Merge branch 'ghc-head' into ghc-9.0

23 files changed, 1287 insertions, 924 deletions

diff --git a/haddock-api/haddock-api.cabal b/haddock-api/haddock-api.cabal
index f3dbe2e2..e6de8b81 100644
--- a/haddock-api/haddock-api.cabal
+++ b/haddock-api/haddock-api.cabal
@@ -43,8 +43,8 @@ library
   default-language: Haskell2010
 
   -- this package typically supports only single major versions
-  build-depends: base            ^>= 4.15.0
-               , ghc             ^>= 9.0
+  build-depends: base            ^>= 4.16.0
+               , ghc             ^>= 9.1
                , ghc-paths       ^>= 0.1.0.9
                , haddock-library ^>= 1.9.0
                , xhtml           ^>= 3000.2.2
@@ -60,6 +60,7 @@ library
                , exceptions
                , filepath
                , ghc-boot
+               , mtl
                , transformers
 
   hs-source-dirs: src
@@ -173,7 +174,7 @@ test-suite spec
     Haddock.Backends.Hyperlinker.Parser
     Haddock.Backends.Hyperlinker.Types
 
-  build-depends: ghc             ^>= 9.0
+  build-depends: ghc             ^>= 9.1
                , ghc-paths       ^>= 0.1.0.12
                , haddock-library ^>= 1.9.0
                , xhtml           ^>= 3000.2.2
diff --git a/haddock-api/src/Haddock.hs b/haddock-api/src/Haddock.hs
index 8dfee5bc..2b6e2d57 100644
--- a/haddock-api/src/Haddock.hs
+++ b/haddock-api/src/Haddock.hs
@@ -70,6 +70,7 @@ import GHC hiding (verbosity)
 import GHC.Settings.Config
 import GHC.Driver.Session hiding (projectVersion, verbosity)
 import GHC.Utils.Outputable (defaultUserStyle, withPprStyle)
+import GHC.Driver.Env
 import GHC.Utils.Error
 import GHC.Unit
 import GHC.Utils.Panic (handleGhcException)
@@ -152,12 +153,17 @@ haddockWithGhc ghc args = handleTopExceptions $ do
   sinceQual <- rightOrThrowE (sinceQualification flags)
 
   -- inject dynamic-too into flags before we proceed
-  flags' <- ghc flags $ do
+  flags'' <- ghc flags $ do
         df <- getDynFlags
         case lookup "GHC Dynamic" (compilerInfo df) of
           Just "YES" -> return $ Flag_OptGhc "-dynamic-too" : flags
           _ -> return flags
 
+  flags' <- pure $ case optParCount flags'' of
+    Nothing       -> flags''
+    Just Nothing  -> Flag_OptGhc "-j" : flags''
+    Just (Just n) -> Flag_OptGhc ("-j" ++ show n) : flags''
+
   -- bypass the interface version check
   let noChecks = Flag_BypassInterfaceVersonCheck `elem` flags
 
@@ -179,6 +185,7 @@ haddockWithGhc ghc args = handleTopExceptions $ do
 
   ghc flags' $ withDir $ do
     dflags <- getDynFlags
+    unit_state <- hsc_units <$> getSession
 
     forM_ (optShowInterfaceFile flags) $ \path -> liftIO $ do
       mIfaceFile <- readInterfaceFiles freshNameCache [(("", Nothing), path)] noChecks
@@ -196,7 +203,7 @@ haddockWithGhc ghc args = handleTopExceptions $ do
           }
 
       -- Render the interfaces.
-      liftIO $ renderStep dflags flags sinceQual qual packages ifaces
+      liftIO $ renderStep dflags unit_state flags sinceQual qual packages ifaces
 
     else do
       when (any (`elem` [Flag_Html, Flag_Hoogle, Flag_LaTeX]) flags) $
@@ -206,7 +213,7 @@ haddockWithGhc ghc args = handleTopExceptions $ do
       packages <- liftIO $ readInterfaceFiles freshNameCache (readIfaceArgs flags) noChecks
 
       -- Render even though there are no input files (usually contents/index).
-      liftIO $ renderStep dflags flags sinceQual qual packages []
+      liftIO $ renderStep dflags unit_state flags sinceQual qual packages []
 
 -- | Run the GHC action using a temporary output directory
 withTempOutputDir :: Ghc a -> Ghc a
@@ -255,9 +262,9 @@ readPackagesAndProcessModules flags files = do
     return (packages, ifaces, homeLinks)
 
 
-renderStep :: DynFlags -> [Flag] -> SinceQual -> QualOption
+renderStep :: DynFlags -> UnitState -> [Flag] -> SinceQual -> QualOption
            -> [(DocPaths, InterfaceFile)] -> [Interface] -> IO ()
-renderStep dflags flags sinceQual nameQual pkgs interfaces = do
+renderStep dflags unit_state flags sinceQual nameQual pkgs interfaces = do
   updateHTMLXRefs pkgs
   let
     ifaceFiles = map snd pkgs
@@ -266,12 +273,12 @@ renderStep dflags flags sinceQual nameQual pkgs interfaces = do
       ((_, Just path), ifile) <- pkgs
       iface <- ifInstalledIfaces ifile
       return (instMod iface, path)
-  render dflags flags sinceQual nameQual interfaces installedIfaces extSrcMap
+  render dflags unit_state flags sinceQual nameQual interfaces installedIfaces extSrcMap
 
 -- | Render the interfaces with whatever backend is specified in the flags.
-render :: DynFlags -> [Flag] -> SinceQual -> QualOption -> [Interface]
+render :: DynFlags -> UnitState -> [Flag] -> SinceQual -> QualOption -> [Interface]
        -> [InstalledInterface] -> Map Module FilePath -> IO ()
-render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
+render dflags unit_state flags sinceQual qual ifaces installedIfaces extSrcMap = do
 
   let
     title                = fromMaybe "" (optTitle flags)
@@ -284,7 +291,6 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
     opt_latex_style      = optLaTeXStyle     flags
     opt_source_css       = optSourceCssFile  flags
     opt_mathjax          = optMathjax        flags
-    pkgs                 = unitState dflags
     dflags'
       | unicode          = gopt_set dflags Opt_PrintUnicodeSyntax
       | otherwise        = dflags
@@ -298,7 +304,7 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
     pkgMod           = fmap ifaceMod (listToMaybe ifaces)
     pkgKey           = fmap moduleUnit pkgMod
     pkgStr           = fmap unitString pkgKey
-    pkgNameVer       = modulePackageInfo dflags flags pkgMod
+    pkgNameVer       = modulePackageInfo unit_state flags pkgMod
     pkgName          = fmap (unpackFS . (\(PackageName n) -> n)) (fst pkgNameVer)
     sincePkg         = case sinceQual of
                          External -> pkgName
@@ -343,7 +349,7 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
     -- records the *wired in* identity base.  So untranslate it
     -- so that we can service the request.
     unwire :: Module -> Module
-    unwire m = m { moduleUnit = unwireUnit (unitState dflags) (moduleUnit m) }
+    unwire m = m { moduleUnit = unwireUnit unit_state (moduleUnit m) }
 
   reexportedIfaces <- concat `fmap` (for (reexportFlags flags) $ \mod_str -> do
     let warn = hPutStrLn stderr . ("Warning: " ++)
@@ -374,7 +380,7 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
   when (Flag_GenContents `elem` flags) $ do
     withTiming dflags' "ppHtmlContents" (const ()) $ do
       _ <- {-# SCC ppHtmlContents #-}
-           ppHtmlContents pkgs odir title pkgStr
+           ppHtmlContents unit_state odir title pkgStr
                      themes opt_mathjax opt_index_url sourceUrls' opt_wiki_urls
                      allVisibleIfaces True prologue pretty
                      sincePkg (makeContentsQual qual)
@@ -384,7 +390,7 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
   when (Flag_Html `elem` flags) $ do
     withTiming dflags' "ppHtml" (const ()) $ do
       _ <- {-# SCC ppHtml #-}
-           ppHtml pkgs title pkgStr visibleIfaces reexportedIfaces odir
+           ppHtml unit_state title pkgStr visibleIfaces reexportedIfaces odir
                   prologue
                   themes opt_mathjax sourceUrls' opt_wiki_urls
                   opt_contents_url opt_index_url unicode sincePkg qual
@@ -404,7 +410,7 @@ render dflags flags sinceQual qual ifaces installedIfaces extSrcMap = do
 
             pkgVer =
               fromMaybe (makeVersion []) mpkgVer
-          in ppHoogle dflags' pkgNameStr pkgVer title (fmap _doc prologue)
+          in ppHoogle dflags' unit_state pkgNameStr pkgVer title (fmap _doc prologue)
                visibleIfaces odir
       _ -> putStrLn . unlines $
           [ "haddock: Unable to find a package providing module "
@@ -494,9 +500,9 @@ withGhc' libDir needHieFiles flags ghcActs = runGhc (Just libDir) $ do
       let extra_opts | needHieFiles = [Opt_WriteHie, Opt_Haddock]
                      | otherwise = [Opt_Haddock]
           dynflags' = (foldl' gopt_set dynflags extra_opts)
-                        { hscTarget = HscNothing
-                        , ghcMode   = CompManager
-                        , ghcLink   = NoLink
+                        { backend = NoBackend
+                        , ghcMode = CompManager
+                        , ghcLink = NoLink
                         }
           flags' = filterRtsFlags flags
 
diff --git a/haddock-api/src/Haddock/Backends/Hoogle.hs b/haddock-api/src/Haddock/Backends/Hoogle.hs
index 9a304030..f7e1c77b 100644
--- a/haddock-api/src/Haddock/Backends/Hoogle.hs
+++ b/haddock-api/src/Haddock/Backends/Hoogle.hs
@@ -18,8 +18,9 @@ module Haddock.Backends.Hoogle (
     ppHoogle
   ) where
 
-import GHC.Types.Basic ( OverlapFlag(..), OverlapMode(..), SourceText(..)
-                  , PromotionFlag(..), TopLevelFlag(..) )
+import GHC.Types.Basic ( OverlapFlag(..), OverlapMode(..),
+                         PromotionFlag(..), TopLevelFlag(..) )
+import GHC.Types.SourceText
 import GHC.Core.InstEnv (ClsInst(..))
 import Documentation.Haddock.Markup
 import Haddock.GhcUtils
@@ -27,8 +28,11 @@ import Haddock.Types hiding (Version)
 import Haddock.Utils hiding (out)
 
 import GHC
+import GHC.Driver.Ppr
 import GHC.Utils.Outputable as Outputable
+import GHC.Utils.Panic
 import GHC.Parser.Annotation (IsUnicodeSyntax(..))
+import GHC.Unit.State
 
 import Data.Char
 import Data.List (intercalate, isPrefixOf)
@@ -37,15 +41,14 @@ import Data.Version
 
 import System.Directory
 import System.FilePath
-
 prefix :: [String]
 prefix = ["-- Hoogle documentation, generated by Haddock"
          ,"-- See Hoogle, http://www.haskell.org/hoogle/"
          ,""]
 
 
-ppHoogle :: DynFlags -> String -> Version -> String -> Maybe (Doc RdrName) -> [Interface] -> FilePath -> IO ()
-ppHoogle dflags package version synopsis prologue ifaces odir = do
+ppHoogle :: DynFlags -> UnitState -> String -> Version -> String -> Maybe (Doc RdrName) -> [Interface] -> FilePath -> IO ()
+ppHoogle dflags unit_state package version synopsis prologue ifaces odir = do
     let -- Since Hoogle is line based, we want to avoid breaking long lines.
         dflags' = dflags{ pprCols = maxBound }
         filename = package ++ ".txt"
@@ -54,42 +57,46 @@ ppHoogle dflags package version synopsis prologue ifaces odir = do
                    ["@package " ++ package] ++
                    ["@version " ++ showVersion version
                    | not (null (versionBranch version)) ] ++
-                   concat [ppModule dflags' i | i <- ifaces, OptHide `notElem` ifaceOptions i]
+                   concat [ppModule dflags' unit_state i | i <- ifaces, OptHide `notElem` ifaceOptions i]
     createDirectoryIfMissing True odir
     writeUtf8File (odir </> filename) (unlines contents)
 
-ppModule :: DynFlags -> Interface -> [String]
-ppModule dflags iface =
+ppModule :: DynFlags -> UnitState -> Interface -> [String]
+ppModule dflags unit_state iface =
   "" : ppDocumentation dflags (ifaceDoc iface) ++
   ["module " ++ moduleString (ifaceMod iface)] ++
   concatMap (ppExport dflags) (ifaceExportItems iface) ++
-  concatMap (ppInstance dflags) (ifaceInstances iface)
+  concatMap (ppInstance dflags unit_state) (ifaceInstances iface)
 
 
 ---------------------------------------------------------------------
 -- Utility functions
 
-dropHsDocTy :: HsType a -> HsType a
-dropHsDocTy = f
+dropHsDocTy :: HsSigType (GhcPass p) -> HsSigType (GhcPass p)
+dropHsDocTy = drop_sig_ty
     where
-        g (L src x) = L src (f x)
-        f (HsForAllTy x a e) = HsForAllTy x a (g e)
-        f (HsQualTy x a e) = HsQualTy x a (g e)
-        f (HsBangTy x a b) = HsBangTy x a (g b)
-        f (HsAppTy x a b) = HsAppTy x (g a) (g b)
-        f (HsAppKindTy x a b) = HsAppKindTy x (g a) (g b)
-        f (HsFunTy x w a b) = HsFunTy x w (g a) (g b)
-        f (HsListTy x a) = HsListTy x (g a)
-        f (HsTupleTy x a b) = HsTupleTy x a (map g b)
-        f (HsOpTy x a b c) = HsOpTy x (g a) b (g c)
-        f (HsParTy x a) = HsParTy x (g a)
-        f (HsKindSig x a b) = HsKindSig x (g a) b
-        f (HsDocTy _ a _) = f $ unLoc a
-        f x = x
-
-outHsType :: (OutputableBndrId p)
-          => DynFlags -> HsType (GhcPass p) -> String
-outHsType dflags = out dflags . reparenType . dropHsDocTy
+        drop_sig_ty (HsSig x a b)  = HsSig x a (drop_lty b)
+        drop_sig_ty x@XHsSigType{} = x
+
+        drop_lty (L src x) = L src (drop_ty x)
+
+        drop_ty (HsForAllTy x a e) = HsForAllTy x a (drop_lty e)
+        drop_ty (HsQualTy x a e) = HsQualTy x a (drop_lty e)
+        drop_ty (HsBangTy x a b) = HsBangTy x a (drop_lty b)
+        drop_ty (HsAppTy x a b) = HsAppTy x (drop_lty a) (drop_lty b)
+        drop_ty (HsAppKindTy x a b) = HsAppKindTy x (drop_lty a) (drop_lty b)
+        drop_ty (HsFunTy x w a b) = HsFunTy x w (drop_lty a) (drop_lty b)
+        drop_ty (HsListTy x a) = HsListTy x (drop_lty a)
+        drop_ty (HsTupleTy x a b) = HsTupleTy x a (map drop_lty b)
+        drop_ty (HsOpTy x a b c) = HsOpTy x (drop_lty a) b (drop_lty c)
+        drop_ty (HsParTy x a) = HsParTy x (drop_lty a)
+        drop_ty (HsKindSig x a b) = HsKindSig x (drop_lty a) b
+        drop_ty (HsDocTy _ a _) = drop_ty $ unL a
+        drop_ty x = x
+
+outHsSigType :: (OutputableBndrId p, NoGhcTcPass p ~ p)
+             => DynFlags -> HsSigType (GhcPass p) -> String
+outHsSigType dflags = out dflags . reparenSigType . dropHsDocTy
 
 
 dropComment :: String -> String
@@ -106,14 +113,14 @@ outWith p = f . unwords . map (dropWhile isSpace) . lines . p . ppr
         f [] = []
 
 out :: Outputable a => DynFlags -> a -> String
-out dflags = outWith $ showSDocUnqual dflags
+out dflags = outWith $ showSDoc dflags
 
 operator :: String -> String
 operator (x:xs) | not (isAlphaNum x) && x `notElem` "_' ([{" = '(' : x:xs ++ ")"
 operator x = x
 
 commaSeparate :: Outputable a => DynFlags -> [a] -> String
-commaSeparate dflags = showSDocUnqual dflags . interpp'SP
+commaSeparate dflags = showSDoc dflags . interpp'SP
 
 ---------------------------------------------------------------------
 -- How to print each export
@@ -133,8 +140,8 @@ ppExport dflags ExportDecl { expItemDecl    = L _ decl
         f (TyClD _ d@SynDecl{})   = ppSynonym dflags d
         f (TyClD _ d@ClassDecl{}) = ppClass dflags d subdocs
         f (TyClD _ (FamDecl _ d)) = ppFam dflags d
-        f (ForD _ (ForeignImport _ name typ _)) = [pp_sig dflags [name] (hsSigType typ)]
-        f (ForD _ (ForeignExport _ name typ _)) = [pp_sig dflags [name] (hsSigType typ)]
+        f (ForD _ (ForeignImport _ name typ _)) = [pp_sig dflags [name] typ]
+        f (ForD _ (ForeignExport _ name typ _)) = [pp_sig dflags [name] typ]
         f (SigD _ sig) = ppSig dflags sig
         f _ = []
 
@@ -143,8 +150,8 @@ ppExport _ _ = []
 
 ppSigWithDoc :: DynFlags -> Sig GhcRn -> [(Name, DocForDecl Name)] -> [String]
 ppSigWithDoc dflags sig subdocs = case sig of
-    TypeSig _ names t -> concatMap (mkDocSig "" (hsSigWcType t)) names
-    PatSynSig _ names t -> concatMap (mkDocSig "pattern " (hsSigType t)) names
+    TypeSig _ names t -> concatMap (mkDocSig "" (dropWildCards t)) names
+    PatSynSig _ names t -> concatMap (mkDocSig "pattern " t) names
     _ -> []
   where
     mkDocSig leader typ n = mkSubdoc dflags n subdocs
@@ -153,9 +160,9 @@ ppSigWithDoc dflags sig subdocs = case sig of
 ppSig :: DynFlags -> Sig GhcRn -> [String]
 ppSig dflags x  = ppSigWithDoc dflags x []
 
-pp_sig :: DynFlags -> [Located Name] -> LHsType GhcRn -> String
+pp_sig :: DynFlags -> [Located Name] -> LHsSigType GhcRn -> String
 pp_sig dflags names (L _ typ)  =
-    operator prettyNames ++ " :: " ++ outHsType dflags typ
+    operator prettyNames ++ " :: " ++ outHsSigType dflags typ
     where
       prettyNames = intercalate ", " $ map (out dflags) names
 
@@ -173,7 +180,7 @@ ppClass dflags decl subdocs =
 
         ppTyFams
             | null $ tcdATs decl = ""
-            | otherwise = (" " ++) . showSDocUnqual dflags . whereWrapper $ concat
+            | otherwise = (" " ++) . showSDoc dflags . whereWrapper $ concat
                 [ map pprTyFam (tcdATs decl)
                 , map (pprTyFamInstDecl NotTopLevel . unLoc) (tcdATDefs decl)
                 ]
@@ -198,9 +205,9 @@ ppFam dflags decl@(FamilyDecl { fdInfo = info })
               ClosedTypeFamily{} -> decl { fdInfo = OpenTypeFamily }
               _                  -> decl
 
-ppInstance :: DynFlags -> ClsInst -> [String]
-ppInstance dflags x =
-  [dropComment $ outWith (showSDocForUser dflags alwaysQualify) cls]
+ppInstance :: DynFlags -> UnitState -> ClsInst -> [String]
+ppInstance dflags unit_state x =
+  [dropComment $ outWith (showSDocForUser dflags unit_state alwaysQualify) cls]
   where
     -- As per #168, we don't want safety information about the class
     -- in Hoogle output. The easiest way to achieve this is to set the
@@ -234,13 +241,13 @@ lookupCon dflags subdocs (L _ name) = case lookup name subdocs of
   _ -> []
 
 ppCtor :: DynFlags -> TyClDecl GhcRn -> [(Name, DocForDecl Name)] -> ConDecl GhcRn -> [String]
-ppCtor dflags dat subdocs con@ConDeclH98 {}
+ppCtor dflags dat subdocs con@ConDeclH98 { con_args = con_args' }
   -- AZ:TODO get rid of the concatMap
-   = concatMap (lookupCon dflags subdocs) [con_name con] ++ f (getConArgs con)
+   = concatMap (lookupCon dflags subdocs) [con_name con] ++ f con_args'
     where
-        f (PrefixCon args) = [typeSig name $ (map hsScaledThing args) ++ [resType]]
-        f (InfixCon a1 a2) = f $ PrefixCon [a1,a2]
-        f (RecCon (L _ recs)) = f (PrefixCon $ map (hsLinear . cd_fld_type . unLoc) recs) ++ concat
+        f (PrefixCon _ args) = [typeSig name $ (map hsScaledThing args) ++ [resType]]
+        f (InfixCon a1 a2) = f $ PrefixCon [] [a1,a2]
+        f (RecCon (L _ recs)) = f (PrefixCon [] $ map (hsLinear . cd_fld_type . unLoc) recs) ++ concat
                           [(concatMap (lookupCon dflags subdocs . noLoc . extFieldOcc . unLoc) (cd_fld_names r)) ++
                            [out dflags (map (extFieldOcc . unLoc) $ cd_fld_names r) `typeSig` [resType, cd_fld_type r]]
                           | r <- map unLoc recs]
@@ -248,11 +255,12 @@ ppCtor dflags dat subdocs con@ConDeclH98 {}
         funs = foldr1 (\x y -> reL $ HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) x y)
         apps = foldl1 (\x y -> reL $ HsAppTy noExtField x y)
 
-        typeSig nm flds = operator nm ++ " :: " ++ outHsType dflags (unL $ funs flds)
+        typeSig nm flds = operator nm ++ " :: " ++
+                          outHsSigType dflags (unL $ mkEmptySigType $ funs flds)
 
         -- We print the constructors as comma-separated list. See GHC
         -- docs for con_names on why it is a list to begin with.
-        name = commaSeparate dflags . map unLoc $ getConNames con
+        name = commaSeparate dflags . map unL $ getConNames con
 
         tyVarArg (UserTyVar _ _ n) = HsTyVar noExtField NotPromoted n
         tyVarArg (KindedTyVar _ _ n lty) = HsKindSig noExtField (reL (HsTyVar noExtField NotPromoted n)) lty
@@ -262,13 +270,23 @@ ppCtor dflags dat subdocs con@ConDeclH98 {}
                         (HsTyVar noExtField NotPromoted (reL (tcdName dat))) :
                         map (tyVarArg . unLoc) (hsQTvExplicit $ tyClDeclTyVars dat)
 
-ppCtor dflags _dat subdocs con@(ConDeclGADT { })
-   = concatMap (lookupCon dflags subdocs) (getConNames con) ++ f
+ppCtor dflags _dat subdocs (ConDeclGADT { con_names = names
+                                        , con_bndrs = L _ outer_bndrs
+                                        , con_mb_cxt = mcxt
+                                        , con_g_args = args
+                                        , con_res_ty = res_ty })
+   = concatMap (lookupCon dflags subdocs) names ++ [typeSig]
     where
-        f = [typeSig name (getGADTConTypeG con)]
-
-        typeSig nm ty = operator nm ++ " :: " ++ outHsType dflags (unLoc ty)
-        name = out dflags $ map unLoc $ getConNames con
+        typeSig = operator name ++ " :: " ++ outHsSigType dflags con_sig_ty
+        name = out dflags $ map unL names
+        con_sig_ty = HsSig noExtField outer_bndrs theta_ty where
+          theta_ty = case mcxt of
+            Just theta -> noLoc (HsQualTy { hst_xqual = noExtField, hst_ctxt = theta, hst_body = tau_ty })
+            Nothing -> tau_ty
+          tau_ty = foldr mkFunTy res_ty $
+            case args of PrefixConGADT pos_args -> map hsScaledThing pos_args
+                         RecConGADT (L _ flds) -> map (cd_fld_type . unL) flds
+          mkFunTy a b = noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) a b)
 
 ppFixity :: DynFlags -> (Name, Fixity) -> [String]
 ppFixity dflags (name, fixity) = [out dflags ((FixitySig noExtField [noLoc name] fixity) :: FixitySig GhcRn)]
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker.hs b/haddock-api/src/Haddock/Backends/Hyperlinker.hs
index 03be8c22..d85a3970 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker.hs
@@ -70,10 +70,10 @@ ppHyperlinkedModuleSource verbosity srcdir pretty srcs iface = case ifaceHieFile
         -- Get the AST and tokens corresponding to the source file we want
         let fileFs = mkFastString file
             mast | M.size asts == 1 = snd <$> M.lookupMin asts
-                 | otherwise        = M.lookup fileFs asts
+                 | otherwise        = M.lookup (HiePath (mkFastString file)) asts
+            tokens = parse df file rawSrc
             ast = fromMaybe (emptyHieAst fileFs) mast
             fullAst = recoverFullIfaceTypes df types ast
-            tokens = parse df file rawSrc
 
         -- Warn if we didn't find an AST, but there were still ASTs
         if M.null asts
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
index 3db3c685..52d73265 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
@@ -10,15 +10,18 @@ import Data.List           ( isPrefixOf, isSuffixOf )
 
 import qualified Data.ByteString as BS
 
-import GHC.Types.Basic     ( IntegralLit(..) )
+import GHC.Types.SourceText
 import GHC.Driver.Session
-import GHC.Utils.Error     ( pprLocErrMsg )
+import GHC.Utils.Error     ( pprLocMsgEnvelope )
 import GHC.Data.FastString ( mkFastString )
+import GHC.Parser.Errors.Ppr ( pprError )
 import GHC.Parser.Lexer    as Lexer
                            ( P(..), ParseResult(..), PState(..), Token(..)
-                           , mkPStatePure, lexer, mkParserFlags', getErrorMessages)
+                           , initParserState, lexer, mkParserOpts, getErrorMessages)
 import GHC.Data.Bag         ( bagToList )
-import GHC.Utils.Outputable ( showSDoc, panic, text, ($$) )
+import GHC.Utils.Outputable ( text, ($$) )
+import GHC.Utils.Panic      ( panic )
+import GHC.Driver.Ppr       ( showSDoc )
 import GHC.Types.SrcLoc
 import GHC.Data.StringBuffer ( StringBuffer, atEnd )
 
