Respect inline configs that happen to appear deep in AST

comments between top-level decls should be considered
for inline-config. But despite being placed between
top-level decls, occasionally they get connected
somewhere nested inside the AST of the first decl.
We fix this by extracting such comments in a
pre-processing step. The control flow was significantly
altered to allow for this;
before:
  parsing -> extract inline configs
          -> compute final config(s)
          -> split module into head/decls/comments/whitespace
          -> ... bridoc -> transformations -> printing
after:
  parsing -> split module into head/decl/comments/whitespace
          -> extract inline configs respecting comments that
             got extracted from decls in the previous step
          -> compute final config(s)
          -> ... bridoc -> transformations -> printing

source/library/Language/Haskell/Brittany/Internal.hs

@@ -10,6 +10,8 @@ module Language.Haskell.Brittany.Internal
    -- re-export from utils:
   , extractCommentConfigs
   , TraceFunc(TraceFunc)
+  , Splitting.splitModuleDecls
+  , Splitting.extractDeclMap
   )
 where
 
@@ -17,7 +19,6 @@ import           Control.Monad.Trans.Except
 import           Data.CZipWith
 import qualified Data.Text                     as Text
 import qualified Data.Text.Lazy                as TextL
-import qualified GHC                     hiding ( parseModule )
 import qualified GHC.Driver.Session            as GHC
 import           GHC.Hs
 import qualified GHC.LanguageExtensions.Type   as GHC
@@ -29,6 +30,8 @@ import           Language.Haskell.Brittany.Internal.S3_ToBriDocTools
 import           Language.Haskell.Brittany.Internal.Prelude
 import qualified Language.Haskell.Brittany.Internal.S1_Parsing
                                                as Parsing
+import qualified Language.Haskell.Brittany.Internal.S2_SplitModule
+                                               as Splitting
 import           Language.Haskell.Brittany.Internal.StepOrchestrate
                                                 ( processModule )
 import           Language.Haskell.Brittany.Internal.Types
@@ -79,9 +82,13 @@ parsePrintModule traceFunc configWithDebugs inputText = runExceptT $ do
     case parseResult of
       Left  err -> throwE [ErrorInput err]
       Right x   -> pure x
+  let moduleElementList = Splitting.splitModuleDecls parsedSource
   (inlineConf, perItemConf) <-
     mapExceptT (fmap $ bimap (\(a, b) -> [ErrorMacroConfig a b]) id)
-      $ extractCommentConfigs (useTraceFunc traceFunc) parsedSource
+      $ extractCommentConfigs
+        (useTraceFunc traceFunc)
+        (Splitting.extractDeclMap parsedSource)
+        moduleElementList
   let moduleConfig = cZipWith fromOptionIdentity config inlineConf
   let disableFormatting =
         moduleConfig & _conf_disable_formatting & confUnpack
@@ -96,11 +103,12 @@ parsePrintModule traceFunc configWithDebugs inputText = runExceptT $ do
                 & _econf_omit_output_valid_check
                 & confUnpack
         (ews, outRaw) <- if hasCPP || omitCheck
-          then lift $ processModule traceFunc moduleConfig perItemConf parsedSource
+          then lift
+            $ processModule traceFunc moduleConfig perItemConf moduleElementList
           else lift $ pPrintModuleAndCheck traceFunc
                                            moduleConfig
                                            perItemConf
-                                           parsedSource
+                                           moduleElementList
         let hackF s = fromMaybe s
               $ TextL.stripPrefix (TextL.pack "-- BRITANY_INCLUDE_HACK ") s
         pure $ if hackAroundIncludes
@@ -134,11 +142,11 @@ pPrintModuleAndCheck
   :: TraceFunc
   -> Config
   -> PerItemConfig
-  -> GHC.ParsedSource
+  -> FinalList ModuleElement p
   -> IO ([BrittanyError], TextL.Text)
-pPrintModuleAndCheck traceFunc conf inlineConf parsedModule = do
+pPrintModuleAndCheck traceFunc conf inlineConf moduleElementList = do
   let ghcOptions     = conf & _conf_forward & _options_ghc & runIdentity
-  (errs, output) <- processModule traceFunc conf inlineConf parsedModule
+  (errs, output) <- processModule traceFunc conf inlineConf moduleElementList
   parseResult <- Parsing.parseModuleFromString ghcOptions
                                                "output"
                                                (\_ -> return $ Right ())
@@ -162,10 +170,14 @@ parsePrintModuleTests conf filename input = do
   case parseResult of
     Left  err               -> return $ Left err
     Right (parsedModule, _) -> runExceptT $ do
+      let moduleElementList = Splitting.splitModuleDecls parsedModule
       (inlineConf, perItemConf) <-
         mapExceptT
           (fmap (bimap (\(a, _) -> "when parsing inline config: " ++ a) id))
-          $ extractCommentConfigs (\_ -> pure ()) parsedModule
+          $ extractCommentConfigs
+            (\_ -> pure ())
+            (Splitting.extractDeclMap parsedModule)
+            moduleElementList
       let moduleConf = cZipWith fromOptionIdentity conf inlineConf
       let omitCheck =
             conf
@@ -176,11 +188,11 @@ parsePrintModuleTests conf filename input = do
         then lift $ processModule (TraceFunc $ \_ -> pure ())
                                    moduleConf
                                    perItemConf
-                                   parsedModule
+                                   moduleElementList
         else lift $ pPrintModuleAndCheck (TraceFunc $ \_ -> pure ())
                                          moduleConf
                                          perItemConf
-                                         parsedModule
+                                         moduleElementList
       if null errs
         then pure $ TextL.toStrict $ ltext
         else throwE

