Fix non-idempotent transformation of partly documented data definition

CHANGELOG.md

@@ -32,6 +32,9 @@
   syntax. [Issue 445](https://github.com/tweag/ormolu/issues/445) and [Issue
   428](https://github.com/tweag/ormolu/issues/428).
 
+* Fixed non-idempotent transformation of partly documented data definition.
+  [Issue 590](https://github.com/tweag/ormolu/issues/590).
+
 * Renamed the `--check-idempotency` flag to `--check-idempotence`.
   Apparently only the latter is correct.
 

data/examples/declaration/data/partly-documented-out.hs

@@ -0,0 +1,5 @@
+data Optimisation
+  = PETransform
+  | -- | partial eval and associated transforms
+    GeneralisedNatHack
+  deriving (Show, Eq, Generic)

data/examples/declaration/data/partly-documented.hs

@@ -0,0 +1,2 @@
+data Optimisation = PETransform | GeneralisedNatHack -- ^ partial eval and associated transforms
+  deriving (Show, Eq, Generic)

expected-failures/idris.txt

@@ -10,12 +10,6 @@ Formatting is not idempotent:
   after:  "   text op\n        <"
 Please, consider reporting the bug.
 
-Formatting is not idempotent:
-  src/Idris/Options.hs<rendered>:178:15
-  before: "ETransform | -- | pa"
-  after:  "ETransform\n  | -- | "
-Please, consider reporting the bug.
-
 The GHC parser (in Haddock mode) failed:
   src/Idris/Parser.hs:1052:1
   parse error on input `@'

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

@@ -72,10 +72,11 @@ p_dataDecl style name tpats fixity HsDataDefn {..} = do
                 else breakpoint
           equals
           space
+          layout <- getLayout
           let s =
-                vlayout
-                  (space >> txt "|" >> space)
-                  (newline >> txt "|" >> space)
+                if layout == MultiLine || hasHaddocks dd_cons
+                  then newline >> txt "|" >> space
+                  else space >> txt "|" >> space
               sitcc' =
                 if singleConstRec
                   then id