Don't start a GHC session before answering --version/--numeric-version

This also fixes bootstrapping issues, as when bootstrapping we don't
have a package.conf when we run configure, so it fails to work out
what version of GHC it is which causes breakage later on.

diff --git a/compiler/main/Main.hs b/compiler/main/Main.hs
index 09d8185..758451f 100644 (file)
--- a/compiler/main/Main.hs
+++ b/compiler/main/Main.hs
@@ -78,6 +78,18 @@ main =
   -- 2. Parse the "mode" flags (--make, --interactive etc.)
   (cli_mode, argv3) <- parseModeFlags argv2
 
+  -- If all we want to do is to show the version number then do it
+  -- now, before we start a GHC session etc.
+  -- If we do it later then bootstrapping gets confused as it tries
+  -- to find out what version of GHC it's using before package.conf
+  -- exists, so starting the session fails.
+  case cli_mode of
+    ShowVersion     -> do showVersion
+                          exitWith ExitSuccess
+    ShowNumVersion  -> do putStrLn cProjectVersion
+                          exitWith ExitSuccess
+    _               -> return ()
+
   let mode = case cli_mode of
                DoInteractive   -> Interactive
                DoEval _        -> Interactive
@@ -145,16 +157,16 @@ main =
 
        ---------------- Do the business -----------
   case cli_mode of
-       ShowUsage       -> showGhcUsage dflags cli_mode
-       PrintLibdir     -> putStrLn (topDir dflags)
-       ShowVersion     -> showVersion
-        ShowNumVersion  -> putStrLn cProjectVersion
-        ShowInterface f -> doShowIface dflags f
-       DoMake          -> doMake session srcs
-       DoMkDependHS    -> doMkDependHS session (map fst srcs)
-       StopBefore p    -> oneShot dflags p srcs
-       DoInteractive   -> interactiveUI session srcs Nothing
-       DoEval expr     -> interactiveUI session srcs (Just expr)
+    ShowUsage       -> showGhcUsage dflags cli_mode
+    PrintLibdir     -> putStrLn (topDir dflags)
+    ShowVersion     -> panic "ShowVersion should already have been handled"
+    ShowNumVersion  -> panic "ShowNumVersion should already have been handled"
+    ShowInterface f -> doShowIface dflags f
+    DoMake          -> doMake session srcs
+    DoMkDependHS    -> doMkDependHS session (map fst srcs)
+    StopBefore p    -> oneShot dflags p srcs
+    DoInteractive   -> interactiveUI session srcs Nothing
+    DoEval expr     -> interactiveUI session srcs (Just expr)
 
   dumpFinalStats dflags
   exitWith ExitSuccess