Merge branch 'ghc-8.8' into ghc-8.10

13 files changed, 332 insertions, 75 deletions

diff --git a/haddock-library/.ghci b/haddock-library/.ghci
deleted file mode 100644
index 78950a5b..00000000
--- a/haddock-library/.ghci
+++ /dev/null
@@ -1 +0,0 @@
-:set -isrc -ivendor/attoparsec-0.12.1.1 -itest -idist/build -idist/build/autogen -optP-include -optPdist/build/autogen/cabal_macros.h
diff --git a/haddock-library/CHANGES.md b/haddock-library/CHANGES.md
index 265579ca..d112db45 100644
--- a/haddock-library/CHANGES.md
+++ b/haddock-library/CHANGES.md
@@ -1,3 +1,7 @@
+## Changes in version 1.8.0.1
+
+ * Fix build-time regression for `base < 4.7` (#1119)
+
 ## Changes in version 1.8.0
 
  * Support inline markup in markdown-style links (#875)
diff --git a/haddock-library/fixtures/examples/list-blocks1.input b/haddock-library/fixtures/examples/list-blocks1.input
new file mode 100644
index 00000000..72a0640b
--- /dev/null
+++ b/haddock-library/fixtures/examples/list-blocks1.input
@@ -0,0 +1,15 @@
+* Something about foo
+
+    @
+    foo :: a -> b -> c
+    foo a b = bar c b
+    @
+
+* Something about bar
+
+    @
+    bar :: a -> b -> c
+    bar a b = foo b a
+    @
+
+* And then we continue
diff --git a/haddock-library/fixtures/examples/list-blocks1.parsed b/haddock-library/fixtures/examples/list-blocks1.parsed
new file mode 100644
index 00000000..9fc4f0ba
--- /dev/null
+++ b/haddock-library/fixtures/examples/list-blocks1.parsed
@@ -0,0 +1,12 @@
+DocUnorderedList
+  [DocAppend
+     (DocParagraph (DocString "Something about foo"))
+     (DocCodeBlock
+        (DocString
+           (concat ["foo :: a -> b -> c\n", "foo a b = bar c b\n"]))),
+   DocAppend
+     (DocParagraph (DocString "Something about bar"))
+     (DocCodeBlock
+        (DocString
+           (concat ["bar :: a -> b -> c\n", "bar a b = foo b a\n"]))),
+   DocParagraph (DocString "And then we continue")]
diff --git a/haddock-library/fixtures/examples/list-blocks2.input b/haddock-library/fixtures/examples/list-blocks2.input
new file mode 100644
index 00000000..91492adb
--- /dev/null
+++ b/haddock-library/fixtures/examples/list-blocks2.input
@@ -0,0 +1,10 @@
+=== Title
+
+* List directly
+* after the title
+
+    @
+    with some inline things
+    @
+
+* is parsed weirdly
diff --git a/haddock-library/fixtures/examples/list-blocks2.parsed b/haddock-library/fixtures/examples/list-blocks2.parsed
new file mode 100644
index 00000000..169677b7
--- /dev/null
+++ b/haddock-library/fixtures/examples/list-blocks2.parsed
@@ -0,0 +1,10 @@
+DocAppend
+  (DocAppend
+     (DocHeader
+        Header {headerLevel = 3, headerTitle = DocString "Title"})
+     (DocUnorderedList
+        [DocParagraph (DocString "List directly"),
+         DocAppend
+           (DocParagraph (DocString "after the title"))
+           (DocCodeBlock (DocString "with some inline things\n"))]))
+  (DocUnorderedList [DocParagraph (DocString "is parsed weirdly")])
diff --git a/haddock-library/haddock-library.cabal b/haddock-library/haddock-library.cabal
index b24db5d4..e58fe2ef 100644
--- a/haddock-library/haddock-library.cabal
+++ b/haddock-library/haddock-library.cabal
@@ -1,6 +1,6 @@
 cabal-version:        2.2
 name:                 haddock-library
-version:              1.8.0
+version:              1.8.0.1
 synopsis:             Library exposing some functionality of Haddock.
 
