4 files changed, 38 insertions, 24 deletions
diff --git a/testsuite/tests/polykinds/T10516.hs b/testsuite/tests/polykinds/T10516.hs
new file mode 100644
index 0000000000..388f3421b8
--- /dev/null
+++ b/testsuite/tests/polykinds/T10516.hs
@@ -0,0 +1,9 @@
+{-# LANGUAGE PolyKinds #-}
+module T10516 where
+
+type App f a = f a
+
+newtype X f a = X (f a)
+
+f :: f a -> X (App f) a
+f = X
diff --git a/testsuite/tests/polykinds/T10516.stderr b/testsuite/tests/polykinds/T10516.stderr
new file mode 100644
index 0000000000..0242722ea5
--- /dev/null
+++ b/testsuite/tests/polykinds/T10516.stderr
@@ -0,0 +1,4 @@
+
+T10516.hs:8:6: error:
+    The type synonym ‘App’ should have 2 arguments, but has been given 1
+    In the type signature for ‘f’: f :: f a -> X (App f) a
diff --git a/testsuite/tests/polykinds/T9222.stderr b/testsuite/tests/polykinds/T9222.stderr
index 01869edd45..1d1a1df779 100644
--- a/testsuite/tests/polykinds/T9222.stderr
+++ b/testsuite/tests/polykinds/T9222.stderr
@@ -1,24 +1,24 @@
-
-T9222.hs:13:3:
-    Couldn't match type ‘b0’ with ‘b’
-      ‘b0’ is untouchable
-        inside the constraints: a ~ '(b0, c0)
-        bound by the type of the constructor ‘Want’:
-                   (a ~ '(b0, c0)) => Proxy b0
-        at T9222.hs:13:3
-      ‘b’ is a rigid type variable bound by
-          the type of the constructor ‘Want’:
-            ((a ~ '(b, c)) => Proxy b) -> Want a
-          at T9222.hs:13:3
-    Expected type: '(b, c)
-      Actual type: a
-    In the ambiguity check for the type of the constructor ‘Want’:
-      Want :: forall (k :: BOX)
-                     (k1 :: BOX)
-                     (a :: (,) k k1)
-                     (b :: k)
-                     (c :: k1).
-              ((a ~ '(b, c)) => Proxy b) -> Want a
-    To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
-    In the definition of data constructor ‘Want’
-    In the data declaration for ‘Want’
+
+T9222.hs:13:3: error:
+    Couldn't match type ‘b0’ with ‘b’
+      ‘b0’ is untouchable
+        inside the constraints: a ~ '(b0, c0)
+        bound by the type of the constructor ‘Want’:
+                   (a ~ '(b0, c0)) => Proxy b0
+        at T9222.hs:13:3
+      ‘b’ is a rigid type variable bound by
+          the type of the constructor ‘Want’:
+            ((a ~ '(b, c)) => Proxy b) -> Want a
+          at T9222.hs:13:3
+    Expected type: '(b, c)
+      Actual type: a
+    In the ambiguity check for the type of the constructor ‘Want’:
+      Want :: forall (k :: BOX)
+                     (k1 :: BOX)
+                     (a :: (,) k k1)
+                     (b :: k)
+                     (c :: k1).
+              ((a ~ '(b, c)) => Proxy b) -> Want a
+    To defer the ambiguity check to use sites, enable AllowAmbiguousTypes
+    In the definition of data constructor ‘Want’
+    In the data type declaration for ‘Want’
diff --git a/testsuite/tests/polykinds/all.T b/testsuite/tests/polykinds/all.T
index 75d2321aad..76af3ecf00 100644
--- a/testsuite/tests/polykinds/all.T
+++ b/testsuite/tests/polykinds/all.T
@@ -116,3 +116,4 @@ test('T9833', normal, compile, [''])
 test('T7908', normal, compile, [''])
 test('T10041', normal, compile, [''])
 test('T10451', normal, compile_fail, [''])
+test('T10516', normal, compile_fail, [''])