Use hie files as source of truth for name source spans.

Since we started reusing `.hi` files, this exposes a bug where definitions
aren't available since a bad source span from the `.hi` file gets put into
the NameCache. We rectify by ensuring the span in the NameCache always matches
the one from the `.hie` file.

This has surfaced because an interaction between the commit which uses `.hi`
instead of retypechecking and the change to use the shared global NameCache
to read `.hie` files.

src-ghc86/Development/IDE/GHC/HieBin.hs

@@ -339,7 +339,12 @@ fromHieName :: NameCache -> HieName -> (NameCache, Name)
 fromHieName nc (ExternalName mod occ span) =
     let cache = nsNames nc
     in case lookupOrigNameCache cache mod occ of
-         Just name -> (nc, name)
+         Just name
+           | nameSrcSpan name == span -> (nc, name)
+           | otherwise ->
+             let name' = setNameLoc name span
+                 new_cache = extendNameCache cache mod occ name'
+             in ( nc{ nsNames = new_cache }, name' )
          Nothing ->
            let (uniq, us) = takeUniqFromSupply (nsUniqs nc)
                name       = mkExternalName uniq mod occ span

src/Development/IDE/GHC/Compat.hs

@@ -52,9 +52,16 @@ module Development.IDE.GHC.Compat(
     upNameCache,
 
     module GHC,
+#if MIN_GHC_API_VERSION(8,6,0)
+
 #if MIN_GHC_API_VERSION(8,8,0)
     module HieTypes,
     module HieUtils,
+#else
+    module Development.IDE.GHC.HieTypes,
+    module Development.IDE.GHC.HieUtils,
+#endif
+
 #endif
     ) where
 
@@ -95,36 +102,34 @@ import FastString (FastString)
 
 #if MIN_GHC_API_VERSION(8,6,0)
 import Development.IDE.GHC.HieAst (mkHieFile)
-import Development.IDE.GHC.HieBin (readHieFile,writeHieFile,NameCacheUpdater(..),HieFileResult(..))
-#endif
-#if MIN_GHC_API_VERSION(8,10,0)
-import HscTypes (mi_mod_hash)
-#endif
+import Development.IDE.GHC.HieBin
 
 #if MIN_GHC_API_VERSION(8,8,0)
-import HscTypes (srcErrorMessages)
-import Control.Applicative ((<|>))
-import Development.IDE.GHC.HieAst (mkHieFile)
-import Development.IDE.GHC.HieBin
 import HieUtils
 import HieTypes
+#else
+import Development.IDE.GHC.HieUtils
+import Development.IDE.GHC.HieTypes
+import System.FilePath ((-<.>))
+#endif
 
+#endif
 
-import HieUtils
-
-#else
+#if !MIN_GHC_API_VERSION(8,8,0)
 
-import IfaceEnv
 #if MIN_GHC_API_VERSION(8,6,0)
+import GhcPlugins (srcErrorMessages)
+#else
 import System.IO.Error
-import Development.IDE.GHC.HieTypes
-import Development.IDE.GHC.HieUtils
-#endif
-
-import Control.Exception (catch)
+import IfaceEnv
+import Binary
 import Data.ByteString (ByteString)
 import GhcPlugins (Hsc, srcErrorMessages)
 import TcRnTypes
+import MkIface
+#endif
+
+import Control.Exception (catch)
 import System.IO
 import Foreign.ForeignPtr
 
@@ -136,6 +141,20 @@ hPutStringBuffer hdl (StringBuffer buf len cur)
 
 #endif
 
+#if MIN_GHC_API_VERSION(8,6,0)
+supportsHieFiles :: Bool
+supportsHieFiles = True
+
+hieExportNames :: HieFile -> [(SrcSpan, Name)]
+hieExportNames = nameListFromAvails . hie_exports
+
+#if !MIN_GHC_API_VERSION(8,8,0)
+ml_hie_file :: GHC.ModLocation -> FilePath
+ml_hie_file ml = ml_hi_file ml -<.> ".hie"
+#endif
+
+#endif
+
 upNameCache :: IORef NameCache -> (NameCache -> (NameCache, c)) -> IO c
 #if !MIN_GHC_API_VERSION(8,8,0)
 upNameCache ref upd_fn
@@ -275,11 +294,48 @@ nameListFromAvails :: [AvailInfo] -> [(SrcSpan, Name)]
 nameListFromAvails as =
   map (\n -> (nameSrcSpan n, n)) (concatMap availNames as)
 
-#if !MIN_GHC_API_VERSION(8,8,0)
+#if !MIN_GHC_API_VERSION(8,6,0)
 -- Reimplementations of functions for HIE files for GHC 8.6
 
+mkHieFile :: ModSummary -> TcGblEnv -> RenamedSource -> ByteString -> Hsc HieFile
+mkHieFile ms ts _ _ = return (HieFile (ms_mod ms) es)
+  where
+    es = nameListFromAvails (mkIfaceExports (tcg_exports ts))
+
 ml_hie_file :: GHC.ModLocation -> FilePath
 ml_hie_file ml = ml_hi_file ml ++ ".hie"
+
+data HieFile = HieFile {hie_module :: Module, hie_exports :: [(SrcSpan, Name)]}
+
+hieExportNames :: HieFile -> [(SrcSpan, Name)]
+hieExportNames = hie_exports
+
+instance Binary HieFile where
+  put_ bh (HieFile m es) = do
+    put_ bh m
+    put_ bh es
+
+  get bh = do
+    mod <- get bh
+    es <- get bh
+    return (HieFile mod es)
+
+data HieFileResult = HieFileResult { hie_file_result :: HieFile }
+
+writeHieFile :: FilePath -> HieFile -> IO ()
+readHieFile :: NameCacheUpdater -> FilePath -> IO HieFileResult
+supportsHieFiles :: Bool
+
+#if MIN_GHC_API_VERSION(8,4,0)
+
+supportsHieFiles = False
+
+writeHieFile _ _ = return ()
+
+readHieFile _ fp = ioError $ mkIOError doesNotExistErrorType "" Nothing (Just fp)
+
+#endif
+
 #endif
 
 getHeaderImports
@@ -330,11 +386,5 @@ getConArgs = GHC.getConArgs
 getConArgs = GHC.getConDetails
 #endif
 
-supportsHieFiles :: Bool
-supportsHieFiles = True
-
-hieExportNames :: HieFile -> [(SrcSpan, Name)]
-hieExportNames = nameListFromAvails . hie_exports
-
 getPackageName :: DynFlags -> Module.InstalledUnitId -> Maybe PackageName
 getPackageName dfs i = packageName <$> lookupPackage dfs (Module.DefiniteUnitId (Module.DefUnitId i))