From d355f8fe28218b1e8b984d6d491f02c414e922d5 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 12 Apr 2017 15:39:54 +0200
Subject: Dealias before type erasing

... and likewise for taking a signature. The previous case worked
in all cases except when faced with an alias like `type Id[T] = T`.
In that case, it would disregard the argument and erase to Object.
---
 compiler/src/dotty/tools/dotc/core/TypeErasure.scala | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/core/TypeErasure.scala b/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
index f35752644..02f1f549f 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -355,7 +355,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
    *   - For NoType or NoPrefix, the type itself.
    *   - For any other type, exception.
    */
-  private def apply(tp: Type)(implicit ctx: Context): Type = tp match {
+  private def apply(tp: Type)(implicit ctx: Context): Type = tp.dealias match {
     case _: ErasedValueType =>
       tp
     case tp: TypeRef =>
@@ -487,7 +487,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
    *  Need to ensure correspondence with erasure!
    */
   private def sigName(tp: Type)(implicit ctx: Context): TypeName = try {
-    tp match {
+    tp.dealias match {
       case ErasedValueType(_, underlying) =>
         sigName(underlying)
       case tp: TypeRef =>
-- 
cgit v1.2.3


From 02cffa49ede84dbd0dbb93329c9a4117251ca658 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 12 Apr 2017 23:56:57 +0200
Subject: Alternative fix

Special case HKApply only. This is simpler and potentially
more efficient.
---
 compiler/src/dotty/tools/dotc/core/TypeErasure.scala | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/core/TypeErasure.scala b/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
index 02f1f549f..1eb90b8eb 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeErasure.scala
@@ -355,7 +355,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
    *   - For NoType or NoPrefix, the type itself.
    *   - For any other type, exception.
    */
-  private def apply(tp: Type)(implicit ctx: Context): Type = tp.dealias match {
+  private def apply(tp: Type)(implicit ctx: Context): Type = tp match {
     case _: ErasedValueType =>
       tp
     case tp: TypeRef =>
@@ -377,6 +377,8 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
       defn.FunctionType(0)
     case AndType(tp1, tp2) =>
       erasedGlb(this(tp1), this(tp2), isJava)
+    case tp: HKApply =>
+      apply(tp.superType)
     case OrType(tp1, tp2) =>
       ctx.typeComparer.orType(this(tp1), this(tp2), erased = true)
     case tp: MethodType =>
@@ -487,7 +489,7 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
    *  Need to ensure correspondence with erasure!
    */
   private def sigName(tp: Type)(implicit ctx: Context): TypeName = try {
-    tp.dealias match {
+    tp match {
       case ErasedValueType(_, underlying) =>
         sigName(underlying)
       case tp: TypeRef =>
@@ -508,6 +510,8 @@ class TypeErasure(isJava: Boolean, semiEraseVCs: Boolean, isConstructor: Boolean
           normalizeClass(sym.asClass).fullName.asTypeName
       case defn.ArrayOf(elem) =>
         sigName(this(tp))
+      case tp: HKApply =>
+        sigName(tp.superType)
       case JavaArrayType(elem) =>
         sigName(elem) ++ "[]"
       case tp: TermRef =>
-- 
cgit v1.2.3


From 37120df19265da923703de00911e33937e5a66de Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Thu, 13 Apr 2017 11:00:37 +0200
Subject: Add test

---
 tests/pos/i2234.scala | 13 +++++++++++++
 1 file changed, 13 insertions(+)
 create mode 100644 tests/pos/i2234.scala

diff --git a/tests/pos/i2234.scala b/tests/pos/i2234.scala
new file mode 100644
index 000000000..8173c2091
--- /dev/null
+++ b/tests/pos/i2234.scala
@@ -0,0 +1,13 @@
+object Test {
+  type Dummy[A] = A
+
+  def a(d: Dummy[String]) = ()
+  def a(d: Dummy[Int]) = ()
+
+  implicit def dummy[A]: Dummy[A] = null.asInstanceOf[A]
+  def m(x: List[String])(implicit d: Dummy[String]) = "string"
+  def m(x: List[Int])(implicit d: Dummy[Int]) = "int"
+
+  m(List(1, 2, 3))
+  m(List("a"))
+}
-- 
cgit v1.2.3