From 58379db562194fb83457f232d71db5ee20daedf3 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Fri, 26 May 2017 10:28:00 +0200
Subject: [PATCH] Fix #2533: Fold refinement with error info to error

---
 compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala | 3 ++-
 tests/neg/i2533.scala                                  | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)
 create mode 100644 tests/neg/i2533.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala b/compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala
index 93bd2528c380..10f2cf7e726d 100644
--- a/compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala
+++ b/compiler/src/dotty/tools/dotc/typer/TypeAssigner.scala
@@ -465,7 +465,8 @@ trait TypeAssigner {
     def addRefinement(parent: Type, refinement: Tree): Type = {
       val rsym = refinement.symbol
       val rinfo = if (rsym is Accessor) rsym.info.resultType else rsym.info
-      RefinedType(parent, rsym.name, rinfo)
+      if (rinfo.isError) rinfo
+      else RefinedType(parent, rsym.name, rinfo)
     }
     val refined = (parent.tpe /: refinements)(addRefinement)
     tree.withType(RecType.closeOver(rt => refined.substThis(refineCls, RecThis(rt))))
diff --git a/tests/neg/i2533.scala b/tests/neg/i2533.scala
new file mode 100644
index 000000000000..8913d8fe2869
--- /dev/null
+++ b/tests/neg/i2533.scala
@@ -0,0 +1,3 @@
+object Foo {
+  def test(f: { type A = A }): Int = ??? // error
+}