 description:          Haddock is a documentation-generation tool for Haskell
@@ -19,12 +19,14 @@ bug-reports:          https://github.com/haskell/haddock/issues
 category:             Documentation
 extra-source-files:
   CHANGES.md
+  fixtures/examples/*.input
+  fixtures/examples/*.parsed
 
 common lib-defaults
   default-language: Haskell2010
 
   build-depends:
-    , base         >= 4.5     && < 4.14
+    , base         >= 4.5     && < 4.15
     , bytestring   ^>= 0.9.2.1 || ^>= 0.10.0.0
     , containers   ^>= 0.4.2.1 || ^>= 0.5.0.0 || ^>= 0.6.0.1
     , transformers ^>= 0.3.0.0 || ^>= 0.4.1.0 || ^>= 0.5.0.0
@@ -33,7 +35,7 @@ common lib-defaults
 
   ghc-options: -funbox-strict-fields -Wall -fwarn-tabs
   if impl(ghc >= 8.0)
-    ghc-options: -Wcompat -Wnoncanonical-monad-instances -Wnoncanonical-monadfail-instances
+    ghc-options: -Wcompat -Wnoncanonical-monad-instances
 
 library
   import: lib-defaults
@@ -47,8 +49,10 @@ library
     Documentation.Haddock.Types
 
   other-modules:
+    CompatPrelude
     Documentation.Haddock.Parser.Util
     Documentation.Haddock.Parser.Monad
+    Documentation.Haddock.Parser.Identifier
 
 test-suite spec
   import: lib-defaults
@@ -70,10 +74,11 @@ test-suite spec
       Documentation.Haddock.Parser.UtilSpec
       Documentation.Haddock.ParserSpec
       Documentation.Haddock.Types
+      Documentation.Haddock.Parser.Identifier
 
   build-depends:
-    , base-compat  ^>= 0.9.3 || ^>= 0.10.0
-    , QuickCheck   ^>= 2.11.3
+    , base-compat  ^>= 0.9.3 || ^>= 0.11.0
+    , QuickCheck   ^>= 2.11  || ^>= 2.13.2
     , deepseq      ^>= 1.3.0.0 || ^>= 1.4.0.0
 
   -- NB: build-depends & build-tool-depends have independent
@@ -81,10 +86,10 @@ test-suite spec
   --     version of `hspec` & `hspec-discover` to ensure
   --     intercompatibility
   build-depends:
-    , hspec                         ^>= 2.5.5
+    , hspec                          >= 2.4.4    && < 2.8
 
   build-tool-depends:
-    , hspec-discover:hspec-discover ^>= 2.5.5
+    , hspec-discover:hspec-discover  >= 2.4.4    && < 2.8
 
 test-suite fixtures
   type:             exitcode-stdio-1.0
@@ -92,7 +97,6 @@ test-suite fixtures
   main-is:          Fixtures.hs
   ghc-options:      -Wall
   hs-source-dirs:   fixtures
-  buildable:        False
   build-depends:
       -- intra-package dependency
     , haddock-library
@@ -100,11 +104,11 @@ test-suite fixtures
     , base
 
       -- extra dependencies
-    , base-compat  >= 0.9.3   && < 0.11
+    , base-compat           ^>= 0.9.3 || ^>= 0.11.0
     , directory             ^>= 1.3.0.2
     , filepath              ^>= 1.4.1.2
-    , optparse-applicative  ^>= 0.14.0.0
-    , tree-diff             ^>= 0.0.0.1
+    , optparse-applicative  ^>= 0.15
+    , tree-diff             ^>= 0.1
 