source/library/Language/Haskell/Brittany/Internal/Config/InlineParsing.hs

@@ -26,7 +26,7 @@ import           Control.Monad.Trans.Except
 
 import           Language.Haskell.Brittany.Internal.Config.Config
 import           Language.Haskell.Brittany.Internal.Config.Types
-import Language.Haskell.Brittany.Internal.Util.AST
+import Language.Haskell.Brittany.Internal.Types
 import Language.Haskell.Brittany.Internal.Config.Types.Instances1 ()
 import Language.Haskell.Brittany.Internal.Config.Types.Instances2 ()
 -- import Language.Haskell.Brittany.Internal.Utils
@@ -44,46 +44,26 @@ data InlineConfigTarget
 
 extractCommentConfigs
   :: (String -> IO ())
-  -> GHC.ParsedSource
+  -> Map GHC.RealSrcSpan [String]
+  -> FinalList ModuleElement a
   -> ExceptT (String, String) IO (CConfig Maybe, PerItemConfig)
-extractCommentConfigs _putErrorLn modul = do
+extractCommentConfigs _putErrorLn declMap moduleElementList = do
-  let (L _ (GHC.HsModule modAnn _ _ _ _ decls _ _)) = modul
+  let comments = concatMapFinal (void moduleElementList) $ \case
-  let declMap :: Map GHC.RealSrcSpan [String]
+        MEExactModuleHead modul -> case GHC.hsmodAnn $ GHC.unLoc modul of
-      declMap = Map.fromList
-        [ ( case span of
-            GHC.RealSrcSpan s _ -> s
-            GHC.UnhelpfulSpan _ -> error "unexpected UnhelpfulSpan"
-          , getDeclBindingNames decl
-          )
-        | decl <- decls
-        , let (L (GHC.SrcSpanAnn _ span) _) = decl
-        ]
-  let epAnnComms = \case
           GHC.EpAnn _ _ (GHC.EpaComments prior) -> prior
           GHC.EpAnn _ _ (GHC.EpaCommentsBalanced prior following) ->
             prior ++ following
           GHC.EpAnnNotUsed -> []
-  let gatheredComments =
+        MEPrettyModuleHead{}   -> []
-        join
+        MEImportDecl{}         -> []
-          $ epAnnComms modAnn
+        MEDecl{}               -> []
-          : [ epAnnComms epAnn | L (GHC.SrcSpanAnn epAnn _) _x <- decls ]
+        MEComment (_, comment) -> [comment]
-  -- gatheredComments `forM_` \comm@(L anchor _) -> do
+        MEWhitespace{}         -> []
-  --   liftIO $ putErrorLn $ showOutputable comm
-  --   case Map.lookupLE (GHC.anchor anchor) declMap of
-  --     Nothing -> pure ()
-  --     Just (pos, le) -> do
-  --       liftIO $ putErrorLn $ "  le = " ++ show (toConstr le) ++ " at " ++ show
-  --         (ExactPrint.Utils.ss2deltaEnd pos (GHC.anchor anchor))
-  --   case Map.lookupGE (GHC.anchor anchor) declMap of
-  --     Nothing -> pure ()
-  --     Just (pos, ge) -> do
-  --       liftIO $ putErrorLn $ "  ge = " ++ show (toConstr ge) ++ " at " ++ show
-  --         (ExactPrint.Utils.ss2deltaStart (GHC.anchor anchor) pos)
   lineConfigs <- sequence
     [ case Butcher.runCmdParserSimpleString line2 parser of
         Left  err            -> throwE (err, line2)
         Right (target, conf) -> pure $ (GHC.anchor anchr, target, conf)
-    | L anchr (EpaComment comm _) <- gatheredComments
+    | L anchr (EpaComment comm _) <- comments
     , Just line1                  <- case comm of
       EpaLineComment l ->
         [ List.stripPrefix "-- BRITTANY" l

source/library/Language/Haskell/Brittany/Internal/S2_SplitModule.hs

@@ -3,15 +3,17 @@
 -- TODO92
 
 module Language.Haskell.Brittany.Internal.S2_SplitModule
-  ( splitModule
+  ( extractDeclMap
-  )
+  , splitModuleDecls
-where
+  , splitModuleStart
+  ) where
 
 
 
 import           Language.Haskell.Brittany.Internal.Prelude
 
 import qualified Data.Generics                 as SYB
+import qualified Data.Map                      as Map
 import qualified GHC
 import           GHC                            ( AddEpAnn(AddEpAnn)
                                                 , Anchor(Anchor)
@@ -64,58 +66,41 @@ import qualified Language.Haskell.GHC.ExactPrint.Types
 import qualified Language.Haskell.GHC.ExactPrint.Utils
                                                as ExactPrint
 import           Safe                           ( maximumMay )
+import qualified Control.Monad.Trans.Writer.Strict
+                                               as WriterS
 
 import           Language.Haskell.Brittany.Internal.Components.BriDoc
 import           Language.Haskell.Brittany.Internal.ToBriDoc.Module
 import           Language.Haskell.Brittany.Internal.Types
+import           Language.Haskell.Brittany.Internal.Util.AST
 
 
 
