Merge pull request scala#593 from som-snytt/ticket/5760-pkgobj-warn

SI-5760: Improve error message for package$Klass conflict with Klass

Author: Adriaan Moors

src/compiler/scala/tools/nsc/typechecker/ContextErrors.scala

@@ -874,8 +874,12 @@ trait ContextErrors {
         val s1 = if (prevSym.isModule) "case class companion " else ""
         val s2 = if (prevSym.isSynthetic) "(compiler-generated) " + s1 else ""
         val s3 = if (prevSym.isCase) "case class " + prevSym.name else "" + prevSym
+        val where = if (currentSym.owner.isPackageClass != prevSym.owner.isPackageClass) {
+                      val inOrOut = if (prevSym.owner.isPackageClass) "outside of" else "in"
+                      " %s package object %s".format(inOrOut, ""+prevSym.effectiveOwner.name)
+                    } else ""
 
-        issueSymbolTypeError(currentSym, prevSym.name + " is already defined as " + s2 + s3)
+        issueSymbolTypeError(currentSym, prevSym.name + " is already defined as " + s2 + s3 + where)
       }
 
       def MaxParametersCaseClassError(tree: Tree) =

test/files/neg/t5760-pkgobj-warn.check

@@ -0,0 +1,4 @@
+stalepkg_2.scala:6: error: Foo is already defined as class Foo in package object stalepkg
+  class Foo
+        ^
+one error found

test/files/neg/t5760-pkgobj-warn/stalepkg_1.scala

@@ -0,0 +1,11 @@
+
+package object stalepkg {
+  class Foo
+}
+
+package stalepkg {
+  object Test {
+    def main(args: Array[String]) {
+    }
+  }
+}

test/files/neg/t5760-pkgobj-warn/stalepkg_2.scala

@@ -0,0 +1,11 @@
+
+package object stalepkg {
+}
+
+package stalepkg {
+  class Foo
+  object Test {
+    def main(args: Array[String]) {
+    }
+  }
+}