1 files changed, 17 insertions, 0 deletions
diff --git a/testsuite/tests/deriving/should_compile/T14339.hs b/testsuite/tests/deriving/should_compile/T14339.hs
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index 0000000000..e2521f2de0
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+++ b/testsuite/tests/deriving/should_compile/T14339.hs
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+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE UndecidableInstances #-}
+module Bug where
+
+import GHC.TypeLits
+
+newtype Baz = Baz Foo
+  deriving Bar
+
+newtype Foo = Foo Int
+
+class Bar a where
+  bar :: a
+
+instance (TypeError (Text "Boo")) => Bar Foo where
+  bar = undefined