From 6f8e1791a10899408483c148cac74f4aae339cae Mon Sep 17 00:00:00 2001
From: Matthew Pickering <matthewtpickering@gmail.com>
Date: Thu, 8 Apr 2021 15:26:01 +0100
Subject: Add regression test for T19615

Fixes #19615
---
 testsuite/tests/typecheck/should_fail/T19615.hs     | 17 +++++++++++++++++
 testsuite/tests/typecheck/should_fail/T19615.stderr |  6 ++++++
 testsuite/tests/typecheck/should_fail/all.T         |  1 +
 3 files changed, 24 insertions(+)
 create mode 100644 testsuite/tests/typecheck/should_fail/T19615.hs
 create mode 100644 testsuite/tests/typecheck/should_fail/T19615.stderr

diff --git a/testsuite/tests/typecheck/should_fail/T19615.hs b/testsuite/tests/typecheck/should_fail/T19615.hs
new file mode 100644
index 0000000000..8d71ca925e
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T19615.hs
@@ -0,0 +1,17 @@
+{-# LANGUAGE RankNTypes     #-}
+{-# LANGUAGE PolyKinds      #-}
+{-# LANGUAGE DataKinds      #-}
+{-# LANGUAGE TypeFamilies #-}
+module T19615 where
+
+import GHC.Exts
+
+class Call (r :: RuntimeRep) where
+  type Lev (a :: TYPE r)
+  lift' :: (a :: TYPE r) -> (Lev a -> b) -> b
+  mapF  :: forall r' (a :: TYPE r) (b :: TYPE r'). Call r' => (a -> b) -> Lev a -> Lev b
+
+instance Call LiftedRep where
+  type Lev a = a
+  lift' a k = k a
+  mapF f x = lift' (f x) id
diff --git a/testsuite/tests/typecheck/should_fail/T19615.stderr b/testsuite/tests/typecheck/should_fail/T19615.stderr
new file mode 100644
index 0000000000..b2e4f40231
--- /dev/null
+++ b/testsuite/tests/typecheck/should_fail/T19615.stderr
@@ -0,0 +1,6 @@
+
+T19615.hs:17:20: error:
+    A levity-polymorphic type is not allowed here:
+      Type: b
+      Kind: TYPE r'
+    In the type of expression: (f x)
diff --git a/testsuite/tests/typecheck/should_fail/all.T b/testsuite/tests/typecheck/should_fail/all.T
index d875b75909..7891e4543c 100644
--- a/testsuite/tests/typecheck/should_fail/all.T
+++ b/testsuite/tests/typecheck/should_fail/all.T
@@ -627,3 +627,4 @@ test('T19397E3', extra_files(['T19397S.hs']), multimod_compile_fail,
 test('T19397E4', extra_files(['T19397S.hs']), multimod_compile_fail,
     ['T19397E4.hs', '-v0 -main-is foo'])
 test('T19415', normal, compile_fail, [''])
+test('T19615', normal, compile_fail, [''])
-- 
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