Add comment-aware alternative filtering (type sig)

src-unittests/IdentityTests.hs

@@ -596,10 +596,12 @@ regressionTests = do
   it "comment inline placement (temporary)" $ do
     roundTripEqual $
       [text|
-      func :: Int -> -- basic indentation amount
-                     Int -> -- currently used width in current line (after indent)
-                            -- used to accurately calc placing of the current-line
-                            LayoutDesc -> Int
+      func
+        :: Int -- basic indentation amount
+        -> Int -- currently used width in current line (after indent)
+               -- used to accurately calc placing of the current-line
+        -> LayoutDesc
+        -> Int
       |]
   it "some indentation thingy" $ do
     roundTripEqual $

src/Language/Haskell/Brittany/LayoutBasics.hs

@@ -76,6 +76,7 @@ module Language.Haskell.Brittany.LayoutBasics
   , briDocMToPPM
   , allocateNode
   , docSharedWrapper
+  , hasAnyCommentsBelow
   )
 where
 
@@ -698,15 +699,15 @@ layoutWritePostComments ast = do
         layoutWriteAppendMultiline $ Text.pack $ comment
 
 layoutIndentRestorePostComment
-  :: ( Monad m
-     , MonadMultiState LayoutState m
+  :: ( MonadMultiState LayoutState m
      , MonadMultiWriter Text.Builder.Builder m
      , MonadMultiWriter (Seq String) m
      )
   => m ()
 layoutIndentRestorePostComment = do
-  mCommentCol <- _lstate_commentCol <$> mGet
-  eCurYAddNL  <- _lstate_curYOrAddNewline <$> mGet
+  state <- mGet
+  let mCommentCol = _lstate_commentCol state
+  let eCurYAddNL  = _lstate_curYOrAddNewline state
 #if INSERTTRACES
   tellDebugMessShow ("layoutIndentRestorePostComment", mCommentCol)
 #endif
@@ -714,7 +715,7 @@ layoutIndentRestorePostComment = do
   case (mCommentCol, eCurYAddNL) of
     (Just commentCol, Left{}) -> do
       layoutWriteEnsureNewlineBlock
-      layoutWriteEnsureAbsoluteN commentCol
+      layoutWriteEnsureAbsoluteN $ commentCol + fromMaybe 0 (_lstate_addSepSpace state)
     _                              -> return ()
 
 -- layoutWritePriorCommentsRestore :: (Data.Data.Data ast,
@@ -770,6 +771,14 @@ filterAnns :: Data.Data.Data ast
 filterAnns ast anns =
   Map.filterWithKey (\k _ -> k `Set.member` foldedAnnKeys ast) anns
 
+hasAnyCommentsBelow :: Data ast => GHC.Located ast -> ToBriDocM Bool
+hasAnyCommentsBelow ast@(L l _) = do
+  anns <- filterAnns ast <$> mAsk
+  return $ List.any (\(c, _) -> ExactPrint.commentIdentifier c > l) 
+         $ (=<<) extractAllComments
+         $ Map.elems
+         $ anns
+
 -- new BriDoc stuff
 
 allocateNode :: MonadMultiState NodeAllocIndex m

src/Language/Haskell/Brittany/Layouters/Decl.hs

@@ -37,18 +37,21 @@ import           Bag ( mapBagM )
 
 
 layoutSig :: ToBriDoc Sig
-layoutSig lsig@(L _loc sig) = docWrapNode lsig $ case sig of
-  TypeSig names (HsIB _ (HsWC _ _ typ)) -> do
+layoutSig lsig@(L _loc sig) = case sig of
+  TypeSig names (HsIB _ (HsWC _ _ typ)) -> docWrapNode lsig $ do
     nameStrs <- names `forM` lrdrNameToTextAnn
     let nameStr = Text.intercalate (Text.pack ", ") $ nameStrs
     typeDoc <- docSharedWrapper layoutType typ
-    docAlt
+    hasComments <- hasAnyCommentsBelow lsig
+    docAlt $
       [ docSeq
         [ appSep $ docWrapNodeRest lsig $ docLit nameStr
         , appSep $ docLit $ Text.pack "::"
         , docForceSingleline typeDoc
         ]
-      , docAddBaseY BrIndentRegular
+      | not hasComments
+      ] ++
+      [ docAddBaseY BrIndentRegular
       $ docPar
         (docWrapNodeRest lsig $ docLit nameStr)
         ( docCols ColTyOpPrefix
@@ -57,7 +60,7 @@ layoutSig lsig@(L _loc sig) = docWrapNode lsig $ case sig of
           ]
         )
       ]
-  _ -> briDocByExact lsig -- TODO: should not be necessary
+  _ -> briDocByExactNoComment lsig -- TODO
 
 layoutGuardLStmt :: ToBriDoc' (Stmt RdrName (LHsExpr RdrName))
 layoutGuardLStmt lgstmt@(L _ stmtLR) = docWrapNode lgstmt $ case stmtLR of