@@ -37,17 +40,16 @@ parse
 parse dflags fpath bs = case unP (go False []) initState of
     POk _ toks -> reverse toks
     PFailed pst ->
-      let err:_ = bagToList (getErrorMessages pst dflags) in
+      let err:_ = bagToList (fmap pprError (getErrorMessages pst)) in
       panic $ showSDoc dflags $
-        text "Hyperlinker parse error:" $$ pprLocErrMsg err
+        text "Hyperlinker parse error:" $$ pprLocMsgEnvelope err
   where
 
-    initState = mkPStatePure pflags buf start
+    initState = initParserState pflags buf start
     buf = stringBufferFromByteString bs
     start = mkRealSrcLoc (mkFastString fpath) 1 1
-    pflags = mkParserFlags' (warningFlags dflags)
+    pflags = mkParserOpts   (warningFlags dflags)
                             (extensionFlags dflags)
-                            (homeUnitId dflags)
                             (safeImportsOn dflags)
                             False -- lex Haddocks as comment tokens
                             True  -- produce comment tokens
@@ -240,7 +242,6 @@ classify tok =
     ITline_prag         {} -> TkPragma
     ITcolumn_prag       {} -> TkPragma
     ITscc_prag          {} -> TkPragma
-    ITgenerated_prag    {} -> TkPragma
     ITunpack_prag       {} -> TkPragma
     ITnounpack_prag     {} -> TkPragma
     ITann_prag          {} -> TkPragma
@@ -381,7 +382,6 @@ inPragma False tok =
     ITline_prag         {} -> True
     ITcolumn_prag       {} -> True
     ITscc_prag          {} -> True
-    ITgenerated_prag    {} -> True
     ITunpack_prag       {} -> True
     ITnounpack_prag     {} -> True
     ITann_prag          {} -> True
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker/Utils.hs b/haddock-api/src/Haddock/Backends/Hyperlinker/Utils.hs
index b093b5a4..5c3bddef 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker/Utils.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker/Utils.hs
@@ -21,7 +21,7 @@ import GHC
 import GHC.Iface.Ext.Types ( HieAST(..), HieType(..), HieArgs(..), TypeIndex, HieTypeFlat )
 import GHC.Iface.Type
 import GHC.Types.Name      ( getOccFS, getOccString )
-import GHC.Utils.Outputable( showSDoc )
+import GHC.Driver.Ppr      ( showSDoc )
 import GHC.Types.Var       ( VarBndr(..) )
 
 import System.FilePath.Posix ((</>), (<.>))
diff --git a/haddock-api/src/Haddock/Backends/LaTeX.hs b/haddock-api/src/Haddock/Backends/LaTeX.hs
index ac904273..df1f94e6 100644
--- a/haddock-api/src/Haddock/Backends/LaTeX.hs
+++ b/haddock-api/src/Haddock/Backends/LaTeX.hs
@@ -31,7 +31,7 @@ import GHC.Types.Name        ( nameOccName )
 import GHC.Types.Name.Reader ( rdrNameOcc )
 import GHC.Core.Type         ( Specificity(..) )
 import GHC.Data.FastString   ( unpackFS )
-import GHC.Utils.Outputable  ( panic)
+import GHC.Utils.Panic       ( panic)
 
 import qualified Data.Map as Map
 import System.Directory
@@ -108,7 +108,7 @@ type LaTeX = Pretty.Doc
 -- | Default way of rendering a 'LaTeX'. The width is 90 by default (since 100
 -- often overflows the line).
 latex2String :: LaTeX -> String
-latex2String = fullRender PageMode 90 1 txtPrinter ""
+latex2String = fullRender (PageMode True) 90 1 txtPrinter ""
 
 ppLaTeXTop
    :: String
@@ -177,7 +177,7 @@ ppLaTeXModule _title odir iface = do
 
       body = processExports exports
   --
-  writeUtf8File (odir </> moduleLaTeXFile mdl) (show tex)
+  writeUtf8File (odir </> moduleLaTeXFile mdl) (fullRender (PageMode True) 80 1 txtPrinter "" tex)
 
 -- | Prints out an entry in a module export list.
 exportListItem :: ExportItem DocNameI -> LaTeX
@@ -215,10 +215,10 @@ processExports (e : es) =
   processExport e $$ processExports es
 
 
-isSimpleSig :: ExportItem DocNameI -> Maybe ([DocName], HsType DocNameI)
+isSimpleSig :: ExportItem DocNameI -> Maybe ([DocName], HsSigType DocNameI)
 isSimpleSig ExportDecl { expItemDecl = L _ (SigD _ (TypeSig _ lnames t))
                        , expItemMbDoc = (Documentation Nothing Nothing, argDocs) }
-  | Map.null argDocs = Just (map unLoc lnames, unLoc (hsSigWcType t))
+  | Map.null argDocs = Just (map unLoc lnames, unLoc (dropWildCards t))
 isSimpleSig _ = Nothing
 
 
@@ -301,7 +301,7 @@ ppDecl decl pats (doc, fnArgsDoc) instances subdocs _fxts = case unLoc decl of
 --    | Just _  <- tcdTyPats d    -> ppTyInst False loc doc d unicode
 -- Family instances happen via FamInst now
   TyClD _ d@ClassDecl{}          -> ppClassDecl instances doc subdocs d unicode
-  SigD _ (TypeSig _ lnames ty)   -> ppFunSig Nothing (doc, fnArgsDoc) (map unLoc lnames) (hsSigWcType ty) unicode
+  SigD _ (TypeSig _ lnames ty)   -> ppFunSig Nothing (doc, fnArgsDoc) (map unLoc lnames) (dropWildCards ty) unicode
   SigD _ (PatSynSig _ lnames ty) -> ppLPatSig (doc, fnArgsDoc) (map unLoc lnames) ty unicode
   ForD _ d                       -> ppFor (doc, fnArgsDoc) d unicode
   InstD _ _                      -> empty
@@ -313,7 +313,7 @@ ppDecl decl pats (doc, fnArgsDoc) instances subdocs _fxts = case unLoc decl of
 
 ppFor :: DocForDecl DocName -> ForeignDecl DocNameI -> Bool -> LaTeX
 ppFor doc (ForeignImport _ (L _ name) typ _) unicode =
-  ppFunSig Nothing doc [name] (hsSigTypeI typ) unicode
+  ppFunSig Nothing doc [name] typ unicode
 ppFor _ _ _ = error "ppFor error in Haddock.Backends.LaTeX"
 --  error "foreign declarations are currently not supported by --latex"
 
@@ -350,9 +350,9 @@ ppFamDecl associated doc instances decl unicode =
 
     -- Individual equations of a closed type family
     ppFamDeclEqn :: TyFamInstEqn DocNameI -> LaTeX
-    ppFamDeclEqn (HsIB { hsib_body = FamEqn { feqn_tycon = L _ n
-                                            , feqn_rhs = rhs
-                                            , feqn_pats = ts } })
+    ppFamDeclEqn (FamEqn { feqn_tycon = L _ n
+                         , feqn_rhs = rhs
+                         , feqn_pats = ts })
       = hsep [ ppAppNameTypeArgs n ts unicode
              , equals
              , ppType unicode (unLoc rhs)
@@ -407,7 +407,7 @@ ppTySyn :: DocForDecl DocName -> TyClDecl DocNameI -> Bool -> LaTeX
 
 ppTySyn doc (SynDecl { tcdLName = L _ name, tcdTyVars = ltyvars
                          , tcdRhs = ltype }) unicode
-  = ppTypeOrFunSig (unLoc ltype) doc (full, hdr, char '=') unicode
+  = ppTypeOrFunSig (mkHsImplicitSigTypeI ltype) doc (full, hdr, char '=') unicode
   where
     hdr  = hsep (keyword "type"
                  : ppDocBinder name
@@ -426,7 +426,7 @@ ppFunSig
   :: Maybe LaTeX         -- ^ a prefix to put right before the signature
   -> DocForDecl DocName  -- ^ documentation
   -> [DocName]           -- ^ pattern names in the pattern signature
-  -> LHsType DocNameI    -- ^ type of the pattern synonym
+  -> LHsSigType DocNameI -- ^ type of the pattern synonym
   -> Bool                -- ^ unicode
   -> LaTeX
 ppFunSig leader doc docnames (L _ typ) unicode =
@@ -447,11 +447,11 @@ ppLPatSig :: DocForDecl DocName  -- ^ documentation
           -> Bool                -- ^ unicode
           -> LaTeX
 ppLPatSig doc docnames ty unicode
-  = ppFunSig (Just (keyword "pattern")) doc docnames (hsSigTypeI ty) unicode
+  = ppFunSig (Just (keyword "pattern")) doc docnames ty unicode
 
 -- | Pretty-print a type, adding documentation to the whole type and its
 -- arguments as needed.
-ppTypeOrFunSig :: HsType DocNameI
+ppTypeOrFunSig :: HsSigType DocNameI
                -> DocForDecl DocName  -- ^ documentation
                -> ( LaTeX             --   first-line (no-argument docs only)
                   , LaTeX             --   first-line (argument docs only)
@@ -471,13 +471,24 @@ ppTypeOrFunSig typ (doc, argDocs) (pref1, pref2, sep0) unicode
 -- to the arguments. The output is a list of (leader/seperator, argument and
 -- its doc)
 ppSubSigLike :: Bool                  -- ^ unicode
-             -> HsType DocNameI       -- ^ type signature
+             -> HsSigType DocNameI    -- ^ type signature
              -> FnArgsDoc DocName     -- ^ docs to add
              -> [(DocName, DocForDecl DocName)] -- ^ all subdocs (useful when we have `HsRecTy`)
              -> LaTeX                 -- ^ seperator (beginning of first line)
              -> [(LaTeX, LaTeX)]      -- ^ arguments (leader/sep, type)
-ppSubSigLike unicode typ argDocs subdocs leader = do_args 0 leader typ
+ppSubSigLike unicode typ argDocs subdocs leader = do_sig_args 0 leader typ
   where
+    do_sig_args :: Int -> LaTeX -> HsSigType DocNameI -> [(LaTeX, LaTeX)]
+    do_sig_args n leader (HsSig { sig_bndrs = outer_bndrs, sig_body = ltype }) =
+      case outer_bndrs of
+        HsOuterExplicit{hso_bndrs = bndrs} ->
+          [ ( decltt leader
+            , decltt (ppHsForAllTelescope (mkHsForAllInvisTeleI bndrs) unicode)
+                <+> ppLType unicode ltype
+            ) ]
+        HsOuterImplicit{} -> do_largs n leader ltype
+
+    do_largs :: Int -> LaTeX -> LHsType DocNameI -> [(LaTeX, LaTeX)]
     do_largs n leader (L _ t) = do_args n leader t
 
     arg_doc n = rDoc . fmap _doc $ Map.lookup n argDocs
@@ -515,12 +526,16 @@ ppSubSigLike unicode typ argDocs subdocs leader = do_args 0 leader typ
     gadtOpen = char '{'
 
 
-ppTypeSig :: [Name] -> HsType DocNameI  -> Bool -> LaTeX
+ppTypeSig :: [Name] -> HsSigType DocNameI  -> Bool -> LaTeX
 ppTypeSig nms ty unicode =
   hsep (punctuate comma $ map ppSymName nms)
     <+> dcolon unicode
-    <+> ppType unicode ty
+    <+> ppSigType unicode ty
 
+ppHsOuterTyVarBndrs :: HsOuterTyVarBndrs flag DocNameI -> Bool -> LaTeX
+ppHsOuterTyVarBndrs (HsOuterImplicit{}) _ = empty
+ppHsOuterTyVarBndrs (HsOuterExplicit{hso_bndrs = bndrs}) unicode =
+    hsep (forallSymbol unicode : ppTyVars bndrs) <> dot
 
 ppHsForAllTelescope :: HsForAllTelescope DocNameI -> Bool -> LaTeX
 ppHsForAllTelescope tele unicode = case tele of
@@ -635,7 +650,7 @@ ppClassDecl instances doc subdocs
 
     methodTable =
       text "\\haddockpremethods{}" <> emph (text "Methods") $$
-      vcat  [ ppFunSig leader doc names (hsSigTypeI typ) unicode
+      vcat  [ ppFunSig leader doc names typ unicode
             | L _ (ClassOpSig _ is_def lnames typ) <- lsigs
             , let doc | is_def = noDocForDecl
                       | otherwise = lookupAnySubdoc (head names) subdocs
@@ -795,7 +810,7 @@ ppSideBySideConstr subdocs unicode leader (L _ con) =
                          header_ = ppConstrHdr forall_ tyVars context unicode
                      in case det of
         -- Prefix constructor, e.g. 'Just a'
-        PrefixCon args
+        PrefixCon _ args
           | hasArgDocs -> header_ <+> ppOcc
           | otherwise -> hsep [ header_
                               , ppOcc
@@ -819,23 +834,25 @@ ppSideBySideConstr subdocs unicode leader (L _ con) =
         | otherwise -> hsep [ ppOcc
                             , dcolon unicode
                             -- ++AZ++ make this prepend "{..}" when it is a record style GADT
-                            , ppLType unicode (getGADTConType con)
+                            , ppLSigType unicode (getGADTConType con)
                             ]
 
-    fieldPart = case (con, getConArgsI con) of
-        -- Record style GADTs
-        (ConDeclGADT{}, RecCon _)            -> doConstrArgsWithDocs []
-
-        -- Regular record declarations
-        (_, RecCon (L _ fields))             -> doRecordFields fields
-
-        -- Any GADT or a regular H98 prefix data constructor
-        (_, PrefixCon args)     | hasArgDocs -> doConstrArgsWithDocs (map hsScaledThing args)
-
-        -- An infix H98 data constructor
-        (_, InfixCon arg1 arg2) | hasArgDocs -> doConstrArgsWithDocs (map hsScaledThing [arg1,arg2])
-
-        _ -> empty
+    fieldPart = case con of
+        ConDeclGADT{con_g_args = con_args'} -> case con_args' of
+          -- GADT record declarations
+          RecConGADT _                    -> doConstrArgsWithDocs []
+          -- GADT prefix data constructors
+          PrefixConGADT args | hasArgDocs -> doConstrArgsWithDocs (map hsScaledThing args)
+          _                               -> empty
+
+        ConDeclH98{con_args = con_args'} -> case con_args' of
+          -- H98 record declarations
+          RecCon (L _ fields)             -> doRecordFields fields
+          -- H98 prefix data constructors
+          PrefixCon _ args | hasArgDocs   -> doConstrArgsWithDocs (map hsScaledThing args)
+          -- H98 infix data constructor
+          InfixCon arg1 arg2 | hasArgDocs -> doConstrArgsWithDocs (map hsScaledThing [arg1,arg2])
+          _                               -> empty
 
     doRecordFields fields =
       vcat [ empty <-> tt (text begin) <+> ppSideBySideField subdocs unicode field <+> nl
@@ -892,18 +909,16 @@ ppSideBySidePat lnames typ (doc, argDocs) unicode =
          | otherwise = hsep [ keyword "pattern"
                             , ppOcc
                             , dcolon unicode
-                            , ppLType unicode (hsSigTypeI typ)
+                            , ppLSigType unicode typ
                             ]
 
     fieldPart
       | not hasArgDocs = empty
       | otherwise = vcat
           [ empty <-> text "\\qquad" <+> l <+> text "\\enspace" <+> r
-          | (l,r) <- ppSubSigLike unicode (unLoc patTy) argDocs [] (dcolon unicode)
+          | (l,r) <- ppSubSigLike unicode (unLoc typ) argDocs [] (dcolon unicode)
           ]
 
-    patTy = hsSigTypeI typ
-
     mDoc = fmap _doc $ combineDocumentation doc
 
 
@@ -1024,12 +1039,18 @@ ppLType       unicode y = ppType unicode (unLoc y)
 ppLParendType unicode y = ppParendType unicode (unLoc y)
 ppLFunLhType  unicode y = ppFunLhType unicode (unLoc y)
 
+ppLSigType :: Bool -> LHsSigType DocNameI -> LaTeX
+ppLSigType unicode y = ppSigType unicode (unLoc y)
+
 ppType, ppParendType, ppFunLhType, ppCtxType :: Bool -> HsType DocNameI -> LaTeX
 ppType       unicode ty = ppr_mono_ty (reparenTypePrec PREC_TOP ty) unicode
-ppParendType unicode ty = ppr_mono_ty (reparenTypePrec PREC_CON ty) unicode
+ppParendType unicode ty = ppr_mono_ty (reparenTypePrec PREC_TOP ty) unicode
 ppFunLhType  unicode ty = ppr_mono_ty (reparenTypePrec PREC_FUN ty) unicode
 ppCtxType    unicode ty = ppr_mono_ty (reparenTypePrec PREC_CTX ty) unicode
 
+ppSigType :: Bool -> HsSigType DocNameI -> LaTeX
+ppSigType unicode sig_ty = ppr_sig_ty (reparenSigType sig_ty) unicode
+
 ppLHsTypeArg :: Bool -> LHsTypeArg DocNameI -> LaTeX
 ppLHsTypeArg unicode (HsValArg ty) = ppLParendType unicode ty
 ppLHsTypeArg unicode (HsTypeArg _ ki) = atSign unicode <>
@@ -1061,6 +1082,11 @@ ppKind unicode ki = ppr_mono_ty (reparenTypePrec PREC_TOP ki) unicode
 -- Drop top-level for-all type variables in user style
 -- since they are implicit in Haskell
 
+ppr_sig_ty :: HsSigType DocNameI -> Bool -> LaTeX
+ppr_sig_ty (HsSig { sig_bndrs = outer_bndrs, sig_body = ltype }) unicode
+  = sep [ ppHsOuterTyVarBndrs outer_bndrs unicode
+        , ppr_mono_lty ltype unicode ]
+
 ppr_mono_lty :: LHsType DocNameI -> Bool -> LaTeX
 ppr_mono_lty ty unicode = ppr_mono_ty (unLoc ty) unicode
 
@@ -1090,7 +1116,7 @@ ppr_mono_ty (HsListTy _ ty)       u = brackets (ppr_mono_lty ty u)
 ppr_mono_ty (HsIParamTy _ (L _ n) ty) u = ppIPName n <+> dcolon u <+> ppr_mono_lty ty u
 ppr_mono_ty (HsSpliceTy v _)    _ = absurd v
 ppr_mono_ty (HsRecTy {})        _ = text "{..}"
-ppr_mono_ty (XHsType (NHsCoreTy {}))  _ = error "ppr_mono_ty HsCoreTy"
+ppr_mono_ty (XHsType {})        _ = error "ppr_mono_ty HsCoreTy"
 ppr_mono_ty (HsExplicitListTy _ IsPromoted tys) u = Pretty.quote $ brackets $ hsep $ punctuate comma $ map (ppLType u) tys
 ppr_mono_ty (HsExplicitListTy _ NotPromoted tys) u = brackets $ hsep $ punctuate comma $ map (ppLType u) tys
 ppr_mono_ty (HsExplicitTupleTy _ tys) u = Pretty.quote $ parenList $ map (ppLType u) tys
@@ -1123,6 +1149,7 @@ ppr_mono_ty (HsStarTy _ isUni) unicode = starSymbol (isUni || unicode)
 ppr_tylit :: HsTyLit -> Bool -> LaTeX
 ppr_tylit (HsNumTy _ n) _ = integer n
 ppr_tylit (HsStrTy _ s) _ = text (show s)
+ppr_tylit (HsCharTy _ c) _ = text (show c)
   -- XXX: Ok in verbatim, but not otherwise
   -- XXX: Do something with Unicode parameter?
 
diff --git a/haddock-api/src/Haddock/Backends/Xhtml.hs b/haddock-api/src/Haddock/Backends/Xhtml.hs
index f8c22e0a..1bdbf81b 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml.hs
@@ -223,10 +223,7 @@ moduleInfo iface =
           ("Language", lg)
           ] ++ extsForm
         where
-          lg inf = case hmi_language inf of
-            Nothing -> Nothing
-            Just Haskell98 -> Just "Haskell98"
-            Just Haskell2010 -> Just "Haskell2010"
+          lg inf = fmap show (hmi_language inf)
 
           multilineRow :: String -> [String] -> HtmlTable
           multilineRow title xs = (th ! [valign "top"]) << title <-> td << (toLines xs)
diff --git a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
index 0b0050df..de37e42a 100644
--- a/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
+++ b/haddock-api/src/Haddock/Backends/Xhtml/Decl.hs
@@ -63,9 +63,9 @@ ppDecl summ links (L loc decl) pats (mbDoc, fnArgsDoc) instances fixities subdoc
   TyClD _ d@(SynDecl {})         -> ppTySyn summ links fixities loc (mbDoc, fnArgsDoc) d splice unicode pkg qual
   TyClD _ d@(ClassDecl {})       -> ppClassDecl summ links instances fixities loc mbDoc subdocs d splice unicode pkg qual
   SigD _ (TypeSig _ lnames lty)  -> ppLFunSig summ links loc (mbDoc, fnArgsDoc) lnames
-                                         (hsSigWcType lty) fixities splice unicode pkg qual
+                                         (dropWildCards lty) fixities splice unicode pkg qual
   SigD _ (PatSynSig _ lnames lty) -> ppLPatSig summ links loc (mbDoc, fnArgsDoc) lnames
-                                         (hsSigTypeI lty) fixities splice unicode pkg qual
+                                         lty fixities splice unicode pkg qual
   ForD _ d                       -> ppFor summ links loc (mbDoc, fnArgsDoc) d fixities splice unicode pkg qual
   InstD _ _                      -> noHtml
   DerivD _ _                     -> noHtml
@@ -73,25 +73,25 @@ ppDecl summ links (L loc decl) pats (mbDoc, fnArgsDoc) instances fixities subdoc
 
 
 ppLFunSig :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName ->
-             [Located DocName] -> LHsType DocNameI -> [(DocName, Fixity)] ->
+             [Located DocName] -> LHsSigType DocNameI -> [(DocName, Fixity)] ->
              Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppLFunSig summary links loc doc lnames lty fixities splice unicode pkg qual =
   ppFunSig summary links loc noHtml doc (map unLoc lnames) lty fixities
            splice unicode pkg qual
 
 ppFunSig :: Bool -> LinksInfo -> SrcSpan -> Html -> DocForDecl DocName ->
-            [DocName] -> LHsType DocNameI -> [(DocName, Fixity)] ->
+            [DocName] -> LHsSigType DocNameI -> [(DocName, Fixity)] ->
             Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppFunSig summary links loc leader doc docnames typ fixities splice unicode pkg qual =
   ppSigLike summary links loc leader doc docnames fixities (unLoc typ, pp_typ)
             splice unicode pkg qual HideEmptyContexts
   where
-    pp_typ = ppLType unicode qual HideEmptyContexts typ
+    pp_typ = ppLSigType unicode qual HideEmptyContexts typ
 
 -- | Pretty print a pattern synonym
 ppLPatSig :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName
           -> [Located DocName]     -- ^ names of patterns in declaration
-          -> LHsType DocNameI      -- ^ type of patterns in declaration
+          -> LHsSigType DocNameI   -- ^ type of patterns in declaration
           -> [(DocName, Fixity)]
           -> Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppLPatSig summary links loc doc lnames typ fixities splice unicode pkg qual =
@@ -102,7 +102,7 @@ ppLPatSig summary links loc doc lnames typ fixities splice unicode pkg qual =
 
 
 ppSigLike :: Bool -> LinksInfo -> SrcSpan -> Html -> DocForDecl DocName ->
-             [DocName] -> [(DocName, Fixity)] -> (HsType DocNameI, Html) ->
+             [DocName] -> [(DocName, Fixity)] -> (HsSigType DocNameI, Html) ->
              Splice -> Unicode -> Maybe Package -> Qualification -> HideEmptyContexts -> Html
 ppSigLike summary links loc leader doc docnames fixities (typ, pp_typ)
           splice unicode pkg qual emptyCtxts =
@@ -119,7 +119,7 @@ ppSigLike summary links loc leader doc docnames fixities (typ, pp_typ)
       | otherwise = html <+> ppFixities fixities qual
 
 
-ppTypeOrFunSig :: Bool -> LinksInfo -> SrcSpan -> [DocName] -> HsType DocNameI
+ppTypeOrFunSig :: Bool -> LinksInfo -> SrcSpan -> [DocName] -> HsSigType DocNameI
                -> DocForDecl DocName -> (Html, Html, Html)
                -> Splice -> Unicode -> Maybe Package -> Qualification
                -> HideEmptyContexts -> Html
@@ -140,15 +140,24 @@ ppTypeOrFunSig summary links loc docnames typ (doc, argDocs) (pref1, pref2, sep)
 -- If one passes in a list of the available subdocs, any top-level `HsRecTy`
 -- found will be expanded out into their fields.
 ppSubSigLike :: Unicode -> Qualification
-             -> HsType DocNameI                  -- ^ type signature
+             -> HsSigType DocNameI               -- ^ type signature
              -> FnArgsDoc DocName                -- ^ docs to add
              -> [(DocName, DocForDecl DocName)]  -- ^ all subdocs (useful when
                                                  -- we expand an `HsRecTy`)
              -> Html -> HideEmptyContexts -> [SubDecl]
-ppSubSigLike unicode qual typ argDocs subdocs sep emptyCtxts = do_args 0 sep typ
+ppSubSigLike unicode qual typ argDocs subdocs sep emptyCtxts = do_sig_args 0 sep typ
   where
+    do_sig_args :: Int -> Html -> HsSigType DocNameI -> [SubDecl]
+    do_sig_args n leader (HsSig { sig_bndrs = outer_bndrs, sig_body = ltype }) =
+      case outer_bndrs of
+        HsOuterExplicit{hso_bndrs = bndrs} -> do_largs n (leader' bndrs) ltype
+        HsOuterImplicit{}                  -> do_largs n leader          ltype
+      where
+        leader' bndrs = leader <+> ppForAllPart unicode qual (mkHsForAllInvisTeleI bndrs)
+
     argDoc n = Map.lookup n argDocs
 
