Better handle multi-line following comments

data/examples/declaration/foreign/foreign-export-out.hs

@@ -2,7 +2,7 @@ foreign export ccall foo :: Int -> IO Int
 
 -- | 'foreignTomFun' is a very important thing
 foreign export ccall "tomography"
-  foreignTomFun :: StablePtr Storage -> TomForegin {- Storage is bad -}
+  foreignTomFun :: StablePtr Storage {- Storage is bad -} -> TomForegin
 
 foreign export {- We can't use capi here -} ccall "dynamic"
   export_nullaryMeth :: (IO HRESULT) -> IO (Ptr ())

data/examples/declaration/foreign/foreign-import-out.hs

@@ -17,7 +17,7 @@ foreign import javascript
 
 foreign import {- We use capi here -} capi "pi.h value pi" c_pi :: CDouble
 
-foreign import stdcall "dynamic" {- This is a bad place for a comment -}
+foreign import stdcall {- This is a bad place for a comment -} "dynamic"
   dyn_gluBeginSurface
     :: FunPtr (Ptr GLUnurbs -> IO ())
     -- ^ This 'FunPtr' is extremely dangerous, beware

data/examples/declaration/value/function/operator-comments-0-out.hs

@@ -7,10 +7,10 @@ foo =
 
 foo =
   bar
-    ++ case foo of {- some comment -}
+    ++ {- some comment -} case foo of
       a -> a
 
 foo =
   bar
-    ++ case foo of {- some comment -}
+    ++ case foo {- some comment -} of
       a -> a

data/examples/declaration/value/function/operator-comments-1-out.hs

@@ -0,0 +1,16 @@
+foo =
+  bar
+    ++
+    -- some comment
+    case foo of
+      a -> a
+
+foo =
+  bar
+    ++ case foo of -- some comment
+      a -> a
+
+foo =
+  bar
+    ++ case foo of -- some comment
+      a -> a

data/examples/declaration/value/function/operator-comments-1.hs

@@ -0,0 +1,17 @@
+foo =
+  bar
+  ++
+    -- some comment
+    case foo of
+      a -> a
+
+foo =
+  bar
+    ++ -- some comment
+    case foo of
+      a -> a
+
+foo =
+  bar
+    ++ case foo of -- some comment
+      a -> a

data/examples/other/comment-multiline-after-out.hs

@@ -0,0 +1 @@
+foo :: Int {- ^ start index -} -> Int {- ^ length -} -> t a -> t a

data/examples/other/comment-multiline-after.hs

@@ -0,0 +1 @@
+foo :: Int {- ^ start index -} -> Int {- ^ length -} -> t a -> t a

src/Ormolu/Parser/CommentStream.hs

@@ -11,6 +11,7 @@ module Ormolu.Parser.CommentStream
   , Comment (..)
   , mkCommentStream
   , isPrevHaddock
+  , isMultilineComment
   , showCommentStream
   )
 where
@@ -71,6 +72,11 @@ mkCommentStream extraComments pstate =
 isPrevHaddock :: Comment -> Bool
 isPrevHaddock (Comment (x :| _)) = "-- ^" `isPrefixOf` x
 
+-- | Is this comment multiline-style?
+
+isMultilineComment :: Comment -> Bool
+isMultilineComment (Comment (x :| _)) = "{-" `isPrefixOf` x
+
 -- | Pretty-print a 'CommentStream'.
 
 showCommentStream :: CommentStream -> String

src/Ormolu/Printer/Comments.hs

@@ -91,7 +91,9 @@ spitFollowingComment (L ref a) mlastSpn = do
   meSpn <- getEnclosingSpan (/= ref)
   withPoppedComment (commentFollowsElt ref mnSpn meSpn mlastSpn) $ \l comment ->
     if theSameLinePost l ref && not (isModule a)
-      then spitCommentPending OnTheSameLine l comment
+      then if isMultilineComment comment
+             then space >> spitCommentNow l comment
+             else spitCommentPending OnTheSameLine l comment
       else do
         when (needsNewlineBefore l mlastSpn) $
           registerPendingCommentLine OnNextLine ""