-splitModule
+extractDeclMap :: GHC.ParsedSource -> Map GHC.RealSrcSpan [String]
-  :: Bool
+extractDeclMap modul =
-  -> GHC.ParsedSource
+  Map.fromList
-  -> Maybe GHC.RealSrcLoc
+    [ ( case span of
-  -> FinalList ModuleElement ExactPrint.Pos
+          GHC.RealSrcSpan s _ -> s
-splitModule shouldReformatHead lmod posWhere = do
+          GHC.UnhelpfulSpan _ -> error "unexpected UnhelpfulSpan"
+      , getDeclBindingNames decl
+      )
+    | decl <- decls
+    , let (L (GHC.SrcSpanAnn _ span) _) = decl
+    ]
+  where (L _ (GHC.HsModule _ _ _ _ _ decls _ _)) = modul
+
+splitModuleDecls :: GHC.ParsedSource -> FinalList ModuleElement ExactPrint.Pos
+splitModuleDecls lmod = do
   let L moduleSpan modl          = lmod
-      HsModule _ _layout _name _exports imports decls _ _ = modl
+      HsModule _ _layout _name _exports _imports decls _ _ = modl
       (hsModAnn', finalComments) = case GHC.hsmodAnn modl of
         EpAnn a modAnns (EpaCommentsBalanced prior post) ->
           (EpAnn a modAnns (EpaCommentsBalanced prior []), post)
         _ -> (GHC.hsmodAnn modl, [])
-      moduleWithoutComments =
+      moduleWithoutComments = L moduleSpan modl { GHC.hsmodAnn   = hsModAnn'
-        L moduleSpan modl { GHC.hsmodAnn = hsModAnn', GHC.hsmodDecls = [] }
+                                                , GHC.hsmodDecls = []
-  lastSpan <- if shouldReformatHead
+                                                }
-    then do
+  lastSpan <- do
-      finalYield $ MEPrettyModuleHead moduleWithoutComments
-      let locBeforeImports =
-            maximumMay 
-              $  [ realSrcSpanEnd $ anchor a
-                 | L a _ <- case hsModAnn' of
-                   EpAnn _ _ (EpaComments cs             ) -> cs
-                   EpAnn _ _ (EpaCommentsBalanced cs1 cs2) -> cs1 ++ cs2
-                   EpAnnNotUsed -> error "unexpected EpAnnNotUsed"
-                 ]
-              ++ [ pos | Just pos <- [posWhere] ]
-      let (importLines, lastSpan) = finalToList $ transformToImportLine
-            ( maybe 0 srcLocLine locBeforeImports
-            , maybe 1 srcLocCol  locBeforeImports
-            )
-            imports
-      let commentedImports = groupifyImportLines importLines
-      sortCommentedImports commentedImports `forM_` \case
-        EmptyLines n ->
-          finalYield $ MEWhitespace $ DifferentLine n 1
-        SamelineComment{} ->
-          error "brittany internal error: splitModule SamelineComment"
-        NewlineComment  comm   -> finalYield $ MEComment comm
-        ImportStatement record -> do
-          forM_ (commentsBefore record) $ finalYield . MEComment
-          finalYield
-            $ MEImportDecl (importStatement record) (commentsSameline record)
-          forM_ (commentsAfter record) $ finalYield . MEComment
-      pure $ lastSpan
-    else do
     finalYield $ MEExactModuleHead moduleWithoutComments
     pure
       $  maybe (1, 1) (ExactPrint.ss2posEnd)
@@ -134,12 +119,43 @@ splitModule shouldReformatHead lmod posWhere = do
            EpAnnNotUsed                        -> []
          ]
       ++ [ span
-           | L (SrcSpanAnn _ (GHC.RealSrcSpan span _)) _ <- GHC.hsmodImports
+         | L (SrcSpanAnn _ (GHC.RealSrcSpan span _)) _ <- GHC.hsmodImports modl
-             modl
          ]
   spanAfterDecls <- enrichDecls lastSpan decls
   enrichComms spanAfterDecls finalComments
 
+splitModuleStart
+  :: GHC.ParsedSource
+  -> Maybe GHC.RealSrcLoc
+  -> FinalList ModuleElement ExactPrint.Pos
+splitModuleStart modul posWhere = do
+  finalYield $ MEPrettyModuleHead modul
+  let locBeforeImports =
+        maximumMay
+          $  [ realSrcSpanEnd $ anchor a
+             | L a _ <- case GHC.hsmodAnn $ unLoc modul of
+               EpAnn _ _ (EpaComments cs             ) -> cs
+               EpAnn _ _ (EpaCommentsBalanced cs1 cs2) -> cs1 ++ cs2
+               EpAnnNotUsed -> error "unexpected EpAnnNotUsed"
+             ]
+          ++ [ pos | Just pos <- [posWhere] ]
+  let (importLines, lastSpan) = finalToList $ transformToImportLine
+        ( maybe 0 srcLocLine locBeforeImports
+        , maybe 1 srcLocCol  locBeforeImports
+        )
+        (GHC.hsmodImports $ unLoc modul)
+  let commentedImports = groupifyImportLines importLines
+  sortCommentedImports commentedImports `forM_` \case
+    EmptyLines n -> finalYield $ MEWhitespace $ DifferentLine n 1
+    SamelineComment{} ->
+      error "brittany internal error: splitModuleStart SamelineComment"
+    NewlineComment  comm   -> finalYield $ MEComment comm
+    ImportStatement record -> do
+      forM_ (commentsBefore record) $ finalYield . MEComment
+      finalYield $ MEImportDecl (importStatement record)
+                                (commentsSameline record)
+      forM_ (commentsAfter record) $ finalYield . MEComment
+  pure $ lastSpan
 