+    do_largs :: Int -> Html -> LHsType DocNameI -> [SubDecl]
     do_largs n leader (L _ t) = do_args n leader t
 
     do_args :: Int -> Html -> HsType DocNameI -> [SubDecl]
@@ -222,7 +231,7 @@ ppFor :: Bool -> LinksInfo -> SrcSpan -> DocForDecl DocName
       -> Splice -> Unicode -> Maybe Package -> Qualification -> Html
 ppFor summary links loc doc (ForeignImport _ (L _ name) typ _) fixities
       splice unicode pkg qual
-  = ppFunSig summary links loc noHtml doc [name] (hsSigTypeI typ) fixities splice unicode pkg qual
+  = ppFunSig summary links loc noHtml doc [name] typ fixities splice unicode pkg qual
 ppFor _ _ _ _ _ _ _ _ _ _ = error "ppFor"
 
 
@@ -233,13 +242,14 @@ ppTySyn :: Bool -> LinksInfo -> [(DocName, Fixity)] -> SrcSpan
 ppTySyn summary links fixities loc doc (SynDecl { tcdLName = L _ name, tcdTyVars = ltyvars
                                                 , tcdRhs = ltype })
         splice unicode pkg qual
-  = ppTypeOrFunSig summary links loc [name] (unLoc ltype) doc
+  = ppTypeOrFunSig summary links loc [name] sig_type doc
                    (full <+> fixs, hdr <+> fixs, spaceHtml +++ equals)
                    splice unicode pkg qual ShowEmptyToplevelContexts
   where
+    sig_type = mkHsImplicitSigTypeI ltype
     hdr  = hsep ([keyword "type", ppBinder summary occ]
                  ++ ppTyVars unicode qual (hsQTvExplicit ltyvars))
-    full = hdr <+> equals <+> ppPatSigType unicode qual ltype
+    full = hdr <+> equals <+> ppPatSigType unicode qual (noLoc sig_type)
     occ  = nameOccName . getName $ name
     fixs
       | summary   = noHtml
@@ -253,15 +263,14 @@ ppTypeSig summary nms pp_ty unicode =
   where
     htmlNames = intersperse (stringToHtml ", ") $ map (ppBinder summary) nms
 
-
 ppSimpleSig :: LinksInfo -> Splice -> Unicode -> Qualification -> HideEmptyContexts -> SrcSpan
-            -> [DocName] -> HsType DocNameI
+            -> [DocName] -> HsSigType DocNameI
             -> Html
 ppSimpleSig links splice unicode qual emptyCtxts loc names typ =
     topDeclElem' names $ ppTypeSig True occNames ppTyp unicode
   where
     topDeclElem' = topDeclElem links loc splice
-    ppTyp = ppType unicode qual emptyCtxts typ
+    ppTyp = ppSigType unicode qual emptyCtxts typ
     occNames = map getOccName names
 
 
@@ -301,9 +310,9 @@ ppFamDecl summary associated links instances fixities loc doc decl splice unicod
 
     -- Individual equation of a closed type family
     ppFamDeclEqn :: TyFamInstEqn DocNameI -> SubDecl
-    ppFamDeclEqn (HsIB { hsib_body = FamEqn { feqn_tycon = L _ n
-                                            , feqn_rhs = rhs
-                                            , feqn_pats = ts } })
+    ppFamDeclEqn (FamEqn { feqn_tycon = L _ n
+                         , feqn_rhs = rhs
+                         , feqn_pats = ts })
       = ( ppAppNameTypeArgs n ts unicode qual
           <+> equals <+> ppType unicode qual HideEmptyContexts (unLoc rhs)
         , Nothing
@@ -497,7 +506,7 @@ ppShortClassDecl summary links (ClassDecl { tcdCtxt = lctxt, tcdLName = lname, t
 
                 -- ToDo: add associated type defaults
 
-            [ ppFunSig summary links loc noHtml doc names (hsSigTypeI typ)
+            [ ppFunSig summary links loc noHtml doc names typ
                        [] splice unicode pkg qual
               | L _ (ClassOpSig _ False lnames typ) <- sigs
               , let doc = lookupAnySubdoc (head names) subdocs
@@ -561,14 +570,14 @@ ppClassDecl summary links instances fixities loc d subdocs
     lookupDAT name = Map.lookup (getName name) defaultAssocTys
     defaultAssocTys = Map.fromList
       [ (getName name, (vs, typ))
-      | L _ (TyFamInstDecl (HsIB _ (FamEqn { feqn_rhs = typ
-                                           , feqn_tycon = L _ name
-                                           , feqn_pats = vs }))) <- atsDefs
+      | L _ (TyFamInstDecl (FamEqn { feqn_rhs = typ
+                                   , feqn_tycon = L _ name
+                                   , feqn_pats = vs })) <- atsDefs
       ]
 
     -- Methods
     methodBit = subMethods
-      [ ppFunSig summary links loc noHtml doc [name] (hsSigTypeI typ)
+      [ ppFunSig summary links loc noHtml doc [name] typ
                  subfixs splice unicode pkg qual
           <+>
         subDefaults (maybeToList defSigs)
@@ -583,7 +592,7 @@ ppClassDecl summary links instances fixities loc d subdocs
 
     -- Default methods
     ppDefaultFunSig n (t, d') = ppFunSig summary links loc (keyword "default")
-      d' [n] (hsSigTypeI t) [] splice unicode pkg qual
+      d' [n] t [] splice unicode pkg qual
 
     lookupDM name = Map.lookup (getOccString name) defaultMethods
     defaultMethods = Map.fromList
@@ -709,7 +718,7 @@ ppInstanceSigs :: LinksInfo -> Splice -> Unicode -> Qualification
 ppInstanceSigs links splice unicode qual sigs = do
     TypeSig _ lnames typ <- sigs
     let names = map unLoc lnames
-        L _ rtyp = hsSigWcType typ
+        L _ rtyp = dropWildCards typ
     -- Instance methods signatures are synified and thus don't have a useful
     -- SrcSpan value. Use the methods name location instead.
     return $ ppSimpleSig links splice unicode qual HideEmptyContexts (getLoc $ head $ lnames) names rtyp
@@ -772,7 +781,7 @@ ppShortDataDecl summary dataInst dataDecl pats unicode qual
     pats1 = [ hsep [ keyword "pattern"
                    , hsep $ punctuate comma $ map (ppBinder summary . getOccName) lnames
                    , dcolon unicode
-                   , ppPatSigType unicode qual (hsSigTypeI typ)
+                   , ppPatSigType unicode qual typ
                    ]
             | (SigD _ (PatSynSig _ lnames typ),_) <- pats
             ]
@@ -851,7 +860,7 @@ ppShortConstrParts summary dataInst con unicode qual
                      in case det of
 
         -- Prefix constructor, e.g. 'Just a'
-        PrefixCon args ->
+        PrefixCon _ args ->
           ( header_ <+> hsep (ppOcc : map (ppLParendType unicode qual HideEmptyContexts . hsScaledThing) args)
           , noHtml
           , noHtml
@@ -878,7 +887,7 @@ ppShortConstrParts summary dataInst con unicode qual
 
       -- GADT constructor, e.g. 'Foo :: Int -> Foo'
       ConDeclGADT {} ->
-          ( hsep [ ppOcc, dcolon unicode, ppLType unicode qual HideEmptyContexts (getGADTConType con) ]
+          ( hsep [ ppOcc, dcolon unicode, ppLSigType unicode qual HideEmptyContexts (getGADTConType con) ]
           , noHtml
           , noHtml
           )
@@ -922,7 +931,7 @@ ppSideBySideConstr subdocs fixities unicode pkg qual (L _ con)
                          header_ = ppConstrHdr forall_ tyVars context unicode qual
                      in case det of
         -- Prefix constructor, e.g. 'Just a'
-        PrefixCon args
+        PrefixCon _ args
           | hasArgDocs -> header_ <+> ppOcc <+> fixity
           | otherwise -> hsep [ header_ <+> ppOcc
                               , hsep (map (ppLParendType unicode qual HideEmptyContexts . hsScaledThing) args)
@@ -947,24 +956,26 @@ ppSideBySideConstr subdocs fixities unicode pkg qual (L _ con)
           | otherwise -> hsep [ ppOcc
                               , dcolon unicode
                               -- ++AZ++ make this prepend "{..}" when it is a record style GADT
-                              , ppLType unicode qual HideEmptyContexts (getGADTConType con)
+                              , ppLSigType unicode qual HideEmptyContexts (getGADTConType con)
                               , fixity
                               ]
 
-    fieldPart = case (con, getConArgsI con) of
-        -- Record style GADTs
-        (ConDeclGADT{}, RecCon _)            -> [ doConstrArgsWithDocs [] ]
-
-        -- Regular record declarations
-        (_, RecCon (L _ fields))             -> [ doRecordFields fields ]
-
-        -- Any GADT or a regular H98 prefix data constructor
-        (_, PrefixCon args)     | hasArgDocs -> [ doConstrArgsWithDocs args ]
-
-        -- An infix H98 data constructor
-        (_, InfixCon arg1 arg2) | hasArgDocs -> [ doConstrArgsWithDocs [arg1,arg2] ]
-
-        _ -> []
+    fieldPart = case con of
+        ConDeclGADT{con_g_args = con_args'} -> case con_args' of
+          -- GADT record declarations
+          RecConGADT _                    -> [ doConstrArgsWithDocs [] ]
+          -- GADT prefix data constructors
+          PrefixConGADT args | hasArgDocs -> [ doConstrArgsWithDocs args ]
+          _                               -> []
+
+        ConDeclH98{con_args = con_args'} -> case con_args' of
+          -- H98 record declarations
+          RecCon (L _ fields)             -> [ doRecordFields fields ]
+          -- H98 prefix data constructors
+          PrefixCon _ args | hasArgDocs   -> [ doConstrArgsWithDocs args ]
+          -- H98 infix data constructor
+          InfixCon arg1 arg2 | hasArgDocs -> [ doConstrArgsWithDocs [arg1,arg2] ]
+          _                               -> []
 
     doRecordFields fields = subFields pkg qual
       (map (ppSideBySideField subdocs unicode qual) (map unLoc fields))
@@ -1049,18 +1060,17 @@ ppSideBySidePat fixities unicode qual lnames typ (doc, argDocs) =
          | otherwise = hsep [ keyword "pattern"
                             , ppOcc
                             , dcolon unicode
-                            , ppPatSigType unicode qual (hsSigTypeI typ)
+                            , ppPatSigType unicode qual typ
                             , fixity
                             ]
 
     fieldPart
       | not hasArgDocs = []
-      | otherwise = [ subFields Nothing qual (ppSubSigLike unicode qual (unLoc patTy)
+      | otherwise = [ subFields Nothing qual (ppSubSigLike unicode qual (unLoc typ)
                                                         argDocs [] (dcolon unicode)
                                                         emptyCtxt) ]
 
-    patTy = hsSigTypeI typ
-    emptyCtxt = patSigContext patTy
+    emptyCtxt = patSigContext typ
 
 
 -- | Print the LHS of a data\/newtype declaration.
@@ -1114,6 +1124,9 @@ ppLType       unicode qual emptyCtxts y = ppType unicode qual emptyCtxts (unLoc
 ppLParendType unicode qual emptyCtxts y = ppParendType unicode qual emptyCtxts (unLoc y)
 ppLFunLhType  unicode qual emptyCtxts y = ppFunLhType unicode qual emptyCtxts (unLoc y)
 
+ppLSigType ::  Unicode -> Qualification -> HideEmptyContexts -> LHsSigType DocNameI -> Html
+ppLSigType unicode qual emptyCtxts y = ppSigType unicode qual emptyCtxts (unLoc y)
+
 ppCtxType :: Unicode -> Qualification -> HsType DocNameI -> Html
 ppCtxType unicode qual ty = ppr_mono_ty (reparenTypePrec PREC_CTX ty) unicode qual HideEmptyContexts
 
@@ -1122,6 +1135,9 @@ ppType       unicode qual emptyCtxts ty = ppr_mono_ty (reparenTypePrec PREC_TOP
 ppParendType unicode qual emptyCtxts ty = ppr_mono_ty (reparenTypePrec PREC_CON ty) unicode qual emptyCtxts
 ppFunLhType  unicode qual emptyCtxts ty = ppr_mono_ty (reparenTypePrec PREC_FUN ty) unicode qual emptyCtxts
 
+ppSigType ::  Unicode -> Qualification -> HideEmptyContexts -> HsSigType DocNameI -> Html
+ppSigType unicode qual emptyCtxts sig_ty = ppr_sig_ty (reparenSigType sig_ty) unicode qual emptyCtxts
+
 ppLHsTypeArg :: Unicode -> Qualification -> HideEmptyContexts -> LHsTypeArg DocNameI -> Html
 ppLHsTypeArg unicode qual emptyCtxts (HsValArg ty) = ppLParendType unicode qual emptyCtxts ty
 ppLHsTypeArg unicode qual emptyCtxts (HsTypeArg _ ki) = atSign unicode <>
@@ -1156,18 +1172,18 @@ ppLKind unicode qual y = ppKind unicode qual (unLoc y)
 ppKind :: Unicode -> Qualification -> HsKind DocNameI -> Html
 ppKind unicode qual ki = ppr_mono_ty (reparenTypePrec PREC_TOP ki) unicode qual HideEmptyContexts
 
-patSigContext :: LHsType name -> HideEmptyContexts
-patSigContext typ | hasNonEmptyContext typ && isFirstContextEmpty typ =  ShowEmptyToplevelContexts
-                  | otherwise = HideEmptyContexts
+patSigContext :: LHsSigType DocNameI -> HideEmptyContexts
+patSigContext sig_typ | hasNonEmptyContext typ && isFirstContextEmpty typ =  ShowEmptyToplevelContexts
+                      | otherwise = HideEmptyContexts
   where
-    hasNonEmptyContext :: LHsType name -> Bool
+    typ = sig_body (unLoc sig_typ)
+
     hasNonEmptyContext t =
       case unLoc t of
         HsForAllTy _ _ s -> hasNonEmptyContext s
         HsQualTy _ cxt s -> if null (unLoc cxt) then hasNonEmptyContext s else True
         HsFunTy _ _ _ s    -> hasNonEmptyContext s
         _ -> False
-    isFirstContextEmpty :: LHsType name -> Bool
     isFirstContextEmpty t =
       case unLoc t of
         HsForAllTy _ _ s -> isFirstContextEmpty s
@@ -1178,10 +1194,16 @@ patSigContext typ | hasNonEmptyContext typ && isFirstContextEmpty typ =  ShowEmp
 
 -- | Pretty-print a pattern signature (all this does over 'ppLType' is slot in
 -- the right 'HideEmptyContext' value)
-ppPatSigType :: Unicode -> Qualification -> LHsType DocNameI -> Html
+ppPatSigType :: Unicode -> Qualification -> LHsSigType DocNameI -> Html
 ppPatSigType unicode qual typ =
-  let emptyCtxts = patSigContext typ in ppLType unicode qual emptyCtxts typ
+  let emptyCtxts = patSigContext typ in ppLSigType unicode qual emptyCtxts typ
 
+ppHsOuterTyVarBndrs :: RenderableBndrFlag flag
+                    => Unicode -> Qualification -> HsOuterTyVarBndrs flag DocNameI -> Html
+ppHsOuterTyVarBndrs unicode qual outer_bndrs = case outer_bndrs of
+  HsOuterImplicit{} -> noHtml
+  HsOuterExplicit{hso_bndrs = bndrs} ->
+    hsep (forallSymbol unicode : ppTyVars unicode qual bndrs) +++ dot
 
 ppForAllPart :: Unicode -> Qualification -> HsForAllTelescope DocNameI -> Html
 ppForAllPart unicode qual tele = case tele of
@@ -1191,6 +1213,10 @@ ppForAllPart unicode qual tele = case tele of
   HsForAllInvis { hsf_invis_bndrs = bndrs } ->
     hsep (forallSymbol unicode : ppTyVars unicode qual bndrs) +++ dot
 
+ppr_sig_ty :: HsSigType DocNameI -> Unicode -> Qualification -> HideEmptyContexts -> Html
+ppr_sig_ty (HsSig { sig_bndrs = outer_bndrs, sig_body = ltype }) unicode qual emptyCtxts
+  = ppHsOuterTyVarBndrs unicode qual outer_bndrs <+> ppr_mono_lty ltype unicode qual emptyCtxts
+
 ppr_mono_lty :: LHsType DocNameI -> Unicode -> Qualification -> HideEmptyContexts -> Html
 ppr_mono_lty ty = ppr_mono_ty (unLoc ty)
 
@@ -1236,7 +1262,7 @@ ppr_mono_ty (HsRecTy {})        _ _ _ = toHtml "{..}"
        -- Can now legally occur in ConDeclGADT, the output here is to provide a
        -- placeholder in the signature, which is followed by the field
        -- declarations.
-ppr_mono_ty (XHsType (NHsCoreTy {})) _ _ _ = error "ppr_mono_ty HsCoreTy"
+ppr_mono_ty (XHsType {})        _ _ _ = error "ppr_mono_ty HsCoreTy"
 ppr_mono_ty (HsExplicitListTy _ IsPromoted tys) u q _ = promoQuote $ brackets $ hsep $ punctuate comma $ map (ppLType u q HideEmptyContexts) tys
 ppr_mono_ty (HsExplicitListTy _ NotPromoted tys) u q _ = brackets $ hsep $ punctuate comma $ map (ppLType u q HideEmptyContexts) tys
 ppr_mono_ty (HsExplicitTupleTy _ tys) u q _ = promoQuote $ parenList $ map (ppLType u q HideEmptyContexts) tys
@@ -1272,3 +1298,4 @@ ppr_mono_ty (HsTyLit _ n) _ _ _ = ppr_tylit n
 ppr_tylit :: HsTyLit -> Html
 ppr_tylit (HsNumTy _ n) = toHtml (show n)
 ppr_tylit (HsStrTy _ s) = toHtml (show s)
+ppr_tylit (HsCharTy _ c) = toHtml (show c)
diff --git a/haddock-api/src/Haddock/Convert.hs b/haddock-api/src/Haddock/Convert.hs
index 980af379..10e13152 100644
--- a/haddock-api/src/Haddock/Convert.hs
+++ b/haddock-api/src/Haddock/Convert.hs
@@ -22,8 +22,9 @@ module Haddock.Convert (
 #include "HsVersions.h"
 
 import GHC.Data.Bag ( emptyBag )
-import GHC.Types.Basic ( TupleSort(..), SourceText(..), LexicalFixity(..)
-                  , PromotionFlag(..), DefMethSpec(..) )
+import GHC.Types.Basic ( TupleSort(..), PromotionFlag(..), DefMethSpec(..) )
+import GHC.Types.SourceText (SourceText(..))
+import GHC.Types.Fixity (LexicalFixity(..))
 import GHC.Core.Class
 import GHC.Core.Coercion.Axiom
 import GHC.Core.ConLike
@@ -31,6 +32,7 @@ import Data.Either (lefts, rights)
 import GHC.Core.DataCon
 import GHC.Core.FamInstEnv
 import GHC.Hs
+import GHC.Types.TyThing
 import GHC.Types.Name
 import GHC.Types.Name.Set    ( emptyNameSet )
 import GHC.Types.Name.Reader ( mkVarUnqual )
@@ -47,7 +49,7 @@ import GHC.Builtin.Names ( hasKey, eqTyConKey, ipClassKey, tYPETyConKey
 import GHC.Types.Unique ( getUnique )
 import GHC.Utils.Misc ( chkAppend, debugIsOn, dropList, equalLength
                       , filterByList, filterOut )
-import GHC.Utils.Outputable ( assertPanic )
+import GHC.Utils.Panic ( assertPanic )
 import GHC.Types.Var
 import GHC.Types.Var.Set
 import GHC.Types.SrcLoc
@@ -55,7 +57,7 @@ import GHC.Parser.Annotation (IsUnicodeSyntax(..))
 
 import Haddock.Types
 import Haddock.Interface.Specialize
-import Haddock.GhcUtils                      ( orderedFVs, defaultRuntimeRepVars )
+import Haddock.GhcUtils                      ( orderedFVs, defaultRuntimeRepVars, mkEmptySigType )
 
 import Data.Maybe                            ( catMaybes, mapMaybe, maybeToList )
 
@@ -90,10 +92,11 @@ tyThingToLHsDecl prr t = case t of
            extractFamilyDecl _           =
              Left "tyThingToLHsDecl: impossible associated tycon"
 
+           cvt :: HsTyVarBndr flag (GhcPass p) -> HsType (GhcPass p)
+             -- Without this signature, we trigger GHC#18932
            cvt (UserTyVar _ _ n) = HsTyVar noExtField NotPromoted n
            cvt (KindedTyVar _ _ (L name_loc n) kind) = HsKindSig noExtField
               (L name_loc (HsTyVar noExtField NotPromoted (L name_loc n))) kind
-           cvt (XTyVarBndr nec) = noExtCon nec
 
            -- | Convert a LHsTyVarBndr to an equivalent LHsType.
            hsLTyVarBndrToType :: LHsTyVarBndr flag (GhcPass p) -> LHsType (GhcPass p)
@@ -101,15 +104,14 @@ tyThingToLHsDecl prr t = case t of
 
            extractFamDefDecl :: FamilyDecl GhcRn -> Type -> TyFamDefltDecl GhcRn
            extractFamDefDecl fd rhs =
-             TyFamInstDecl $ HsIB { hsib_ext = hsq_ext (fdTyVars fd)
-                                  , hsib_body = FamEqn
+             TyFamInstDecl $ FamEqn
              { feqn_ext = noExtField
              , feqn_tycon = fdLName fd
-             , feqn_bndrs = Nothing
+             , feqn_bndrs = HsOuterImplicit{hso_ximplicit = hsq_ext (fdTyVars fd)}
              , feqn_pats = map (HsValArg . hsLTyVarBndrToType) $
                            hsq_explicit $ fdTyVars fd
              , feqn_fixity = fdFixity fd
-             , feqn_rhs = synifyType WithinType [] rhs }}
+             , feqn_rhs = synifyType WithinType [] rhs }
 
            extractAtItem
              :: ClassATItem
@@ -166,14 +168,14 @@ synifyAxBranch tc (CoAxBranch { cab_tvs = tkvs, cab_lhs = args, cab_rhs = rhs })
         typats          = map (synifyType WithinType []) args_types_only
         annot_typats    = zipWith3 annotHsType args_poly args_types_only typats
         hs_rhs          = synifyType WithinType [] rhs
-    in HsIB { hsib_ext = map tyVarName tkvs
-            , hsib_body   = FamEqn { feqn_ext    = noExtField
-                                   , feqn_tycon  = name
-                                   , feqn_bndrs  = Nothing
+        outer_bndrs     = HsOuterImplicit{hso_ximplicit = map tyVarName tkvs}
                                        -- TODO: this must change eventually
-                                   , feqn_pats   = map HsValArg annot_typats
-                                   , feqn_fixity = synifyFixity name
-                                   , feqn_rhs    = hs_rhs } }
+    in FamEqn { feqn_ext    = noExtField
+              , feqn_tycon  = name
+              , feqn_bndrs  = outer_bndrs
+              , feqn_pats   = map HsValArg annot_typats
+              , feqn_fixity = synifyFixity name
+              , feqn_rhs    = hs_rhs }
   where
     args_poly = tyConArgsPolyKinded tc
 
@@ -227,7 +229,7 @@ synifyTyCon prr _coax tc
       | otherwise = noLoc $ KindedTyVar noExtField () (noLoc (getName fakeTyVar)) (synifyKindSig realKind)
 
     conKind = defaultType prr (tyConKind tc)
-    tyVarKinds = fst . splitFunTys . snd . splitPiTysInvisible $ conKind
+    tyVarKinds = fst . splitFunTys . snd . splitInvisPiTys $ conKind
 
 synifyTyCon _prr _coax tc
   | Just flav <- famTyConFlav_maybe tc
@@ -367,6 +369,12 @@ synifyDataCon use_gadt_syntax dc =
   (_univ_tvs, ex_tvs, _eq_spec, theta, arg_tys, res_ty) = dataConFullSig dc
   user_tvbndrs = dataConUserTyVarBinders dc -- Used for GADT data constructors
 
