1 files changed, 20 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_run/tcrun030.hs b/testsuite/tests/typecheck/should_run/tcrun030.hs
new file mode 100644
index 0000000000..fe28a33091
--- /dev/null
+++ b/testsuite/tests/typecheck/should_run/tcrun030.hs
@@ -0,0 +1,20 @@
+{-# LANGUAGE UndecidableInstances #-}
+
+-- Test recursive dictionaries
+
+module Main where
+
+data D r = ZeroD | SuccD (r (D r));
+
+instance (Eq (r (D r))) => Eq (D r) where
+    ZeroD     == ZeroD     = True
+    (SuccD a) == (SuccD b) = a == b
+    _         == _         = False;
+
+equalDC :: D [] -> D [] -> Bool;
+equalDC = (==);
+
+foo :: D []
+foo = SuccD [SuccD [ZeroD], ZeroD]
+
+main = print (foo == foo)