[#52] Implement WARNING/DEPRECATED in module header

data/examples/module-header/warning-pragma-list-multiline-out.hs

@@ -0,0 +1,11 @@
+module Test
+  {-# DEPRECATED
+    [ "This module is deprecated."
+    , "Please use OtherModule instead."
+    ]
+    #-}
+  ( foo
+  , bar
+  , baz
+  )
+where

data/examples/module-header/warning-pragma-list-multiline.hs

@@ -0,0 +1,8 @@
+module Test {-# DEPRECATED ["This module is deprecated.",
+  "Please use OtherModule instead."
+ ]#-}
+  ( foo
+  , bar
+  , baz
+  )
+where

data/examples/module-header/warning-pragma-multiline-out.hs

@@ -0,0 +1,8 @@
+module Test {-# DEPRECATED "This module is unstable" #-}
+  ( foo
+  , bar
+  , baz
+  )
+where
+
+import Blah

data/examples/module-header/warning-pragma-multiline.hs

@@ -0,0 +1,4 @@
+module Test {-# DEPRECATED "This module is unstable" #-}
+  (foo, bar, baz) where
+
+import Blah

data/examples/module-header/warning-pragma-out.hs

@@ -0,0 +1 @@
+module Test {-# WARNING "This module is very internal" #-} where

data/examples/module-header/warning-pragma-singleton-list-out.hs

@@ -0,0 +1 @@
+module Test {-# WARNING "There's only one line here." #-} where

data/examples/module-header/warning-pragma-singleton-list.hs

@@ -0,0 +1 @@
+module Test {-# WArnING ["There's only one line here."]     #-} where

data/examples/module-header/warning-pragma.hs

@@ -0,0 +1,2 @@
+module Test {-# WARNING "This module is very internal"
+  #-} where

src/Ormolu/Printer/Combinators.hs

@@ -38,6 +38,7 @@ module Ormolu.Printer.Combinators
   , parens
   , parensHash
   , pragmaBraces
+  , pragma
     -- ** Literals
   , comma
   , space
@@ -270,6 +271,19 @@ pragmaBraces m = sitcc $ do
   vlayout space (newline >> txt "  ")
   txt "#-}"
 
+-- | This surrounds the body in a pragma, which includes the 'pragmaBraces' and
+---  the keyword for the pragma. It also takes a 'SrcSpan', which should be the
+---  combined span of the body. This means multiline layouts are only triggered
+---  when the body spans multiple lines, not just when the braces or pragma
+---  keyword do.
+
+pragma :: SrcSpan -> Text -> R () -> R ()
+pragma srcSpan pragmaText body = switchLayout srcSpan . pragmaBraces $ do
+  txt pragmaText
+  breakpoint
+  inci body
+
+
 -- | Surround given entity by optional space before and a newline after, iff
 -- current layout is multiline.
 

src/Ormolu/Printer/Meat/Module.hs

@@ -1,3 +1,4 @@
+{-# LANGUAGE LambdaCase        #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE PatternSynonyms   #-}
 {-# LANGUAGE RecordWildCards   #-}
@@ -9,8 +10,10 @@ module Ormolu.Printer.Meat.Module
   )
 where
 
+import BasicTypes hiding (InlinePragma)
 import Control.Monad
 import Data.Maybe (isJust)
+import Data.Text (Text)
 import GHC
 import Ormolu.Imports
 import Ormolu.Printer.Combinators
@@ -35,6 +38,7 @@ p_hsModule loc@(L moduleSpan hsModule) = do
       Nothing -> pure ()
       Just hsmodName' -> line $ do
         located hsmodName' p_hsmodName
+        maybe (pure ()) (located' p_warningTxt) hsmodDeprecMessage
         case hsmodExports of
           Nothing -> return ()
           Just hsmodExports' -> do
@@ -59,6 +63,26 @@ p_hsModule loc@(L moduleSpan hsModule) = do
     when (trailingComments && isJust hsmodName) newline
     spitRemainingComments
 
+-- | Layout the WARNING/DEPRECATED pragmas in the module head
+
+p_warningTxt :: WarningTxt -> R ()
+p_warningTxt = \case
+  WarningTxt _ lits -> p_pragma "WARNING" lits
+  DeprecatedTxt _ lits -> p_pragma "DEPRECATED" lits
+  where
+    p_pragma :: Text -> [Located StringLiteral] -> R ()
+    p_pragma pragmaText lits = switchLayout (litsSpan lits) $ do
+      breakpoint
+      inci $ pragma (litsSpan lits) pragmaText (p_lits lits)
+
+    litsSpan :: [Located StringLiteral] -> SrcSpan
+    litsSpan lits = combineSrcSpans (getLoc $ head lits) (getLoc $ last lits)
+
+    p_lits :: [Located StringLiteral] -> R ()
+    p_lits = \case
+      [l] -> atom l
+      ls -> brackets . velt $ withSep comma atom ls
+
 -- | Determine if these declarations should be separated by a blank line.
 
 separatedDecls