 enrichComms
   :: ExactPrint.Pos -> [LEpaComment] -> FinalList ModuleElement ExactPrint.Pos
@@ -150,60 +166,46 @@ enrichComms lastSpanEnd = \case
       SameLine i        -> SameLine i
       DifferentLine l c -> DifferentLine (l - 1) c
     enrichComms (ExactPrint.ss2posEnd span) commRest
-  (L (Anchor span _) (EpaComment comm _) : commRest) -> do
+  lcomm@(L (Anchor span _) _) : commRest -> do
     case ExactPrint.ss2delta lastSpanEnd span of
       SameLine i -> do
-        finalYield $ MEComment (i, comm)
+        finalYield $ MEComment (i, lcomm)
       DifferentLine l c -> do
         finalYield $ MEWhitespace $ DifferentLine (l - 1) c
-        finalYield $ MEComment (0, comm)
+        finalYield $ MEComment (0, lcomm)
     enrichComms (ExactPrint.ss2posEnd span) commRest
 
 enrichDecls
   :: ExactPrint.Pos -> [LHsDecl GhcPs] -> FinalList ModuleElement ExactPrint.Pos
 enrichDecls lastSpanEnd = \case
   [] -> finalPure $ lastSpanEnd
-  L (SrcSpanAnn dAnn rlspan@(GHC.RealSrcSpan span _)) decl : declRest ->
+  ldecl@(L (SrcSpanAnn dAnn (GHC.RealSrcSpan span _)) _) : declRest ->
     case dAnn of
-      EpAnn dAnchor items (EpaComments dComments) -> do
+      EpAnn _dAnchor _items (EpaComments _dComments) -> do
         let
-          (innerComments, outerComments) =
+          commentExtract
+            :: [LEpaComment] -> WriterS.Writer [LEpaComment] [LEpaComment]
+          commentExtract comms = do
+            let (innerComments, outerComments) =
                   partition
                     (\(L (Anchor anch _) _) ->
-                realSrcSpanStart anch < realSrcSpanEnd span
+                      (  realSrcSpanStart anch < realSrcSpanEnd span
+                      && realSrcSpanEnd anch > realSrcSpanStart span
                       )
-              dComments
-          withoutOuterComments =
-            (L
-              (SrcSpanAnn (EpAnn dAnchor items (EpaComments innerComments))
-                          rlspan
                     )
-              decl
+                    comms
-            )
+            WriterS.tell outerComments
-          commentExtract = \case
+            pure innerComments
-            L (GHC.Anchor anch _) EpaComment{} -> ExactPrint.ss2posEnd anch
+          (ldecl', extractedComments) = WriterS.runWriter
-          -- It would be really nice if `ExactPrint.ss2posEnd span` was
+            $ SYB.everywhereM (SYB.mkM commentExtract) ldecl
-          -- sufficient. But for some reason the comments are not
-          -- (consistently) included in the length of the anchor. I.e.
-          -- there are cases where a syntax tree node has an anchor from
-          -- pos A -> pos B. But then somewhere _below_ that node is a
-          -- comment that has an anchor pos B -> pos C.
-          -- We simply detect this here.
-          -- We probably do some redundant `SYB.everything` lookups
-          -- throughout the code now. But optimizing it is not easy, and
-          -- at worst it is larger constant factor on the size of the
-          -- input, so it isn't _that_ bad.
-          fixedSpanEnd =
-            SYB.everything
-              max
-              (SYB.mkQ (ExactPrint.ss2posEnd span) commentExtract)
-              decl
         case ExactPrint.ss2delta lastSpanEnd span of
           SameLine{} -> pure ()
           DifferentLine n _ ->
             finalYield $ MEWhitespace $ DifferentLine (n - 1) 1
+        let fixedSpanEnd = ExactPrint.ss2posEnd span
         let (afterComms, span2) = finalToList
-              $ enrichComms fixedSpanEnd (reverse outerComments)
+              $ enrichComms fixedSpanEnd
+                            (List.sortOn (\(L l _) -> l) extractedComments)
         let (immediate, later) =
               List.span
                 (\case
@@ -212,8 +214,9 @@ enrichDecls lastSpanEnd = \case
                 )
                 afterComms
         finalYield
-          $ MEDecl withoutOuterComments [ comm | MEComment comm <- immediate ]
+          $ MEDecl
-          -- $ MEDecl ldecl []
+            ldecl'
+            [ (ind, GHC.ac_tok comm) | MEComment (ind, L _ comm) <- immediate ]
         later `forM_` finalYield
         enrichDecls span2 declRest
       EpAnn _anchor _items (EpaCommentsBalanced{}) ->
@@ -227,8 +230,8 @@ enrichDecls lastSpanEnd = \case
 
 data ImportLine
   = EmptyLines Int
-  | SamelineComment (Int, EpaCommentTok)
+  | SamelineComment (Int, LEpaComment)
-  | NewlineComment  (Int, EpaCommentTok) -- indentation and comment
+  | NewlineComment  (Int, LEpaComment) -- indentation and comment
   | ImportStatement ImportStatementRecord
 
 instance Show ImportLine where
@@ -241,10 +244,10 @@ instance Show ImportLine where
         (length $ commentsAfter r)
 
 data ImportStatementRecord = ImportStatementRecord
-  { commentsBefore   :: [(Int, EpaCommentTok)]
+  { commentsBefore   :: [(Int, LEpaComment)]
   , importStatement  :: LImportDecl GhcPs
   , commentsSameline :: [(Int, EpaCommentTok)]
-  , commentsAfter    :: [(Int, EpaCommentTok)]
+  , commentsAfter    :: [(Int, LEpaComment)]
   }
 
