1 files changed, 29 insertions, 0 deletions
diff --git a/testsuite/tests/quantified-constraints/T19921.hs b/testsuite/tests/quantified-constraints/T19921.hs
new file mode 100644
index 0000000000..a0ed436784
--- /dev/null
+++ b/testsuite/tests/quantified-constraints/T19921.hs
@@ -0,0 +1,29 @@
+{-# LANGUAGE
+    QuantifiedConstraints
+  , StandaloneKindSignatures
+  , TypeOperators
+  , GADTs
+  , ConstraintKinds
+  , RankNTypes
+  , UndecidableInstances
+  , ImpredicativeTypes
+#-}
+module Typelevel.Constraint.Repro where
+
+import Data.Kind (Constraint, Type)
+
+type Dict :: Constraint -> Type
+data Dict c
+  where
+  Dict :: c => Dict c
+
+type (⇒) :: Constraint -> Constraint -> Constraint
+type c ⇒ d = c => d
+infixr 0 ⇒
+
+type (\/) :: Constraint -> Constraint -> Constraint
+type a \/ b = (forall r. (a ⇒ r, b ⇒ r) ⇒ r)
+infixr 5 \/
+
+dict :: Dict ((x \/ y) \/ z ⇒ x \/ y \/ z)
+dict = Dict