Test for existential record update (cf Trac #2595)

testsuite/tests/ghc-regress/typecheck/should_compile/all.T

@@ -258,6 +258,7 @@ test('tc240', normal, compile, [''])
 test('tc241', normal, compile, [''])
 test('tc242', normal, compile, [''])
 test('tc243', normal, compile, [''])
+test('tc244', normal, compile, [''])
 
 test('FD1', normal, compile_fail, [''])
 test('FD2', normal, compile_fail, [''])

testsuite/tests/ghc-regress/typecheck/should_compile/tc244.hs

+{-# LANGUAGE TypeFamilies, GADTs #-}
+
+-- Tests record update in the presence of 
+-- existentials, GADTs, type families
+
+module Rec where
+
+----------------- Existential
+data S a where
+   S1 { fs1 :: a, fs2 :: b } :: S a
+   S2 { fs1 :: a } :: S a
+
+updS s x = s { fs1=x }
+
+------------------ GADT
+data T a b where
+   T1 { ft1 :: a, ft2 :: c, ft3 :: d } :: T a Int
+   T2 { ft1 :: a, ft3 :: c } :: T a Int
+   T3 :: T Int b
+
+f :: T a1 b -> a2 -> T a2 b
+f x v = x { ft1 = v }
+
+------------------ Type family
+data family R a
+data instance R (a,b) where
+   R1 { fr1 :: a, fr2 :: b, fr3 :: c } :: R (a,b)
+   R2 { fr1 :: a, fr3 :: c } :: R (a,b)
+
+updR r x = r { fr1=x }