+  outer_bndrs | null user_tvbndrs
+              = HsOuterImplicit { hso_ximplicit = [] }
+              | otherwise
+              = HsOuterExplicit { hso_xexplicit = noExtField
+                                , hso_bndrs = map synifyTyVarBndr user_tvbndrs }
+
   -- skip any EqTheta, use 'orig'inal syntax
   ctx | null theta = Nothing
       | otherwise = Just $ synifyCtx theta
@@ -383,34 +391,43 @@ synifyDataCon use_gadt_syntax dc =
   con_decl_field fl synTy = noLoc $
     ConDeclField noExtField [noLoc $ FieldOcc (flSelector fl) (noLoc $ mkVarUnqual $ flLabel fl)] synTy
                  Nothing
-  hs_arg_tys = case (use_named_field_syntax, use_infix_syntax) of
-          (True,True) -> Left "synifyDataCon: contradiction!"
-          (True,False) -> return $ RecCon (noLoc field_tys)
-          (False,False) -> return $ PrefixCon (map hsUnrestricted linear_tys)
-          (False,True) -> case linear_tys of
-                           [a,b] -> return $ InfixCon (hsUnrestricted a) (hsUnrestricted b)
-                           _ -> Left "synifyDataCon: infix with non-2 args?"
+
+  mk_h98_arg_tys :: Either ErrMsg (HsConDeclH98Details GhcRn)
+  mk_h98_arg_tys = case (use_named_field_syntax, use_infix_syntax) of
+    (True,True) -> Left "synifyDataCon: contradiction!"
+    (True,False) -> return $ RecCon (noLoc field_tys)
+    (False,False) -> return $ PrefixCon noTypeArgs (map hsUnrestricted linear_tys)
+    (False,True) -> case linear_tys of
+                     [a,b] -> return $ InfixCon (hsUnrestricted a) (hsUnrestricted b)
+                     _ -> Left "synifyDataCon: infix with non-2 args?"
+
+  mk_gadt_arg_tys :: HsConDeclGADTDetails GhcRn
+  mk_gadt_arg_tys
+    | use_named_field_syntax = RecConGADT (noLoc field_tys)
+    | otherwise              = PrefixConGADT (map hsUnrestricted linear_tys)
+
  -- finally we get synifyDataCon's result!
- in hs_arg_tys >>=
-      \hat ->
-        if use_gadt_syntax
-           then return $ noLoc $
-              ConDeclGADT { con_g_ext  = []
-                          , con_names  = [name]
-                          , con_forall = noLoc $ not $ null user_tvbndrs
-                          , con_qvars  = map synifyTyVarBndr user_tvbndrs
-                          , con_mb_cxt = ctx
-                          , con_args   = hat
-                          , con_res_ty = synifyType WithinType [] res_ty
-                          , con_doc    = Nothing }
-           else return $ noLoc $
-              ConDeclH98 { con_ext    = noExtField
-                         , con_name   = name
-                         , con_forall = noLoc False
-                         , con_ex_tvs = map (synifyTyVarBndr . (mkTyCoVarBinder InferredSpec)) ex_tvs
-                         , con_mb_cxt = ctx
-                         , con_args   = hat
-                         , con_doc    = Nothing }
+ in if use_gadt_syntax
+       then do
+         let hat = mk_gadt_arg_tys
+         return $ noLoc $ ConDeclGADT
+           { con_g_ext  = noExtField
+           , con_names  = [name]
+           , con_bndrs  = noLoc outer_bndrs
+           , con_mb_cxt = ctx
+           , con_g_args = hat
+           , con_res_ty = synifyType WithinType [] res_ty
+           , con_doc    = Nothing }
+       else do
+         hat <- mk_h98_arg_tys
+         return $ noLoc $ ConDeclH98
+           { con_ext    = noExtField
+           , con_name   = name
+           , con_forall = noLoc False
+           , con_ex_tvs = map (synifyTyVarBndr . (mkTyCoVarBinder InferredSpec)) ex_tvs
+           , con_mb_cxt = ctx
+           , con_args   = hat
+           , con_doc    = Nothing }
 
 synifyName :: NamedThing n => n -> Located Name
 synifyName n = L (srcLocSpan (getSrcLoc n)) (getName n)
@@ -526,17 +543,17 @@ data SynifyTypeState
 
 
 synifySigType :: SynifyTypeState -> [TyVar] -> Type -> LHsSigType GhcRn
--- The empty binders is a bit suspicious;
--- what if the type has free variables?
-synifySigType s vs ty = mkEmptyImplicitBndrs (synifyType s vs ty)
+-- The use of mkEmptySigType (which uses empty binders in OuterImplicit)
+-- is a bit suspicious; what if the type has free variables?
+synifySigType s vs ty = mkEmptySigType (synifyType s vs ty)
 
 synifySigWcType :: SynifyTypeState -> [TyVar] -> Type -> LHsSigWcType GhcRn
 -- Ditto (see synifySigType)
-synifySigWcType s vs ty = mkEmptyWildCardBndrs (mkEmptyImplicitBndrs (synifyType s vs ty))
+synifySigWcType s vs ty = mkEmptyWildCardBndrs (mkEmptySigType (synifyType s vs ty))
 
 synifyPatSynSigType :: PatSyn -> LHsSigType GhcRn
 -- Ditto (see synifySigType)
-synifyPatSynSigType ps = mkEmptyImplicitBndrs (synifyPatSynType ps)
+synifyPatSynSigType ps = mkEmptySigType (synifyPatSynType ps)
 
 -- | Depending on the first argument, try to default all type variables of kind
 -- 'RuntimeRep' to 'LiftedType'.
@@ -566,8 +583,8 @@ synifyType _ vs (TyConApp tc tys)
       , tyConArity tc == tys_len
       = noLoc $ HsTupleTy noExtField
                           (case sort of
-                              BoxedTuple      -> HsBoxedTuple
-                              ConstraintTuple -> HsConstraintTuple
+                              BoxedTuple      -> HsBoxedOrConstraintTuple
+                              ConstraintTuple -> HsBoxedOrConstraintTuple
                               UnboxedTuple    -> HsUnboxedTuple)
                            (map (synifyType WithinType vs) vis_tys)
       | isUnboxedSumTyCon tc = noLoc $ HsSumTy noExtField (map (synifyType WithinType vs) vis_tys)
@@ -804,6 +821,7 @@ synifyPatSynType ps =
 synifyTyLit :: TyLit -> HsTyLit
 synifyTyLit (NumTyLit n) = HsNumTy NoSourceText n
 synifyTyLit (StrTyLit s) = HsStrTy NoSourceText s
+synifyTyLit (CharTyLit c) = HsCharTy NoSourceText c
 
 synifyKindSig :: Kind -> LHsKind GhcRn
 synifyKindSig k = synifyType WithinType [] k
diff --git a/haddock-api/src/Haddock/GhcUtils.hs b/haddock-api/src/Haddock/GhcUtils.hs
index 10725ee5..546e2941 100644
--- a/haddock-api/src/Haddock/GhcUtils.hs
+++ b/haddock-api/src/Haddock/GhcUtils.hs
@@ -1,5 +1,8 @@
 {-# LANGUAGE BangPatterns, StandaloneDeriving, FlexibleInstances, ViewPatterns #-}
 {-# LANGUAGE TypeFamilies #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE TypeApplications #-}
+{-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE FlexibleContexts #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 {-# OPTIONS_GHC -Wno-incomplete-record-updates #-}
@@ -26,14 +29,14 @@ import Data.Maybe ( mapMaybe )
 import Haddock.Types( DocName, DocNameI )
 
 import GHC.Utils.FV as FV
-import GHC.Utils.Outputable ( Outputable, panic, showPpr )
-import GHC.Types.Basic (PromotionFlag(..))
+import GHC.Utils.Outputable ( Outputable )
+import GHC.Utils.Panic ( panic )
+import GHC.Driver.Ppr (showPpr )
 import GHC.Types.Name
 import GHC.Unit.Module
-import GHC.Driver.Types
 import GHC
-import GHC.Core.Class
 import GHC.Driver.Session
+import GHC.Types.Basic
 import GHC.Types.SrcLoc  ( advanceSrcLoc )
 import GHC.Types.Var     ( Specificity, VarBndr(..), TyVarBinder
                          , tyVarKind, updateTyVarKind, isInvisibleArgFlag )
@@ -51,6 +54,8 @@ import           Data.ByteString ( ByteString )
 import qualified Data.ByteString          as BS
 import qualified Data.ByteString.Internal as BS
 
+import GHC.HsToCore.Docs
+
 moduleString :: Module -> String
 moduleString = moduleNameString . moduleName
 
@@ -90,25 +95,12 @@ ifTrueJust :: Bool -> name -> Maybe name
 ifTrueJust True  = Just
 ifTrueJust False = const Nothing
 
-sigName :: LSig name -> [IdP name]
+sigName :: LSig GhcRn -> [IdP GhcRn]
 sigName (L _ sig) = sigNameNoLoc sig
 
-sigNameNoLoc :: Sig name -> [IdP name]
-sigNameNoLoc (TypeSig    _   ns _)         = map unLoc ns
-sigNameNoLoc (ClassOpSig _ _ ns _)         = map unLoc ns
-sigNameNoLoc (PatSynSig  _   ns _)         = map unLoc ns
-sigNameNoLoc (SpecSig    _   n _ _)        = [unLoc n]
-sigNameNoLoc (InlineSig  _   n _)          = [unLoc n]
-sigNameNoLoc (FixSig _ (FixitySig _ ns _)) = map unLoc ns
-sigNameNoLoc _                             = []
-
 -- | Was this signature given by the user?
-isUserLSig :: LSig name -> Bool
-isUserLSig (L _ (TypeSig {}))    = True
-isUserLSig (L _ (ClassOpSig {})) = True
-isUserLSig (L _ (PatSynSig {}))  = True
-isUserLSig _                     = False
-
+isUserLSig :: forall p. UnXRec p => LSig p -> Bool
+isUserLSig = isUserSig . unXRec @p
 
 isClassD :: HsDecl a -> Bool
 isClassD (TyClD _ d) = isClassDecl d
@@ -123,10 +115,10 @@ pretty = showPpr
 -- instantiated at DocNameI instead of (GhcPass _).
 
 -- | Like 'hsTyVarName' from GHC API, but not instantiated at (GhcPass _)
-hsTyVarBndrName :: (XXTyVarBndr n ~ NoExtCon) => HsTyVarBndr flag n -> IdP n
-hsTyVarBndrName (UserTyVar _ _ name) = unLoc name
-hsTyVarBndrName (KindedTyVar _ _ (L _ name) _) = name
-hsTyVarBndrName (XTyVarBndr nec) = noExtCon nec
+hsTyVarBndrName :: forall flag n. (XXTyVarBndr n ~ NoExtCon, UnXRec n)
+                => HsTyVarBndr flag n -> IdP n
+hsTyVarBndrName (UserTyVar _ _ name) = unXRec @n name
+hsTyVarBndrName (KindedTyVar _ _ name _) = unXRec @n name
 
 hsTyVarNameI :: HsTyVarBndr flag DocNameI -> DocName
 hsTyVarNameI (UserTyVar _ _ (L _ n))     = n
@@ -139,33 +131,45 @@ getConNamesI :: ConDecl DocNameI -> [Located DocName]
 getConNamesI ConDeclH98  {con_name  = name}  = [name]
 getConNamesI ConDeclGADT {con_names = names} = names
 
-hsImplicitBodyI :: HsImplicitBndrs DocNameI thing -> thing
-hsImplicitBodyI (HsIB { hsib_body = body }) = body
-
 hsSigTypeI :: LHsSigType DocNameI -> LHsType DocNameI
-hsSigTypeI = hsImplicitBodyI
+hsSigTypeI = sig_body . unLoc
+
+mkEmptySigType :: LHsType GhcRn -> LHsSigType GhcRn
+-- Dubious, because the implicit binders are empty even
+-- though the type might have free varaiables
+mkEmptySigType lty@(L loc ty) = L loc $ case ty of
+  HsForAllTy { hst_tele = HsForAllInvis { hsf_invis_bndrs = bndrs }
+             , hst_body = body }
+    -> HsSig { sig_ext = noExtField
+             , sig_bndrs = HsOuterExplicit { hso_xexplicit = noExtField
+                                           , hso_bndrs     = bndrs }
+             , sig_body = body }
+  _ -> HsSig { sig_ext   = noExtField
+             , sig_bndrs = HsOuterImplicit{hso_ximplicit = []}
+             , sig_body = lty }
 
 mkHsForAllInvisTeleI ::
   [LHsTyVarBndr Specificity DocNameI] -> HsForAllTelescope DocNameI
 mkHsForAllInvisTeleI invis_bndrs =
   HsForAllInvis { hsf_xinvis = noExtField, hsf_invis_bndrs = invis_bndrs }
 
-getConArgsI :: ConDecl DocNameI -> HsConDeclDetails DocNameI
-getConArgsI d = con_args d
+mkHsImplicitSigTypeI :: LHsType DocNameI -> HsSigType DocNameI
+mkHsImplicitSigTypeI body =
+  HsSig { sig_ext   = noExtField
+        , sig_bndrs = HsOuterImplicit{hso_ximplicit = noExtField}
+        , sig_body  = body }
 
-getGADTConType :: ConDecl DocNameI -> LHsType DocNameI
+getGADTConType :: ConDecl DocNameI -> LHsSigType DocNameI
 -- The full type of a GADT data constructor We really only get this in
 -- order to pretty-print it, and currently only in Haddock's code.  So
 -- we are cavalier about locations and extensions, hence the
 -- 'undefined's
-getGADTConType (ConDeclGADT { con_forall = L _ has_forall
-                            , con_qvars = qtvs
-                            , con_mb_cxt = mcxt, con_args = args
+getGADTConType (ConDeclGADT { con_bndrs = L _ outer_bndrs
+                            , con_mb_cxt = mcxt, con_g_args = args
                             , con_res_ty = res_ty })
- | has_forall = noLoc (HsForAllTy { hst_xforall = noExtField
-                                  , hst_tele = mkHsForAllInvisTeleI qtvs
-                                  , hst_body  = theta_ty })
- | otherwise  = theta_ty
+ = noLoc (HsSig { sig_ext   = noExtField
+                , sig_bndrs = outer_bndrs
+                , sig_body  = theta_ty })
  where
    theta_ty | Just theta <- mcxt
             = noLoc (HsQualTy { hst_xqual = noExtField, hst_ctxt = theta, hst_body = tau_ty })
@@ -174,9 +178,8 @@ getGADTConType (ConDeclGADT { con_forall = L _ has_forall
 
 --  tau_ty :: LHsType DocNameI
    tau_ty = case args of
-              RecCon flds ->  mkFunTy (noLoc (HsRecTy noExtField (unLoc flds))) res_ty
-              PrefixCon pos_args -> foldr mkFunTy res_ty (map hsScaledThing pos_args)
-              InfixCon arg1 arg2 -> (hsScaledThing arg1) `mkFunTy` ((hsScaledThing arg2) `mkFunTy` res_ty)
+              RecConGADT flds -> mkFunTy (noLoc (HsRecTy noExtField (unLoc flds))) res_ty
+              PrefixConGADT pos_args -> foldr mkFunTy res_ty (map hsScaledThing pos_args)
 
    mkFunTy a b = noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) a b)
 
@@ -186,7 +189,7 @@ getGADTConType (ConDeclH98 {}) = panic "getGADTConType"
 getMainDeclBinderI :: HsDecl DocNameI -> [IdP DocNameI]
 getMainDeclBinderI (TyClD _ d) = [tcdNameI d]
 getMainDeclBinderI (ValD _ d) =
-  case collectHsBindBinders d of
+  case collectHsBindBinders CollNoDictBinders d of
     []       -> []
     (name:_) -> [name]
 getMainDeclBinderI (SigD _ d) = sigNameNoLoc d
@@ -206,73 +209,33 @@ tyClDeclLNameI (ClassDecl { tcdLName = ln }) = ln
 tcdNameI :: TyClDecl DocNameI -> DocName
 tcdNameI = unLoc . tyClDeclLNameI
 
--- -------------------------------------
-
-getGADTConTypeG :: ConDecl GhcRn -> LHsType GhcRn
--- The full type of a GADT data constructor We really only get this in
--- order to pretty-print it, and currently only in Haddock's code.  So
--- we are cavalier about locations and extensions, hence the
--- 'undefined's
-getGADTConTypeG (ConDeclGADT { con_forall = L _ has_forall
-                            , con_qvars = qtvs
-                            , con_mb_cxt = mcxt, con_args = args
-                            , con_res_ty = res_ty })
- | has_forall = noLoc (HsForAllTy { hst_xforall = noExtField
-                                  , hst_tele = mkHsForAllInvisTele qtvs
-                                  , hst_body  = theta_ty })
- | otherwise  = theta_ty
- where
-   theta_ty | Just theta <- mcxt
-            = noLoc (HsQualTy { hst_xqual = noExtField, hst_ctxt = theta, hst_body = tau_ty })
-            | otherwise
-            = tau_ty
-
---   tau_ty :: LHsType DocNameI
-   tau_ty = case args of
-              RecCon flds ->  mkFunTy (noLoc (HsRecTy noExtField (unLoc flds))) res_ty
-              PrefixCon pos_args -> foldr mkFunTy res_ty (map hsScaledThing pos_args)
-              InfixCon arg1 arg2 -> (hsScaledThing arg1) `mkFunTy` ((hsScaledThing arg2) `mkFunTy` res_ty)
-
-   -- mkFunTy :: LHsType DocNameI -> LHsType DocNameI -> LHsType DocNameI
-   mkFunTy a b = noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) a b)
-
-getGADTConTypeG (ConDeclH98 {}) = panic "getGADTConTypeG"
-  -- Should only be called on ConDeclGADT
-
-
-mkEmptySigWcType :: LHsType GhcRn -> LHsSigWcType GhcRn
--- Dubious, because the implicit binders are empty even
--- though the type might have free varaiables
-mkEmptySigWcType ty = mkEmptyWildCardBndrs (mkEmptyImplicitBndrs ty)
-
-
 addClassContext :: Name -> LHsQTyVars GhcRn -> LSig GhcRn -> LSig GhcRn
 -- Add the class context to a class-op signature
 addClassContext cls tvs0 (L pos (ClassOpSig _ _ lname ltype))
-  = L pos (TypeSig noExtField lname (mkEmptySigWcType (go (hsSigType ltype))))
-          -- The mkEmptySigWcType is suspicious
+  = L pos (TypeSig noExtField lname (mkEmptyWildCardBndrs (go_sig_ty ltype)))
   where
-    go (L loc (HsForAllTy { hst_tele = tele, hst_body = ty }))
-       = L loc (HsForAllTy { hst_tele = tele, hst_xforall = noExtField
-                           , hst_body = go ty })
-    go (L loc (HsQualTy { hst_ctxt = ctxt, hst_body = ty }))
+    go_sig_ty (L loc (HsSig { sig_bndrs = bndrs, sig_body = ty }))
+       = L loc (HsSig { sig_ext = noExtField
+                      , sig_bndrs = bndrs, sig_body = go_ty ty })
+
+    go_ty (L loc (HsForAllTy { hst_tele = tele, hst_body = ty }))
+       = L loc (HsForAllTy { hst_xforall = noExtField
+                           , hst_tele = tele, hst_body = go_ty ty })
+    go_ty (L loc (HsQualTy { hst_ctxt = ctxt, hst_body = ty }))
        = L loc (HsQualTy { hst_xqual = noExtField
                          , hst_ctxt = add_ctxt ctxt, hst_body = ty })
-    go (L loc ty)
+    go_ty (L loc ty)
        = L loc (HsQualTy { hst_xqual = noExtField
                          , hst_ctxt = add_ctxt (L loc []), hst_body = L loc ty })
 
-    extra_pred :: LHsType GhcRn
-    extra_pred = nlHsTyConApp Prefix cls (map HsValArg (lHsQTyVarsToTypes tvs0))
-
-    add_ctxt :: LHsContext GhcRn -> LHsContext GhcRn
+    extra_pred = nlHsTyConApp Prefix cls (lHsQTyVarsToTypes tvs0)
     add_ctxt (L loc preds) = L loc (extra_pred : preds)
 
 addClassContext _ _ sig = sig   -- E.g. a MinimalSig is fine
 
-lHsQTyVarsToTypes :: LHsQTyVars GhcRn -> [LHsType GhcRn]
+lHsQTyVarsToTypes :: LHsQTyVars GhcRn -> [LHsTypeArg GhcRn]
 lHsQTyVarsToTypes tvs
-  = [ noLoc (HsTyVar noExtField NotPromoted (noLoc (hsLTyVarName tv)))
+  = [ HsValArg $ noLoc (HsTyVar noExtField NotPromoted (noLoc (hsLTyVarName tv)))
     | tv <- hsQTvExplicit tvs ]
 
 
@@ -280,7 +243,6 @@ lHsQTyVarsToTypes tvs
 -- * Making abstract declarations
 --------------------------------------------------------------------------------
 
-
 restrictTo :: [Name] -> LHsDecl GhcRn -> LHsDecl GhcRn
 restrictTo names (L loc decl) = L loc $ case decl of
   TyClD x d | isDataDecl d  ->
@@ -303,17 +265,27 @@ restrictDataDefn names defn@(HsDataDefn { dd_ND = new_or_data, dd_cons = cons })
 restrictCons :: [Name] -> [LConDecl GhcRn] -> [LConDecl GhcRn]
 restrictCons names decls = [ L p d | L p (Just d) <- map (fmap keep) decls ]
   where
-    keep d | any (\n -> n `elem` names) (map unLoc $ getConNames d) =
-      case con_args d of
-        PrefixCon _ -> Just d
-        RecCon fields
-          | all field_avail (unLoc fields) -> Just d
-          | otherwise -> Just (d { con_args = PrefixCon (field_types $ unLoc fields) })
-          -- if we have *all* the field names available, then
-          -- keep the record declaration.  Otherwise degrade to
-          -- a constructor declaration.  This isn't quite right, but
-          -- it's the best we can do.
-        InfixCon _ _ -> Just d
+    keep :: ConDecl GhcRn -> Maybe (ConDecl GhcRn)
+    keep d
+      | any (\n -> n `elem` names) (map unLoc $ getConNames d) =
+        case d of
+          ConDeclH98 { con_args = con_args' } -> case con_args' of
+            PrefixCon {} -> Just d
+            RecCon fields
+              | all field_avail (unLoc fields) -> Just d
+              | otherwise -> Just (d { con_args = PrefixCon [] (field_types $ unLoc fields) })
+              -- if we have *all* the field names available, then
+              -- keep the record declaration.  Otherwise degrade to
+              -- a constructor declaration.  This isn't quite right, but
+              -- it's the best we can do.
+            InfixCon _ _ -> Just d
+
+          ConDeclGADT { con_g_args = con_args' } -> case con_args' of
+            PrefixConGADT {} -> Just d
+            RecConGADT fields
+              | all field_avail (unLoc fields) -> Just d
+              | otherwise -> Just (d { con_g_args = PrefixConGADT (field_types $ unLoc fields) })
+              -- see above
       where
         field_avail :: LConDeclField GhcRn -> Bool
         field_avail (L _ (ConDeclField _ fs _ _))
@@ -358,17 +330,19 @@ data Precedence
 --
 -- We cannot add parens that may be required by fixities because we do not have
 -- any fixity information to work with in the first place :(.
-reparenTypePrec :: (XParTy a ~ NoExtField) => Precedence -> HsType a -> HsType a
+reparenTypePrec :: forall a. ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                             , MapXRec a, UnXRec a, WrapXRec a )
+                => Precedence -> HsType a -> HsType a
 reparenTypePrec = go
   where
 
   -- Shorter name for 'reparenType'
-  go :: (XParTy a ~ NoExtField) => Precedence -> HsType a -> HsType a
+  go :: Precedence -> HsType a -> HsType a
   go _ (HsBangTy x b ty)     = HsBangTy x b (reparenLType ty)
   go _ (HsTupleTy x con tys) = HsTupleTy x con (map reparenLType tys)
   go _ (HsSumTy x tys)       = HsSumTy x (map reparenLType tys)
   go _ (HsListTy x ty)       = HsListTy x (reparenLType ty)
-  go _ (HsRecTy x flds)      = HsRecTy x (map (fmap reparenConDeclField) flds)
+  go _ (HsRecTy x flds)      = HsRecTy x (map (mapXRec @a reparenConDeclField) flds)
   go p (HsDocTy x ty d)      = HsDocTy x (goL p ty) d
   go _ (HsExplicitListTy x p tys) = HsExplicitListTy x p (map reparenLType tys)
   go _ (HsExplicitTupleTy x tys) = HsExplicitTupleTy x (map reparenLType tys)
@@ -381,7 +355,8 @@ reparenTypePrec = go
   go p (HsQualTy x ctxt ty)
     = let p' [_] = PREC_CTX
           p' _   = PREC_TOP -- parens will get added anyways later...
-      in paren p PREC_CTX $ HsQualTy x (fmap (\xs -> map (goL (p' xs)) xs) ctxt) (goL PREC_TOP ty)
+          ctxt' = mapXRec @a (\xs -> map (goL (p' xs)) xs) ctxt
+      in paren p PREC_CTX $ HsQualTy x ctxt' (goL PREC_TOP ty)
   go p (HsFunTy x w ty1 ty2)
     = paren p PREC_FUN $ HsFunTy x w (goL PREC_FUN ty1) (goL PREC_TOP ty2)
   go p (HsAppTy x fun_ty arg_ty)
@@ -390,7 +365,7 @@ reparenTypePrec = go
     = paren p PREC_CON $ HsAppKindTy x (goL PREC_FUN fun_ty) (goL PREC_CON arg_ki)
   go p (HsOpTy x ty1 op ty2)
     = paren p PREC_FUN $ HsOpTy x (goL PREC_OP ty1) op (goL PREC_OP ty2)
-  go p (HsParTy _ t) = unLoc $ goL p t -- pretend the paren doesn't exist - it will be added back if needed
+  go p (HsParTy _ t) = unXRec @a $ goL p t -- pretend the paren doesn't exist - it will be added back if needed
   go _ t@HsTyVar{} = t
   go _ t@HsStarTy{} = t
   go _ t@HsSpliceTy{} = t
@@ -399,43 +374,68 @@ reparenTypePrec = go
   go _ t@XHsType{} = t
 
   -- Located variant of 'go'
-  goL :: (XParTy a ~ NoExtField) => Precedence -> LHsType a -> LHsType a
-  goL ctxt_prec = fmap (go ctxt_prec)
+  goL :: Precedence -> LHsType a -> LHsType a
+  goL ctxt_prec = mapXRec @a (go ctxt_prec)
 
   -- Optionally wrap a type in parens
-  paren :: (XParTy a ~ NoExtField)
-        => Precedence            -- Precedence of context
+  paren :: Precedence            -- Precedence of context
         -> Precedence            -- Precedence of top-level operator
         -> HsType a -> HsType a  -- Wrap in parens if (ctxt >= op)
-  paren ctxt_prec op_prec | ctxt_prec >= op_prec = HsParTy noExtField . noLoc
+  paren ctxt_prec op_prec | ctxt_prec >= op_prec = HsParTy noExtField . wrapXRec @a
                           | otherwise            = id
 
 
 -- | Add parenthesis around the types in a 'HsType' (see 'reparenTypePrec')
-reparenType :: (XParTy a ~ NoExtField) => HsType a -> HsType a
+reparenType :: ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+               , MapXRec a, UnXRec a, WrapXRec a )
+            => HsType a -> HsType a
 reparenType = reparenTypePrec PREC_TOP
 
 -- | Add parenthesis around the types in a 'LHsType' (see 'reparenTypePrec')
-reparenLType :: (XParTy a ~ NoExtField) => LHsType a -> LHsType a
-reparenLType = fmap reparenType
+reparenLType :: forall a. ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                          , MapXRec a, UnXRec a, WrapXRec a )
+             => LHsType a -> LHsType a
+reparenLType = mapXRec @a reparenType
+
+-- | Add parentheses around the types in an 'HsSigType' (see 'reparenTypePrec')
+reparenSigType :: forall a. ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                            , MapXRec a, UnXRec a, WrapXRec a )
+               => HsSigType a -> HsSigType a
+reparenSigType (HsSig x bndrs body) =
+  HsSig x (reparenOuterTyVarBndrs bndrs) (reparenLType body)
+reparenSigType v@XHsSigType{} = v
+
+-- | Add parentheses around the types in an 'HsOuterTyVarBndrs' (see 'reparenTypePrec')
+reparenOuterTyVarBndrs :: forall flag a. ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                                         , MapXRec a, UnXRec a, WrapXRec a )
+                       => HsOuterTyVarBndrs flag a -> HsOuterTyVarBndrs flag a
+reparenOuterTyVarBndrs imp@HsOuterImplicit{} = imp
+reparenOuterTyVarBndrs (HsOuterExplicit x exp_bndrs) =
+  HsOuterExplicit x (map (mapXRec @(NoGhcTc a) reparenTyVar) exp_bndrs)
+reparenOuterTyVarBndrs v@XHsOuterTyVarBndrs{} = v
 
