[project @ 2000-09-14 08:17:54 by simonpj]

Fix bug in the driver that led to

	Fail: system error
	Action: getFileStatus

It was due to Simon M's recent addition of modification-time
checking.  You forgot to check whether the file M.o existed!

diff --git a/ghc/driver/Main.hs b/ghc/driver/Main.hs
index b93b0ec..a393134 100644 (file)
--- a/ghc/driver/Main.hs
+++ b/ghc/driver/Main.hs
@@ -1,6 +1,6 @@
 {-# OPTIONS -W -fno-warn-incomplete-patterns #-}
 -----------------------------------------------------------------------------
--- $Id: Main.hs,v 1.58 2000/09/12 13:19:20 simonmar Exp $
+-- $Id: Main.hs,v 1.59 2000/09/14 08:17:54 simonpj Exp $
 --
 -- GHC Driver program
 --
@@ -507,7 +507,6 @@ hsc_minusO_flags = do
                "-fmax-simplifier-iterations2",
          "]",
 
-
        "-fsimplify",
          "[", 
                "-fmax-simplifier-iterations2",
@@ -1770,17 +1769,26 @@ run_phase Hsc   basename suff input_fn output_fn
   -- figure out if the source has changed, for recompilation avoidance.
   -- only do this if we're eventually going to generate a .o file.
   -- (ToDo: do when generating .hc files too?)
+  --
+  -- Setting source_unchanged to "-fsource_unchanged" means that M.o seems
+  -- to be up to date wrt M.hs; so no need to recompile unless imports have
+  -- changed (which the compiler itself figures out).
+  -- Setting source_unchanged to "" tells the compiler that M.o is out of
+  -- date wrt M.hs (or M.o doesn't exist) so we must recompile regardless.
        do_recomp <- readIORef recomp
        todo <- readIORef v_todo
        source_unchanged <- 
-          if do_recomp && ( todo == DoLink || todo == StopBefore Ln )
-            then do t1 <- getModificationTime (basename ++ '.':suff)
+          if not (do_recomp && ( todo == DoLink || todo == StopBefore Ln ))
+            then return ""
+            else do t1 <- getModificationTime (basename ++ '.':suff)
                     o_file <- odir_ify (basename ++ '.':phase_input_ext Ln)
-                    t2 <- getModificationTime o_file
-                    if t2 > t1
-                       then return "-fsource-unchanged"
-                       else return ""
-            else return ""
+                    o_file_exists <- doesFileExist o_file
+                    if not o_file_exists
+                       then return ""  -- Need to recompile
+                       else do t2 <- getModificationTime o_file
+                               if t2 > t1
+                                 then return "-fsource-unchanged"
+                                 else return ""
 
   -- run the compiler!
        run_something "Haskell Compiler"