 source-repository head
   type:     git
diff --git a/haddock-library/src/CompatPrelude.hs b/haddock-library/src/CompatPrelude.hs
new file mode 100644
index 00000000..60fa94d9
--- /dev/null
+++ b/haddock-library/src/CompatPrelude.hs
@@ -0,0 +1,52 @@
+{-# LANGUAGE CPP #-}
+
+#if !MIN_VERSION_base(4,5,0)
+# error This module doesn't provide compat-shims for versions prior to base-4.5
+#endif
+
+-- | Bridge impedance mismatch of different @base@ versions back till @base-4.5@ (GHC 7.4.2)
+module CompatPrelude
+    ( ($>)
+    , isSymbolChar
+    ) where
+
+#if MIN_VERSION_base(4,7,0)
+import           Data.Functor                ( ($>) )
+#else
+import           Data.Functor                ( (<$) )
+#endif
+
+#if MIN_VERSION_base(4,9,0)
+import           Text.Read.Lex                      (isSymbolChar)
+#else
+import           Data.Char (GeneralCategory(..), generalCategory)
+#endif
+
+
+#if !MIN_VERSION_base(4,7,0)
+infixl 4 $>
+
+-- | Flipped version of '<$'.
+--
+-- @since 4.7.0.0
+($>) :: Functor f => f a -> b -> f b
+($>) = flip (<$)
+#endif
+
+#if !MIN_VERSION_base(4,9,0)
+-- inlined from base-4.10.0.0
+isSymbolChar :: Char -> Bool
+isSymbolChar c = not (isPuncChar c) && case generalCategory c of
+    MathSymbol           -> True
+    CurrencySymbol       -> True
+    ModifierSymbol       -> True
+    OtherSymbol          -> True
+    DashPunctuation      -> True
+    OtherPunctuation     -> c `notElem` "'\""
+    ConnectorPunctuation -> c /= '_'
+    _                    -> False
+  where
+    -- | The @special@ character class as defined in the Haskell Report.
+    isPuncChar :: Char -> Bool
+    isPuncChar = (`elem` (",;()[]{}`" :: String))
+#endif
diff --git a/haddock-library/src/Documentation/Haddock/Parser.hs b/haddock-library/src/Documentation/Haddock/Parser.hs
index 82d65a0a..028422a7 100644
--- a/haddock-library/src/Documentation/Haddock/Parser.hs
+++ b/haddock-library/src/Documentation/Haddock/Parser.hs
@@ -1,4 +1,3 @@
-{-# LANGUAGE CPP               #-}
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE ViewPatterns      #-}
 -- |
@@ -27,7 +26,7 @@ module Documentation.Haddock.Parser (
 import           Control.Applicative
 import           Control.Arrow (first)
 import           Control.Monad
-import           Data.Char (chr, isUpper, isAlpha, isAlphaNum, isSpace)
+import           Data.Char (chr, isUpper, isAlpha, isSpace)
 import           Data.List (intercalate, unfoldr, elemIndex)
 import           Data.Maybe (fromMaybe, mapMaybe)
 import           Data.Monoid
@@ -36,6 +35,7 @@ import           Documentation.Haddock.Doc
 import           Documentation.Haddock.Markup ( markup, plainMarkup )
 import           Documentation.Haddock.Parser.Monad
 import           Documentation.Haddock.Parser.Util
+import           Documentation.Haddock.Parser.Identifier
 import           Documentation.Haddock.Types
 import           Prelude hiding (takeWhile)
 import qualified Prelude as P
@@ -46,53 +46,26 @@ import           Text.Parsec (try)
 import qualified Data.Text as T
 import           Data.Text (Text)
 
-#if MIN_VERSION_base(4,9,0)
-import           Text.Read.Lex                      (isSymbolChar)
-#else
-import           Data.Char                          (GeneralCategory (..),
-                                                     generalCategory)
-#endif
 
 -- $setup
 -- >>> :set -XOverloadedStrings
 
-#if !MIN_VERSION_base(4,9,0)
--- inlined from base-4.10.0.0
-isSymbolChar :: Char -> Bool
-isSymbolChar c = not (isPuncChar c) && case generalCategory c of
-    MathSymbol           -> True
-    CurrencySymbol       -> True
-    ModifierSymbol       -> True
-    OtherSymbol          -> True
-    DashPunctuation      -> True
-    OtherPunctuation     -> c `notElem` ("'\"" :: String)
-    ConnectorPunctuation -> c /= '_'
-    _                    -> False
-  where
-    -- | The @special@ character class as defined in the Haskell Report.
-    isPuncChar :: Char -> Bool
-    isPuncChar = (`elem` (",;()[]{}`" :: String))
-#endif
-
--- | Identifier string surrounded with opening and closing quotes/backticks.
-type Identifier = (Char, String, Char)
-
 -- | Drops the quotes/backticks around all identifiers, as if they
 -- were valid but still 'String's.
 toRegular :: DocH mod Identifier -> DocH mod String
-toRegular = fmap (\(_, x, _) -> x)
+toRegular = fmap (\(Identifier _ _ x _) -> x)
 