 -- | Add parentheses around the types in an 'HsForAllTelescope' (see 'reparenTypePrec')
-reparenHsForAllTelescope :: (XParTy a ~ NoExtField)
+reparenHsForAllTelescope :: forall a. ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                                      , MapXRec a, UnXRec a, WrapXRec a )
                          => HsForAllTelescope a -> HsForAllTelescope a
 reparenHsForAllTelescope (HsForAllVis x bndrs) =
-  HsForAllVis x (map (fmap reparenTyVar) bndrs)
+  HsForAllVis x (map (mapXRec @a reparenTyVar) bndrs)
 reparenHsForAllTelescope (HsForAllInvis x bndrs) =
-  HsForAllInvis x (map (fmap reparenTyVar) bndrs)
+  HsForAllInvis x (map (mapXRec @a reparenTyVar) bndrs)
 reparenHsForAllTelescope v@XHsForAllTelescope{} = v
 
 -- | Add parenthesis around the types in a 'HsTyVarBndr' (see 'reparenTypePrec')
-reparenTyVar :: (XParTy a ~ NoExtField) => HsTyVarBndr flag a -> HsTyVarBndr flag a
+reparenTyVar :: ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                , MapXRec a, UnXRec a, WrapXRec a )
+             => HsTyVarBndr flag a -> HsTyVarBndr flag a
 reparenTyVar (UserTyVar x flag n) = UserTyVar x flag n
 reparenTyVar (KindedTyVar x flag n kind) = KindedTyVar x flag n (reparenLType kind)
 reparenTyVar v@XTyVarBndr{} = v
 
 -- | Add parenthesis around the types in a 'ConDeclField' (see 'reparenTypePrec')
-reparenConDeclField :: (XParTy a ~ NoExtField) => ConDeclField a -> ConDeclField a
+reparenConDeclField :: ( XParTy a ~ NoExtField, NoGhcTc a ~ a
+                       , MapXRec a, UnXRec a, WrapXRec a )
+                    => ConDeclField a -> ConDeclField a
 reparenConDeclField (ConDeclField x n t d) = ConDeclField x n (reparenLType t) d
 reparenConDeclField c@XConDeclField{} = c
 
@@ -471,10 +471,9 @@ class Parent a where
 
 instance Parent (ConDecl GhcRn) where
   children con =
-    case con_args con of
-      RecCon fields -> map (extFieldOcc . unLoc) $
-                         concatMap (cd_fld_names . unLoc) (unLoc fields)
-      _             -> []
+    case getRecConArgs_maybe con of
+      Nothing -> []
+      Just flds -> map (extFieldOcc . unLoc) $ concatMap (cd_fld_names . unLoc) (unLoc flds)
 
 instance Parent (TyClDecl GhcRn) where
   children d
@@ -526,14 +525,6 @@ modifySessionDynFlags f = do
   return ()
 
 
--- Extract the minimal complete definition of a Name, if one exists
-minimalDef :: GhcMonad m => Name -> m (Maybe ClassMinimalDef)
-minimalDef n = do
-  mty <- lookupGlobalName n
-  case mty of
-    Just (ATyCon (tyConClass_maybe -> Just c)) -> return . Just $ classMinimalDef c
-    _ -> return Nothing
-
 -------------------------------------------------------------------------------
 -- * DynFlags
 -------------------------------------------------------------------------------
diff --git a/haddock-api/src/Haddock/Interface.hs b/haddock-api/src/Haddock/Interface.hs
index b68cc4a9..f1403def 100644
--- a/haddock-api/src/Haddock/Interface.hs
+++ b/haddock-api/src/Haddock/Interface.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE CPP, OverloadedStrings, BangPatterns #-}
+{-# LANGUAGE CPP, OverloadedStrings, BangPatterns, NamedFieldPuns #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Haddock.Interface
@@ -29,7 +29,8 @@
 -- using this environment.
 -----------------------------------------------------------------------------
 module Haddock.Interface (
-  processModules
+    plugin
+  , processModules
 ) where
 
 
@@ -43,26 +44,34 @@ import Haddock.Types
 import Haddock.Utils
 
 import Control.Monad
-import Control.Monad.IO.Class ( liftIO )
-import Control.Exception (evaluate)
+import Control.Monad.IO.Class ( MonadIO, liftIO )
+import Data.IORef
 import Data.List (foldl', isPrefixOf, nub)
 import qualified Data.Map as Map
 import qualified Data.Set as Set
 import Text.Printf
 
 import GHC.Unit.Module.Env (mkModuleSet, emptyModuleSet, unionModuleSet, ModuleSet)
+import GHC.Unit.Module.ModSummary
+import GHC.Unit.Module.Graph
+import GHC.Unit.Types
 import GHC.Data.Graph.Directed
 import GHC.Driver.Session hiding (verbosity)
 import GHC hiding (verbosity)
-import GHC.Driver.Types
+import GHC.Driver.Env
+import GHC.Driver.Monad (Session(..), modifySession, reflectGhc)
 import GHC.Data.FastString (unpackFS)
-import GHC.Tc.Types (tcg_rdr_env)
+import GHC.Tc.Types (TcM, TcGblEnv(..))
+import GHC.Tc.Utils.Monad (getTopEnv, setGblEnv)
+import GHC.Tc.Utils.Env (tcLookupGlobal)
 import GHC.Types.Name (nameIsFromExternalPackage, nameOccName)
 import GHC.Types.Name.Occurrence (isTcOcc)
-import GHC.Types.Name.Reader (unQualOK, gre_name, globalRdrEnvElts)
+import GHC.Types.Name.Reader (unQualOK, greMangledName, globalRdrEnvElts)
 import GHC.Utils.Error (withTimingD)
 import GHC.HsToCore.Docs
 import GHC.Runtime.Loader (initializePlugins)
+import GHC.Plugins (Outputable, StaticPlugin(..), Plugin(..), PluginWithArgs(..),
+                     defaultPlugin, keepRenamedSource)
 
 #if defined(mingw32_HOST_OS)
 import System.IO
@@ -88,8 +97,14 @@ processModules verbosity modules flags extIfaces = do
 #endif
 
   out verbosity verbose "Creating interfaces..."
-  let instIfaceMap =  Map.fromList [ (instMod iface, iface) | ext <- extIfaces
-                                   , iface <- ifInstalledIfaces ext ]
+  let
+    instIfaceMap :: InstIfaceMap
+    instIfaceMap = Map.fromList
+      [ (instMod iface, iface)
+      | ext <- extIfaces
+      , iface <- ifInstalledIfaces ext
+      ]
+
   (interfaces, ms) <- createIfaces verbosity modules flags instIfaceMap
 
   let exportedNames =
@@ -125,98 +140,202 @@ processModules verbosity modules flags extIfaces = do
 
 createIfaces :: Verbosity -> [String] -> [Flag] -> InstIfaceMap -> Ghc ([Interface], ModuleSet)
 createIfaces verbosity modules flags instIfaceMap = do
-  -- Ask GHC to tell us what the module graph is
+  (haddockPlugin, getIfaces, getModules) <- liftIO $ plugin
+    verbosity flags instIfaceMap
+
+  let
+    installHaddockPlugin :: HscEnv -> HscEnv
+    installHaddockPlugin hsc_env = hsc_env
+      {
+        hsc_dflags =
+          gopt_set (hsc_dflags hsc_env) Opt_PluginTrustworthy
+      , hsc_static_plugins =
+          haddockPlugin : hsc_static_plugins hsc_env
+      }
+
+  -- Note that we would rather use withTempSession but as long as we
+  -- have the separate attachInstances step we need to keep the session
+  -- alive to be able to find all the instances.
+  modifySession installHaddockPlugin
+
   targets <- mapM (\filePath -> guessTarget filePath Nothing) modules
   setTargets targets
-  modGraph <- depanal [] False
 
-  -- Visit modules in that order
-  let sortedMods = flattenSCCs $ topSortModuleGraph False modGraph Nothing
-  out verbosity normal "Haddock coverage:"
-  (ifaces, _, !ms) <- foldM f ([], Map.empty, emptyModuleSet) sortedMods
-  return (reverse ifaces, ms)
-  where
-    f (ifaces, ifaceMap, !ms) modSummary = do
-      x <- {-# SCC processModule #-}
-           withTimingD "processModule" (const ()) $ do
-             processModule verbosity modSummary flags ifaceMap instIfaceMap
-      return $ case x of
-        Just (iface, ms') -> ( iface:ifaces
-                             , Map.insert (ifaceMod iface) iface ifaceMap
-                             , unionModuleSet ms ms' )
-        Nothing           -> ( ifaces
-                             , ifaceMap
-                             , ms ) -- Boot modules don't generate ifaces.
-
-
-processModule :: Verbosity -> ModSummary -> [Flag] -> IfaceMap -> InstIfaceMap -> Ghc (Maybe (Interface, ModuleSet))
-processModule verbosity modsum flags modMap instIfaceMap = do
-  out verbosity verbose $ "Checking module " ++ moduleString (ms_mod modsum) ++ "..."
-
-  -- Since GHC 8.6, plugins are initialized on a per module basis
-  hsc_env' <- getSession
-  dynflags' <- liftIO (initializePlugins hsc_env' (GHC.ms_hspp_opts modsum))
-  let modsum' = modsum { ms_hspp_opts = dynflags' }
-
-  tm <- {-# SCC "parse/typecheck/load" #-} loadModule =<< typecheckModule =<< parseModule modsum'
-
-  case isBootSummary modsum of
-    IsBoot ->
-      return Nothing
-    NotBoot -> do
-      out verbosity verbose "Creating interface..."
-      (interface, msgs) <- {-# SCC createIterface #-}
-                          withTimingD "createInterface" (const ()) $ do
-                            runWriterGhc $ createInterface tm flags modMap instIfaceMap
-
-      -- We need to keep track of which modules were somehow in scope so that when
-      -- Haddock later looks for instances, it also looks in these modules too.
-      --
-      -- See https://github.com/haskell/haddock/issues/469.
-      hsc_env <- getSession
-      let new_rdr_env = tcg_rdr_env . fst . GHC.tm_internals_ $ tm
-          this_pkg = homeUnit (hsc_dflags hsc_env)
-          !mods = mkModuleSet [ nameModule name
-                              | gre <- globalRdrEnvElts new_rdr_env
-                              , let name = gre_name gre
-                              , nameIsFromExternalPackage this_pkg name
-                              , isTcOcc (nameOccName name)   -- Types and classes only
-                              , unQualOK gre ]               -- In scope unqualified
-
-      liftIO $ mapM_ putStrLn (nub msgs)
-      dflags <- getDynFlags
-      let (haddockable, haddocked) = ifaceHaddockCoverage interface
-          percentage = div (haddocked * 100) haddockable
-          modString = moduleString (ifaceMod interface)
-          coverageMsg = printf " %3d%% (%3d /%3d) in '%s'" percentage haddocked haddockable modString
-          header = case ifaceDoc interface of
-            Documentation Nothing _ -> False
-            _ -> True
-          undocumentedExports = [ formatName s n | ExportDecl { expItemDecl = L s n
-                                                              , expItemMbDoc = (Documentation Nothing _, _)
-                                                              } <- ifaceExportItems interface ]
-            where
-              formatName :: SrcSpan -> HsDecl GhcRn -> String
-              formatName loc n = p (getMainDeclBinder n) ++ case loc of
-                RealSrcSpan rss _ -> " (" ++ unpackFS (srcSpanFile rss) ++ ":" ++ show (srcSpanStartLine rss) ++ ")"
-                _ -> ""
-
-              p [] = ""
-              p (x:_) = let n = pretty dflags x
-                            ms = modString ++ "."
-                        in if ms `isPrefixOf` n
-                           then drop (length ms) n
-                           else n
-
-      when (OptHide `notElem` ifaceOptions interface) $ do
-        out verbosity normal coverageMsg
-        when (Flag_NoPrintMissingDocs `notElem` flags
-              && not (null undocumentedExports && header)) $ do
-          out verbosity normal "  Missing documentation for:"
-          unless header $ out verbosity normal "    Module header"
-          mapM_ (out verbosity normal . ("    " ++)) undocumentedExports
-      interface' <- liftIO $ evaluate interface
-      return (Just (interface', mods))
+  loadOk <- withTimingD "load" (const ()) $
+    {-# SCC load #-} GHC.load LoadAllTargets
+
+  case loadOk of
+    Failed ->
+      throwE "Cannot typecheck modules"
+    Succeeded -> do
+      modGraph <- GHC.getModuleGraph
+      ifaceMap  <- liftIO getIfaces
+      moduleSet <- liftIO getModules
+
+      let
+        ifaces :: [Interface]
+        ifaces =
+          [ Map.findWithDefault
+              (error "haddock:iface")
+              (ms_mod (emsModSummary ems))
+              ifaceMap
+          | ModuleNode ems <- flattenSCCs $ topSortModuleGraph True modGraph Nothing
+          ]
+
+      return (ifaces, moduleSet)
+
+
+-- | A `Plugin` that hooks into GHC's compilation pipeline to generate Haddock
+-- interfaces. Due to the plugin nature we benefit from GHC's capabilities to
+-- parallelize the compilation process.
+plugin
+  :: MonadIO m
+  => Verbosity
+  -> [Flag]
+  -> InstIfaceMap
+  -> m
+     (
+       StaticPlugin -- the plugin to install with GHC
+     , m IfaceMap  -- get the processed interfaces
+     , m ModuleSet -- get the loaded modules
+     )
+plugin verbosity flags instIfaceMap = liftIO $ do
+  ifaceMapRef  <- newIORef Map.empty
+  moduleSetRef <- newIORef emptyModuleSet
+
+  let
+    processTypeCheckedResult :: ModSummary -> TcGblEnv -> TcM ()
+    processTypeCheckedResult mod_summary tc_gbl_env
+      -- Don't do anything for hs-boot modules
+      | IsBoot <- isBootSummary mod_summary =
+          pure ()
+      | otherwise = do
+          hsc_env <- getTopEnv
+          ifaces <- liftIO $ readIORef ifaceMapRef
+          (iface, modules) <- withTimingD "processModule" (const ()) $
+            processModule1 verbosity flags ifaces instIfaceMap hsc_env mod_summary tc_gbl_env
+
+          liftIO $ do
+            atomicModifyIORef' ifaceMapRef $ \xs ->
+              (Map.insert (ms_mod mod_summary) iface xs, ())
+
+            atomicModifyIORef' moduleSetRef $ \xs ->
+              (modules `unionModuleSet` xs, ())
+
+    staticPlugin :: StaticPlugin
+    staticPlugin = StaticPlugin
+      {
+        spPlugin = PluginWithArgs
+        {
+          paPlugin = defaultPlugin
+          {
+            renamedResultAction = keepRenamedSource
+          , typeCheckResultAction = \_ mod_summary tc_gbl_env -> setGblEnv tc_gbl_env $ do
+              processTypeCheckedResult mod_summary tc_gbl_env
+              pure tc_gbl_env
+
+          }
+        , paArguments = []
+        }
+      }
+
+  pure
+    ( staticPlugin
+    , liftIO (readIORef ifaceMapRef)
+    , liftIO (readIORef moduleSetRef)
+    )
+
+
+processModule1
+  :: Verbosity
+  -> [Flag]
+  -> IfaceMap
+  -> InstIfaceMap
+  -> HscEnv
+  -> ModSummary
+  -> TcGblEnv
+  -> TcM (Interface, ModuleSet)
+processModule1 verbosity flags ifaces inst_ifaces hsc_env mod_summary tc_gbl_env = do
+  out verbosity verbose "Creating interface..."
+
+  let
+    TcGblEnv { tcg_rdr_env } = tc_gbl_env
+
+    unit_state = hsc_units hsc_env
+
+  (!interface, messages) <- {-# SCC createInterface #-}
+    withTimingD "createInterface" (const ()) $ runIfM (fmap Just . tcLookupGlobal) $
+      createInterface1 flags unit_state mod_summary tc_gbl_env
+        ifaces inst_ifaces
+
+  -- We need to keep track of which modules were somehow in scope so that when
+  -- Haddock later looks for instances, it also looks in these modules too.
+  --
+  -- See https://github.com/haskell/haddock/issues/469.
+  let
+    mods :: ModuleSet
+    !mods = mkModuleSet
+      [ nameModule name
+      | gre <- globalRdrEnvElts tcg_rdr_env
+      , let name = greMangledName gre
+      , nameIsFromExternalPackage (hsc_home_unit hsc_env) name
+      , isTcOcc (nameOccName name)   -- Types and classes only
+      , unQualOK gre -- In scope unqualified
+      ]
+
+  liftIO $ mapM_ putStrLn (nub messages)
+  dflags <- getDynFlags
+
+  let
+    (haddockable, haddocked) =
+      ifaceHaddockCoverage interface
+
+    percentage :: Int
+    percentage = div (haddocked * 100) haddockable
+
+    modString :: String
+    modString = moduleString (ifaceMod interface)
+
+    coverageMsg :: String
+    coverageMsg =
+      printf " %3d%% (%3d /%3d) in '%s'" percentage haddocked haddockable modString
+
+    header :: Bool
+    header = case ifaceDoc interface of
+      Documentation Nothing _ -> False
+      _ -> True
+
+    undocumentedExports :: [String]
+    undocumentedExports =
+      [ formatName s n
+      | ExportDecl { expItemDecl = L s n
+                   , expItemMbDoc = (Documentation Nothing _, _)
+                   } <- ifaceExportItems interface
+      ]
+        where
+          formatName :: SrcSpan -> HsDecl GhcRn -> String
+          formatName loc n = p (getMainDeclBinder n) ++ case loc of
+            RealSrcSpan rss _ -> " (" ++ unpackFS (srcSpanFile rss) ++ ":" ++
+              show (srcSpanStartLine rss) ++ ")"
+            _ -> ""
+
+          p :: Outputable a => [a] -> String
+          p [] = ""
+          p (x:_) = let n = pretty dflags x
+                        ms = modString ++ "."
+                    in if ms `isPrefixOf` n
+                       then drop (length ms) n
+                       else n
+
+  when (OptHide `notElem` ifaceOptions interface) $ do
+    out verbosity normal coverageMsg
+    when (Flag_NoPrintMissingDocs `notElem` flags
+          && not (null undocumentedExports && header)) $ do
+      out verbosity normal "  Missing documentation for:"
+      unless header $ out verbosity normal "    Module header"
+      mapM_ (out verbosity normal . ("    " ++)) undocumentedExports
+
+  pure (interface, mods)
 
 
 --------------------------------------------------------------------------------
diff --git a/haddock-api/src/Haddock/Interface/Create.hs b/haddock-api/src/Haddock/Interface/Create.hs
index c4988480..9a773b6c 100644
--- a/haddock-api/src/Haddock/Interface/Create.hs
+++ b/haddock-api/src/Haddock/Interface/Create.hs
@@ -1,6 +1,8 @@
-{-# LANGUAGE CPP, TupleSections, BangPatterns, LambdaCase #-}
+{-# LANGUAGE StandaloneDeriving, FlexibleInstances, MultiParamTypeClasses, CPP, TupleSections, BangPatterns, LambdaCase, NamedFieldPuns, ScopedTypeVariables, RecordWildCards #-}
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE ViewPatterns #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# OPTIONS_GHC -Wwarn #-}
 -----------------------------------------------------------------------------
 -- |
@@ -18,234 +20,321 @@
 -- which creates a Haddock 'Interface' from the typechecking
 -- results 'TypecheckedModule' from GHC.
 -----------------------------------------------------------------------------
-module Haddock.Interface.Create (createInterface) where
+module Haddock.Interface.Create (IfM, runIfM, createInterface1) where
 
 import Documentation.Haddock.Doc (metaDocAppend)
-import Haddock.Types
+import Haddock.Types hiding (liftErrMsg)
 import Haddock.Options
 import Haddock.GhcUtils
 import Haddock.Utils
 import Haddock.Convert
 import Haddock.Interface.LexParseRn
 
-import Data.Bifunctor
+import Control.Monad.Reader
+import Control.Monad.Writer.Strict hiding (tell)
 import Data.Bitraversable
 import qualified Data.Map as M
-import qualified Data.Set as S
 import Data.Map (Map)
-import Data.List (find, foldl')
+import Data.List
 import Data.Maybe
-import Control.Monad
 import Data.Traversable
-import GHC.Stack (HasCallStack)
+import GHC.Stack
 
+import GHC.Tc.Utils.Monad (finalSafeMode)
 import GHC.Types.Avail hiding (avail)
 import qualified GHC.Types.Avail  as Avail
 import qualified GHC.Unit.Module as Module
+import GHC.Unit.Module.ModSummary
 import qualified GHC.Types.SrcLoc as SrcLoc
+import GHC.Types.SourceFile
+import GHC.Core.Class
 import GHC.Core.ConLike (ConLike(..))
-import GHC
-import GHC.Driver.Types
+import GHC hiding (lookupName)
+import GHC.Driver.Ppr
 import GHC.Types.Name
 import GHC.Types.Name.Set
 import GHC.Types.Name.Env
 import GHC.Unit.State
 import GHC.Types.Name.Reader
-import GHC.Tc.Types
+import GHC.Tc.Types hiding (IfM)
 import GHC.Data.FastString ( unpackFS, bytesFS )
-import GHC.Types.Basic ( StringLiteral(..), SourceText(..), PromotionFlag(..) )
+import GHC.Types.Basic ( PromotionFlag(..) )
+import GHC.Types.SourceText
 import qualified GHC.Utils.Outputable as O
+import GHC.Utils.Panic
 import GHC.HsToCore.Docs hiding (mkMaps)
 import GHC.Parser.Annotation (IsUnicodeSyntax(..))
+import GHC.Unit.Module.Warnings
 
