Respect newlines in data declarations in more cases

CHANGELOG.md

@@ -7,6 +7,9 @@
 * Now command line options for fixity overrides and module re-exports
   overwrite information from `.ormolu` files. [Issue
   1030](https://github.com/tweag/ormolu/issues/1030).
+* Respect newlines in data declarations in more cases. [Issue
+  1077](https://github.com/tweag/ormolu/issues/1077) and [issue
+  947](https://github.com/tweag/ormolu/issues/947).
 
 ## Ormolu 0.7.3.0
 

data/examples/declaration/data/ctype-1-out.hs

@@ -0,0 +1,6 @@
+data
+  {-# CTYPE "header.h" "an-ffi-type-with-along-name" #-}
+  AnFFITypeWithAlongName = AnFFITypeWithAlongName
+  { a :: X,
+    b :: Y
+  }

data/examples/declaration/data/ctype-1.hs

@@ -0,0 +1,6 @@
+data
+  {-# CTYPE "header.h" "an-ffi-type-with-along-name"  #-}
+  AnFFITypeWithAlongName = AnFFITypeWithAlongName
+  { a :: X,
+    b :: Y
+  }

data/examples/declaration/data/field-layout/record-out.hs → data/examples/declaration/data/field-layout/record-0-out.hs

@@ -1,5 +1,3 @@
-module Main where
-
 -- | Foo.
 data Foo = Foo
   { -- | Something

data/examples/declaration/data/field-layout/record.hs → data/examples/declaration/data/field-layout/record-0.hs

@@ -1,5 +1,3 @@
-module Main where
-
 -- | Foo.
 
 data Foo = Foo

data/examples/declaration/data/field-layout/record-1-out.hs

@@ -0,0 +1,11 @@
+-- | Foo.
+data Foo
+  = Foo
+  { -- | Something
+    foo :: Foo Int Int,
+    -- | Something else
+    bar ::
+      Bar
+        Char
+        Char
+  }

data/examples/declaration/data/field-layout/record-1.hs

@@ -0,0 +1,10 @@
+-- | Foo.
+
+data Foo =
+  Foo
+  { foo :: Foo Int Int
+    -- ^ Something
+  , bar :: Bar Char
+           Char
+    -- ^ Something else
+  }

data/examples/declaration/data/field-layout/record-2-out.hs

@@ -0,0 +1,7 @@
+data IndexWithInfo schema
+  = forall x.
+  IndexWithInfo
+  { checkedIndex :: Index schema x,
+    checkedIndexName :: U.Variable,
+    checkedIndexType :: Type x
+  }

data/examples/declaration/data/field-layout/record-2.hs

@@ -0,0 +1,7 @@
+data IndexWithInfo schema =
+  forall x.
+  IndexWithInfo
+    { checkedIndex :: Index schema x
+    , checkedIndexName :: U.Variable
+    , checkedIndexType :: Type x
+    }

data/examples/declaration/data/simple-broken-out.hs

@@ -1,7 +1,8 @@
 module Main where
 
 -- | Here we go.
-data Foo = Foo {unFoo :: Int}
+data Foo
+  = Foo {unFoo :: Int}
   deriving (Eq)
 
 -- | And once again.

src/Ormolu/Printer/Meat/Declaration/Data.hs

@@ -50,42 +50,37 @@ p_dataDecl style name tyVars getTyVarLoc p_tyVar fixity HsDataDefn {..} = do
   txt $ case style of
     Associated -> mempty
     Free -> " instance"
-  case unLoc <$> dd_cType of
-    Nothing -> pure ()
-    Just (CType prag header (type_, _)) -> do
-      space
-      p_sourceText prag
-      case header of
-        Nothing -> pure ()
-        Just (Header h _) -> space *> p_sourceText h
-      space
-      p_sourceText type_
-      txt " #-}"
   let constructorSpans = getLocA name : fmap getTyVarLoc tyVars
       sigSpans = maybeToList . fmap getLocA $ dd_kindSig
+      contextSpans = maybeToList . fmap getLocA $ dd_ctxt
+      ctypeSpans = maybeToList . fmap getLocA $ dd_cType
       declHeaderSpans =
-        maybeToList (getLocA <$> dd_ctxt) ++ constructorSpans ++ sigSpans
-  switchLayout declHeaderSpans $ do
-    breakpoint
-    inci $ do
-      case dd_ctxt of
-        Nothing -> pure ()
-        Just ctxt -> do
-          located ctxt p_hsContext
-          space
-          txt "=>"
-          breakpoint
-      switchLayout constructorSpans $
-        p_infixDefHelper
-          (isInfix fixity)
-          True
-          (p_rdrName name)
-          (p_tyVar <$> tyVars)
-      forM_ dd_kindSig $ \k -> do
-        space
-        txt "::"
+        constructorSpans ++ sigSpans ++ contextSpans ++ ctypeSpans
+  switchLayout declHeaderSpans . inci $ do
+    case unLoc <$> dd_cType of
+      Nothing -> pure ()
+      Just (CType prag header (type_, _)) -> do
         breakpoint
-        inci $ located k p_hsType
+        p_sourceText prag
+        case header of
+          Nothing -> pure ()
+          Just (Header h _) -> space *> p_sourceText h
+        space
+        p_sourceText type_
+        txt " #-}"
+    breakpoint
+    forM_ dd_ctxt p_lhsContext
+    switchLayout constructorSpans $
+      p_infixDefHelper
+        (isInfix fixity)
+        True
+        (p_rdrName name)
+        (p_tyVar <$> tyVars)
+    forM_ dd_kindSig $ \k -> do
+      space
+      txt "::"
+      breakpoint
+      inci $ located k p_hsType
   let dd_cons' = case dd_cons of
         NewTypeCon a -> [a]
         DataTypeCons _ as -> as
@@ -100,12 +95,18 @@ p_dataDecl style name tyVars getTyVarLoc p_tyVar fixity HsDataDefn {..} = do
         sepSemi (located' (p_conDecl False)) dd_cons'
       else switchLayout (getLocA name : (getLocA <$> dd_cons')) . inci $ do
         let singleConstRec = isSingleConstRec dd_cons'
+            compactLayoutAroundEquals =
+              onTheSameLine
+                (getLocA name)
+                (combineSrcSpans' (conDeclConsSpans (unLoc (head dd_cons'))))
+            conDeclConsSpans = \case
+              ConDeclGADT {..} -> getLocA <$> con_names
+              ConDeclH98 {..} -> getLocA con_name :| []
         if hasHaddocks dd_cons'
           then newline
-          else
-            if singleConstRec
-              then space
-              else breakpoint
+          else if singleConstRec && compactLayoutAroundEquals
+                 then space
+                 else breakpoint
         equals
         space
         layout <- getLayout