Add json1 format that ignores tabs

The new json1 format works just like json except that it treats tabs as
single characters instead of 8-character tabstops.

The main use case is to allow editors to pass -fjson1 so that they can
consume the json output in a character-oriented way without breaking
backwards compatibility.

Also addresses #1048.

src/ShellCheck/Formatter/JSON.hs

@@ -30,11 +30,12 @@ import GHC.Exts
 import System.IO
 import qualified Data.ByteString.Lazy.Char8 as BL
 
-format = do
+format :: Bool -> IO Formatter
+format removeTabs = do
     ref <- newIORef []
     return Formatter {
         header = return (),
-        onResult = collectResult ref,
+        onResult = collectResult removeTabs ref,
         onFailure = outputError,
         footer = finish ref
     }
@@ -96,8 +97,20 @@ instance ToJSON Fix where
         ]
 
 outputError file msg = hPutStrLn stderr $ file ++ ": " ++ msg
-collectResult ref result _ =
-    modifyIORef ref (\x -> crComments result ++ x)
+
+collectResult removeTabs ref cr sys = mapM_ f groups
+  where
+    comments = crComments cr
+    groups = groupWith sourceFile comments
+    f :: [PositionedComment] -> IO ()
+    f group = do
+        let filename = sourceFile (head group)
+        result <- siReadFile sys filename
+        let contents = either (const "") id result
+        let comments' = if removeTabs
+                        then makeNonVirtual comments contents
+                        else comments
+        modifyIORef ref (\x -> comments' ++ x)
 
 finish ref = do
     list <- readIORef ref