Improve one HsLet layout

- Allow parSpacing for single-clause layout
- Allow par/sl layout when no where-clause was present
  (not sure why this was disabled in the first place)

data/15-regressions.blt

@@ -917,8 +917,9 @@ alignColsLines layoutBriDocM bridocs = do -- colInfos `forM_` \colInfo -> do
         $ List.intersperse layoutWriteEnsureNewlineBlock
         $ colInfos <&> processInfo layoutBriDocM colMax processedMap
      where
-      (colInfos, finalState) =
+      (colInfos, finalState) = StateS.runState
-        StateS.runState (mergeBriDocs bridocs) (ColBuildState IntMapS.empty 0)
+        (mergeBriDocs bridocs)
+        (ColBuildState IntMapS.empty 0)
       -- maxZipper :: [Int] -> [Int] -> [Int]
       -- maxZipper [] ys = ys
       -- maxZipper xs [] = xs

source/library/Language/Haskell/Brittany/Internal/S3_ToBriDocTools.hs

@@ -242,6 +242,19 @@ hasCommentsBetween ast left right = do
     )
     ast
 
+startsWithComments :: EpAnn a -> Bool
+startsWithComments = \case
+  EpAnnNotUsed                         -> False
+  EpAnn (GHC.Anchor srcSpan _) _ comms -> case comms of
+    EpaComments cs                 -> anyCheck cs
+    EpaCommentsBalanced comms1 comms2 -> anyCheck comms1 || anyCheck comms2
+   where
+    anyCheck cs =
+      any
+        (\(L _ (GHC.EpaComment _ commSpan)) ->
+          GHC.realSrcSpanStart srcSpan == GHC.realSrcSpanStart commSpan
+        )
+        cs
 
 
   -- mAnn <- astAnn ast
@@ -523,6 +536,10 @@ instance DocHandleComms (EpAnn a) (ToBriDocM BriDocNumbered) where
         )
     EpAnnNotUsed -> bdm
 
+instance DocHandleComms (Maybe (EpAnn a)) (ToBriDocM BriDocNumbered) where
+  docHandleComms Nothing = id
+  docHandleComms (Just epAnn) = docHandleComms epAnn
+
 instance DocHandleComms (GHC.RealSrcSpan) (ToBriDocM BriDocNumbered) where
   docHandleComms loc = docHandleComms (GHC.realSrcSpanStart loc)
 

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

@@ -229,7 +229,7 @@ layoutLocalBinds binds = case binds of
 layoutGrhs
   :: LGRHS GhcPs (LHsExpr GhcPs)
   -> ToBriDocM
-       ( ToBriDocM BriDocNumbered -> ToBriDocM BriDocNumbered
+       ( Maybe (EpAnn GrhsAnn)
        , [BriDocNumbered]
        , BriDocNumbered
        )
@@ -239,7 +239,7 @@ layoutGrhs (L _ (GRHS epAnn guards body)) = do
     [] -> pure []
     _  -> docFlushCommsPost False posArrow $ callLayouter layout_stmt `mapM` guards
   bodyDoc <- callLayouter layout_expr body
-  return (docHandleComms epAnn, guardDocs, bodyDoc)
+  return (Just epAnn, guardDocs, bodyDoc)
 
 layoutPatternBind
   :: Maybe Text
@@ -409,17 +409,18 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
     clauseDocs <- case clauses of
       Left expr -> do
         e <- callLayouter layout_expr expr
-        pure [(id, [], e)]
+        pure [(Nothing, [], e)]
       Right grhss -> layoutGrhs `mapM` grhss
 