-mkExceptionContext :: TypecheckedModule -> String
-mkExceptionContext =
-  ("creating Haddock interface for " ++) . moduleNameString . ms_mod_name . pm_mod_summary . tm_parsed_module
-
--- | Use a 'TypecheckedModule' to produce an 'Interface'.
--- To do this, we need access to already processed modules in the topological
--- sort. That's what's in the 'IfaceMap'.
-createInterface :: HasCallStack
-                => TypecheckedModule
-                -> [Flag]       -- Boolean flags
-                -> IfaceMap     -- Locally processed modules
-                -> InstIfaceMap -- External, already installed interfaces
-                -> ErrMsgGhc Interface
-createInterface tm flags modMap instIfaceMap =
- withExceptionContext (mkExceptionContext tm) $ do
-
-  let ms             = pm_mod_summary . tm_parsed_module $ tm
-      mi             = moduleInfo tm
-      L _ hsm        = parsedSource tm
-      !safety        = modInfoSafe mi
-      mdl            = ms_mod ms
-      sem_mdl        = tcg_semantic_mod (fst (tm_internals_ tm))
-      is_sig         = ms_hsc_src ms == HsigFile
-      dflags         = ms_hspp_opts ms
-      !instances     = modInfoInstances mi
-      !fam_instances = md_fam_insts md
-      !exportedNames = modInfoExportsWithSelectors mi
-      (pkgNameFS, _) = modulePackageInfo dflags flags (Just mdl)
-      pkgName        = fmap (unpackFS . (\(PackageName n) -> n)) pkgNameFS
-
-      (TcGblEnv { tcg_rdr_env = gre
-                , tcg_warns   = warnings
-                , tcg_exports = all_exports0
-                }, md) = tm_internals_ tm
-      all_local_avails = gresToAvailInfo . filter isLocalGRE . globalRdrEnvElts $ gre
-
-  -- The 'pkgName' is necessary to decide what package to mention in "@since"
-  -- annotations. Not having it is not fatal though.
-  --
-  -- Cabal can be trusted to pass the right flags, so this warning should be
-  -- mostly encountered when running Haddock outside of Cabal.
-  when (isNothing pkgName) $
-    liftErrMsg $ tell [ "Warning: Package name is not available." ]
-
-  -- The renamed source should always be available to us, but it's best
-  -- to be on the safe side.
-  (group_, imports, mayExports, mayDocHeader) <-
-    case renamedSource tm of
-      Nothing -> do
-        liftErrMsg $ tell [ "Warning: Renamed source is not available." ]
-        return (emptyRnGroup, [], Nothing, Nothing)
-      Just x -> return x
-
-  opts <- liftErrMsg $ mkDocOpts (haddockOptions dflags) flags mdl
+newtype IfEnv m = IfEnv
+  {
+    -- | Lookup names in the enviroment.
+    ife_lookup_name :: Name -> m (Maybe TyThing)
+  }
+
+
+-- | A monad in which we create Haddock interfaces. Not to be confused with
+-- `GHC.Tc.Types.IfM` which is used to write GHC interfaces.
+--
+-- In the past `createInterface` was running in the `Ghc` monad but proved hard
+-- to sustain as soon as we moved over for Haddock to be a plugin. Also abstracting
+-- over the Ghc specific clarifies where side effects happen.
+newtype IfM m a = IfM { unIfM :: ReaderT (IfEnv m) (WriterT [ErrMsg] m) a }
+
+
+deriving newtype instance Functor m => Functor (IfM m)
+deriving newtype instance Applicative m => Applicative (IfM m)
+deriving newtype instance Monad m => Monad (IfM m)
+deriving newtype instance MonadIO m => MonadIO (IfM m)
+deriving newtype instance Monad m => MonadReader (IfEnv m) (IfM m)
+deriving newtype instance Monad m => MonadWriter [ErrMsg] (IfM m)
+
+
+-- | Run an `IfM` action.
+runIfM
+  -- | Lookup a global name in the current session. Used in cases
+  -- where declarations don't
+  :: (Name -> m (Maybe TyThing))
+  -- | The action to run.
+  -> IfM m a
+  -- | Result and accumulated error/warning messages.
+  -> m (a, [ErrMsg])
+runIfM lookup_name action = do
+  let
+    if_env = IfEnv
+      {
+        ife_lookup_name = lookup_name
+      }
+  runWriterT (runReaderT (unIfM action) if_env)
+
+
+liftErrMsg :: Monad m => ErrMsgM a -> IfM m a
+liftErrMsg action = do
+  writer (runWriter action)
+
+
+lookupName :: Monad m => Name -> IfM m (Maybe TyThing)
+lookupName name = IfM $ do
+  lookup_name <- asks ife_lookup_name
+  lift $ lift (lookup_name name)
+
+
+createInterface1
+  :: MonadIO m
+  => [Flag]
+  -> UnitState
+  -> ModSummary
+  -> TcGblEnv
+  -> IfaceMap
+  -> InstIfaceMap
+  -> IfM m Interface
+createInterface1 flags unit_state mod_sum tc_gbl_env ifaces inst_ifaces = do
+
+  let
+    ModSummary
+      {
+        -- Cached flags from OPTIONS, INCLUDE and LANGUAGE
+        -- pragmas in the modules source code. Used to infer
+        -- safety of module.
+        ms_hspp_opts
+      , ms_location = ModLocation
+        {
+          ml_hie_file
+        }
+      } = mod_sum
+
+    TcGblEnv
+      {
+        tcg_mod
+      , tcg_src
+      , tcg_semantic_mod
+      , tcg_rdr_env
+      , tcg_exports
+      , tcg_insts
+      , tcg_fam_insts
+      , tcg_warns
+
+      -- Renamed source
+      , tcg_rn_imports
+      , tcg_rn_exports
+      , tcg_rn_decls
+
+      , tcg_doc_hdr
+      } = tc_gbl_env
+
+    dflags = ms_hspp_opts
+
+    is_sig = tcg_src == HsigFile
+
+    (pkg_name_fs, _) =
+      modulePackageInfo unit_state flags (Just tcg_mod)
+
+    pkg_name :: Maybe Package
+    pkg_name =
+      let
+        unpack (PackageName name) = unpackFS name
+      in
+        fmap unpack pkg_name_fs
+
+    fixities :: FixMap
+    fixities = case tcg_rn_decls of
+      Nothing -> mempty
+      Just dx -> mkFixMap dx
+
+    -- Locations of all the TH splices
+    loc_splices :: [SrcSpan]
+    loc_splices = case tcg_rn_decls of
+      Nothing -> []
+      Just HsGroup { hs_splcds } -> [ loc | L loc _ <- hs_splcds ]
+
+  decls <- case tcg_rn_decls of
+    Nothing -> do
+      tell [ "Warning: Renamed source is not available" ]
+      pure []
+    Just dx ->
+      pure (topDecls dx)
+
+  -- Derive final options to use for haddocking this module
+  doc_opts <- liftErrMsg $ mkDocOpts (haddockOptions ms_hspp_opts) flags tcg_mod
+
+  let
+    -- All elements of an explicit export list, if present
+    export_list :: Maybe [(IE GhcRn, Avails)]
+    export_list
+      | OptIgnoreExports `elem` doc_opts  =
+          Nothing
+      | Just rn_exports <- tcg_rn_exports =
+          Just [ (ie, avail) | (L _ ie, avail) <- rn_exports ]
+      | otherwise =
+          Nothing
+
+    -- All the exported Names of this module.
+    exported_names :: [Name]
+    exported_names =
+      concatMap availNamesWithSelectors tcg_exports
+
+    -- Module imports of the form `import X`. Note that there is
+    -- a) no qualification and
+    -- b) no import list
+    imported_modules :: Map ModuleName [ModuleName]
+    imported_modules
+      | Just{} <- export_list =
+          unrestrictedModuleImports (map unLoc tcg_rn_imports)
+      | otherwise =
+          M.empty
+
+    -- TyThings that have instances defined in this module
+    local_instances :: [Name]
+    local_instances =
+      [ name
+      | name <- map getName tcg_insts ++ map getName tcg_fam_insts
+      , nameIsLocalOrFrom tcg_semantic_mod name
+      ]
+
+  -- Infer module safety
+  safety   <- liftIO (finalSafeMode ms_hspp_opts tc_gbl_env)
 
   -- Process the top-level module header documentation.
-  (!info, mbDoc) <- liftErrMsg $ processModuleHeader dflags pkgName gre safety mayDocHeader
-
-  let declsWithDocs = topDecls group_
-
-      exports0 = fmap (map (first unLoc)) mayExports
-      (all_exports, exports)
-        | OptIgnoreExports `elem` opts = (all_local_avails, Nothing)
-        | otherwise = (all_exports0, exports0)
-
-      unrestrictedImportedMods
-        -- module re-exports are only possible with
-        -- explicit export list
-        | Just{} <- exports
-        = unrestrictedModuleImports (map unLoc imports)
-        | otherwise = M.empty
-
-      fixMap = mkFixMap group_
-      (decls, _) = unzip declsWithDocs
-      localInsts = filter (nameIsLocalOrFrom sem_mdl)
-                        $  map getName fam_instances
-                        ++ map getName instances
-      -- Locations of all TH splices
-      splices = [ l | L l (SpliceD _ _) <- hsmodDecls hsm ]
-
-  warningMap <- liftErrMsg (mkWarningMap dflags warnings gre exportedNames)
-
-  maps@(!docMap, !argMap, !declMap, _) <-
-    liftErrMsg (mkMaps dflags pkgName gre localInsts declsWithDocs)
-
-  let allWarnings = M.unions (warningMap : map ifaceWarningMap (M.elems modMap))
-
-  -- The MAIN functionality: compute the export items which will
-  -- each be the actual documentation of this module.
-  exportItems <- mkExportItems is_sig modMap pkgName mdl sem_mdl allWarnings gre
-                   exportedNames decls maps fixMap unrestrictedImportedMods
-                   splices exports all_exports instIfaceMap dflags
-
-  let !visibleNames = mkVisibleNames maps exportItems opts
-
-  -- Measure haddock documentation coverage.
-  let prunedExportItems0 = pruneExportItems exportItems
-      !haddockable = 1 + length exportItems -- module + exports
-      !haddocked = (if isJust mbDoc then 1 else 0) + length prunedExportItems0
-      !coverage = (haddockable, haddocked)
-
-  -- Prune the export list to just those declarations that have
-  -- documentation, if the 'prune' option is on.
-  let prunedExportItems'
-        | OptPrune `elem` opts = prunedExportItems0
-        | otherwise = exportItems
-      !prunedExportItems = seqList prunedExportItems' `seq` prunedExportItems'
-
-  let !aliases =
-        mkAliasMap (unitState dflags) $ tm_renamed_source tm
-
-  modWarn <- liftErrMsg (moduleWarning dflags gre warnings)
-
-  -- Prune the docstring 'Map's to keep only docstrings that are not private.
-  --
-  -- Besides all the names that GHC has told us this module exports, we also
-  -- keep the docs for locally defined class instances. This is more names than
-  -- we need, but figuring out which instances are fully private is tricky.
-  --
-  -- We do this pruning to avoid having to rename, emit warnings, and save
-  -- docstrings which will anyways never be rendered.
-  let !localVisibleNames = S.fromList (localInsts ++ exportedNames)
-      !prunedDocMap = M.restrictKeys docMap localVisibleNames
-      !prunedArgMap = M.restrictKeys argMap localVisibleNames
-
-  return $! Interface {
-    ifaceMod               = mdl
-  , ifaceIsSig             = is_sig
-  , ifaceOrigFilename      = msHsFilePath ms
-  , ifaceInfo              = info
-  , ifaceDoc               = Documentation mbDoc modWarn
-  , ifaceRnDoc             = Documentation Nothing Nothing
-  , ifaceOptions           = opts
-  , ifaceDocMap            = prunedDocMap
-  , ifaceArgMap            = prunedArgMap
-  , ifaceRnDocMap          = M.empty -- Filled in `renameInterface`
-  , ifaceRnArgMap          = M.empty -- Filled in `renameInterface`
-  , ifaceExportItems       = prunedExportItems
-  , ifaceRnExportItems     = [] -- Filled in `renameInterface`
-  , ifaceExports           = exportedNames
-  , ifaceVisibleExports    = visibleNames
-  , ifaceDeclMap           = declMap
-  , ifaceFixMap            = fixMap
-  , ifaceModuleAliases     = aliases
-  , ifaceInstances         = instances
-  , ifaceFamInstances      = fam_instances
-  , ifaceOrphanInstances   = [] -- Filled in `attachInstances`
-  , ifaceRnOrphanInstances = [] -- Filled in `renameInterface`
-  , ifaceHaddockCoverage   = coverage
-  , ifaceWarningMap        = warningMap
-  , ifaceHieFile           = Just $ ml_hie_file $ ms_location ms
-  , ifaceDynFlags          = dflags
-  }
+  (!info, header_doc) <- liftErrMsg $ processModuleHeader dflags pkg_name
+    tcg_rdr_env safety tcg_doc_hdr
+
+  -- Warnings on declarations in this module
+  decl_warnings <- liftErrMsg (mkWarningMap dflags tcg_warns tcg_rdr_env exported_names)
+
+  -- Warning on the module header
+  mod_warning <- liftErrMsg (moduleWarning dflags tcg_rdr_env tcg_warns)
+
+  let
+    -- Warnings in this module and transitive warnings from dependend modules
+    warnings :: Map Name (Doc Name)
+    warnings = M.unions (decl_warnings : map ifaceWarningMap (M.elems ifaces))
+
+  maps@(!docs, !arg_docs, !decl_map, _) <-
+    liftErrMsg (mkMaps dflags pkg_name tcg_rdr_env local_instances decls)
+
+  export_items <- mkExportItems is_sig ifaces pkg_name tcg_mod tcg_semantic_mod
+    warnings tcg_rdr_env exported_names (map fst decls) maps fixities
+    imported_modules loc_splices export_list tcg_exports inst_ifaces dflags
+
+  let
+    visible_names :: [Name]
+    visible_names = mkVisibleNames maps export_items doc_opts
+
+    -- Measure haddock documentation coverage.
+    pruned_export_items :: [ExportItem GhcRn]
+    pruned_export_items = pruneExportItems export_items
+
+    !haddockable = 1 + length export_items -- module + exports
+    !haddocked = (if isJust tcg_doc_hdr then 1 else 0) + length pruned_export_items
+
+    coverage :: (Int, Int)
+    !coverage = (haddockable, haddocked)
+
+    aliases :: Map Module ModuleName
+    aliases = mkAliasMap unit_state tcg_rn_imports
+
+  return $! Interface
+    {
+      ifaceMod               = tcg_mod
+    , ifaceIsSig             = is_sig
+    , ifaceOrigFilename      = msHsFilePath mod_sum
+    , ifaceHieFile           = Just ml_hie_file
+    , ifaceInfo              = info
+    , ifaceDoc               = Documentation header_doc mod_warning
+    , ifaceRnDoc             = Documentation Nothing Nothing
+    , ifaceOptions           = doc_opts
+    , ifaceDocMap            = docs
+    , ifaceArgMap            = arg_docs
+    , ifaceRnDocMap          = M.empty
+    , ifaceRnArgMap          = M.empty
+    , ifaceExportItems       = if OptPrune `elem` doc_opts then
+                                 pruned_export_items else export_items
+    , ifaceRnExportItems     = []
+    , ifaceExports           = exported_names
+    , ifaceVisibleExports    = visible_names
+    , ifaceDeclMap           = decl_map
+    , ifaceFixMap            = fixities
+    , ifaceModuleAliases     = aliases
+    , ifaceInstances         = tcg_insts
+    , ifaceFamInstances      = tcg_fam_insts
+    , ifaceOrphanInstances   = [] -- Filled in attachInstances
+    , ifaceRnOrphanInstances = [] -- Filled in attachInstances
+    , ifaceHaddockCoverage   = coverage
+    , ifaceWarningMap        = warnings
+    , ifaceDynFlags          = dflags
+    }
 
 
 -- | Given all of the @import M as N@ declarations in a package,
 -- create a mapping from the module identity of M, to an alias N
 -- (if there are multiple aliases, we pick the last one.)  This
 -- will go in 'ifaceModuleAliases'.
-mkAliasMap :: UnitState -> Maybe RenamedSource -> M.Map Module ModuleName
-mkAliasMap state mRenamedSource =
-  case mRenamedSource of
-    Nothing -> M.empty
-    Just (_,impDecls,_,_) ->
-      M.fromList $
-      mapMaybe (\(SrcLoc.L _ impDecl) -> do
-        SrcLoc.L _ alias <- ideclAs impDecl
-        return $
-          (lookupModuleDyn state
-             -- TODO: This is supremely dodgy, because in general the
-             -- UnitId isn't going to look anything like the package
-             -- qualifier (even with old versions of GHC, the
-             -- IPID would be p-0.1, but a package qualifier never
-             -- has a version number it.  (Is it possible that in
-             -- Haddock-land, the UnitIds never have version numbers?
-             -- I, ezyang, have not quite understand Haddock's package
-             -- identifier model.)
-             --
-             -- Additionally, this is simulating some logic GHC already
-             -- has for deciding how to qualify names when it outputs
-             -- them to the user.  We should reuse that information;
-             -- or at least reuse the renamed imports, which know what
-             -- they import!
-             (fmap Module.fsToUnit $
-              fmap sl_fs $ ideclPkgQual impDecl)
-             (case ideclName impDecl of SrcLoc.L _ name -> name),
-           alias))
-        impDecls
+mkAliasMap :: UnitState -> [LImportDecl GhcRn] -> M.Map Module ModuleName
+mkAliasMap state impDecls =
+  M.fromList $
+  mapMaybe (\(SrcLoc.L _ impDecl) -> do
+    SrcLoc.L _ alias <- ideclAs impDecl
+    return $
+      (lookupModuleDyn state
+         -- TODO: This is supremely dodgy, because in general the
+         -- UnitId isn't going to look anything like the package
+         -- qualifier (even with old versions of GHC, the
+         -- IPID would be p-0.1, but a package qualifier never
+         -- has a version number it.  (Is it possible that in
+         -- Haddock-land, the UnitIds never have version numbers?
+         -- I, ezyang, have not quite understand Haddock's package
+         -- identifier model.)
+         --
+         -- Additionally, this is simulating some logic GHC already
+         -- has for deciding how to qualify names when it outputs
+         -- them to the user.  We should reuse that information;
+         -- or at least reuse the renamed imports, which know what
+         -- they import!
+         (fmap Module.fsToUnit $
+          fmap sl_fs $ ideclPkgQual impDecl)
+         (case ideclName impDecl of SrcLoc.L _ name -> name),
+       alias))
+    impDecls
 
 -- We want to know which modules are imported without any qualification. This
 -- way we can display module reexports more compactly. This mapping also looks
@@ -257,7 +346,7 @@ mkAliasMap state mRenamedSource =
 --
 -- With our mapping we know that we can display exported modules M1 and M2.
 --
-unrestrictedModuleImports :: [ImportDecl name] -> M.Map ModuleName [ModuleName]
+unrestrictedModuleImports :: [ImportDecl GhcRn] -> M.Map ModuleName [ModuleName]
 unrestrictedModuleImports idecls =
   M.map (map (unLoc . ideclName))
   $ M.filter (all isInteresting) impModMap
@@ -306,7 +395,7 @@ mkWarningMap dflags warnings gre exps = case warnings of
     let ws' = [ (n, w)
               | (occ, w) <- ws
               , elt <- lookupGlobalRdrEnv gre occ
-              , let n = gre_name elt, n `elem` exps ]
+              , let n = greMangledName elt, n `elem` exps ]
     in M.fromList <$> traverse (bitraverse pure (parseWarning dflags gre)) ws'
 
 moduleWarning :: DynFlags -> GlobalRdrEnv -> Warnings -> ErrMsgM (Maybe (Doc Name))
@@ -436,7 +525,7 @@ mkMaps dflags pkgName gre instances decls = do
               -- The CoAx's loc is the whole line, but only for TFs. The
               -- workaround is to dig into the family instance declaration and
               -- get the identifier with the right location.
-              TyFamInstD _ (TyFamInstDecl d') -> getLoc (feqn_tycon (hsib_body d'))
+              TyFamInstD _ (TyFamInstDecl d') -> getLoc (feqn_tycon d')
               _ -> getInstLoc d
     names l (DerivD {}) = maybeToList (M.lookup l instanceMap) -- See note [2].
     names _ decl = getMainDeclBinder decl
@@ -470,7 +559,7 @@ mkFixMap group_ =
 -- We create the export items even if the module is hidden, since they
 -- might be useful when creating the export items for other modules.
 mkExportItems
-  :: HasCallStack
+  :: Monad m
   => Bool               -- is it a signature
   -> IfaceMap
   -> Maybe Package      -- this package
@@ -488,7 +577,7 @@ mkExportItems
   -> Avails             -- exported stuff from this module
   -> InstIfaceMap
   -> DynFlags
-  -> ErrMsgGhc [ExportItem GhcRn]
+  -> IfM m [ExportItem GhcRn]
 mkExportItems
   is_sig modMap pkgName thisMod semMod warnings gre exportedNames decls
   maps fixMap unrestricted_imp_mods splices exportList allExports
@@ -509,7 +598,7 @@ mkExportItems
       return [ExportDoc doc]
 
     lookupExport (IEDocNamed _ str, _)      = liftErrMsg $
-      findNamedDoc str [ unLoc d | d <- decls ] >>= \case
+      findNamedDoc str [ unL d | d <- decls ] >>= \case
         Nothing -> return  []
         Just docStr -> do
           doc <- processDocStringParas dflags pkgName gre docStr
@@ -530,25 +619,39 @@ mkExportItems
       availExportItem is_sig modMap thisMod semMod warnings exportedNames
         maps fixMap splices instIfaceMap dflags avail
 
-availExportItem :: HasCallStack
-                => Bool               -- is it a signature
-                -> IfaceMap
-                -> Module             -- this module
-                -> Module             -- semantic module
-                -> WarningMap
-                -> [Name]             -- exported names (orig)
-                -> Maps
-                -> FixMap
-                -> [SrcSpan]          -- splice locations
-                -> InstIfaceMap
-                -> DynFlags
-                -> AvailInfo
-                -> ErrMsgGhc [ExportItem GhcRn]
+
+-- Extract the minimal complete definition of a Name, if one exists
+minimalDef :: Monad m => Name -> IfM m (Maybe ClassMinimalDef)
+minimalDef n = do
+  mty <- lookupName n
+  case mty of
+    Just (ATyCon (tyConClass_maybe -> Just c)) ->
+      return . Just $ classMinimalDef c
+    _ ->
+      return Nothing
+
+
+availExportItem
+  :: forall m
+  .  Monad m
+  => Bool               -- is it a signature
+  -> IfaceMap
+  -> Module             -- this module
+  -> Module             -- semantic module
+  -> WarningMap
+  -> [Name]             -- exported names (orig)
+  -> Maps
+  -> FixMap
+  -> [SrcSpan]          -- splice locations
+  -> InstIfaceMap
+  -> DynFlags
+  -> AvailInfo
+  -> IfM m [ExportItem GhcRn]
 availExportItem is_sig modMap thisMod semMod warnings exportedNames
   (docMap, argMap, declMap, _) fixMap splices instIfaceMap
   dflags availInfo = declWith availInfo
   where
-    declWith :: AvailInfo -> ErrMsgGhc [ ExportItem GhcRn ]
+    declWith :: AvailInfo -> IfM m [ ExportItem GhcRn ]
     declWith avail = do
       let t = availName avail
       r    <- findDecl avail
@@ -558,13 +661,13 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
           export <- hiValExportItem dflags t l doc (l `elem` splices) $ M.lookup t fixMap
           return [export]
         (ds, docs_) | decl : _ <- filter (not . isValD . unLoc) ds ->
-          let declNames = getMainDeclBinder (unLoc decl)
+          let declNames = getMainDeclBinder (unL decl)
           in case () of
             _
               -- We should not show a subordinate by itself if any of its
               -- parents is also exported. See note [1].
               | t `notElem` declNames,
-                Just p <- find isExported (parents t $ unLoc decl) ->
+                Just p <- find isExported (parents t $ unL decl) ->
                 do liftErrMsg $ tell [
                      "Warning: " ++ moduleString thisMod ++ ": " ++
                      pretty dflags (nameOccName t) ++ " is exported separately but " ++
@@ -584,11 +687,11 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
                     let newDecl = L loc . SigD noExtField . fromJust $ filterSigNames (== t) sig
                     in availExportDecl avail newDecl docs_
 
-                  L loc (TyClD _ cl@ClassDecl{}) -> do
-                    mdef <- liftGhcToErrMsgGhc $ minimalDef t
+                  L loc (TyClD _ ClassDecl {..}) -> do
+                    mdef <- minimalDef t
                     let sig = maybeToList $ fmap (noLoc . MinimalSig noExtField NoSourceText . noLoc . fmap noLoc) mdef
                     availExportDecl avail
-                      (L loc $ TyClD noExtField cl { tcdSigs = sig ++ tcdSigs cl }) docs_
+                      (L loc $ TyClD noExtField ClassDecl { tcdSigs = sig ++ tcdSigs, .. }) docs_
 
                   _ -> availExportDecl avail decl docs_
 
@@ -614,7 +717,7 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
         _ -> return []
 
     -- Tries 'extractDecl' first then falls back to 'hiDecl' if that fails
-    availDecl :: Name -> LHsDecl GhcRn -> ErrMsgGhc (LHsDecl GhcRn)
+    availDecl :: Name -> LHsDecl GhcRn -> IfM m (LHsDecl GhcRn)
     availDecl declName parentDecl =
       case extractDecl declMap declName parentDecl of
         Right d -> pure d
@@ -622,11 +725,11 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
           synifiedDeclOpt <- hiDecl dflags declName
           case synifiedDeclOpt of
             Just synifiedDecl -> pure synifiedDecl
-            Nothing -> O.pprPanic "availExportItem" (O.text err)
+            Nothing -> pprPanic "availExportItem" (O.text err)
 
     availExportDecl :: AvailInfo -> LHsDecl GhcRn
                     -> (DocForDecl Name, [(Name, DocForDecl Name)])
-                    -> ErrMsgGhc [ ExportItem GhcRn ]
+                    -> IfM m [ ExportItem GhcRn ]
     availExportDecl avail decl (doc, subs)
       | availExportsDecl avail = do
           extractedDecl <- availDecl (availName avail) decl
@@ -672,7 +775,7 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
     exportedNameSet = mkNameSet exportedNames
     isExported n = elemNameSet n exportedNameSet
 
-    findDecl :: AvailInfo -> ErrMsgGhc ([LHsDecl GhcRn], (DocForDecl Name, [(Name, DocForDecl Name)]))
+    findDecl :: AvailInfo -> IfM m ([LHsDecl GhcRn], (DocForDecl Name, [(Name, DocForDecl Name)]))
     findDecl avail
       | m == semMod =
           case M.lookup n declMap of
@@ -701,10 +804,10 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
         n = availName avail
         m = nameModule n
 
-    findBundledPatterns :: AvailInfo -> ErrMsgGhc [(HsDecl GhcRn, DocForDecl Name)]
+    findBundledPatterns :: AvailInfo -> IfM m [(HsDecl GhcRn, DocForDecl Name)]
     findBundledPatterns avail = do
       patsyns <- for constructor_names $ \name -> do
-        mtyThing <- liftGhcToErrMsgGhc (lookupName name)
+        mtyThing <- lookupName name
         case mtyThing of
           Just (AConLike PatSynCon{}) -> do
             export_items <- declWith (Avail.avail name)
@@ -720,16 +823,8 @@ availExportItem is_sig modMap thisMod semMod warnings exportedNames
         constructor_names =
           filter isDataConName (availSubordinates avail)
 
--- this heavily depends on the invariants stated in Avail
-availExportsDecl :: AvailInfo -> Bool
-availExportsDecl (AvailTC ty_name names _)
-  | n : _ <- names = ty_name == n
-  | otherwise      = False
-availExportsDecl _ = True
-
 availSubordinates :: AvailInfo -> [Name]
-availSubordinates avail =
-  filter (/= availName avail) (availNamesWithSelectors avail)
+availSubordinates = map greNameMangledName . availSubordinateGreNames
 
 availNoDocs :: AvailInfo -> [(Name, DocForDecl Name)]
 availNoDocs avail =
@@ -742,10 +837,9 @@ semToIdMod this_uid m
     | Module.isHoleModule m = mkModule this_uid (moduleName m)
     | otherwise             = m
 
--- | Reify a declaration from the GHC internal 'TyThing' representation.
-hiDecl :: DynFlags -> Name -> ErrMsgGhc (Maybe (LHsDecl GhcRn))
+hiDecl :: Monad m => DynFlags -> Name -> IfM m (Maybe (LHsDecl GhcRn))
 hiDecl dflags t = do
-  mayTyThing <- liftGhcToErrMsgGhc $ lookupName t
+  mayTyThing <- lookupName t
   case mayTyThing of
     Nothing -> do
       liftErrMsg $ tell ["Warning: Not found in environment: " ++ pretty dflags t]
@@ -758,14 +852,15 @@ hiDecl dflags t = do
       warnLine x = O.text "haddock-bug:" O.<+> O.text x O.<>
                    O.comma O.<+> O.quotes (O.ppr t) O.<+>
                    O.text "-- Please report this on Haddock issue tracker!"
-      bugWarn = O.showSDoc dflags . warnLine
+      bugWarn = showSDoc dflags . warnLine
 
 -- | This function is called for top-level bindings without type signatures.
 -- It gets the type signature from GHC and that means it's not going to
 -- have a meaningful 'SrcSpan'. So we pass down 'SrcSpan' for the
 -- declaration and use it instead - 'nLoc' here.
-hiValExportItem :: DynFlags -> Name -> SrcSpan -> DocForDecl Name -> Bool
-                -> Maybe Fixity -> ErrMsgGhc (ExportItem GhcRn)
+hiValExportItem
+  :: Monad m => DynFlags -> Name -> SrcSpan -> DocForDecl Name -> Bool
+  -> Maybe Fixity -> IfM m (ExportItem GhcRn)
 hiValExportItem dflags name nLoc doc splice fixity = do
   mayDecl <- hiDecl dflags name
   case mayDecl of
@@ -795,12 +890,14 @@ lookupDocs avail warnings docMap argMap =
 
 -- | Export the given module as `ExportModule`. We are not concerned with the
 -- single export items of the given module.
-moduleExport :: Module           -- ^ Module A (identity, NOT semantic)
-             -> DynFlags         -- ^ The flags used when typechecking A
-             -> IfaceMap         -- ^ Already created interfaces
-             -> InstIfaceMap     -- ^ Interfaces in other packages
-             -> ModuleName       -- ^ The exported module
-             -> ErrMsgGhc [ExportItem GhcRn] -- ^ Resulting export items
+moduleExport
+  :: Monad m
+  => Module           -- ^ Module A (identity, NOT semantic)
+  -> DynFlags         -- ^ The flags used when typechecking A
+  -> IfaceMap         -- ^ Already created interfaces
+  -> InstIfaceMap     -- ^ Interfaces in other packages
+  -> ModuleName       -- ^ The exported module
+  -> IfM m [ExportItem GhcRn] -- ^ Resulting export items
 moduleExport thisMod dflags ifaceMap instIfaceMap expMod =
     -- NB: we constructed the identity module when looking up in
     -- the IfaceMap.
@@ -814,9 +911,8 @@ moduleExport thisMod dflags ifaceMap instIfaceMap expMod =
         case M.lookup expMod (M.mapKeys moduleName instIfaceMap) of
           Just iface -> return [ ExportModule (instMod iface) ]
           Nothing -> do
-            liftErrMsg $
-              tell ["Warning: " ++ pretty dflags thisMod ++ ": Could not find " ++
-                    "documentation for exported module: " ++ pretty dflags expMod]
+            liftErrMsg $ tell ["Warning: " ++ pretty dflags thisMod ++ ": Could not find " ++
+                               "documentation for exported module: " ++ pretty dflags expMod]
             return []
   where
     m = mkModule (moduleUnit thisMod) expMod -- Identity module!
@@ -842,22 +938,24 @@ moduleExport thisMod dflags ifaceMap instIfaceMap expMod =
 -- every locally defined declaration is exported; thus, we just
 -- zip through the renamed declarations.
 
