From 16a688fb24b2926aad47e2977444e0b9249db50b Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 27 Jul 2016 22:10:15 +0200
Subject: Fix HkApply#superType if type constructor is a TypeVar

In this case, supertype is not stable and should not be cached.
---
 src/dotty/tools/dotc/core/Types.scala | 3 +++
 1 file changed, 3 insertions(+)

(limited to 'src/dotty/tools/dotc/core/Types.scala')

diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 373428108..3e8a8da21 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -2645,6 +2645,9 @@ object Types {
       if (ctx.period != validSuper) {
         cachedSuper = tycon match {
           case tp: TypeLambda => defn.AnyType
+          case tp: TypeVar =>
+            // supertype not stable, since underlying might change
+            return tp.underlying.applyIfParameterized(args)
           case tp: TypeProxy => tp.superType.applyIfParameterized(args)
           case _ => defn.AnyType
         }
-- 
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