1 files changed, 37 insertions, 0 deletions
diff --git a/testsuite/tests/th/T1835.hs b/testsuite/tests/th/T1835.hs
new file mode 100644
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+++ b/testsuite/tests/th/T1835.hs
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+{-# LANGUAGE TemplateHaskell, FlexibleInstances,
+          MultiParamTypeClasses, TypeSynonymInstances #-}
+module Main where
+
+import Language.Haskell.TH
+import Language.Haskell.TH.Syntax
+
+class Eq a => MyClass a 
+data Foo = Foo deriving Eq
+
+instance MyClass Foo 
+
+data Bar = Bar
+  deriving Eq
+
+type Baz = Bar
+instance MyClass Baz
+
+data Quux a  = Quux a   deriving Eq
+data Quux2 a = Quux2 a  deriving Eq
+instance Eq a  => MyClass (Quux a)
+instance Num a => MyClass (Quux2 a)
+
+class MyClass2 a b
+instance MyClass2 Int Bool
+
+main = do
+    putStrLn $(do { info <- reify ''MyClass; lift (pprint info) })
+    print $(isClassInstance ''Eq [ConT ''Foo] >>= lift)
+    print $(isClassInstance ''MyClass [ConT ''Foo] >>= lift)
+    print $ not $(isClassInstance ''Show [ConT ''Foo] >>= lift)
+    print $(isClassInstance ''MyClass [ConT ''Bar] >>= lift) -- this one
+    print $(isClassInstance ''MyClass [ConT ''Baz] >>= lift)
+    print $(isClassInstance ''MyClass [AppT (ConT ''Quux) (ConT ''Int)] >>= lift) --this one
+    print $(isClassInstance ''MyClass [AppT (ConT ''Quux2) (ConT ''Int)] >>= lift) -- this one
+    print $(isClassInstance ''MyClass2 [ConT ''Int, ConT ''Bool] >>= lift)
+    print $(isClassInstance ''MyClass2 [ConT ''Bool, ConT ''Bool] >>= lift)