Remove workaround for now-fixed Clang CPP bug (#1028)

Before LLVM 6.0.1 (or 10.0 on Apple LLVM), there was a bug where
lines that started with an octothorpe but turned out not
to lex like pragmas would have an extra line added after them.

Since this bug has been fixed upstream and that it doesn't have dire
consequences anyways, the workaround is not really worth it
anymore - we can just tell people to update their clang version (or re-structure
their pragma code).

2 files changed, 3 insertions, 48 deletions

diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker.hs b/haddock-api/src/Haddock/Backends/Hyperlinker.hs
index 5ef7d9bb..251c886b 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker.hs
@@ -25,7 +25,6 @@ import FastString     ( mkFastString )
 import Module         ( Module, moduleName )
 import NameCache      ( initNameCache )
 import UniqSupply     ( mkSplitUniqSupply )
-import SysTools.Info  ( getCompilerInfo' )
 
 
 -- | Generate hyperlinked source for given interfaces.
@@ -62,12 +61,11 @@ ppHyperlinkedModuleSource srcdir pretty srcs iface = case ifaceHieFile iface of
                 , hie_types = types
                 , hie_hs_src = rawSrc
                 } <- fmap fst (readHieFile (initNameCache u []) hfp)
-        comp <- getCompilerInfo' df
 
         -- Get the AST and tokens corresponding to the source file we want
         let mast | M.size asts == 1 = snd <$> M.lookupMin asts
                  | otherwise        = M.lookup (mkFastString file) asts
-            tokens = parse comp df file rawSrc
+            tokens = parse df file rawSrc
 
         -- Produce and write out the hyperlinked sources
         case mast of
diff --git a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
index 1d5576cc..0bd467e1 100644
--- a/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
+++ b/haddock-api/src/Haddock/Backends/Hyperlinker/Parser.hs
@@ -6,13 +6,9 @@ import Control.Applicative ( Alternative(..) )
 import Data.List           ( isPrefixOf, isSuffixOf )
 
 import qualified Data.ByteString as BS
-import qualified Data.ByteString.Char8 as BSC
-
-import GHC.LanguageExtensions.Type
 
 import BasicTypes          ( IntegralLit(..) )
 import DynFlags
-import qualified EnumSet as E
 import ErrUtils            ( emptyMessages )
 import FastString          ( mkFastString )
 import Lexer               ( P(..), ParseResult(..), PState(..), Token(..)
@@ -29,12 +25,11 @@ import Haddock.GhcUtils
 -- Result should retain original file layout (including comments,
 -- whitespace, and CPP).
 parse
-  :: CompilerInfo  -- ^ Underlying CC compiler (whatever expanded CPP)
-  -> DynFlags      -- ^ Flags for this module
+  :: DynFlags      -- ^ Flags for this module
   -> FilePath      -- ^ Path to the source of this module
   -> BS.ByteString -- ^ Raw UTF-8 encoded source of this module
   -> [T.Token]
-parse comp dflags fpath bs = case unP (go False []) initState of
+parse dflags fpath bs = case unP (go False []) initState of
     POk _ toks -> reverse toks
     PFailed _ ss errMsg -> panic $ "Hyperlinker parse error at " ++ show ss ++
                                    ": " ++ showSDoc dflags errMsg
@@ -43,7 +38,6 @@ parse comp dflags fpath bs = case unP (go False []) initState of
     initState = mkPStatePure pflags buf start
     buf = stringBufferFromByteString bs
     start = mkRealSrcLoc (mkFastString fpath) 1 1
-    needPragHack' = needPragHack comp dflags
     pflags = mkParserFlags' (warningFlags dflags)
                             (extensionFlags dflags)
                             (thisPackage dflags)
@@ -125,12 +119,6 @@ parse comp dflags fpath bs = case unP (go False []) initState of
 
               pure (bEnd'', False)
 
-            -- See 'needPragHack'
-            ITclose_prag{}
-              | needPragHack'
-              , '\n' `BSC.elem` spaceBStr
-              -> getInput >>= \(b,p) -> setInput (b,advanceSrcLoc p '\n') >> pure (bEnd, False)
-
             _ -> pure (bEnd, inPragDef)
 
           let tokBStr = splitStringBuffer bStart bEnd'
@@ -155,37 +143,6 @@ parse comp dflags fpath bs = case unP (go False []) initState of
       pure ([unkTok], False)
 
 
--- | This is really, really, /really/ gross. Problem: consider a Haskell
--- file that looks like:
---
--- @
--- {-# LANGUAGE CPP #-}
--- module SomeMod where
---
--- #define SIX 6
---
--- {-# INLINE foo
---   #-}
--- foo = 1
--- @
---
--- Clang's CPP replaces the @#define SIX 6@ line with an empty line (as it
--- should), but get confused about @#-}@. I'm guessing it /starts/ by
--- parsing that as a pre-processor directive and, when it fails to, it just
--- leaves the line alone. HOWEVER, it still adds an extra newline. =.=
---
--- This function makes sure that the Hyperlinker backend also adds that
--- extra newline (or else our spans won't line up with GHC's anymore).
-needPragHack :: CompilerInfo -> DynFlags -> Bool
-needPragHack comp dflags = isCcClang && E.member Cpp (extensionFlags dflags)
-  where
-    isCcClang = case comp of
-      GCC -> False
-      Clang -> True
-      AppleClang -> True
-      AppleClang51 -> True
-      UnknownCC -> False
-
 -- | Get the input
 getInput :: P (StringBuffer, RealSrcLoc)
 getInput = P $ \p @ PState { buffer = buf, loc = srcLoc } -> POk p (buf, srcLoc)