 instance Show ImportStatementRecord where
@@ -263,13 +266,13 @@ transformToImportLine startPos is =
       :: [LEpaComment] -> ExactPrint.Pos -> FinalList ImportLine ExactPrint.Pos
     flattenComms = \case
       [] -> finalPure
-      (L (Anchor span _) (EpaComment comm _) : commRest) -> \lastSpanEnd -> do
+      lcomm@(L (Anchor span _) _) : commRest -> \lastSpanEnd -> do
         case ExactPrint.ss2delta lastSpanEnd span of
           SameLine i -> do
-            finalYield $ SamelineComment (i, comm)
+            finalYield $ SamelineComment (i, lcomm)
           DifferentLine l c -> do
             finalYield $ EmptyLines (l - 1)
-            finalYield $ NewlineComment (c - 1, comm)
+            finalYield $ NewlineComment (c - 1, lcomm)
         flattenComms commRest (ExactPrint.ss2posEnd span)
     flattenDecls
       :: [LImportDecl GhcPs]
@@ -285,14 +288,12 @@ transformToImportLine startPos is =
                 EpAnn anch s (EpaCommentsBalanced cs1 cs2) ->
                   (reverse cs1, reverse cs2, EpAnn anch s (EpaComments []))
                 EpAnnNotUsed -> ([], [], EpAnnNotUsed)
-          in
+          in  do
-            do
                 span1 <- flattenComms commsBefore lastSpanEnd
                 let newlines = case ExactPrint.ss2delta span1 declSpan of
                       SameLine _        -> 0
                       DifferentLine i _ -> i - 1
-              finalYield
+                finalYield $ EmptyLines newlines
-                $ EmptyLines newlines
                 finalYield $ ImportStatement ImportStatementRecord
                   { commentsBefore   = []
                   , importStatement  = L (SrcSpanAnn cleanEpAnn srcSpan) decl
@@ -306,15 +307,15 @@ transformToImportLine startPos is =
   in
     flattenDecls is startPos
 
-data Partial = PartialCommsOnly [(Int, EpaCommentTok)]
+data Partial = PartialCommsOnly [(Int, LEpaComment)]
              | PartialImport ImportStatementRecord
 
 groupifyImportLines :: [ImportLine] -> [ImportLine]
 groupifyImportLines ls = finalToList_ $ go (PartialCommsOnly []) ls
  where
   go acc [] = case acc of
-    PartialCommsOnly comms ->
+    PartialCommsOnly comms -> reverse comms `forM_` \comm ->
-      reverse comms `forM_` \comm -> finalYield $ NewlineComment comm
+      finalYield $ NewlineComment comm
     PartialImport partialRecord ->
       finalYield $ ImportStatement $ unpartial partialRecord
   go acc (line1 : lineR) = do
@@ -327,8 +328,9 @@ groupifyImportLines ls = finalToList_ $ go (PartialCommsOnly []) ls
         SamelineComment comm -> do
           pure $ PartialCommsOnly (comm : comms)
         NewlineComment  comm   -> pure $ PartialCommsOnly (comm : comms)
-        ImportStatement record ->
+        ImportStatement record -> pure $ PartialImport $ record
-          pure $ PartialImport $ record { commentsBefore = comms }
+          { commentsBefore = comms
+          }
       PartialImport partialRecord -> case line1 of
         e@EmptyLines{} -> do
           finalYield $ ImportStatement $ unpartial partialRecord
@@ -337,7 +339,8 @@ groupifyImportLines ls = finalToList_ $ go (PartialCommsOnly []) ls
         SamelineComment comm -> do
           if (null $ commentsAfter partialRecord)
             then pure $ PartialImport partialRecord
-              { commentsSameline = comm : commentsSameline partialRecord
+              { commentsSameline = tokenOnly comm
+                                   : commentsSameline partialRecord
               }
             else pure $ PartialImport partialRecord
               { commentsAfter = comm : commentsAfter partialRecord
@@ -353,6 +356,8 @@ groupifyImportLines ls = finalToList_ $ go (PartialCommsOnly []) ls
           pure $ PartialImport $ record { commentsBefore = contestedComments }
             -- comments in between will stay connected to the following decl
     go newAcc lineR
+  tokenOnly :: (Int, LEpaComment) -> (Int, EpaCommentTok)
+  tokenOnly (ind, L _ (EpaComment tok _)) = (ind, tok)
   unpartial :: ImportStatementRecord -> ImportStatementRecord
   unpartial partialRecord = ImportStatementRecord
     { commentsBefore   = reverse (commentsBefore partialRecord)
@@ -381,8 +386,8 @@ sortCommentedImports =
     Left  x -> [x]
     Right y -> ImportStatement <$> y
   sortGroups :: [ImportStatementRecord] -> [ImportStatementRecord]
-  sortGroups =
+  sortGroups = List.sortOn
-    List.sortOn (moduleNameString . unLoc . ideclName . unLoc . importStatement)
+    (moduleNameString . unLoc . ideclName . unLoc . importStatement)
   groupify :: [ImportLine] -> [Either ImportLine [ImportStatementRecord]]
   groupify cs = go [] cs
    where

source/library/Language/Haskell/Brittany/Internal/StepOrchestrate.hs

@@ -1,9 +1,9 @@
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE DataKinds #-}
 
 module Language.Haskell.Brittany.Internal.StepOrchestrate
   ( processModule
-  )
+  ) where
-where
 