     runFilteredAlternative $ do
 
       case clauseDocs of
-        [(wrapClause, guards, body)] -> do
+        [(grhsEpAnn, guards, body)] -> do
-          let guardPart = wrapClause $ singleLineGuardsDoc guards
+          let grhsHasComms = hasAnyCommentsBelow grhsEpAnn
+          let guardPart = docHandleComms grhsEpAnn $ singleLineGuardsDoc guards
           forM_ wherePart $ \wherePart' ->
             -- one-line solution
-            addAlternativeCond (not hasComments) $ docCols
+            addAlternativeCond (not hasComments && not grhsHasComms) $ docCols
               (ColBindingLine alignmentToken)
               [ docSeq (patPartInline ++ [guardPart])
               , docSeq
@@ -429,13 +430,17 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
                 ]
               ]
           -- one-line solution + where in next line(s)
-          addAlternativeCond (Data.Maybe.isJust mWhereDocs)
+          addAlternativeCond (not $ maybe False startsWithComments grhsEpAnn)
             $ docLines
             $ [ docCols
                   (ColBindingLine alignmentToken)
                   [ docSeq (patPartInline ++ [guardPart])
                   , docSeq
                     [ appSep $ return binderDoc
+                      -- TODO I did it this way just to reduce test breakage,
+                      --      but arguably we should modify tests instead.
+                      --      I _think_ we really want to drop this alternative
+                      --      when grhsHasComms
                     , docForceParSpacing
                     $ docAddBaseY BrIndentRegular
                     $ return body
@@ -499,7 +504,7 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
                   , docSetBaseY
                   $ docLines
                   $ clauseDocs
-                  <&> \(wrapClause, guardDocs, bodyDoc) -> wrapClause $ do -- TODO92
+                  <&> \(epAnn, guardDocs, bodyDoc) -> docHandleComms epAnn $ do
                         let guardPart = singleLineGuardsDoc guardDocs
                         -- the docForceSingleline might seems superflous, but it
                         -- helps the alternative resolving impl.
@@ -525,7 +530,7 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
             $ docLines
             $ map docSetBaseY
             $ clauseDocs
-            <&> \(wrapClause, guardDocs, bodyDoc) -> wrapClause $ do -- TODO92
+            <&> \(epAnn, guardDocs, bodyDoc) -> docHandleComms epAnn $ do
                   let guardPart = singleLineGuardsDoc guardDocs
                   -- the docForceSingleline might seems superflous, but it
                   -- helps the alternative resolving impl.
@@ -552,8 +557,8 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
             $ docLines
             $ map docSetBaseY
             $ clauseDocs
-            <&> \(wrapClause, guardDocs, bodyDoc) -> -- TODO92
+            <&> \(grhsEpAnn, guardDocs, bodyDoc) -> -- TODO92
-                  wrapClause $ docSeq
+                  docHandleComms grhsEpAnn $ docSeq
                     $ (case guardDocs of
                         [] -> []
                         [g] ->
@@ -587,15 +592,15 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
             $ docLines
             $ map docSetBaseY
             $ clauseDocs
-            >>= \(wrapClause, guardDocs, bodyDoc) -> -- TODO92
+            >>= \(grhsEpAnn, guardDocs, bodyDoc) -> -- TODO92
                   (case guardDocs of
-                      [] -> [wrapClause docEmpty]
+                      [] -> [docHandleComms grhsEpAnn docEmpty]
                       [g] ->
-                        [ wrapClause $ docForceSingleline
+                        [ docHandleComms grhsEpAnn $ docForceSingleline
                             $ docSeq [appSep $ docLit $ Text.pack "|", return g]
                         ]
                       gs ->
-                        [ wrapClause $ docForceSingleline
+                        [ docHandleComms grhsEpAnn $ docForceSingleline
                             $ docSeq
                             $ [appSep $ docLit $ Text.pack "|"]
                             ++ List.intersperse docCommaSep (return <$> gs)
@@ -619,14 +624,18 @@ layoutPatternBindFinal alignmentToken binderDoc mPatDoc clauses (wrapBinds, mWhe
             $ docLines
             $ map docSetBaseY
             $ clauseDocs
-            >>= \(wrapClause, guardDocs, bodyDoc) -> -- TODO92
+            >>= \(grhsEpAnn, guardDocs, bodyDoc) -> -- TODO92
                   (case guardDocs of
-                      [] -> [wrapClause docEmpty]
+                      [] -> [docHandleComms grhsEpAnn docEmpty]
                       [g] ->
-                        [ wrapClause $ docSeq [appSep $ docLit $ Text.pack "|", return g]
+                        [ docHandleComms grhsEpAnn
+                        $ docSeq [appSep
+                        $ docLit $ Text.pack "|", return g]
                         ]
                       (g1 : gr) ->
-                        ( (wrapClause $ docSeq [appSep $ docLit $ Text.pack "|", return g1])
+                        ( ( docHandleComms grhsEpAnn
+                          $ docSeq [appSep $ docLit $ Text.pack "|", return g1]
+                          )
                         : (gr <&> \g ->
                             docSeq [appSep $ docLit $ Text.pack ",", return g]
                           )

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

@@ -202,7 +202,7 @@ data Layouters = Layouters
   , layout_grhs
     :: GHC.LGRHS GhcPs (GHC.LHsExpr GhcPs)
     -> ToBriDocM
-         ( ToBriDocM BriDocNumbered -> ToBriDocM BriDocNumbered
+         ( Maybe (GHC.EpAnn GHC.GrhsAnn)
          , [BriDocNumbered]
          , BriDocNumbered
          )