From 300b42714e304df63272692f34480895b97ef53d Mon Sep 17 00:00:00 2001
From: Liu Fengyun <liu@fengy.me>
Date: Fri, 13 Sep 2019 22:44:05 +0200
Subject: [PATCH] Fix #7219: export forwarder should use TypeAlias for
 parameterless class

---
 .../src/dotty/tools/dotc/typer/Namer.scala    |  3 ++-
 tests/pos-special/fatal-warnings/i7219.scala  | 24 +++++++++++++++++++
 tests/pos/i7219.scala                         |  9 +++++++
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 tests/pos-special/fatal-warnings/i7219.scala
 create mode 100644 tests/pos/i7219.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/Namer.scala b/compiler/src/dotty/tools/dotc/typer/Namer.scala
index 34be6ad819bf..0a5faf69592a 100644
--- a/compiler/src/dotty/tools/dotc/typer/Namer.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Namer.scala
@@ -969,7 +969,8 @@ class Namer { typer: Typer =>
              */
             def fwdInfo(ref: Type, info: Type): Type = info match {
               case _: ClassInfo =>
-                HKTypeLambda.fromParams(info.typeParams, ref)
+                if (info.typeParams.isEmpty) TypeAlias(ref)
+                else HKTypeLambda.fromParams(info.typeParams, ref)
               case _: TypeBounds =>
                 TypeAlias(ref)
               case info: HKTypeLambda =>
diff --git a/tests/pos-special/fatal-warnings/i7219.scala b/tests/pos-special/fatal-warnings/i7219.scala
new file mode 100644
index 000000000000..fedfe9498b2c
--- /dev/null
+++ b/tests/pos-special/fatal-warnings/i7219.scala
@@ -0,0 +1,24 @@
+object Foo {
+  enum MyEnum {
+    case Red
+    case Blue(msg: String)
+  }
+  export MyEnum._
+}
+
+object Bar {
+  type Blue = Foo.Blue
+  
+  // Related Issue -- my expectation is that
+  // `export Foo.Blue` should be equivalent to
+  // `type Blue = Foo.Blue`, but it's not:
+  
+  // export Foo.Blue // Uncommenting this (and commenting `type Blue = ...`) results in compile error
+}
+
+import Foo._
+
+def foo(a: MyEnum): Seq[Bar.Blue] = a match {
+  case Red => Seq.empty
+  case m: Foo.Blue => Seq(m)
+}
diff --git a/tests/pos/i7219.scala b/tests/pos/i7219.scala
new file mode 100644
index 000000000000..6cb1268ba871
--- /dev/null
+++ b/tests/pos/i7219.scala
@@ -0,0 +1,9 @@
+class Foo {
+  object MyEnum {
+    class Blue
+  }
+  export MyEnum._
+
+  val a: MyEnum.Blue = ???
+  a : Blue   // ok
+}