 import           Language.Haskell.Brittany.Internal.Prelude
 
@@ -15,7 +15,8 @@ import qualified Data.Text.Lazy                as TextL
 import qualified Data.Text.Lazy.Builder        as TextL.Builder
 import qualified Data.Text.Lazy.Builder        as Text.Builder
 import qualified GHC
-import           GHC                            ( EpaCommentTok
+import           GHC                            ( EpaComment(EpaComment)
+                                                , EpaCommentTok
                                                   ( EpaBlockComment
                                                   , EpaEofComment
                                                   , EpaLineComment
@@ -36,7 +37,7 @@ import           Language.Haskell.Brittany.Internal.Config.Types
 import           Language.Haskell.Brittany.Internal.Config.Types.Instances2
                                                 ( )
 import           Language.Haskell.Brittany.Internal.S2_SplitModule
-                                                ( splitModule )
+                                                ( splitModuleStart )
 import           Language.Haskell.Brittany.Internal.S3_ToBriDocTools
 import           Language.Haskell.Brittany.Internal.S4_WriteBriDoc
                                                 ( ppBriDoc )
@@ -46,7 +47,8 @@ import           Language.Haskell.Brittany.Internal.ToBriDoc.Module
 import           Language.Haskell.Brittany.Internal.Types
 import           Language.Haskell.Brittany.Internal.Util.AST
 import           Language.Haskell.Brittany.Internal.Utils
-import           Language.Haskell.Brittany.Internal.ToBriDoc (layouters)
+import           Language.Haskell.Brittany.Internal.ToBriDoc
+                                                ( layouters )
 
 
 
