ghc 8.10 compatibility (CPP optP) (#452)

Author: sheaf

src/Development/IDE/Core/Preprocessor.hs

@@ -166,18 +166,11 @@ runLhs dflags filename contents = withTempDir $ \dir -> do
     escape (c:cs)    = c : escape cs
     escape []        = []
 
-
-modifyOptP :: ([String] -> [String]) -> DynFlags -> DynFlags
-modifyOptP op = onSettings (onOptP op)
-  where
-    onSettings f x = x{settings = f $ settings x}
-    onOptP f x = x{sOpt_P = f $ sOpt_P x}
-
 -- | Run CPP on a file
 runCpp :: DynFlags -> FilePath -> Maybe SB.StringBuffer -> IO SB.StringBuffer
 runCpp dflags filename contents = withTempDir $ \dir -> do
     let out = dir </> takeFileName filename <.> "out"
-    dflags <- pure $ modifyOptP ("-D__GHCIDE__":) dflags
+    dflags <- pure $ addOptP "-D__GHCIDE__" dflags
 
     case contents of
         Nothing -> do

src/Development/IDE/GHC/CPP.hs

@@ -19,7 +19,8 @@
 --
 -----------------------------------------------------------------------------
 
-module Development.IDE.GHC.CPP(doCpp) where
+module Development.IDE.GHC.CPP(doCpp, addOptP)
+where
 
 import Development.IDE.GHC.Compat
 import Packages
@@ -33,6 +34,10 @@ import LlvmCodeGen (llvmVersionList)
 #elif MIN_GHC_API_VERSION(8,8,0)
 import LlvmCodeGen (LlvmVersion (..))
 #endif
+#if MIN_GHC_API_VERSION (8,10,0)
+import Fingerprint
+import ToolSettings
+#endif
 
 import System.Directory
 import System.FilePath
@@ -162,6 +167,22 @@ getBackendDefs dflags | hscTarget dflags == HscLlvm = do
 getBackendDefs _ =
     return []
 
+addOptP :: String -> DynFlags -> DynFlags
+#if MIN_GHC_API_VERSION (8,10,0)
+addOptP f = alterToolSettings $ \s -> s
+          { toolSettings_opt_P             = f : toolSettings_opt_P s
+          , toolSettings_opt_P_fingerprint = fingerprintStrings (f : toolSettings_opt_P s)
+          }
+  where
+    fingerprintStrings ss = fingerprintFingerprints $ map fingerprintString ss
+    alterToolSettings f dynFlags = dynFlags { toolSettings = f (toolSettings dynFlags) }
+#else
+addOptP opt = onSettings (onOptP (opt:))
+  where
+    onSettings f x = x{settings = f $ settings x}
+    onOptP f x = x{sOpt_P = f $ sOpt_P x}
+#endif
+
 -- ---------------------------------------------------------------------------
 -- Macros (cribbed from Cabal)