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diff --git a/testsuite/tests/stranal/should_compile/T18982.hs b/testsuite/tests/stranal/should_compile/T18982.hs
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+++ b/testsuite/tests/stranal/should_compile/T18982.hs
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+{-# OPTIONS_GHC -O -fforce-recomp #-}
+{-# LANGUAGE GADTs #-}
+
+module T18982 where
+
+data Box a where
+  Box :: a -> Box a
+
+data Ex a where
+  Ex :: e -> a -> Ex a
+
+data GADT a where
+  GADT :: Int -> GADT Int
+
+data ExGADT a where
+  ExGADT :: (e ~ Int) => e -> Int -> ExGADT Int
+
+-- | Expected worker type:
+-- $wf :: Int# -> Int#
+f :: Box Int -> Int
+f (Box n) = n + 1
+{-# NOINLINE f #-}
+
+-- | Expected worker type:
+-- $wg :: forall {e}. e -> Int# -> Int#
+g :: Ex Int -> Int
+g (Ex e n) = e `seq` n + 1
+{-# NOINLINE g #-}
+
+-- | Expected worker type:
+-- $wh :: Int# -> Int#
+h :: GADT a -> Int
+h (GADT n) = n + 1
+{-# NOINLINE h #-}
+
+-- | Expected worker type:
+-- $wi :: forall {e}. e -> Int# -> Int#
+i :: ExGADT a -> Int
+i (ExGADT e n) = e `seq` n + 1
+{-# NOINLINE i #-}
+