@@ -58,18 +60,10 @@ processModule
   :: TraceFunc
   -> Config
   -> PerItemConfig
-  -> GHC.ParsedSource
+  -> FinalList ModuleElement p
   -> IO ([BrittanyError], TextL.Text)
-processModule traceFunc conf inlineConf parsedModule = do
+processModule traceFunc conf inlineConf moduleElems = do
-  let shouldReformatHead =
+  let FinalList moduleElementsStream = moduleElems
-        conf & _conf_layout & _lconfig_reformatModulePreamble & confUnpack
-  let
-    wrapNonDeclToBriDoc = MultiRWSS.withMultiReader conf
-      . MultiRWSS.withMultiState_ (CommentCounter 0)
-    FinalList moduleElementsStream = splitModule
-      shouldReformatHead
-      parsedModule
-      (fmap GHC.realSrcSpanStart $ obtainAnnPos (GHC.hsmodAnn $ GHC.unLoc parsedModule) GHC.AnnWhere)
       ((out, errs), debugStrings) =
         runIdentity
           $ MultiRWSS.runMultiRWSTNil
@@ -79,59 +73,7 @@ processModule traceFunc conf inlineConf parsedModule = do
           $ MultiRWSS.withMultiReader traceFunc
           $ moduleElementsStream
               (\modElem cont -> do
-              case modElem of
+                processModuleElement modElem
-                MEExactModuleHead modHead -> wrapNonDeclToBriDoc $ do
-                  bdMay <- ppModuleHead modHead
-                  case bdMay of
-                    Nothing -> pure ()
-                    Just bd -> ppBriDoc bd True
-                MEPrettyModuleHead (L loc modHead) -> wrapNonDeclToBriDoc $ do
-                  case modHead of
-                    HsModule epAnn _layoutInfo Nothing Nothing _ _ _ _ -> do
-                      (bd, _) <-
-                        briDocMToPPM layouters
-                        $ maybe id
-                                docFlushRemaining
-                                (srcSpanFileName_maybe loc)
-                        $ docHandleComms epAnn docSeparator
-                      ppBriDoc bd True
-                    HsModule _ _layoutInfo Nothing Just{} _ _ _ _ -> error
-                      "brittany internal error: exports without module name"
-                    HsModule epAnn _layoutInfo (Just n) les _ _ _ _ -> do
-                      (bd, _) <-
-                        briDocMToPPM layouters
-                        $ maybe id
-                                docFlushRemaining
-                                (srcSpanFileName_maybe loc)
-                        $ moduleNameExportBridoc epAnn n les
-                      ppBriDoc bd True
-                MEImportDecl importDecl immediateAfterComms ->
-                  wrapNonDeclToBriDoc $ do
-                    (bd, _) <-
-                      briDocMToPPM layouters
-                        $ docSeq
-                            ( layoutImport importDecl
-                            : map commentToDoc immediateAfterComms
-                            )
-                    ppBriDoc bd False
-                MEDecl decl immediateAfterComms -> do
-                  let declConfig = getDeclConfig conf inlineConf decl
-                  MultiRWSS.withMultiReader declConfig
-                    $ MultiRWSS.withMultiState_ (CommentCounter 0)
-                    $ ppToplevelDecl decl immediateAfterComms
-                MEComment (ind, EpaLineComment str) -> do
-                  mTell $ TextL.Builder.fromString (replicate ind ' ' ++ str)
-                  mTell $ TextL.Builder.fromString "\n"
-                MEComment (ind, EpaBlockComment str) -> do
-                  mTell $ TextL.Builder.fromString (replicate ind ' ' ++ str)
-                  mTell $ TextL.Builder.fromString "\n"
-                MEComment (_, EpaEofComment) -> pure ()
-                MEComment _ ->
-                  mTell $ TextL.Builder.fromString "some other comment"
-                MEWhitespace dp -> do
-                  -- mTell $ TextL.Builder.fromString "B"
-                  -- mTell $ TextL.Builder.fromString ("whitespace " ++ show dp)
-                  ppmMoveToExactLoc dp
                 cont
               )
               (\x -> do
@@ -151,14 +93,94 @@ processModule traceFunc conf inlineConf parsedModule = do
   --       MEExactModuleHead{}  -> useTraceFunc traceFunc "MEExactModuleHead"
   --       MEPrettyModuleHead{} -> useTraceFunc traceFunc "MEPrettyModuleHead"
   --       MEImportDecl{}       -> useTraceFunc traceFunc "MEImportDecl"
-  --       MEDecl decl _        -> useTraceFunc traceFunc ("MEDecl " ++ intercalate "," (getDeclBindingNames decl))
+  --       MEDecl decl _ ->
-  --       MEComment (y, EpaLineComment str) -> useTraceFunc traceFunc ("MEComment " ++ show y ++ " " ++ str)
+  --         useTraceFunc
-  --       MEComment (y, _) -> useTraceFunc traceFunc ("MEComment " ++ show y ++ " _")
+  --           traceFunc
+  --           ("MEDecl " ++ intercalate "," (getDeclBindingNames decl))
+  --       MEComment (y, L _ (EpaComment (EpaLineComment str) _)) ->
+  --         useTraceFunc traceFunc ("MEComment " ++ show y ++ " " ++ str)
+  --       MEComment (y, L _ (EpaComment (EpaBlockComment str) _)) ->
+  --         useTraceFunc traceFunc ("MEComment " ++ show y ++ " " ++ take 5 str)
+  --       MEComment (y, _) ->
+  --         useTraceFunc traceFunc ("MEComment " ++ show y ++ " _")
   --       MEWhitespace dp -> useTraceFunc traceFunc ("MEWhitespace " ++ show dp)
   --     rest
   --   )
   --   (\_ -> pure ())
   pure (errs, TextL.Builder.toLazyText out)
+ where
+  shouldReformatHead =
+    conf & _conf_layout & _lconfig_reformatModulePreamble & confUnpack
+  wrapNonDeclToBriDoc =
+    MultiRWSS.withMultiReader conf . MultiRWSS.withMultiState_
+      (CommentCounter 0)
+  processModuleElement
+    :: ModuleElement
+    -> MultiRWSS.MultiRWST
+         '[TraceFunc]
+         '[Text.Builder.Builder , [BrittanyError] , Seq String]
+         '[]
+         Identity
+         ()
+  processModuleElement = \case
+    MEExactModuleHead modHead -> if shouldReformatHead
+      then do
+        let FinalList startElems =
+              splitModuleStart
+                modHead
+                ( fmap GHC.realSrcSpanStart
+                $ obtainAnnPos (GHC.hsmodAnn $ GHC.unLoc modHead) GHC.AnnWhere
+                )
+        startElems
+          (\modElem cont -> do
+            processModuleElement modElem
+            cont
+          )
+          (\_ -> pure ())
+      else wrapNonDeclToBriDoc $ do
+        bdMay <- ppModuleHead modHead
+        case bdMay of
+          Nothing -> pure ()
+          Just bd -> do
+            ppBriDoc bd True
+        mTell $ Text.Builder.fromString "\n"
+    MEPrettyModuleHead (L loc modHead) -> wrapNonDeclToBriDoc $ do
+      case modHead of
+        HsModule epAnn _layoutInfo Nothing Nothing _ _ _ _ -> do
+          (bd, _) <-
+            briDocMToPPM layouters
+            $ maybe id docFlushRemaining (srcSpanFileName_maybe loc)
+            $ docHandleComms epAnn docSeparator
+          ppBriDoc bd True
+        HsModule _ _layoutInfo Nothing Just{} _ _ _ _ ->
+          error "brittany internal error: exports without module name"
+        HsModule epAnn _layoutInfo (Just n) les _ _ _ _ -> do
+          (bd, _) <-
+            briDocMToPPM layouters
+            $ maybe id docFlushRemaining (srcSpanFileName_maybe loc)
+            $ moduleNameExportBridoc epAnn n les
+          ppBriDoc bd True
+    MEImportDecl importDecl immediateAfterComms -> wrapNonDeclToBriDoc $ do
+      (bd, _) <- briDocMToPPM layouters $ docSeq
+        (layoutImport importDecl : map commentToDoc immediateAfterComms)
+      ppBriDoc bd False
+    MEDecl decl immediateAfterComms -> do
+      let declConfig = getDeclConfig conf inlineConf decl
+      MultiRWSS.withMultiReader declConfig
+        $ MultiRWSS.withMultiState_ (CommentCounter 0)
+        $ ppToplevelDecl decl immediateAfterComms
+    MEComment (ind, L _ (EpaComment (EpaLineComment str) _)) -> do
+      mTell $ TextL.Builder.fromString (replicate ind ' ' ++ str)
+      mTell $ TextL.Builder.fromString "\n"
+    MEComment (ind, L _ (EpaComment (EpaBlockComment str) _)) -> do
+      mTell $ TextL.Builder.fromString (replicate ind ' ' ++ str)
+      mTell $ TextL.Builder.fromString "\n"
+    MEComment (_, L _ (EpaComment EpaEofComment _)) -> pure ()
+    MEComment    _  -> mTell $ TextL.Builder.fromString "some other comment"
+    MEWhitespace dp -> do
+      -- mTell $ TextL.Builder.fromString "B"
+      -- mTell $ TextL.Builder.fromString ("whitespace " ++ show dp)
+      ppmMoveToExactLoc dp
 
 commentToDoc :: (Int, EpaCommentTok) -> ToBriDocM BriDocNumbered
 commentToDoc (indent, c) = case c of
@@ -198,17 +220,13 @@ processDefault x = do
     _    -> mTell $ Text.Builder.fromString $ List.dropWhileEnd ((==) '\n') str
 
