5 files changed, 35 insertions, 4 deletions
diff --git a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
index 5e6a402ef..a2557194c 100644
--- a/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
+++ b/src/dotty/tools/dotc/reporting/diagnostic/messages.scala
@@ -790,7 +790,8 @@ object messages {
     val explanation = ""
   }
 
-  case class SeqWildcardPatternPos()(implicit ctx: Context) extends Message(31) {
+  case class SeqWildcardPatternPos()(implicit ctx: Context)
+  extends Message(31) {
     val kind = "Syntax"
     val msg = "`_*' can be used only for last argument"
     val explanation = {
@@ -891,4 +892,11 @@ object messages {
            |"""
     }
   }
+
+  case class PkgDuplicateSymbol(existing: Symbol)(implicit ctx: Context)
+  extends Message(33) {
+    val kind = "Duplicate Type"
+    val msg = hl"trying to define package with same name as `$existing`"
+    val explanation = ""
+  }
 }
diff --git a/src/dotty/tools/dotc/typer/FrontEnd.scala b/src/dotty/tools/dotc/typer/FrontEnd.scala
index 4ce24b633..7bbf0169b 100644
--- a/src/dotty/tools/dotc/typer/FrontEnd.scala
+++ b/src/dotty/tools/dotc/typer/FrontEnd.scala
@@ -35,7 +35,7 @@ class FrontEnd extends Phase {
       else new Parser(unit.source).parse()
     val printer = if (ctx.settings.Xprint.value.contains("parser")) default else typr
     printer.println("parsed:\n" + unit.untpdTree.show)
-    if (Config.checkPositions) 
+    if (Config.checkPositions)
       unit.untpdTree.checkPos(nonOverlapping = !unit.isJava && !ctx.reporter.hasErrors)
   }
 
diff --git a/src/dotty/tools/dotc/typer/Namer.scala b/src/dotty/tools/dotc/typer/Namer.scala
index 687de1e7a..22b5517dd 100644
--- a/src/dotty/tools/dotc/typer/Namer.scala
+++ b/src/dotty/tools/dotc/typer/Namer.scala
@@ -21,6 +21,7 @@ import Inferencing._
 import transform.ValueClasses._
 import TypeApplications._
 import language.implicitConversions
+import reporting.diagnostic.messages._
 
 trait NamerContextOps { this: Context =>
 
@@ -264,7 +265,7 @@ class Namer { typer: Typer =>
       def preExisting = ctx.effectiveScope.lookup(name)
       if (ctx.owner is PackageClass)
         if (preExisting.isDefinedInCurrentRun)
-          errorName(s"${preExisting.showLocated} is compiled twice")
+          errorName(s"${preExisting.showLocated} has already been compiled\nonce during this run")
         else name
       else
         if ((!ctx.owner.isClass || name.isTypeName) && preExisting.exists)
@@ -343,8 +344,18 @@ class Namer { typer: Typer =>
       case Select(qual: RefTree, _) => createPackageSymbol(qual).moduleClass
     }
     val existing = pkgOwner.info.decls.lookup(pid.name)
+
     if ((existing is Package) && (pkgOwner eq existing.owner)) existing
-    else ctx.newCompletePackageSymbol(pkgOwner, pid.name.asTermName).entered
+    else {
+      // If the name exists as type we should unlink the existing name from the
+      // scope, issue an error and continue, as usual:
+      val existingTpe = pkgOwner.info.decls.lookup(pid.name.toTypeName)
+      if (existingTpe != NoSymbol) {
+        ctx.error(PkgDuplicateSymbol(existingTpe), pid.pos)
+        pkgOwner.info.decls.openForMutations.unlink(existingTpe)
+      }
+      ctx.newCompletePackageSymbol(pkgOwner, pid.name.asTermName).entered
+    }
   }
 
   /** Expand tree and store in `expandedTree` */
diff --git a/tests/neg/i1708.scala b/tests/neg/i1708.scala
new file mode 100644
index 000000000..47bc456f3
--- /dev/null
+++ b/tests/neg/i1708.scala
@@ -0,0 +1,2 @@
+package foo { trait identifier }
+package foo { class identifier } // error
diff --git a/tests/neg/i1708b.scala b/tests/neg/i1708b.scala
new file mode 100644
index 000000000..9bcf1864d
--- /dev/null
+++ b/tests/neg/i1708b.scala
@@ -0,0 +1,10 @@
+package foo {
+  trait id {
+    def bar: Int
+  }
+}
+package foo {
+  package id { // error
+    class Bar
+  }
+}