diff --git a/tests/pos/12944/12944_1.scala b/tests/pos/12944/12944_1.scala
new file mode 100644
index 000000000000..e6b6286c43a3
--- /dev/null
+++ b/tests/pos/12944/12944_1.scala
@@ -0,0 +1,11 @@
+object Test1 {
+  type ++[L, R] = (L, R) match
+    case (Int, Int)       => 2
+    case (String, String) => "2"
+    case (String, Int)    => "2"
+    case (Int, String)    => "2"
+
+  type Bar[W <: Int] = W ++ "" ++ W
+
+  val works = summon[Bar[2] =:= "2"]
+}
diff --git a/tests/pos/12944/12944_2.scala b/tests/pos/12944/12944_2.scala
new file mode 100644
index 000000000000..cb471a59d191
--- /dev/null
+++ b/tests/pos/12944/12944_2.scala
@@ -0,0 +1,5 @@
+import Test1._
+
+object Test2 {
+  val fails = summon[Bar[2] =:= "2"]
+}