content: {-# LANGUAGE FlexibleInstances #-}
  
  module T20946 where
  
  
  class C123 a where c123 :: a
  
  instance                  C123 [[Int]]  where c123 = [[1]]
  instance {-# OVERLAPS #-} C123 [[a]]    where c123 = [[]]
  instance                  C123 [a]      where c123 = []
  
  test123 :: [[Int]]
  test123 = c123
  
  
  class C132 a where c132 :: a
  
  instance                  C132 [[Int]]  where c132 = [[1]]
  instance                  C132 [a]      where c132 = []
  instance {-# OVERLAPS #-} C132 [[a]]    where c132 = [[]]
  
  test132 :: [[Int]]
  test132 = c132
  
  
  class C213 a where c213 :: a
  
  instance {-# OVERLAPS #-} C213 [[a]]    where c213 = [[]]
  instance                  C213 [[Int]]  where c213 = [[1]]
  instance                  C213 [a]      where c213 = []
  
  test213 :: [[Int]]
  test213 = c213
  
  
  class C231 a where c231 :: a
  
  instance {-# OVERLAPS #-} C231 [[a]]    where c231 = [[]]
  instance                  C231 [a]      where c231 = []
  instance                  C231 [[Int]]  where c231 = [[1]]
  
  test231 :: [[Int]]
  test231 = c231
  
  
  class C312 a where c312 :: a
  
  instance                  C312 [a]      where c312 = []
  instance                  C312 [[Int]]  where c312 = [[1]]
  instance {-# OVERLAPS #-} C312 [[a]]    where c312 = [[]]
  
  test312 :: [[Int]]
  test312 = c312
  
  
  class C321 a where c321 :: a
  
  instance                  C321 [a]      where c321 = []
  instance {-# OVERLAPS #-} C321 [[a]]    where c321 = [[]]
  instance                  C321 [[Int]]  where c321 = [[1]]
  
  test321 :: [[Int]]
  test321 = c321
  