-fullModuleContents :: Bool               -- is it a signature
-                   -> IfaceMap
-                   -> Maybe Package      -- this package
-                   -> Module             -- this module
-                   -> Module             -- semantic module
-                   -> WarningMap
-                   -> GlobalRdrEnv      -- ^ The renaming environment
-                   -> [Name]             -- exported names (orig)
-                   -> [LHsDecl GhcRn]    -- renamed source declarations
-                   -> Maps
-                   -> FixMap
-                   -> [SrcSpan]          -- splice locations
-                   -> InstIfaceMap
-                   -> DynFlags
-                   -> Avails
-                   -> ErrMsgGhc [ExportItem GhcRn]
+fullModuleContents
+  :: Monad m
+  => Bool               -- is it a signature
+  -> IfaceMap
+  -> Maybe Package      -- this package
+  -> Module             -- this module
+  -> Module             -- semantic module
+  -> WarningMap
+  -> GlobalRdrEnv      -- ^ The renaming environment
+  -> [Name]             -- exported names (orig)
+  -> [LHsDecl GhcRn]    -- renamed source declarations
+  -> Maps
+  -> FixMap
+  -> [SrcSpan]          -- splice locations
+  -> InstIfaceMap
+  -> DynFlags
+  -> Avails
+  -> IfM m [ExportItem GhcRn]
 fullModuleContents is_sig modMap pkgName thisMod semMod warnings gre exportedNames
   decls maps@(_, _, declMap, _) fixMap splices instIfaceMap dflags avails = do
   let availEnv = availsToNameEnv (nubAvails avails)
@@ -870,7 +968,7 @@ fullModuleContents is_sig modMap pkgName thisMod semMod warnings gre exportedNam
         doc <- liftErrMsg (processDocStringParas dflags pkgName gre docStr)
         return [[ExportDoc doc]]
       (L _ (ValD _ valDecl))
-        | name:_ <- collectHsBindBinders valDecl
+        | name:_ <- collectHsBindBinders CollNoDictBinders valDecl
         , Just (L _ SigD{}:_) <- filter isSigD <$> M.lookup name declMap
         -> return []
       _ ->
@@ -885,7 +983,6 @@ fullModuleContents is_sig modMap pkgName thisMod semMod warnings gre exportedNam
     isSigD (L _ SigD{}) = True
     isSigD _            = False
 
-
 -- | Sometimes the declaration we want to export is not the "main" declaration:
 -- it might be an individual record selector or a class method.  In these
 -- cases we have to extract the required declaration (and somehow cobble
@@ -936,7 +1033,7 @@ extractDecl declMap name decl
 
       TyClD _ d@DataDecl { tcdLName = L _ dataNm
                          , tcdDataDefn = HsDataDefn { dd_cons = dataCons } } -> do
-        let ty_args = map HsValArg (lHsQTyVarsToTypes (tyClDeclTyVars d))
+        let ty_args = lHsQTyVarsToTypes (tyClDeclTyVars d)
         lsig <- if isDataConName name
                   then extractPatternSyn name dataNm ty_args dataCons
                   else extractRecSel name dataNm ty_args dataCons
@@ -946,30 +1043,26 @@ extractDecl declMap name decl
         | isValName name
         , Just (famInst:_) <- M.lookup name declMap
         -> extractDecl declMap name famInst
-      InstD _ (DataFamInstD _ (DataFamInstDecl (HsIB { hsib_body =
-          FamEqn { feqn_tycon = L _ famName
-                 , feqn_pats  = ty_args
-                 , feqn_rhs   = HsDataDefn { dd_cons = dataCons } }}))) -> do
-        lsig <- if isDataConName name
-                  then extractPatternSyn name famName ty_args dataCons
-                  else extractRecSel name famName ty_args dataCons
-        pure (SigD noExtField <$> lsig)
+      InstD _ (DataFamInstD _ (DataFamInstDecl
+                            (FamEqn { feqn_tycon = L _ n
+                                    , feqn_pats  = tys
+                                    , feqn_rhs   = defn }))) ->
+        if isDataConName name
+        then fmap (SigD noExtField) <$> extractPatternSyn name n tys (dd_cons defn)
+        else fmap (SigD noExtField) <$> extractRecSel name n tys (dd_cons defn)
       InstD _ (ClsInstD _ ClsInstDecl { cid_datafam_insts = insts })
         | isDataConName name ->
-            let matches = [ d' | L _ d'@(DataFamInstDecl (HsIB { hsib_body =
-                                          FamEqn { feqn_rhs   = HsDataDefn { dd_cons = dataCons }
-                                                 }
-                                         })) <- insts
-                               , name `elem` map unLoc (concatMap (getConNames . unLoc) dataCons)
+            let matches = [ d' | L _ d'@(DataFamInstDecl (FamEqn { feqn_rhs = dd })) <- insts
+                               , name `elem` map unLoc (concatMap (getConNames . unLoc) (dd_cons dd))
                                ]
             in case matches of
                 [d0] -> extractDecl declMap name (noLoc (InstD noExtField (DataFamInstD noExtField d0)))
                 _    -> Left "internal: extractDecl (ClsInstD)"
         | otherwise ->
-            let matches = [ d' | L _ d'@(DataFamInstDecl (HsIB { hsib_body = d }))
+            let matches = [ d' | L _ d'@(DataFamInstDecl d )
                                    <- insts
                                  -- , L _ ConDecl { con_details = RecCon rec } <- dd_cons (feqn_rhs d)
-                               , RecCon rec <- map (getConArgs . unLoc) (dd_cons (feqn_rhs d))
+                               , Just rec <- map (getRecConArgs_maybe . unLoc) (dd_cons (feqn_rhs d))
                                , ConDeclField { cd_fld_names = ns } <- map unLoc (unLoc rec)
                                , L _ n <- ns
                                , extFieldOcc n == name
@@ -979,10 +1072,13 @@ extractDecl declMap name decl
               _ -> Left "internal: extractDecl (ClsInstD)"
       _ -> Left ("extractDecl: Unhandled decl for " ++ getOccString name)
 
-extractPatternSyn :: Name -> Name -> [LHsTypeArg GhcRn] -> [LConDecl GhcRn] -> Either ErrMsg (LSig GhcRn)
+extractPatternSyn :: HasCallStack
+                  => Name -> Name
+                  -> [LHsTypeArg GhcRn] -> [LConDecl GhcRn]
+                  -> Either ErrMsg (LSig GhcRn)
 extractPatternSyn nm t tvs cons =
   case filter matches cons of
-    [] -> Left . O.showSDocUnsafe $
+    [] -> Left . O.showSDocOneLine O.defaultSDocContext $
           O.text "constructor pattern " O.<+> O.ppr nm O.<+> O.text "not found in type" O.<+> O.ppr t
     con:_ -> pure (extract <$> con)
  where
@@ -991,17 +1087,21 @@ extractPatternSyn nm t tvs cons =
   extract :: ConDecl GhcRn -> Sig GhcRn
   extract con =
     let args =
-          case getConArgs con of
-            PrefixCon args' -> (map hsScaledThing args')
-            RecCon (L _ fields) -> cd_fld_type . unLoc <$> fields
-            InfixCon arg1 arg2 -> map hsScaledThing [arg1, arg2]
+          case con of
+            ConDeclH98 { con_args = con_args' } -> case con_args' of
+              PrefixCon _ args' -> map hsScaledThing args'
+              RecCon (L _ fields) -> cd_fld_type . unLoc <$> fields
+              InfixCon arg1 arg2 -> map hsScaledThing [arg1, arg2]
+            ConDeclGADT { con_g_args = con_args' } -> case con_args' of
+              PrefixConGADT args' -> map hsScaledThing args'
+              RecConGADT (L _ fields) -> cd_fld_type . unLoc <$> fields
         typ = longArrow args (data_ty con)
         typ' =
           case con of
             ConDeclH98 { con_mb_cxt = Just cxt } -> noLoc (HsQualTy noExtField cxt typ)
             _ -> typ
         typ'' = noLoc (HsQualTy noExtField (noLoc []) typ')
-    in PatSynSig noExtField [noLoc nm] (mkEmptyImplicitBndrs typ'')
+    in PatSynSig noExtField [noLoc nm] (mkEmptySigType typ'')
 
   longArrow :: [LHsType GhcRn] -> LHsType GhcRn -> LHsType GhcRn
   longArrow inputs output = foldr (\x y -> noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) x y)) output inputs
@@ -1019,9 +1119,9 @@ extractRecSel :: Name -> Name -> [LHsTypeArg GhcRn] -> [LConDecl GhcRn]
 extractRecSel _ _ _ [] = Left "extractRecSel: selector not found"
 
 extractRecSel nm t tvs (L _ con : rest) =
-  case getConArgs con of
-    RecCon (L _ fields) | ((l,L _ (ConDeclField _ _nn ty _)) : _) <- matching_fields fields ->
-      pure (L l (TypeSig noExtField [noLoc nm] (mkEmptySigWcType (noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) data_ty (getBangType ty))))))
+  case getRecConArgs_maybe con of
+    Just (L _ fields) | ((l,L _ (ConDeclField _ _nn ty _)) : _) <- matching_fields fields ->
+      pure (L l (TypeSig noExtField [noLoc nm] (mkEmptyWildCardBndrs $ mkEmptySigType (noLoc (HsFunTy noExtField (HsUnrestrictedArrow NormalSyntax) data_ty (getBangType ty))))))
     _ -> extractRecSel nm t tvs rest
  where
   matching_fields :: [LConDeclField GhcRn] -> [(SrcSpan, LConDeclField GhcRn)]
diff --git a/haddock-api/src/Haddock/Interface/Json.hs b/haddock-api/src/Haddock/Interface/Json.hs
index 95889a63..92fb2e75 100644
--- a/haddock-api/src/Haddock/Interface/Json.hs
+++ b/haddock-api/src/Haddock/Interface/Json.hs
@@ -5,7 +5,7 @@ module Haddock.Interface.Json (
   , renderJson
   ) where
 
-import GHC.Types.Basic
+import GHC.Types.Fixity
 import GHC.Utils.Json
 import GHC.Unit.Module
 import GHC.Types.Name
diff --git a/haddock-api/src/Haddock/Interface/LexParseRn.hs b/haddock-api/src/Haddock/Interface/LexParseRn.hs
index 87210273..6da89e7c 100644
--- a/haddock-api/src/Haddock/Interface/LexParseRn.hs
+++ b/haddock-api/src/Haddock/Interface/LexParseRn.hs
@@ -1,5 +1,6 @@
 {-# OPTIONS_GHC -Wwarn #-}
 {-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE FlexibleContexts #-}
 {-# LANGUAGE ViewPatterns #-}
   -----------------------------------------------------------------------------
 -- |
@@ -21,8 +22,8 @@ module Haddock.Interface.LexParseRn
 
 import Control.Arrow
 import Control.Monad
-import Data.Functor (($>))
-import Data.List (maximumBy, (\\))
+import Data.Functor
+import Data.List ((\\), maximumBy)
 import Data.Ord
 import Documentation.Haddock.Doc (metaDocConcat)
 import GHC.Driver.Session (languageExtensions)
@@ -32,8 +33,9 @@ import Haddock.Interface.ParseModuleHeader
 import Haddock.Parser
 import Haddock.Types
 import GHC.Types.Name
+import GHC.Types.Avail ( availName )
 import GHC.Parser.PostProcess
-import GHC.Utils.Outputable ( showPpr, showSDoc )
+import GHC.Driver.Ppr ( showPpr, showSDoc )
 import GHC.Types.Name.Reader
 import GHC.Data.EnumSet as EnumSet
 
@@ -134,7 +136,7 @@ rename dflags gre = rn
 
           -- There is only one name in the environment that matches so
           -- use it.
-          [a] -> pure (DocIdentifier (i $> gre_name a))
+          [a] -> pure $ DocIdentifier (i $> greMangledName a)
 
           -- There are multiple names available.
           gres -> ambiguous dflags i gres
@@ -199,9 +201,10 @@ ambiguous :: DynFlags
           -> [GlobalRdrElt] -- ^ More than one @gre@s sharing the same `RdrName` above.
           -> ErrMsgM (Doc Name)
 ambiguous dflags x gres = do
-  let dflt = maximumBy (comparing (gre_lcl &&& isTyConName . gre_name)) gres
+  let noChildren = map availName (gresToAvailInfo gres)
+      dflt = maximumBy (comparing (isLocalName &&& isTyConName)) noChildren
       msg = "Warning: " ++ showNsRdrName dflags x ++ " is ambiguous. It is defined\n" ++
-            concatMap (\n -> "    * " ++ defnLoc n ++ "\n") gres ++
+            concatMap (\n -> "    * " ++ defnLoc n ++ "\n") (map greMangledName gres) ++
             "    You may be able to disambiguate the identifier by qualifying it or\n" ++
             "    by specifying the type/value namespace explicitly.\n" ++
             "    Defaulting to the one defined " ++ defnLoc dflt
@@ -210,10 +213,12 @@ ambiguous dflags x gres = do
   -- of the same name, but not the only constructor.
   -- For example, for @data D = C | D@, someone may want to reference the @D@
   -- constructor.
-  when (length (gresToAvailInfo gres) > 1) $ tell [msg]
-  pure (DocIdentifier (x $> gre_name dflt))
+  when (length noChildren > 1) $ tell [msg]
+  pure (DocIdentifier (x $> dflt))
   where
-    defnLoc = showSDoc dflags . pprNameDefnLoc . gre_name
+    isLocalName (nameSrcLoc -> RealSrcLoc {}) = True
+    isLocalName _ = False
+    defnLoc = showSDoc dflags . pprNameDefnLoc
 
 -- | Handle value-namespaced names that cannot be for values.
 --
diff --git a/haddock-api/src/Haddock/Interface/Rename.hs b/haddock-api/src/Haddock/Interface/Rename.hs
index bb9cd02d..b212adce 100644
--- a/haddock-api/src/Haddock/Interface/Rename.hs
+++ b/haddock-api/src/Haddock/Interface/Rename.hs
@@ -213,10 +213,10 @@ renameLTypeArg (HsTypeArg l ki) = do { ki' <- renameLKind ki
 renameLTypeArg (HsArgPar sp) = return $ HsArgPar sp
 
 renameLSigType :: LHsSigType GhcRn -> RnM (LHsSigType DocNameI)
-renameLSigType = renameImplicit renameLType
+renameLSigType = mapM renameSigType
 
 renameLSigWcType :: LHsSigWcType GhcRn -> RnM (LHsSigWcType DocNameI)
-renameLSigWcType = renameWc (renameImplicit renameLType)
+renameLSigWcType = renameWc renameLSigType
 
 renameLKind :: LHsKind GhcRn -> RnM (LHsKind DocNameI)
 renameLKind = renameLType
@@ -310,12 +310,18 @@ renameType t = case t of
   HsTyLit _ x -> return (HsTyLit noExtField x)
 
   HsRecTy _ a               -> HsRecTy noExtField <$> mapM renameConDeclFieldField a
-  (XHsType (NHsCoreTy a))   -> pure (XHsType (NHsCoreTy a))
+  XHsType a                 -> pure (XHsType a)
   HsExplicitListTy i a b  -> HsExplicitListTy i a <$> mapM renameLType b
   HsExplicitTupleTy a b   -> HsExplicitTupleTy a <$> mapM renameLType b
   HsSpliceTy _ s          -> renameHsSpliceTy s
   HsWildCardTy a          -> pure (HsWildCardTy a)
 
+renameSigType :: HsSigType GhcRn -> RnM (HsSigType DocNameI)
+renameSigType (HsSig { sig_bndrs = bndrs, sig_body = body }) = do
+  bndrs' <- renameOuterTyVarBndrs bndrs
+  body'  <- renameLType body
+  pure $ HsSig { sig_ext = noExtField, sig_bndrs = bndrs', sig_body = body' }
+
 -- | Rename splices, but _only_ those that turn out to be for types.
 -- I think this is actually safe for our possible inputs:
 --
@@ -496,46 +502,55 @@ renameDataDefn (HsDataDefn { dd_ND = nd, dd_ctxt = lcontext, dd_cType = cType
 renameCon :: ConDecl GhcRn -> RnM (ConDecl DocNameI)
 renameCon decl@(ConDeclH98 { con_name = lname, con_ex_tvs = ltyvars
                            , con_mb_cxt = lcontext, con_args = details
-                           , con_doc = mbldoc }) = do
+                           , con_doc = mbldoc
+                           , con_forall = forall }) = do
       lname'    <- renameL lname
       ltyvars'  <- mapM renameLTyVarBndr ltyvars
       lcontext' <- traverse renameLContext lcontext
-      details'  <- renameDetails details
+      details'  <- renameH98Details details
       mbldoc'   <- mapM renameLDocHsSyn mbldoc
       return (decl { con_ext = noExtField, con_name = lname', con_ex_tvs = ltyvars'
                    , con_mb_cxt = lcontext'
+                   , con_forall = forall -- Remove when #18311 is fixed
                    , con_args = details', con_doc = mbldoc' })
 
-renameCon decl@(ConDeclGADT { con_names = lnames, con_qvars = ltyvars
-                            , con_mb_cxt = lcontext, con_args = details
+renameCon ConDeclGADT { con_names = lnames, con_bndrs = bndrs
+                            , con_mb_cxt = lcontext, con_g_args = details
                             , con_res_ty = res_ty
-                            , con_doc = mbldoc }) = do
+                            , con_doc = mbldoc } = do
       lnames'   <- mapM renameL lnames
-      ltyvars'  <- mapM renameLTyVarBndr ltyvars
+      bndrs'    <- mapM renameOuterTyVarBndrs bndrs
       lcontext' <- traverse renameLContext lcontext
-      details'  <- renameDetails details
+      details'  <- renameGADTDetails details
       res_ty'   <- renameLType res_ty
       mbldoc'   <- mapM renameLDocHsSyn mbldoc
-      return (decl { con_g_ext = noExtField, con_names = lnames', con_qvars = ltyvars'
-                   , con_mb_cxt = lcontext', con_args = details'
+      return (ConDeclGADT
+                   { con_g_ext = noExtField, con_names = lnames', con_bndrs = bndrs'
+                   , con_mb_cxt = lcontext', con_g_args = details'
                    , con_res_ty = res_ty', con_doc = mbldoc' })
 
 renameHsScaled :: HsScaled GhcRn (LHsType GhcRn)
                -> RnM (HsScaled DocNameI (LHsType DocNameI))
 renameHsScaled (HsScaled w ty) = HsScaled <$> renameArrow w <*> renameLType ty
 
-renameDetails :: HsConDeclDetails GhcRn -> RnM (HsConDeclDetails DocNameI)
-renameDetails (RecCon (L l fields)) = do
+renameH98Details :: HsConDeclH98Details GhcRn
+                 -> RnM (HsConDeclH98Details DocNameI)
+renameH98Details (RecCon (L l fields)) = do
   fields' <- mapM renameConDeclFieldField fields
   return (RecCon (L l fields'))
-                               -- This causes an assertion failure
---renameDetails (PrefixCon ps) = -- return . PrefixCon =<< mapM (_renameLType) ps
-renameDetails (PrefixCon ps) = PrefixCon <$> mapM renameHsScaled ps
-renameDetails (InfixCon a b) = do
+renameH98Details (PrefixCon ts ps) = PrefixCon ts <$> mapM renameHsScaled ps
+renameH98Details (InfixCon a b) = do
   a' <- renameHsScaled a
   b' <- renameHsScaled b
   return (InfixCon a' b')
 
+renameGADTDetails :: HsConDeclGADTDetails GhcRn
+                  -> RnM (HsConDeclGADTDetails DocNameI)
+renameGADTDetails (RecConGADT (L l fields)) = do
+  fields' <- mapM renameConDeclFieldField fields
+  return (RecConGADT (L l fields'))
+renameGADTDetails (PrefixConGADT ps) = PrefixConGADT <$> mapM renameHsScaled ps
+
 renameConDeclFieldField :: LConDeclField GhcRn -> RnM (LConDeclField DocNameI)
 renameConDeclFieldField (L l (ConDeclField _ names t doc)) = do
   names' <- mapM renameLFieldOcc names
@@ -630,32 +645,26 @@ renameTyFamInstD (TyFamInstDecl { tfid_eqn = eqn })
        ; return (TyFamInstDecl { tfid_eqn = eqn' }) }
 
 renameTyFamInstEqn :: TyFamInstEqn GhcRn -> RnM (TyFamInstEqn DocNameI)
-renameTyFamInstEqn eqn
-  = renameImplicit rename_ty_fam_eqn eqn
-  where
-    rename_ty_fam_eqn
-      :: FamEqn GhcRn (LHsType GhcRn)
-      -> RnM (FamEqn DocNameI (LHsType DocNameI))
-    rename_ty_fam_eqn (FamEqn { feqn_tycon = tc, feqn_bndrs = bndrs
-                              , feqn_pats = pats, feqn_fixity = fixity
-                              , feqn_rhs = rhs })
-      = do { tc' <- renameL tc
-           ; bndrs' <- traverse (mapM renameLTyVarBndr) bndrs
-           ; pats' <- mapM renameLTypeArg pats
-           ; rhs' <- renameLType rhs
-           ; return (FamEqn { feqn_ext    = noExtField
-                            , feqn_tycon  = tc'
-                            , feqn_bndrs  = bndrs'
-                            , feqn_pats   = pats'
-                            , feqn_fixity = fixity
-                            , feqn_rhs    = rhs' }) }
+renameTyFamInstEqn (FamEqn { feqn_tycon = tc, feqn_bndrs = bndrs
+                           , feqn_pats = pats, feqn_fixity = fixity
+                           , feqn_rhs = rhs })
+  = do { tc' <- renameL tc
+       ; bndrs' <- renameOuterTyVarBndrs bndrs
+       ; pats' <- mapM renameLTypeArg pats
+       ; rhs' <- renameLType rhs
+       ; return (FamEqn { feqn_ext    = noExtField
+                        , feqn_tycon  = tc'
+                        , feqn_bndrs  = bndrs'
+                        , feqn_pats   = pats'
+                        , feqn_fixity = fixity
+                        , feqn_rhs    = rhs' }) }
 
 renameTyFamDefltD :: TyFamDefltDecl GhcRn -> RnM (TyFamDefltDecl DocNameI)
 renameTyFamDefltD = renameTyFamInstD
 
 renameDataFamInstD :: DataFamInstDecl GhcRn -> RnM (DataFamInstDecl DocNameI)
 renameDataFamInstD (DataFamInstDecl { dfid_eqn = eqn })
-  = do { eqn' <- renameImplicit rename_data_fam_eqn eqn
+  = do { eqn' <- rename_data_fam_eqn eqn
        ; return (DataFamInstDecl { dfid_eqn = eqn' }) }
   where
     rename_data_fam_eqn
@@ -665,7 +674,7 @@ renameDataFamInstD (DataFamInstDecl { dfid_eqn = eqn })
                                 , feqn_pats = pats, feqn_fixity = fixity
                                 , feqn_rhs = defn })
       = do { tc' <- renameL tc
-           ; bndrs' <- traverse (mapM renameLTyVarBndr) bndrs
+           ; bndrs' <- renameOuterTyVarBndrs bndrs
            ; pats' <- mapM renameLTypeArg pats
            ; defn' <- renameDataDefn defn
            ; return (FamEqn { feqn_ext    = noExtField
@@ -675,13 +684,12 @@ renameDataFamInstD (DataFamInstDecl { dfid_eqn = eqn })
                             , feqn_fixity = fixity
                             , feqn_rhs    = defn' }) }
 
