1 files changed, 41 insertions, 0 deletions
diff --git a/testsuite/tests/typecheck/should_run/T1735_Help/Instances.hs b/testsuite/tests/typecheck/should_run/T1735_Help/Instances.hs
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+++ b/testsuite/tests/typecheck/should_run/T1735_Help/Instances.hs
@@ -0,0 +1,41 @@
+{-# LANGUAGE TemplateHaskell, FlexibleInstances, MultiParamTypeClasses,
+             UndecidableInstances, OverlappingInstances, CPP #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+-- This is a module full of orphans, so don't warn about them
+
+module T1735_Help.Instances () where
+
+import T1735_Help.Basics
+import Data.Typeable
+
+charType :: DataType
+charType = mkStringType "Prelude.Char"
+
+instance Sat (ctx Char) =>
+         Data ctx Char where
+  toConstr _ x = mkStringConstr charType [x]
+  gunfold _ _ z c = case constrRep c of
+                      (StringConstr [x]) -> z x
+                      _ -> error "gunfold Char"
+  dataTypeOf _ _ = charType
+
+nilConstr :: Constr
+nilConstr    = mkConstr listDataType "[]" [] Prefix
+consConstr :: Constr
+consConstr   = mkConstr listDataType "(:)" [] Infix
+listDataType :: DataType
+listDataType = mkDataType "Prelude.[]" [nilConstr,consConstr]
+
+instance (Sat (ctx [a]), Data ctx a) =>
+         Data ctx [a] where
+  gfoldl _ _ z []     = z []
+  gfoldl _ f z (x:xs) = z (:) `f` x `f` xs
+  toConstr _ []    = nilConstr
+  toConstr _ (_:_) = consConstr
+  gunfold _ k z c = case constrIndex c of
+                      1 -> z []
+                      2 -> k (k (z (:)))
+                      _ -> error "gunfold List"
+  dataTypeOf _ _ = listDataType
+  dataCast1 _ f = gcast1 f
+