Fix warnings that apear in GHC 8.10

In this version of the compiler, the pattern match checker is much
smarter. It is able to spot more redundant patterns.

inline-r/src/Foreign/R/Type.hsc

@@ -1,6 +1,7 @@
 {-# LANGUAGE CPP #-}
 {-# LANGUAGE ConstraintKinds #-}
 {-# LANGUAGE DataKinds #-}
+{-# LANGUAGE DeriveLift #-}
 {-# LANGUAGE ExistentialQuantification #-}
 {-# LANGUAGE GADTs #-}
 #if __GLASGOW_HASKELL__ >= 810
@@ -53,7 +54,6 @@ import Foreign.R.Constraints
 import Internal.Error
 
 import qualified Language.Haskell.TH.Syntax as Hs
-import qualified Language.Haskell.TH.Lib as Hs
 
 import Data.Singletons.TH
 
@@ -102,7 +102,7 @@ data SEXPTYPE
  | New
  | Free
  | Fun
- deriving (Eq, Ord, Show)
+ deriving (Eq, Ord, Show, Hs.Lift)
 
 instance Enum SEXPTYPE where
  fromEnum Nil = #const NILSXP
@@ -167,9 +167,6 @@ instance NFData SEXPTYPE where
 
 genSingletons [''SEXPTYPE]
 
-instance Hs.Lift SEXPTYPE where
- lift a = [| $(Hs.conE (Hs.mkName $ "Foreign.R.Type." ++ show a)) |]
-
 -- | Used where the R documentation speaks of "pairlists", which are really just
 -- regular lists.
 type PairList = List

inline-r/src/Language/R/Literal.hs

@@ -144,35 +144,25 @@ mkProtectedSEXPVectorIO ty xs = do
 instance Literal [R.Logical] 'R.Logical where
  mkSEXPIO = mkSEXPVectorIO sing . map return
  fromSEXP (hexp -> Logical v) = SVector.toList v
- fromSEXP _ =
- failure "fromSEXP" "Logical expected where some other expression appeared."
 
 instance Literal [Int32] 'R.Int where
  mkSEXPIO = mkSEXPVectorIO sing . map return
  fromSEXP (hexp -> Int v) = SVector.toList v
- fromSEXP _ =
- failure "fromSEXP" "Int expected where some other expression appeared."
 
 instance Literal [Double] 'R.Real where
  mkSEXPIO = mkSEXPVectorIO sing . map return
  fromSEXP (hexp -> Real v) = SVector.toList v
- fromSEXP _ =
- failure "fromSEXP" "Numeric expected where some other expression appeared."
 
 instance Literal [Complex Double] 'R.Complex where
  mkSEXPIO = mkSEXPVectorIO sing . map return
  fromSEXP (hexp -> Complex v) = SVector.toList v
- fromSEXP _ =
- failure "fromSEXP" "Complex expected where some other expression appeared."
 
 instance Literal [String] 'R.String where
  mkSEXPIO =
  mkSEXPVectorIO sing .
  map (\str -> GHC.withCString utf8 str (R.mkCharCE R.CE_UTF8))
  fromSEXP (hexp -> String v) =
  map (\(hexp -> Char xs) -> SVector.toString xs) (SVector.toList v)
- fromSEXP _ =
- failure "fromSEXP" "String expected where some other expression appeared."
 
 instance Literal Text 'R.String where
  mkSEXPIO s =
@@ -184,8 +174,6 @@ instance Literal Text 'R.String where
  [hexp -> Char x] -> SVector.unsafeWithByteString x $ \p -> do
  pure $ T.decodeUtf8 p
  _ -> failure "fromSEXP" "Not a singleton vector"
- fromSEXP _ =
- failure "fromSEXP" "String expected where some other expression appeared."
 
 -- | Create a pairlist from an association list. Result is either a pairlist or
 -- @nilValue@ if the input is the null list. These are two distinct forms. Hence
@@ -225,8 +213,6 @@ instance Literal String 'R.String where
  fromSEXP x@(hexp -> String {})
  | [h] <- fromSEXP x = h
  | otherwise = failure "fromSEXP" "Not a singleton vector."
- fromSEXP _ =
- failure "fromSEXP" "String expected where some other expression appeared."
 
 instance SVector.SVECTOR ty a => Literal (SVector.Vector ty a) ty where
  mkSEXPIO = return . SVector.toSEXP

inline-r/src/Language/R/Matcher.hs

@@ -294,15 +294,13 @@ getS3Class = charList <$> attribute SString "class"
 charList :: SEXP s 'R.String -> [String]
 charList (H.hexp -> String v) =
  map ((\(Char s) -> SV.toString s) . H.hexp) $ SV.toList v
-charList _ = error "Impossible happened."
 
 -- | Get 'dim' attribute.
 dim :: Matcher s [Int]
 dim = go <$> attribute SInt "dim"
  where
  go :: SEXP s 'R.Int -> [Int]
  go (H.hexp -> Int v) = fromIntegral <$> SV.toList v
- go _ = error "Impossible happened."
 
 -- | Get 'dimnames' attribute.
 dimnames :: Matcher s [[String]]

inline-r/src/Language/R/QQ.hs

@@ -99,7 +99,6 @@ antiSuffix = "_hs"
 
 isAnti :: SEXP s 'R.Char -> Bool
 isAnti (hexp -> Char (Vector.toString -> name)) = antiSuffix `isSuffixOf` name
-isAnti _ = error "Impossible"
 
 -- | Chop antiquotation variable names to get the corresponding Haskell variable name.
 chop :: String -> String