-renameImplicit :: (in_thing -> RnM out_thing)
-               -> HsImplicitBndrs GhcRn in_thing
-               -> RnM (HsImplicitBndrs DocNameI out_thing)
-renameImplicit rn_thing (HsIB { hsib_body = thing })
-  = do { thing' <- rn_thing thing
-       ; return (HsIB { hsib_body = thing'
-                      , hsib_ext = noExtField }) }
+renameOuterTyVarBndrs :: HsOuterTyVarBndrs flag GhcRn
+                      -> RnM (HsOuterTyVarBndrs flag DocNameI)
+renameOuterTyVarBndrs (HsOuterImplicit{}) =
+  pure $ HsOuterImplicit{hso_ximplicit = noExtField}
+renameOuterTyVarBndrs (HsOuterExplicit{hso_bndrs = exp_bndrs}) =
+  HsOuterExplicit noExtField <$> mapM renameLTyVarBndr exp_bndrs
 
 renameWc :: (in_thing -> RnM out_thing)
          -> HsWildCardBndrs GhcRn in_thing
diff --git a/haddock-api/src/Haddock/Interface/Specialize.hs b/haddock-api/src/Haddock/Interface/Specialize.hs
index ad2f61c2..f37e1da9 100644
--- a/haddock-api/src/Haddock/Interface/Specialize.hs
+++ b/haddock-api/src/Haddock/Interface/Specialize.hs
@@ -3,6 +3,7 @@
 {-# LANGUAGE ScopedTypeVariables #-}
 {-# LANGUAGE TypeApplications #-}
 {-# LANGUAGE RecordWildCards #-}
+{-# LANGUAGE GADTs #-}
 {-# OPTIONS_GHC -Wno-incomplete-record-updates #-}
 
 module Haddock.Interface.Specialize
@@ -38,7 +39,7 @@ specialize specs = go spec_map0
     go :: forall x. Data x => Map Name (HsType GhcRn) -> x -> x
     go spec_map = everywhereButType @Name $ mkT $ sugar . strip_kind_sig . specialize_ty_var spec_map
 
-    strip_kind_sig :: HsType name -> HsType name
+    strip_kind_sig :: HsType GhcRn -> HsType GhcRn
     strip_kind_sig (HsKindSig _ (L _ t) _) = t
     strip_kind_sig typ = typ
 
@@ -57,7 +58,7 @@ specialize specs = go spec_map0
 --
 -- Again, it is just a convenience function around 'specialize'. Note that
 -- length of type list should be the same as the number of binders.
-specializeTyVarBndrs :: LHsQTyVars GhcRn -> [HsType GhcRn] -> HsType GhcRn -> HsType GhcRn
+specializeTyVarBndrs :: Data a => LHsQTyVars GhcRn -> [HsType GhcRn] -> a -> a
 specializeTyVarBndrs bndrs typs = specialize $ zip bndrs' typs
   where
     bndrs' = map (hsTyVarBndrName . unLoc) . hsq_explicit $ bndrs
@@ -74,13 +75,13 @@ specializeSig :: LHsQTyVars GhcRn -> [HsType GhcRn]
               -> Sig GhcRn
               -> Sig GhcRn
 specializeSig bndrs typs (TypeSig _ lnames typ) =
-  TypeSig noExtField lnames (typ {hswc_body = (hswc_body typ) {hsib_body = noLoc typ'}})
+  TypeSig noExtField lnames (typ {hswc_body = noLoc typ'})
   where
-    true_type :: HsType GhcRn
-    true_type = unLoc (hsSigWcType typ)
-    typ' :: HsType GhcRn
+    true_type :: HsSigType GhcRn
+    true_type = unLoc (dropWildCards typ)
+    typ' :: HsSigType GhcRn
     typ' = rename fv $ specializeTyVarBndrs bndrs typs true_type
-    fv = foldr Set.union Set.empty . map freeVariables $ typs
+    fv = foldr Set.union Set.empty . map freeVariablesType $ typs
 specializeSig _ _ sig = sig
 
 
@@ -121,7 +122,7 @@ sugarTuples typ =
     aux apps (HsAppTy _ (L _ ftyp) atyp) = aux (atyp:apps) ftyp
     aux apps (HsParTy _ (L _ typ')) = aux apps typ'
     aux apps (HsTyVar _ _ (L _ name))
-        | isBuiltInSyntax name' && suitable = HsTupleTy noExtField HsBoxedTuple apps
+        | isBuiltInSyntax name' && suitable = HsTupleTy noExtField HsBoxedOrConstraintTuple apps
       where
         name' = getName name
         strName = getOccString name
@@ -176,19 +177,25 @@ parseTupleArity _ = Nothing
 -- not converted to 'String' or alike to avoid new allocations. Additionally,
 -- since it is stored mostly in 'Set', fast comparison of 'FastString' is also
 -- quite nice.
-type NameRep = FastString
+newtype NameRep
+   = NameRep FastString
+   deriving (Eq)
+
+instance Ord NameRep where
+   compare (NameRep fs1) (NameRep fs2) = uniqCompareFS fs1 fs2
+
 
 getNameRep :: NamedThing name => name -> NameRep
-getNameRep = getOccFS
+getNameRep = NameRep . getOccFS
 
 nameRepString :: NameRep -> String
-nameRepString = unpackFS
+nameRepString (NameRep fs) = unpackFS fs
 
 stringNameRep :: String -> NameRep
-stringNameRep = mkFastString
+stringNameRep = NameRep . mkFastString
 
 setInternalNameRep :: SetName name => NameRep -> name -> name
-setInternalNameRep = setInternalOccName . mkVarOccFS
+setInternalNameRep (NameRep fs) = setInternalOccName (mkVarOccFS fs)
 
 setInternalOccName :: SetName name => OccName -> name -> name
 setInternalOccName occ name =
@@ -198,23 +205,37 @@ setInternalOccName occ name =
     nname' = mkInternalName (nameUnique nname) occ (nameSrcSpan nname)
 
 
--- | Compute set of free variables of given type.
-freeVariables :: HsType GhcRn -> Set Name
-freeVariables =
-    everythingWithState Set.empty Set.union query
+-- | Compute set of free variables of a given 'HsType'.
+freeVariablesType :: HsType GhcRn -> Set Name
+freeVariablesType =
+    everythingWithState Set.empty Set.union
+      (mkQ (\ctx -> (Set.empty, ctx)) queryType)
+
+-- | Compute set of free variables of a given 'HsType'.
+freeVariablesSigType :: HsSigType GhcRn -> Set Name
+freeVariablesSigType =
+    everythingWithState Set.empty Set.union
+      (mkQ (\ctx -> (Set.empty, ctx)) queryType `extQ` querySigType)
+
+queryType :: HsType GhcRn -> Set Name -> (Set Name, Set Name)
+queryType term ctx = case term of
+    HsForAllTy _ tele _ ->
+        (Set.empty, Set.union ctx (teleNames tele))
+    HsTyVar _ _ (L _ name)
+        | getName name `Set.member` ctx -> (Set.empty, ctx)
+        | otherwise -> (Set.singleton $ getName name, ctx)
+    _ -> (Set.empty, ctx)
   where
-    query term ctx = case cast term :: Maybe (HsType GhcRn) of
-        Just (HsForAllTy _ tele _) ->
-            (Set.empty, Set.union ctx (teleNames tele))
-        Just (HsTyVar _ _ (L _ name))
-            | getName name `Set.member` ctx -> (Set.empty, ctx)
-            | otherwise -> (Set.singleton $ getName name, ctx)
-        _ -> (Set.empty, ctx)
-
+    teleNames :: HsForAllTelescope GhcRn -> Set Name
     teleNames (HsForAllVis   _ bndrs) = bndrsNames bndrs
     teleNames (HsForAllInvis _ bndrs) = bndrsNames bndrs
 
-    bndrsNames = Set.fromList . map (getName . hsTyVarBndrName . unLoc)
+querySigType :: HsSigType GhcRn -> Set Name -> (Set Name, Set Name)
+querySigType (HsSig { sig_bndrs = outer_bndrs }) ctx =
+  (Set.empty, Set.union ctx (bndrsNames (hsOuterExplicitBndrs outer_bndrs)))
+
+bndrsNames :: [LHsTyVarBndr flag GhcRn] -> Set Name
+bndrsNames = Set.fromList . map (getName . tyVarName . unLoc)
 
 
 -- | Make given type visually unambiguous.
@@ -225,12 +246,12 @@ freeVariables =
 -- different type variable than latter one. Applying 'rename' function
 -- will fix that type to be visually unambiguous again (making it something
 -- like @(a -> b0) -> b@).
-rename :: Set Name -> HsType GhcRn -> HsType GhcRn
-rename fv typ = evalState (renameType typ) env
+rename :: Set Name -> HsSigType GhcRn -> HsSigType GhcRn
+rename fv typ = evalState (renameSigType typ) env
   where
     env = RenameEnv
       { rneHeadFVs = Map.fromList . map mkPair . Set.toList $ fv
-      , rneSigFVs = Set.map getNameRep $ freeVariables typ
+      , rneSigFVs = Set.map getNameRep $ freeVariablesSigType typ
       , rneCtx = Map.empty
       }
     mkPair name = (getNameRep name, name)
@@ -245,6 +266,17 @@ data RenameEnv name = RenameEnv
   }
 
 
+renameSigType :: HsSigType GhcRn -> Rename (IdP GhcRn) (HsSigType GhcRn)
+renameSigType (HsSig x bndrs body) =
+  HsSig x <$> renameOuterTyVarBndrs bndrs <*> renameLType body
+
+renameOuterTyVarBndrs :: HsOuterTyVarBndrs flag GhcRn
+                      -> Rename (IdP GhcRn) (HsOuterTyVarBndrs flag GhcRn)
+renameOuterTyVarBndrs (HsOuterImplicit imp_tvs) =
+  HsOuterImplicit <$> mapM renameName imp_tvs
+renameOuterTyVarBndrs (HsOuterExplicit x exp_bndrs) =
+  HsOuterExplicit x <$> mapM renameLBinder exp_bndrs
+
 renameType :: HsType GhcRn -> Rename (IdP GhcRn) (HsType GhcRn)
 renameType (HsForAllTy x tele lt) =
     HsForAllTy x
@@ -271,7 +303,7 @@ renameType t@(HsSpliceTy _ _) = pure t
 renameType (HsDocTy x lt doc) = HsDocTy x <$> renameLType lt <*> pure doc
 renameType (HsBangTy x bang lt) = HsBangTy x bang <$> renameLType lt
 renameType t@(HsRecTy _ _) = pure t
-renameType t@(XHsType (NHsCoreTy _)) = pure t
+renameType t@(XHsType _) = pure t
 renameType (HsExplicitListTy x ip ltys) =
     HsExplicitListTy x ip <$> renameLTypes ltys
 renameType (HsExplicitTupleTy x ltys) =
@@ -362,3 +394,8 @@ alternativeNames name =
 
 located :: Functor f => (a -> f b) -> Located a -> f (Located b)
 located f (L loc e) = L loc <$> f e
+
+
+tyVarName :: HsTyVarBndr flag GhcRn -> IdP GhcRn
+tyVarName (UserTyVar _ _ name) = unLoc name
+tyVarName (KindedTyVar _ _ (L _ name) _) = name
diff --git a/haddock-api/src/Haddock/InterfaceFile.hs b/haddock-api/src/Haddock/InterfaceFile.hs
index 69201eb0..95bfc903 100644
--- a/haddock-api/src/Haddock/InterfaceFile.hs
+++ b/haddock-api/src/Haddock/InterfaceFile.hs
@@ -38,7 +38,7 @@ import GHC.Data.FastMutInt
 import GHC.Data.FastString
 import GHC hiding (NoLink)
 import GHC.Driver.Monad (withSession)
-import GHC.Driver.Types
+import GHC.Driver.Env
 import GHC.Types.Name.Cache
 import GHC.Iface.Env
 import GHC.Types.Name
@@ -94,7 +94,7 @@ binaryInterfaceMagic = 0xD0Cface
 -- (2) set `binaryInterfaceVersionCompatibility` to [binaryInterfaceVersion]
 --
 binaryInterfaceVersion :: Word16
-#if MIN_VERSION_ghc(9,0,0) && !MIN_VERSION_ghc(9,1,0)
+#if MIN_VERSION_ghc(9,1,0) && !MIN_VERSION_ghc(9,2,0)
 binaryInterfaceVersion = 38
 
 binaryInterfaceVersionCompatibility :: [Word16]
diff --git a/haddock-api/src/Haddock/Options.hs b/haddock-api/src/Haddock/Options.hs
index 0b886d1a..4d22505f 100644
--- a/haddock-api/src/Haddock/Options.hs
+++ b/haddock-api/src/Haddock/Options.hs
@@ -24,6 +24,7 @@ module Haddock.Options (
   optSourceCssFile,
   sourceUrls,
   wikiUrls,
+  optParCount,
   optDumpInterfaceFile,
   optShowInterfaceFile,
   optLaTeXStyle,
@@ -45,10 +46,10 @@ import qualified Data.Char as Char
 import           Data.Version
 import           Control.Applicative
 import           GHC.Data.FastString
-import           GHC ( DynFlags, Module, moduleUnit, unitState )
+import           GHC ( Module, moduleUnit )
+import           GHC.Unit.State
 import           Haddock.Types
 import           Haddock.Utils
-import           GHC.Unit.State
 import           System.Console.GetOpt
 import qualified Text.ParserCombinators.ReadP as RP
 
@@ -110,6 +111,7 @@ data Flag
   | Flag_Reexport String
   | Flag_SinceQualification String
   | Flag_IgnoreLinkSymbol String
+  | Flag_ParCount (Maybe Int)
   deriving (Eq, Show)
 
 
@@ -223,7 +225,9 @@ options backwardsCompat =
     Option []  ["since-qual"] (ReqArg Flag_SinceQualification "QUAL")
       "package qualification of @since, one of\n'always' (default) or 'only-external'",
     Option [] ["ignore-link-symbol"] (ReqArg Flag_IgnoreLinkSymbol "SYMBOL")
-      "name of a symbol which does not trigger a warning in case of link issue"
+      "name of a symbol which does not trigger a warning in case of link issue",
+    Option ['j'] [] (OptArg (\count -> Flag_ParCount (fmap read count)) "n")
+      "load modules in parallel"
   ]
 
 
@@ -306,10 +310,11 @@ optShowInterfaceFile flags = optLast [ str | Flag_ShowInterface str <- flags ]
 optLaTeXStyle :: [Flag] -> Maybe String
 optLaTeXStyle flags = optLast [ str | Flag_LaTeXStyle str <- flags ]
 
-
 optMathjax :: [Flag] -> Maybe String
 optMathjax flags = optLast [ str | Flag_Mathjax str <- flags ]
 
+optParCount :: [Flag] -> Maybe (Maybe Int)
+optParCount flags = optLast [ n | Flag_ParCount n <- flags ]
 
 qualification :: [Flag] -> Either String QualOption
 qualification flags =
@@ -375,16 +380,16 @@ optLast xs = Just (last xs)
 --
 -- The @--package-name@ and @--package-version@ Haddock flags allow the user to
 -- specify this information manually and it is returned here if present.
-modulePackageInfo :: DynFlags
+modulePackageInfo :: UnitState
                   -> [Flag] -- ^ Haddock flags are checked as they may contain
                             -- the package name or version provided by the user
                             -- which we prioritise
                   -> Maybe Module
                   -> (Maybe PackageName, Maybe Data.Version.Version)
-modulePackageInfo _dflags _flags Nothing = (Nothing, Nothing)
-modulePackageInfo dflags flags (Just modu) =
+modulePackageInfo _unit_state _flags Nothing = (Nothing, Nothing)
+modulePackageInfo unit_state flags (Just modu) =
   ( optPackageName flags    <|> fmap unitPackageName pkgDb
   , optPackageVersion flags <|> fmap unitPackageVersion pkgDb
   )
   where
-    pkgDb = lookupUnit (unitState dflags) (moduleUnit modu)
+    pkgDb = lookupUnit unit_state (moduleUnit modu)
diff --git a/haddock-api/src/Haddock/Parser.hs b/haddock-api/src/Haddock/Parser.hs
index e335ee19..ab2fa549 100644
--- a/haddock-api/src/Haddock/Parser.hs
+++ b/haddock-api/src/Haddock/Parser.hs
@@ -19,8 +19,9 @@ import Documentation.Haddock.Types
 import Haddock.Types
 
 import GHC.Driver.Session ( DynFlags )
+import GHC.Driver.Config
 import GHC.Data.FastString   ( fsLit )
-import GHC.Parser.Lexer ( mkPState, unP, ParseResult(POk, PFailed) )
+import GHC.Parser.Lexer ( initParserState, unP, ParseResult(POk, PFailed) )
 import GHC.Parser       ( parseIdentifier )
 import GHC.Types.Name.Occurrence ( occNameString )
 import GHC.Types.Name.Reader ( RdrName(..) )
@@ -48,7 +49,7 @@ parseIdent dflags ns str0 =
     PFailed{} -> Nothing
   where
     realSrcLc = mkRealSrcLoc (fsLit "<unknown file>") 0 0
-    pstate str = mkPState dflags (stringToStringBuffer str) realSrcLc
+    pstate str = initParserState (initParserOpts dflags) (stringToStringBuffer str) realSrcLc
     (wrap,str1) = case str0 of
                     '(' : s@(c : _) | c /= ',', c /= ')'  -- rule out tuple names
                                     -> (Parenthesized, init s)
diff --git a/haddock-api/src/Haddock/Syb.hs b/haddock-api/src/Haddock/Syb.hs
index 7e34ae8c..fc946c8e 100644
--- a/haddock-api/src/Haddock/Syb.hs
+++ b/haddock-api/src/Haddock/Syb.hs
@@ -6,7 +6,7 @@
 module Haddock.Syb
     ( everything, everythingButType, everythingWithState
     , everywhere, everywhereButType
-    , mkT
+    , mkT, mkQ, extQ
     , combine
     ) where
 
@@ -91,6 +91,21 @@ mkT f = case cast f of
     Just f' -> f'
     Nothing -> id
 
+-- | Create generic query.
+--
+-- Another function stolen from SYB package.
+mkQ :: (Typeable a, Typeable b) => r -> (b -> r) -> a -> r
+(r `mkQ` br) a = case cast a of
+                        Just b  -> br b
+                        Nothing -> r
+
+
+-- | Extend a generic query by a type-specific case.
+--
+-- Another function stolen from SYB package.
+extQ :: (Typeable a, Typeable b) => (a -> q) -> (b -> q) -> a -> q
+extQ f g a = maybe (f a) g (cast a)
+
 -- | Combine two queries into one using alternative combinator.
 combine :: Alternative f => (forall a. Data a => a -> f r)
                          -> (forall a. Data a => a -> f r)
diff --git a/haddock-api/src/Haddock/Types.hs b/haddock-api/src/Haddock/Types.hs
index 53d01565..83c9dd72 100644
--- a/haddock-api/src/Haddock/Types.hs
+++ b/haddock-api/src/Haddock/Types.hs
@@ -3,6 +3,9 @@
 {-# LANGUAGE PartialTypeSignatures #-}
 {-# LANGUAGE UndecidableInstances #-} -- Note [Pass sensitive types]
 {-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE DerivingStrategies #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 {-# OPTIONS_GHC -fno-warn-orphans #-}
 
 -----------------------------------------------------------------------------
@@ -25,20 +28,24 @@ module Haddock.Types (
   , HsDocString, LHsDocString
   , Fixity(..)
   , module Documentation.Haddock.Types
+
+  -- $ Reexports
+  , runWriter
+  , tell
  ) where
 
-import Control.Arrow hiding ((<+>))
 import Control.DeepSeq
 import Control.Exception (throw)
-import Control.Monad (ap)
 import Control.Monad.Catch
 import Control.Monad.IO.Class (MonadIO(..))
+import Control.Monad.Writer.Strict (Writer, WriterT, MonadWriter(..), lift, runWriter, runWriterT)
 import Data.Typeable (Typeable)
 import Data.Map (Map)
 import Data.Data (Data)
 import Data.Void (Void)
 import Documentation.Haddock.Types
-import GHC.Types.Basic (Fixity(..), PromotionFlag(..))
+import GHC.Types.Basic (PromotionFlag(..))
+import GHC.Types.Fixity (Fixity(..))
 
 import GHC
 import GHC.Driver.Session (Language)
@@ -305,10 +312,12 @@ data DocName
 
 data DocNameI
 
+type instance NoGhcTc DocNameI = DocNameI
+
 type instance IdP DocNameI = DocName
 
 instance CollectPass DocNameI where
-  collectXXPat _ ext = noExtCon ext
+  collectXXPat _ _ ext = noExtCon ext
 
 instance NamedThing DocName where
   getName (Documented name _) = name
@@ -628,26 +637,7 @@ data SinceQual
 
 
 type ErrMsg = String
-newtype ErrMsgM a = Writer { runWriter :: (a, [ErrMsg]) }
-
-
-instance Functor ErrMsgM where
-        fmap f (Writer (a, msgs)) = Writer (f a, msgs)
-
-instance Applicative ErrMsgM where
-    pure a = Writer (a, [])
-    (<*>)  = ap
-
-instance Monad ErrMsgM where
-        return   = pure
-        m >>= k  = Writer $ let
-                (a, w)  = runWriter m
-                (b, w') = runWriter (k a)
-                in (b, w ++ w')
-
-
-tell :: [ErrMsg] -> ErrMsgM ()
-tell w = Writer ((), w)
+type ErrMsgM = Writer [ErrMsg]
 
 
 -- Exceptions
@@ -681,46 +671,36 @@ withExceptionContext ctxt =
 -- @Haddock.Types.ErrMsg@s a lot, like @ErrMsgM@ does,
 -- but we can't just use @GhcT ErrMsgM@ because GhcT requires the
 -- transformed monad to be MonadIO.
-newtype ErrMsgGhc a = WriterGhc { runWriterGhc :: Ghc (a, [ErrMsg]) }
---instance MonadIO ErrMsgGhc where
---  liftIO = WriterGhc . fmap (\a->(a,[])) liftIO
---er, implementing GhcMonad involves annoying ExceptionMonad and
---WarnLogMonad classes, so don't bother.
-liftGhcToErrMsgGhc :: Ghc a -> ErrMsgGhc a
-liftGhcToErrMsgGhc = WriterGhc . fmap (\a->(a,[]))
-liftErrMsg :: ErrMsgM a -> ErrMsgGhc a
-liftErrMsg = WriterGhc . return . runWriter
---  for now, use (liftErrMsg . tell) for this
---tell :: [ErrMsg] -> ErrMsgGhc ()
---tell msgs = WriterGhc $ return ( (), msgs )
+newtype ErrMsgGhc a = ErrMsgGhc { unErrMsgGhc :: WriterT [ErrMsg] Ghc a }
 
 
-instance Functor ErrMsgGhc where
-  fmap f (WriterGhc x) = WriterGhc (fmap (first f) x)
+deriving newtype instance Functor ErrMsgGhc
+deriving newtype instance Applicative ErrMsgGhc
+deriving newtype instance Monad ErrMsgGhc
+deriving newtype instance (MonadWriter [ErrMsg]) ErrMsgGhc
+deriving newtype instance MonadIO ErrMsgGhc
 
-instance Applicative ErrMsgGhc where
-    pure a = WriterGhc (return (a, []))
-    (<*>) = ap
 
-instance Monad ErrMsgGhc where
-  return = pure
-  m >>= k = WriterGhc $ runWriterGhc m >>= \ (a, msgs1) ->
-               fmap (second (msgs1 ++)) (runWriterGhc (k a))
+runWriterGhc :: ErrMsgGhc a -> Ghc (a, [ErrMsg])
+runWriterGhc = runWriterT . unErrMsgGhc
 
-instance MonadIO ErrMsgGhc where
-  liftIO m = WriterGhc (fmap (\x -> (x, [])) (liftIO m))
-
-instance MonadThrow ErrMsgGhc where
-  throwM e = WriterGhc (throwM e)
+liftGhcToErrMsgGhc :: Ghc a -> ErrMsgGhc a
+liftGhcToErrMsgGhc = ErrMsgGhc . lift
 
-instance MonadCatch ErrMsgGhc where
-  catch (WriterGhc m) f = WriterGhc (catch m (runWriterGhc . f))
+liftErrMsg :: ErrMsgM a -> ErrMsgGhc a
+liftErrMsg = writer . runWriter
 
 -----------------------------------------------------------------------------
 -- * Pass sensitive types
 -----------------------------------------------------------------------------
 
-type instance XRec DocNameI f = Located (f DocNameI)
+type instance XRec DocNameI a = Located a
+instance UnXRec DocNameI where
+  unXRec = unLoc
+instance MapXRec DocNameI where
+  mapXRec = fmap
+instance WrapXRec DocNameI where
+  wrapXRec = noLoc
 
 type instance XForAllTy        DocNameI = NoExtField
 type instance XQualTy          DocNameI = NoExtField
@@ -744,7 +724,7 @@ type instance XExplicitListTy  DocNameI = NoExtField
 type instance XExplicitTupleTy DocNameI = NoExtField
 type instance XTyLit           DocNameI = NoExtField
 type instance XWildCardTy      DocNameI = NoExtField
-type instance XXType           DocNameI = NewHsTypeX
+type instance XXType           DocNameI = HsCoreTy
 
 type instance XHsForAllVis        DocNameI = NoExtField
 type instance XHsForAllInvis      DocNameI = NoExtField
@@ -799,9 +779,14 @@ type instance XFamDecl      DocNameI = NoExtField
 type instance XXFamilyDecl  DocNameI = NoExtCon
 type instance XXTyClDecl    DocNameI = NoExtCon
 
-type instance XHsIB             DocNameI _ = NoExtField
-type instance XHsWC             DocNameI _ = NoExtField
-type instance XXHsImplicitBndrs DocNameI _ = NoExtCon
+type instance XHsWC DocNameI _ = NoExtField
+
+type instance XHsOuterExplicit    DocNameI _ = NoExtField
+type instance XHsOuterImplicit    DocNameI   = NoExtField
+type instance XXHsOuterTyVarBndrs DocNameI   = NoExtCon
+
+type instance XHsSig      DocNameI = NoExtField
+type instance XXHsSigType DocNameI = NoExtCon
 
 type instance XHsQTvs        DocNameI = NoExtField
 type instance XConDeclField  DocNameI = NoExtField
diff --git a/haddock-api/src/Haddock/Utils.hs b/haddock-api/src/Haddock/Utils.hs
index 0c9c6073..314b8db9 100644
--- a/haddock-api/src/Haddock/Utils.hs
+++ b/haddock-api/src/Haddock/Utils.hs
@@ -1,4 +1,7 @@
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE GADTs #-}
+
+{-# OPTIONS_GHC -Wno-incomplete-record-updates #-}
 -----------------------------------------------------------------------------
 -- |
 -- Module      :  Haddock.Utils