bump to latest ghc

ShellCheck.cabal

@@ -43,6 +43,9 @@ source-repository head
 
 library
     hs-source-dirs: src
+    if impl(ghc < 8.0)
+      build-depends:
+        semigroups
     build-depends:
       -- GHC 7.6.3 (base 4.6.0.1) is buggy (#1131, #1119) in optimized mode.
       -- Just disable that version entirely to fail fast.
@@ -78,6 +81,9 @@ library
       Paths_ShellCheck
 
 executable shellcheck
+    if impl(ghc < 8.0)
+      build-depends:
+        semigroups
     build-depends:
       base >= 4 && < 5,
       ShellCheck, 

shellcheck.hs

@@ -17,13 +17,13 @@
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 -}
-import ShellCheck.Data
 import           ShellCheck.Checker
+import           ShellCheck.Data
 import           ShellCheck.Interface
 import           ShellCheck.Regex
 
-import ShellCheck.Formatter.Format
 import qualified ShellCheck.Formatter.CheckStyle
+import           ShellCheck.Formatter.Format
 import qualified ShellCheck.Formatter.GCC
 import qualified ShellCheck.Formatter.JSON
 import qualified ShellCheck.Formatter.TTY
@@ -40,6 +40,7 @@ import Data.List
 import qualified Data.Map                        as Map
 import           Data.Maybe
 import           Data.Monoid
+import           Data.Semigroup                  (Semigroup (..))
 import           Prelude                         hiding (catch)
 import           System.Console.GetOpt
 import           System.Directory
@@ -56,9 +57,12 @@ data Status =
     | RuntimeException
   deriving (Ord, Eq, Show)
 
+instance Semigroup Status where
+    (<>) = max
+
 instance Monoid Status where
     mempty = NoProblems
-    mappend = max
+    mappend = (Data.Semigroup.<>)
 
 data Options = Options {
     checkSpec        :: CheckSpec,
@@ -203,7 +207,7 @@ runFormatter sys format options files = do
 
     process :: FilePath -> IO Status
     process filename = do
-        input <- (siReadFile sys) filename
+        input <- siReadFile sys filename
         either (reportFailure filename) check input
       where
         check contents = do

src/ShellCheck/AnalyzerLib.hs

@@ -17,8 +17,8 @@
     You should have received a copy of the GNU General Public License
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 -}
-{-# LANGUAGE TemplateHaskell #-}
 {-# LANGUAGE FlexibleContexts #-}
+{-# LANGUAGE TemplateHaskell  #-}
 module ShellCheck.AnalyzerLib where
 import           ShellCheck.AST
 import           ShellCheck.ASTLib
@@ -34,11 +34,13 @@ import Control.Monad.State
 import           Control.Monad.Writer
 import           Data.Char
 import           Data.List
-import Data.Maybe
 import qualified Data.Map               as Map
+import           Data.Maybe
+import           Data.Semigroup
 
 import           Test.QuickCheck.All    (forAllProperties)
-import Test.QuickCheck.Test (quickCheckWithResult, stdArgs, maxSuccess)
+import           Test.QuickCheck.Test   (maxSuccess, quickCheckWithResult,
+                                         stdArgs)
 
 type Analysis = AnalyzerM ()
 type AnalyzerM a = RWS Parameters [TokenComment] Cache a
@@ -57,16 +59,18 @@ runChecker params checker = notes
         check = perScript checker `composeAnalyzers` (\(Root x) -> void $ doAnalysis (perToken checker) x)
         notes = snd $ evalRWS (check $ Root root) params Cache
 
+instance Semigroup Checker where
+    (<>) x y = Checker {
+        perScript = perScript x `composeAnalyzers` perScript y,
+        perToken = perToken x `composeAnalyzers` perToken y
+        }
+
 instance Monoid Checker where
     mempty = Checker {
         perScript = nullCheck,
         perToken = nullCheck
         }
-    mappend x y = Checker {
-        perScript = perScript x `composeAnalyzers` perScript y,
-        perToken = perToken x `composeAnalyzers` perToken y
-        }
-
+    mappend = (Data.Semigroup.<>)
 
 composeAnalyzers :: (a -> Analysis) -> (a -> Analysis) -> a -> Analysis
 composeAnalyzers f g x = f x >> g x