more improvements for #1119

When GHCi compiles its code framgents for setting buffering, it wants
to refer to base:System.IO rather than whatever System.IO is on the
search path, unfortunately there's no way to do this in source code,
so to hack around it we set the search path to empty before compiling
these expressions (not forgetting to flush the finder cache
afterward).

diff --git a/compiler/ghci/GhciMonad.hs b/compiler/ghci/GhciMonad.hs
index 63c2af7..eaea844 100644 (file)
--- a/compiler/ghci/GhciMonad.hs
+++ b/compiler/ghci/GhciMonad.hs
@@ -16,6 +16,7 @@ import Breakpoints
 import Outputable
 import Panic hiding (showException)
 import Util
+import DynFlags
 
 import Numeric
 import Control.Exception as Exception
@@ -205,8 +206,14 @@ flush_cmd = command_sequence [flush_buffer "stdout", flush_buffer "stderr"]
 
 initInterpBuffering :: GHC.Session -> IO ()
 initInterpBuffering session
- = do maybe_hval <- GHC.compileExpr session no_buf_cmd
-       
+ = do -- we don't want to be fooled by any modules lying around in the current
+      -- directory when we compile these code fragments, so set the import
+      -- path to be empty while we compile them.
+      dflags <- GHC.getSessionDynFlags session
+      GHC.setSessionDynFlags session dflags{importPaths=[]}
+
+      maybe_hval <- GHC.compileExpr session no_buf_cmd
+
       case maybe_hval of
        Just hval -> writeIORef turn_off_buffering (unsafeCoerce# hval :: IO ())
        other     -> panic "interactiveUI:setBuffering"
@@ -216,6 +223,8 @@ initInterpBuffering session
        Just hval -> writeIORef flush_interp (unsafeCoerce# hval :: IO ())
        _         -> panic "interactiveUI:flush"
 
+      GHC.setSessionDynFlags session dflags
+      GHC.workingDirectoryChanged session
       return ()