Don't remove ticks on promoted data types

Author: jhmcstanton

lib/Language/Haskell/Stylish/Printer.hs

@@ -57,6 +57,7 @@ import           Prelude                         hiding (lines)
 
 --------------------------------------------------------------------------------
 import           ApiAnnotation                   (AnnKeywordId(..), AnnotationComment(..))
+import           BasicTypes                      (PromotionFlag(..))
 import           GHC.Hs.Extension                (GhcPs, NoExtField(..))
 import           GHC.Hs.Types                    (HsType(..))
 import           Module                          (ModuleName, moduleNameString)
@@ -229,7 +230,10 @@ putType ltp = case unLocated ltp of
     putRdrName op
     space
     putType rhs
-  HsTyVar NoExtField _ rdrName ->
+  HsTyVar NoExtField flag rdrName -> do
+    case flag of
+      IsPromoted  -> putText "'"
+      NotPromoted -> pure ()
     putRdrName rdrName
   HsTyLit _ tp ->
     putOutputable tp

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

@@ -70,6 +70,7 @@ tests = testGroup "Language.Haskell.Stylish.Step.Data.Tests"
     , testCase "case 55" case55
     , testCase "case 56" case56
     , testCase "case 57" case57
+    , testCase "case 58" case58
     ]
 
 case00 :: Assertion
@@ -1274,6 +1275,22 @@ case57 = assertSnippet (step defaultConfig)
     , "    }"
     ]
 
+-- | Should not break DataKinds in records
+--
+-- See https://github.com/jaspervdj/stylish-haskell/issues/330
+case58 :: Assertion
+case58 = expected @=? testStep (step sameIndentStyle) input
+  where
+    input = unlines
+      [ "module Herp where"
+      , ""
+      , "data Foo a = Foo"
+      , "               { foo :: Foo 'True"
+      , "               }"
+      ]
+
+    expected = input
+
 sameSameStyle :: Config
 sameSameStyle = Config SameLine SameLine 2 2 False True SameLine False True NoMaxColumns