 -- | Maps over 'DocIdentifier's over 'String' with potentially failing
 -- conversion using user-supplied function. If the conversion fails,
 -- the identifier is deemed to not be valid and is treated as a
 -- regular string.
-overIdentifier :: (String -> Maybe a)
+overIdentifier :: (Namespace -> String -> Maybe a)
                -> DocH mod Identifier
                -> DocH mod a
 overIdentifier f d = g d
   where
-    g (DocIdentifier (o, x, e)) = case f x of
-      Nothing -> DocString $ o : x ++ [e]
+    g (DocIdentifier (Identifier ns o x e)) = case f ns x of
+      Nothing -> DocString $ renderNs ns ++ [o] ++ x ++ [e]
       Just x' -> DocIdentifier x'
     g DocEmpty = DocEmpty
     g (DocAppend x x') = DocAppend (g x) (g x')
@@ -314,7 +287,8 @@ markdownImage :: Parser (DocH mod Identifier)
 markdownImage = DocPic . fromHyperlink <$> ("!" *> linkParser)
   where
     fromHyperlink (Hyperlink u l) = Picture u (fmap (markup stringMarkup) l)
-    stringMarkup = plainMarkup (const "") (\(l,c,r) -> [l] <> c <> [r])
+    stringMarkup = plainMarkup (const "") renderIdent
+    renderIdent (Identifier ns l c r) = renderNs ns <> [l] <> c <> [r]
 
 -- | Paragraph parser, called by 'parseParas'.
 paragraph :: Parser (DocH mod Identifier)
@@ -836,30 +810,6 @@ autoUrl = mkLink <$> url
     mkHyperlink lnk = Hyperlink (T.unpack lnk) Nothing
 