 
-getDeclConfig
+getDeclConfig :: Config -> PerItemConfig -> GHC.LHsDecl GhcPs -> Config
-  :: Config
-  -> PerItemConfig
-  -> GHC.LHsDecl GhcPs
-  -> Config
 getDeclConfig config inlineConf decl = cZipWith fromOptionIdentity config
   $ mconcat (catMaybes (mBindingConfs ++ [mDeclConf]))
  where
   declBindingNames = getDeclBindingNames decl
-  mBindingConfs =
+  mBindingConfs    = declBindingNames <&> \n ->
-    declBindingNames <&> \n -> Map.lookup n $ _icd_perBinding inlineConf
+    Map.lookup n $ _icd_perBinding inlineConf
   mDeclConf = case GHC.locA $ GHC.getLoc decl of
     GHC.RealSrcSpan x _ -> Map.lookup x $ _icd_perAnchor inlineConf
     GHC.UnhelpfulSpan{} -> Nothing
@@ -218,16 +236,15 @@ ppToplevelDecl decl immediateAfterComms = do
   exactprintOnly <- mAsk <&> \declConfig ->
     declConfig & _conf_roundtrip_exactprint_only & confUnpack
   bd <- fmap fst $ if exactprintOnly
-    then briDocMToPPM layouters
+    then briDocMToPPM layouters $ docSeq
-      $ docSeq
       (briDocByExactNoComment decl : map commentToDoc immediateAfterComms)
     else do
       let innerDoc = case decl of
             L (SrcSpanAnn _ (GHC.RealSrcSpan s _)) _ ->
               docFlushRemaining (GHC.srcSpanFile s) $ layoutDecl decl
             _ -> layoutDecl decl
-      (r, errorCount) <- briDocMToPPM layouters
+      (r, errorCount) <- briDocMToPPM layouters $ docSeq
-        $ docSeq (innerDoc : map commentToDoc immediateAfterComms)
+        (innerDoc : map commentToDoc immediateAfterComms)
       if errorCount == 0
         then pure (r, 0)
         else briDocMToPPM layouters $ briDocByExactNoComment decl

source/library/Language/Haskell/Brittany/Internal/Types.hs

@@ -24,6 +24,7 @@ import           GHC                            ( Anno
                                                 , ParsedSource
                                                 , XRec
                                                 , LImportDecl
+                                                , LEpaComment
                                                 )
 import GHC.Utils.Outputable(Outputable)
 import Language.Haskell.Brittany.Internal.Config.Types
@@ -89,6 +90,8 @@ finalToList_ :: FinalList a () -> [a]
 finalToList_ (FinalList l) = l (:) (\() -> [])
 finalToList :: FinalList a b -> ([a], b)
 finalToList (FinalList l) = l (\x (a, b) -> (x:a, b)) (\b -> ([], b))
+concatMapFinal :: FinalList a () -> (a -> [b]) -> [b]
+concatMapFinal (FinalList l) f = l (\x rest -> f x ++ rest) (\() -> [])
 
 instance Functor (FinalList a) where
   fmap = _finalRMap
@@ -119,7 +122,7 @@ data ModuleElement
     -- ^ an import decl, only occurs if pretty-printing the module head.
   | MEDecl (LHsDecl GhcPs) [(Int, EpaCommentTok)]
     -- ^ a top-level declaration
-  | MEComment (Int, EpaCommentTok)
+  | MEComment (Int, LEpaComment)
     -- ^ a top-level comment, i.e. a comment located between top-level elements
     --   (and not associated to some nested node, which might in theory happen).
     --   The Int carries the indentation of the comment.

source/library/Language/Haskell/Brittany/Main.hs

@@ -381,9 +381,15 @@ coreIO putErrorLnIO config suppressOutput checkMode inputPathM outputPathM =
         putErrorLn left
         ExceptT.throwE 60
       Right (parsedSource, hasCPP) -> do
+        let moduleElementList = splitModuleDecls parsedSource
         (inlineConf, perItemConf) <- do
           resE <-
-            liftIO $ ExceptT.runExceptT $ extractCommentConfigs putErrorLnIO parsedSource
+            liftIO
+              $ ExceptT.runExceptT
+              $ extractCommentConfigs
+                putErrorLnIO
+                (extractDeclMap parsedSource)
+                moduleElementList
           case resE of
             Left (err, input) -> do
               putErrorLn $ "Error: parse error in inline configuration:"
@@ -414,9 +420,9 @@ coreIO putErrorLnIO config suppressOutput checkMode inputPathM outputPathM =
                     .> _econf_omit_output_valid_check
                     .> confUnpack
               (ews, outRaw) <- if hasCPP || omitCheck
-                then liftIO $ processModule (TraceFunc putErrorLnIO) moduleConf perItemConf parsedSource
+                then liftIO $ processModule (TraceFunc putErrorLnIO) moduleConf perItemConf moduleElementList
                 else liftIO
-                  $ pPrintModuleAndCheck (TraceFunc putErrorLnIO) moduleConf perItemConf parsedSource
+                  $ pPrintModuleAndCheck (TraceFunc putErrorLnIO) moduleConf perItemConf moduleElementList
               let
                 hackF s = fromMaybe s $ TextL.stripPrefix
                   (TextL.pack "-- BRITANY_INCLUDE_HACK ")