5 files changed, 66 insertions, 1 deletions
diff --git a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
index e313edb3f6..35db38ae77 100644
--- a/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/RefChecks.scala
@@ -282,6 +282,7 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
         def otherTp  = self.memberType(other)
         def noErrorType = other.tpe != ErrorType && member.tpe != ErrorType
         def isRootOrNone(sym: Symbol) = sym == RootClass || sym == NoSymbol
+        def isNeitherInClass = (member.owner != clazz) && (other.owner != clazz)
         def objectOverrideErrorMsg = (
           "overriding " + other.fullLocationString + " with " + member.fullLocationString + ":\n" +
           "an overriding object must conform to the overridden object's class bound" +
@@ -383,7 +384,14 @@ abstract class RefChecks extends InfoTransform with reflect.internal.transform.R
             overrideError("cannot override final member");
             // synthetic exclusion needed for (at least) default getters.
           } else if (!other.isDeferred && !member.isAnyOverride && !member.isSynthetic) {
-            overrideError("needs `override' modifier");
+              if (isNeitherInClass && !(other.owner isSubClass member.owner))
+                emitOverrideError(
+                  clazz + " inherits conflicting members:\n  "
+                    + infoStringWithLocation(other) + "  and\n  " + infoStringWithLocation(member)
+                    + "\n(Note: this can be resolved by declaring an override in " + clazz + ".)"
+                )
+              else
+                overrideError("needs `override' modifier")
           } else if (other.isAbstractOverride && other.isIncompleteIn(clazz) && !member.isAbstractOverride) {
             overrideError("needs `abstract override' modifiers")
           } else if (member.isAnyOverride && (other hasFlag ACCESSOR) && other.accessed.isVariable && !other.accessed.isLazy) {
diff --git a/test/files/neg/t5358.check b/test/files/neg/t5358.check
new file mode 100644
index 0000000000..59e83bba2f
--- /dev/null
+++ b/test/files/neg/t5358.check
@@ -0,0 +1,7 @@
+t5358.scala:3: error: class C inherits conflicting members:
+  method hi in trait A of type => String  and
+  method hi in trait B of type => String
+(Note: this can be resolved by declaring an override in class C.)
+class C extends A with B
+      ^
+one error found
diff --git a/test/files/neg/t5358.scala b/test/files/neg/t5358.scala
new file mode 100644
index 0000000000..13d827ed82
--- /dev/null
+++ b/test/files/neg/t5358.scala
@@ -0,0 +1,4 @@
+trait A { def hi = "A" }
+trait B { def hi = "B" }
+class C extends A with B
+
diff --git a/test/pending/pos/bug4704.scala b/test/pending/pos/bug4704.scala
new file mode 100644
index 0000000000..6af719adf7
--- /dev/null
+++ b/test/pending/pos/bug4704.scala
@@ -0,0 +1,36 @@
+trait Bar {
+  def f1 = super.hashCode
+  def f2 = super[Object].hashCode
+  def f3 = super[ScalaObject].hashCode
+  
+  override def hashCode = 1
+}
+trait Barzoo {
+  def g1 = super.hashCode
+  def g2 = super[Object].hashCode
+  def g3 = super[ScalaObject].hashCode
+  
+  override def hashCode = 2
+}
+
+trait Foo extends Bar with Barzoo {
+  def f4 = super.hashCode
+  def f5 = super[Object].hashCode
+  def f6 = super[ScalaObject].hashCode
+  def f6b = super[Bar].hashCode
+  def g4 = super[Barzoo].hashCode
+  
+  override def hashCode = super[Bar].hashCode + super[Barzoo].hashCode
+}
+
+class Quux extends Foo {
+  override def hashCode = super.hashCode + super[Object].hashCode + super[ScalaObject].hashCode + super[Foo].hashCode
+}
+
+trait Borp extends Quux {
+  def f12 = super.hashCode
+  def f14 = super[ScalaObject].hashCode
+  def f15 = super[Quux].hashCode
+  override def hashCode = super[Quux].hashCode
+}
+
diff --git a/test/pending/run/bug4704run.scala b/test/pending/run/bug4704run.scala
new file mode 100644
index 0000000000..af488a56c7
--- /dev/null
+++ b/test/pending/run/bug4704run.scala
@@ -0,0 +1,10 @@
+trait MM {
+  protected def method = "bip"
+}
+trait NN {
+  protected def method = "bop"
+}
+trait OOOOO extends MM with NN {
+  override protected def method = super[MM].method + super[NN].method
+  override def hashCode = super[MM].hashCode + super[NN].hashCode
+}