From 1eee2e0ee20a9b31906746d8a3ca11720bf0a6ae Mon Sep 17 00:00:00 2001
From: Matt Bovel <matthieu@bovel.net>
Date: Mon, 3 Oct 2022 14:36:54 +0200
Subject: [PATCH] Fix #10980

---
 compiler/src/dotty/tools/dotc/core/TypeComparer.scala | 4 +++-
 tests/pos/i10980.scala                                | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)
 create mode 100644 tests/pos/i10980.scala

diff --git a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
index 9e946f430edc..595f5e32eb97 100644
--- a/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
+++ b/compiler/src/dotty/tools/dotc/core/TypeComparer.scala
@@ -1955,9 +1955,11 @@ class TypeComparer(@constructorOnly initctx: Context) extends ConstraintHandling
         isSubInfo(info1, tp2.refinedInfo.widenExpr, m.symbol.info.orElse(info1))
         || matchAbstractTypeMember(m.info)
 
-      tp1.member(name) match // inlined hasAltWith for performance
+      def memberQualifies = tp1.member(name) match // inlined hasAltWith for performance
         case mbr: SingleDenotation => qualifies(mbr)
         case mbr => mbr hasAltWith qualifies
+
+      memberQualifies || (tp1.isStable && isSub(TermRef(tp1, name), tp2.refinedInfo))
     }
 
   final def ensureStableSingleton(tp: Type): SingletonType = tp.stripTypeVar match {
diff --git a/tests/pos/i10980.scala b/tests/pos/i10980.scala
new file mode 100644
index 000000000000..7d951322463b
--- /dev/null
+++ b/tests/pos/i10980.scala
@@ -0,0 +1,9 @@
+class A:
+  val x: AnyRef = Object()
+  val y: AnyRef = Object()
+
+@main def m: Unit =
+  val a = new A
+  val b: a.x.type = a.x
+  val c: A { val x: a.x.type } = a
+  val d: A { val x: a.x.type;  val y: a.y.type } = a