 
-
--- | Parses strings between identifier delimiters. Consumes all input that it
--- deems to be valid in an identifier. Note that it simply blindly consumes
--- characters and does no actual validation itself.
-parseValid :: Parser String
-parseValid = p some
-  where
-    idChar = Parsec.satisfy (\c -> isAlphaNum c || isSymbolChar c || c == '_')
-
-    p p' = do
-      vs <- p' idChar
-      c <- peekChar'
-      case c of
-        '`' -> return vs
-        '\'' -> choice' [ (\x -> vs ++ "'" ++ x) <$> ("'" *> p many), return vs ]
-        _ -> fail "outofvalid"
-
--- | Parses identifiers with help of 'parseValid'. Asks GHC for
--- 'String' from the string it deems valid.
+-- | Parses identifiers with help of 'parseValid'.
 identifier :: Parser (DocH mod Identifier)
-identifier = do
-  o <- idDelim
-  vid <- parseValid
-  e <- idDelim
-  return $ DocIdentifier (o, vid, e)
-  where
-    idDelim = Parsec.satisfy (\c -> c == '\'' || c == '`')
+identifier = DocIdentifier <$> parseValid
diff --git a/haddock-library/src/Documentation/Haddock/Parser/Identifier.hs b/haddock-library/src/Documentation/Haddock/Parser/Identifier.hs
new file mode 100644
index 00000000..b8afb951
--- /dev/null
+++ b/haddock-library/src/Documentation/Haddock/Parser/Identifier.hs
@@ -0,0 +1,160 @@
+{-# LANGUAGE BangPatterns #-}
+{-# LANGUAGE ViewPatterns #-}
+-- |
+-- Module      :  Documentation.Haddock.Parser.Identifier
+-- Copyright   :  (c) Alec Theriault 2019,
+-- License     :  BSD-like
+--
+-- Maintainer  :  haddock@projects.haskell.org
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Functionality for parsing identifiers and operators
+
+module Documentation.Haddock.Parser.Identifier (
+  Identifier(..),
+  parseValid,
+) where
+
+import Documentation.Haddock.Types           ( Namespace(..) )
+import Documentation.Haddock.Parser.Monad
+import qualified Text.Parsec as Parsec
+import           Text.Parsec.Pos             ( updatePosChar )
+import           Text.Parsec                 ( State(..)
+                                             , getParserState, setParserState )
+
+import Data.Text (Text)
+import qualified Data.Text as T
+
+import           Data.Char (isAlpha, isAlphaNum)
+import Control.Monad (guard)
+import Data.Maybe
+import CompatPrelude
+
+-- | Identifier string surrounded with namespace, opening, and closing quotes/backticks.
+data Identifier = Identifier !Namespace !Char String !Char
+  deriving (Show, Eq)
+
+parseValid :: Parser Identifier
+parseValid = do
+  s@State{ stateInput = inp, statePos = pos } <- getParserState
+
+  case takeIdentifier inp of
+    Nothing -> Parsec.parserFail "parseValid: Failed to match a valid identifier"
+    Just (ns, op, ident, cl, inp') ->
+      let posOp = updatePosChar pos op
+          posIdent = T.foldl updatePosChar posOp ident
+          posCl = updatePosChar posIdent cl
+          s' = s{ stateInput = inp', statePos = posCl }
+      in setParserState s' $> Identifier ns op (T.unpack ident) cl
+
+
+-- | Try to parse a delimited identifier off the front of the given input.
+--
+-- This tries to match as many valid Haskell identifiers/operators as possible,
+-- to the point of sometimes accepting invalid things (ex: keywords). Some
+-- considerations:
+--
+--   - operators and identifiers can have module qualifications
+--   - operators can be wrapped in parens (for prefix)
+--   - identifiers can be wrapped in backticks (for infix)
+--   - delimiters are backticks or regular ticks
+--   - since regular ticks are also valid in identifiers, we opt for the
+--     longest successful parse
+--
+-- This function should make /O(1)/ allocations
+takeIdentifier :: Text -> Maybe (Namespace, Char, Text, Char, Text)
+takeIdentifier input = listToMaybe $ do
+
+    -- Optional namespace
+    let (ns, input') = case T.uncons input of
+                         Just ('v', i) -> (Value, i)
+                         Just ('t', i) -> (Type, i)
+                         _             -> (None, input)
+
+    -- Opening tick
+    (op, input'') <- maybeToList (T.uncons input')
+    guard (op == '\'' || op == '`')
+
+    -- Identifier/operator
+    (ident, input''') <- wrapped input''
+
+    -- Closing tick
+    (cl, input'''') <- maybeToList (T.uncons input''')
+    guard (cl == '\'' || cl == '`')
+
+    return (ns, op, ident, cl, input'''')
+
+  where
+
+    -- | Parse out a wrapped, possibly qualified, operator or identifier
+    wrapped t = do
+      (c, t'  ) <- maybeToList (T.uncons t)
+      -- Tuples
+      case c of
+        '(' | Just (c', _) <- T.uncons t'
+            , c' == ',' || c' == ')'
+            -> do let (commas, t'') = T.span (== ',') t'
+                  (')', t''') <- maybeToList (T.uncons t'')
+                  return (T.take (T.length commas + 2) t, t''')
+
+        -- Parenthesized
+        '(' -> do (n,   t'' ) <- general False 0 [] t'
+                  (')', t''') <- maybeToList (T.uncons t'')
+                  return (T.take (n + 2) t, t''')
+
+        -- Backticked
+        '`' -> do (n,   t'' ) <- general False 0 [] t'
+                  ('`', t''') <- maybeToList (T.uncons t'')
+                  return (T.take (n + 2) t, t''')
+
+        -- Unadorned
+        _   -> do (n,   t'' ) <- general False 0 [] t
+                  return (T.take n t, t'')
+
+    -- | Parse out a possibly qualified operator or identifier
+    general :: Bool           -- ^ refuse inputs starting with operators
+            -> Int            -- ^ total characters \"consumed\" so far
+            -> [(Int, Text)]  -- ^ accumulated results
+            -> Text           -- ^ current input
+            -> [(Int, Text)]  -- ^ total characters parsed & what remains
+    general !identOnly !i acc t
+      -- Starts with an identifier (either just an identifier, or a module qual)
+      | Just (n, rest) <- identLike t
+      = if T.null rest
+          then acc
+          else case T.head rest of
+                 '`' -> (n + i, rest) : acc
+                 ')' -> (n + i, rest) : acc
+                 '.' -> general False (n + i + 1) acc (T.tail rest)
+                 '\'' -> let (m, rest') = quotes rest
+                         in general True (n + m + 1 + i) ((n + m + i, rest') : acc) (T.tail rest')
+                 _ -> acc
+
+      -- An operator
+      | Just (n, rest) <- optr t
+      , not identOnly
+      = (n + i, rest) : acc
+
+      -- Anything else
+      | otherwise
+      = acc
+
+    -- | Parse an identifier off the front of the input
+    identLike t
+      | T.null t = Nothing
+      | isAlpha (T.head t) || '_' == T.head t
+      = let !(idt, rest) = T.span (\c -> isAlphaNum c || c == '_') t
+            !(octos, rest') = T.span (== '#') rest
+      in Just (T.length idt + T.length octos, rest')
+      | otherwise = Nothing
+
+    -- | Parse all but the last quote off the front of the input
+    -- PRECONDITION: T.head t == '\''
+    quotes :: Text -> (Int, Text)
+    quotes t = let !n = T.length (T.takeWhile (== '\'') t) - 1
+               in (n, T.drop n t)
+
+    -- | Parse an operator off the front of the input
+    optr t = let !(op, rest) = T.span isSymbolChar t
+             in if T.null op then Nothing else Just (T.length op, rest)
diff --git a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
index 8f5bd217..7c73a168 100644
--- a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
+++ b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
@@ -4,6 +4,18 @@
 {-# LANGUAGE TypeFamilies #-}
 {-# LANGUAGE BangPatterns #-}
 {-# LANGUAGE TypeSynonymInstances #-}
+-- |
+-- Module      :  Documentation.Haddock.Parser.Monad
+-- Copyright   :  (c) Alec Theriault 2018-2019,
+-- License     :  BSD-like
+--
+-- Maintainer  :  haddock@projects.haskell.org
+-- Stability   :  experimental
+-- Portability :  portable
+--
+-- Defines the Parsec monad over which all parsing is done and also provides
+-- more efficient versions of the usual parsec combinator functions (but
+-- specialized to 'Text').
 
