From 1f630025d457807c4a9da513e4a0823e4643b2a6 Mon Sep 17 00:00:00 2001
From: Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io>
Date: Thu, 16 Jan 2020 20:03:27 +0100
Subject: Add a test for #15712

---
 testsuite/tests/typecheck/should_fail/T15712.hs     | 18 ++++++++++++++++++
 testsuite/tests/typecheck/should_fail/T15712.stderr |  6 ++++++
 testsuite/tests/typecheck/should_fail/all.T         |  1 +
 3 files changed, 25 insertions(+)
 create mode 100644 testsuite/tests/typecheck/should_fail/T15712.hs
 create mode 100644 testsuite/tests/typecheck/should_fail/T15712.stderr

diff --git a/testsuite/tests/typecheck/should_fail/T15712.hs b/testsuite/tests/typecheck/should_fail/T15712.hs
new file mode 100644
index 0000000000..a0b1d5f975
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T15712.hs
@@ -0,0 +1,18 @@
+{-# Language RankNTypes    #-}
+{-# Language DerivingVia   #-}
+{-# Language DeriveFunctor #-}
+
+-- import Control.Monad.Codensity
+import Data.Kind
+
+newtype Codensity f a = Codensity (forall xx. (a -> f xx) -> f xx)
+  deriving
+    (Functor)
+
+newtype GEndo m a = GEndo (m a -> m a)
+
+newtype LogicT m a = LogicT (forall xx. (a -> (m xx -> m xx)) -> (m xx -> m xx))
+  deriving
+    (Functor)
+  via
+    (Codensity GEndo)
diff --git a/testsuite/tests/typecheck/should_fail/T15712.stderr b/testsuite/tests/typecheck/should_fail/T15712.stderr
new file mode 100644
index 0000000000..e8b5d397de
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T15712.stderr
@@ -0,0 +1,6 @@
+
+T15712.hs:18:16: error:
+    • Expecting one more argument to ‘GEndo’
+      Expected kind ‘* -> *’, but ‘GEndo’ has kind ‘(* -> *) -> * -> *’
+    • In the first argument of ‘Codensity’, namely ‘GEndo’
+      In the newtype declaration for ‘LogicT’
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index 156042cab1..e2496562e1 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -493,6 +493,7 @@ test('T15592a', normal, compile_fail, [''])
 test('T15629', normal, compile_fail, [''])
 test('T15767', normal, compile_fail, [''])
 test('T15648', [extra_files(['T15648a.hs'])], multimod_compile_fail, ['T15648', '-v0 -fprint-equality-relations'])
+test('T15712', normal, compile_fail, [''])
 test('T15793', normal, compile_fail, [''])
 test('T15796', normal, compile_fail, [''])
 test('T15807', normal, compile_fail, [''])
-- 
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