Disable formatting of data types without records

lib/Language/Haskell/Stylish/Step/Data.hs

@@ -45,9 +45,15 @@ commentsWithin lb = filter within
 
 changeDecl :: [Comment] -> Int -> H.Decl LineBlock -> Maybe ChangeLine
 changeDecl _ _ (H.DataDecl _ (H.DataType _) Nothing _ [] _) = Nothing
-changeDecl allComments indentSize (H.DataDecl block (H.DataType _) Nothing dhead decls derivings) =
-  Just $ change block (const $ concat newLines)
+changeDecl allComments indentSize (H.DataDecl block (H.DataType _) Nothing dhead decls derivings)
+  | hasRecordFields = Just $ change block (const $ concat newLines)
+  | otherwise       = Nothing
   where
+    hasRecordFields = any
+      (\qual -> case qual of
+                  (H.QualConDecl _ _ _ (H.RecDecl {})) -> True
+                  _ -> False)
+      decls
     newLines = fmap constructors zipped ++ [fmap (indented . H.prettyPrint) derivings]
     zipped = zip decls ([1..] ::[Int])
     constructors (decl, 1) = processConstructor allComments typeConstructor indentSize decl

tests/Language/Haskell/Stylish/Step/Data/Tests.hs

@@ -30,6 +30,7 @@ tests = testGroup "Language.Haskell.Stylish.Step.Data.Tests"
     , testCase "case 17" case17
     , testCase "case 18" case18
     , testCase "case 19" case19
+    , testCase "case 20 (issue 262)" case20
     ]
 
 case00 :: Assertion
@@ -155,19 +156,14 @@ case07 = expected @=? testStep (step 2) input
     expected = input
 
 case08 :: Assertion
-case08 = expected @=? testStep (step 2) input
+case08 = input @=? testStep (step 2) input
   where
     input = unlines
       [ "module Herp where"
       , ""
       , "data Phantom a ="
       , "  Phantom"
       ]
-    expected = unlines
-      [ "module Herp where"
-      , ""
-      , "data Phantom a = Phantom"
-      ]
 
 case09 :: Assertion
 case09 = expected @=? testStep (step 4) input
@@ -389,3 +385,15 @@ case19 = expected @=? testStep (step 2) input
        , "  , age :: Int"
        , "  }"
        ]
+
+-- | Should not break Enums (data without records) formating
+--
+-- See https://github.com/jaspervdj/stylish-haskell/issues/262
+case20 :: Assertion
+case20 = input @=? testStep (step 2) input
+  where
+    input = unlines
+       [ "module Herp where"
+       , ""
+       , "data Tag = Title | Text deriving (Eq, Show)"
+       ]

tests/Language/Haskell/Stylish/Tests.hs

@@ -28,10 +28,12 @@ tests = testGroup "Language.Haskell.Stylish.Step.Tabs.Tests"
 case01 :: Assertion
 case01 = (@?= result) =<< format Nothing Nothing input
   where
-    input = "module Herp where\n data Foo = Bar | Baz"
+    input = "module Herp where\ndata Foo = Bar | Baz { baz :: Int }"
     result = Right [ "module Herp where"
                    , "data Foo = Bar"
                    , "    | Baz"
+                   , "    { baz :: Int"
+                   , "    }"
                    ]
 
 
@@ -47,10 +49,12 @@ case02 = withTestDirTree $ do
     actual <- format (Just $ ConfigPath "test-config.yaml") Nothing input
     actual @?= result
   where
-    input = "module Herp where\n data Foo = Bar | Baz"
+    input = "module Herp where\ndata Foo = Bar | Baz { baz :: Int }"
     result = Right [ "module Herp where"
                    , "data Foo = Bar"
                    , "  | Baz"
+                   , "  { baz :: Int"
+                   , "  }"
                    ]