 module Documentation.Haddock.Parser.Monad where
 
@@ -17,7 +29,6 @@ import qualified Data.Text as T
 import           Data.Text                   ( Text )
 
 import           Control.Monad               ( mfilter )
-import           Data.Functor                ( ($>) )
 import           Data.String                 ( IsString(..) )
 import           Data.Bits                   ( Bits(..) )
 import           Data.Char                   ( ord )
@@ -25,7 +36,9 @@ import           Data.List                   ( foldl' )
 import           Control.Applicative as App
 
 import           Documentation.Haddock.Types ( Version )
+
 import           Prelude hiding (takeWhile)
+import           CompatPrelude
 
 -- | The only bit of information we really care about truding along with us
 -- through parsing is the version attached to a @\@since@ annotation - if
@@ -96,7 +109,6 @@ takeWhile f = do
       s' = s{ stateInput = inp', statePos = pos' }
   setParserState s' $> t
 
-
 -- | Like 'takeWhile', but fails if no characters matched.
 --
 -- Equivalent to @fmap T.pack . Parsec.many1@, but more efficient.
diff --git a/haddock-library/src/Documentation/Haddock/Types.hs b/haddock-library/src/Documentation/Haddock/Types.hs
index f8f7d353..4cf61fee 100644
--- a/haddock-library/src/Documentation/Haddock/Types.hs
+++ b/haddock-library/src/Documentation/Haddock/Types.hs
@@ -44,14 +44,17 @@ data MetaDoc mod id =
           } deriving (Eq, Show, Functor, Foldable, Traversable)
 
 #if MIN_VERSION_base(4,8,0)
+-- | __NOTE__: Only defined for @base >= 4.8.0@
 instance Bifunctor MetaDoc where
   bimap f g (MetaDoc m d) = MetaDoc m (bimap f g d)
 #endif
 
 #if MIN_VERSION_base(4,10,0)
+-- | __NOTE__: Only defined for @base >= 4.10.0@
 instance Bifoldable MetaDoc where
   bifoldr f g z d = bifoldr f g z (_doc d)
 
+-- | __NOTE__: Only defined for @base >= 4.10.0@
 instance Bitraversable MetaDoc where
   bitraverse f g (MetaDoc m d) = MetaDoc m <$> bitraverse f g d
 #endif
@@ -131,6 +134,7 @@ data DocH mod id
   deriving (Eq, Show, Functor, Foldable, Traversable)
 
