0000000000..858f9b21fc
--- /dev/null
+++ b/test/files/pos/override-object-yes.scala
@@ -0,0 +1,40 @@
+package case1 {
+  class Bippy {
+    def f = 1
+  }
+
+  trait Foo {
+    object Bar extends Bippy {
+      override def f = 2
+    }
+  }
+
+  trait Foo2 extends Foo {
+    override object Bar extends Bippy {
+      override def f = 3
+    }
+  }
+
+  trait Foo3 {
+    object Bar {
+      def g: Traversable[Int] = Nil
+    }
+  }
+  trait Foo4 extends Foo3 {
+    override object Bar {
+      def g: List[Int] = Nil
+    }
+  }
+}
+
+package case2 {
+  class Bar[T]
+
+  class Foo[T] {
+    object A extends Bar[T]
+  }
+
+  class Baz[S] extends Foo[S] {
+    override object A extends Bar[S]
+  }
+}