Allow inplace refactoring of multiple files

Allow multiple files to be refactored at a time, applying ideas
to each relevant file.

Closes #1539.

src/HLint.hs

@@ -209,18 +209,21 @@ getIdeas cmd@CmdMain{..} settings = do
 -- #746: run refactor even if no hint, which ensures consistent output
 -- whether there are hints or not.
 handleRefactoring :: [Idea] -> [String] -> Cmd -> IO ()
-handleRefactoring ideas files cmd@CmdMain{..} =
-    case cmdFiles of
-        [file] -> do
-            -- Ensure that we can find the executable
-            path <- checkRefactor (if cmdWithRefactor == "" then Nothing else Just cmdWithRefactor)
-            -- writeFile "hlint.refact"
-            let hints =  show $ map (show &&& ideaRefactoring) ideas
-            withTempFile $ \f -> do
-                writeFile f hints
-                let ParseFlags{enabledExtensions, disabledExtensions} = cmdParseFlags cmd
-                exitWith =<< runRefactoring path file f enabledExtensions disabledExtensions cmdRefactorOptions
-        _ -> errorIO "Refactor flag can only be used with an individual file"
+handleRefactoring ideas files cmd@CmdMain{..} = do
+    -- Ensure that we can find the executable
+    path <- checkRefactor (if cmdWithRefactor == "" then Nothing else Just cmdWithRefactor)
+    forM_ cmdFiles $ \file -> do
+        -- writeFile "hlint.refact"
+        let fileIdeas = filter (\i -> file == ideaFile i) ideas
+        let hints =  show $ map (show &&& ideaRefactoring) fileIdeas
+        withTempFile $ \f -> do
+            writeFile f hints
+            let ParseFlags{enabledExtensions, disabledExtensions} = cmdParseFlags cmd
+            exitCode <- runRefactoring path file f enabledExtensions disabledExtensions cmdRefactorOptions
+
+            case exitCode of
+              ExitSuccess   -> return ()
+              ExitFailure _ -> exitWith exitCode
 
 handleReporting :: [Idea] -> Cmd -> IO ()
 handleReporting showideas cmd@CmdMain{..} = do

src/Idea.hs

@@ -6,6 +6,7 @@ module Idea(
     rawIdea, idea, suggest, suggestRemove, ideaRemove, warn, ignore,
     rawIdeaN, suggestN, ignoreNoSuggestion,
     showIdeasJson, showIdeaANSI,
+    ideaFile,
     Note(..), showNotes,
     Severity(..),
     ) where
@@ -16,6 +17,7 @@ import HsColour
 import Refact.Types hiding (SrcSpan)
 import Refact.Types qualified as R
 import Prelude
+import GHC.Data.FastString
 import GHC.Types.SrcLoc
 import GHC.Utils.Outputable
 import GHC.Util
@@ -36,6 +38,12 @@ data Idea = Idea
     }
     deriving Eq
 
+ideaFile :: Idea -> String
+ideaFile idea =
+  case srcSpanFileName_maybe (ideaSpan idea) of
+    Just file -> unpackFS file
+    Nothing   -> error "SrcSpan has no associated file"
+
 -- I don't use aeson here for 2 reasons:
 -- 1) Aeson doesn't escape unicode characters, and I want to (allows me to ignore encoding)
 -- 2) I want to control the format so it's slightly human readable as well