hi haddock: Lex and store haddock docs in interface files

Names appearing in Haddock docstrings are lexed and renamed like any other names
appearing in the AST. We currently rename names irrespective of the namespace,
so both type and constructor names corresponding to an identifier will appear in
the docstring. Haddock will select a given name as the link destination based on
its own heuristics.

This patch also restricts the limitation of `-haddock` being incompatible with
`Opt_KeepRawTokenStream`.

The export and documenation structure is now computed in GHC and serialised in
.hi files. This can be used by haddock to directly generate doc pages without
reparsing or renaming the source. At the moment the operation of haddock
is not modified, that's left to a future patch.

Updates the haddock submodule with the minimum changes needed.

1 files changed, 14 insertions, 0 deletions

diff --git a/compiler/GHC/Data/StringBuffer.hs b/compiler/GHC/Data/StringBuffer.hs
index 03d720eb37..e6dcb14b6b 100644
--- a/compiler/GHC/Data/StringBuffer.hs
+++ b/compiler/GHC/Data/StringBuffer.hs
@@ -26,6 +26,7 @@ module GHC.Data.StringBuffer
         hPutStringBuffer,
         appendStringBuffers,
         stringToStringBuffer,
+        stringBufferFromByteString,
 
         -- * Inspection
         nextChar,
@@ -68,6 +69,10 @@ import System.IO.Unsafe         ( unsafePerformIO )
 import GHC.IO.Encoding.UTF8     ( mkUTF8 )
 import GHC.IO.Encoding.Failure  ( CodingFailureMode(IgnoreCodingFailure) )
 
+import qualified Data.ByteString.Internal as BS
+import qualified Data.ByteString as BS
+import Data.ByteString ( ByteString )
+
 import GHC.Exts
 
 import Foreign
@@ -199,6 +204,15 @@ stringToStringBuffer str =
     -- sentinels for UTF-8 decoding
   return (StringBuffer buf size 0)
 
+-- | Convert a UTF-8 encoded 'ByteString' into a 'StringBuffer. This really
+-- relies on the internals of both 'ByteString' and 'StringBuffer'.
+--
+-- /O(n)/ (but optimized into a @memcpy@ by @bytestring@ under the hood)
+stringBufferFromByteString :: ByteString -> StringBuffer
+stringBufferFromByteString bs =
+  let BS.PS fp off len = BS.append bs (BS.pack [0,0,0])
+  in StringBuffer { buf = fp, len = len - 3, cur = off }
+
 -- -----------------------------------------------------------------------------
 -- Grab a character