 #if MIN_VERSION_base(4,8,0)
+-- | __NOTE__: Only defined for @base >= 4.8.0@
 instance Bifunctor DocH where
   bimap _ _ DocEmpty = DocEmpty
   bimap f g (DocAppend docA docB) = DocAppend (bimap f g docA) (bimap f g docB)
@@ -159,6 +163,7 @@ instance Bifunctor DocH where
 #endif
 
 #if MIN_VERSION_base(4,10,0)
+-- | __NOTE__: Only defined for @base >= 4.10.0@
 instance Bifoldable DocH where
   bifoldr f g z (DocAppend docA docB) = bifoldr f g (bifoldr f g z docA) docB
   bifoldr f g z (DocParagraph doc) = bifoldr f g z doc
@@ -176,6 +181,7 @@ instance Bifoldable DocH where
   bifoldr f g z (DocTable (Table header body)) = foldr (\r acc -> foldr (flip (bifoldr f g)) acc r) (foldr (\r acc -> foldr (flip (bifoldr f g)) acc r) z body) header
   bifoldr _ _ z _ = z
 
+-- | __NOTE__: Only defined for @base >= 4.10.0@
 instance Bitraversable DocH where
   bitraverse _ _ DocEmpty = pure DocEmpty
   bitraverse f g (DocAppend docA docB) = DocAppend <$> bitraverse f g docA <*> bitraverse f g docB
@@ -203,6 +209,16 @@ instance Bitraversable DocH where
   bitraverse f g (DocTable (Table header body)) = (\h b -> DocTable (Table h b)) <$> traverse (traverse (bitraverse f g)) header <*> traverse (traverse (bitraverse f g)) body
 #endif
 
+-- | The namespace qualification for an identifier.
+data Namespace = Value | Type | None deriving (Eq, Ord, Enum, Show)
+
+-- | Render the a namespace into the same format it was initially parsed.
+renderNs :: Namespace -> String
+renderNs Value = "v"
+renderNs Type = "t"
+renderNs None = ""
+
+
 -- | 'DocMarkupH' is a set of instructions for marking up documentation.
 -- In fact, it's really just a mapping from 'Doc' to some other
 -- type [a], where [a] is usually the type of the output (HTML, say).
diff --git a/haddock-library/test/Documentation/Haddock/ParserSpec.hs b/haddock-library/test/Documentation/Haddock/ParserSpec.hs
index 6269184a..bc40a0a2 100644
--- a/haddock-library/test/Documentation/Haddock/ParserSpec.hs
+++ b/haddock-library/test/Documentation/Haddock/ParserSpec.hs
@@ -112,7 +112,7 @@ spec = do
         "``" `shouldParseTo` "``"
 
       it "can parse an identifier in infix notation enclosed within backticks" $ do
-        "``infix``" `shouldParseTo` "`" <> DocIdentifier "infix" <> "`"
+        "``infix``" `shouldParseTo` DocIdentifier "`infix`"
 
       it "can parse identifiers containing a single quote" $ do
         "'don't'" `shouldParseTo` DocIdentifier "don't"
@@ -132,6 +132,19 @@ spec = do
       it "can parse an identifier that starts with an underscore" $ do
         "'_x'" `shouldParseTo` DocIdentifier "_x"
 
+      it "can parse value-namespaced identifiers" $ do
+        "v'foo'" `shouldParseTo` DocIdentifier "foo"
+
+      it "can parse type-namespaced identifiers" $ do
+        "t'foo'" `shouldParseTo` DocIdentifier "foo"
+
+      it "can parse parenthesized operators and backticked identifiers" $ do
+        "'(<|>)'" `shouldParseTo` DocIdentifier "(<|>)"
+        "'`elem`'" `shouldParseTo` DocIdentifier "`elem`"
+
+      it "can properly figure out the end of identifiers" $ do
+        "'DbModule'/'DbUnitId'" `shouldParseTo` DocIdentifier "DbModule" <> "/" <> DocIdentifier "DbUnitId"
+
     context "when parsing operators" $ do
       it "can parse an operator enclosed within single quotes" $ do
         "'.='" `shouldParseTo` DocIdentifier ".="