Improve comments-affecting-layout behaviour for tuples (#231)

src-literatetests/15-regressions.blt

@@ -802,3 +802,25 @@ zItazySunefp twgq nlyo lwojjoBiecao =
 #test module initial comment
 -- test
 module MyModule where
+
+#test issue 231
+
+foo =
+  [ ("xxx", "xx")
+  , --
+    ("xx" , "xx")
+    --
+  , ("xx" , "xxxxx")
+  , ("xx" , "xx")
+  ]
+
+#test issue 231 not
+
+foo =
+  [ ("xx", "xx")
+  , ( "xx" --
+    , "xx"
+    )
+  , ("xx", "xxxxx")
+  , ("xx", "xx")
+  ]

src/Language/Haskell/Brittany/Internal/LayouterBasics.hs

@@ -66,6 +66,7 @@ module Language.Haskell.Brittany.Internal.LayouterBasics
   , allocateNode
   , docSharedWrapper
   , hasAnyCommentsBelow
+  , hasCommentsBetween
   , hasAnyCommentsConnected
   , hasAnyCommentsPrior
   , hasAnyRegularCommentsConnected
@@ -299,6 +300,25 @@ hasAnyCommentsBelow ast@(L l _) =
   List.any (\(c, _) -> ExactPrint.commentIdentifier c > l)
     <$> astConnectedComments ast
 
+hasCommentsBetween
+  :: Data ast
+  => GHC.Located ast
+  -> AnnKeywordId
+  -> AnnKeywordId
+  -> ToBriDocM Bool
+hasCommentsBetween ast leftKey rightKey = do
+  mAnn <- astAnn ast
+  let go1 []         = False
+      go1 ((ExactPrint.G kw, _dp) : rest) | kw == leftKey = go2 rest
+      go1 (_ : rest) = go1 rest
+      go2 []         = False
+      go2 ((ExactPrint.AnnComment _, _dp) : _rest) = True
+      go2 ((ExactPrint.G kw, _dp) : _rest) | kw == rightKey = False
+      go2 (_ : rest) = go2 rest
+  case mAnn of
+    Nothing  -> pure False
+    Just ann -> pure $ go1 $ ExactPrint.annsDP ann
+
 -- | True if there are any comments that are connected to any node below (in AST
 --   sense) the given node
 hasAnyCommentsConnected :: Data ast => GHC.Located ast -> ToBriDocM Bool

src/Language/Haskell/Brittany/Internal/Layouters/Expr.hs

@@ -528,7 +528,10 @@ layoutExpr lexpr@(L _ expr) = do
       argDocs <- forM argExprs
         $ docSharedWrapper
         $ \(arg, exprM) -> docWrapNode arg $ maybe docEmpty layoutExpr exprM
-      hasComments <- hasAnyCommentsBelow lexpr
+      hasComments <- orM
+        ( hasCommentsBetween lexpr  AnnOpenP AnnCloseP
+        : map hasAnyCommentsBelow args
+        )
       let (openLit, closeLit) = case boxity of
             Boxed   -> (docLit $ Text.pack "(", docLit $ Text.pack ")")
             Unboxed -> (docParenHashLSep, docParenHashRSep)