1 files changed, 15 insertions, 0 deletions
diff --git a/testsuite/tests/indexed-types/should_compile/Simple8.hs b/testsuite/tests/indexed-types/should_compile/Simple8.hs
new file mode 100644
index 0000000000..f819763579
--- /dev/null
+++ b/testsuite/tests/indexed-types/should_compile/Simple8.hs
@@ -0,0 +1,15 @@
+{-# LANGUAGE TypeFamilies #-}
+
+module Simple8 where
+
+type family F a
+
+-- Manuel says that duplicate instances are ok. This gives a strange error but
+-- works if one of the duplicates is removed.
+
+type instance F () = ()
+type instance F () = ()
+
+foo :: F () -> ()
+foo x = x
+