Avoid unsafePerformIO for getProgName

getProgName was used to append the name of the program (e.g. "ghc") to
printed error messages in the Show instance of GhcException. It doesn't
belong here as GHCi and GHC API users may want to override this behavior
by setting a different error handler. So we now call it in the
defaultErrorHandler instead.

1 files changed, 8 insertions, 4 deletions

diff --git a/compiler/GHC.hs b/compiler/GHC.hs
index ea1293f2a8..b7dd7dfd35 100644
--- a/compiler/GHC.hs
+++ b/compiler/GHC.hs
@@ -420,7 +420,7 @@ import Control.Monad.Catch as MC
 
 import GHC.Data.Maybe
 import System.IO.Error  ( isDoesNotExistError )
-import System.Environment ( getEnv )
+import System.Environment ( getEnv, getProgName )
 import System.Directory
 import Data.List (isPrefixOf)
 
@@ -465,9 +465,13 @@ defaultErrorHandler fm (FlushOut flushOut) inner =
             (\ge -> liftIO $ do
                 flushOut
                 case ge of
-                     Signal _ -> exitWith (ExitFailure 1)
-                     _ -> do fm (show ge)
-                             exitWith (ExitFailure 1)
+                  Signal _       -> return ()
+                  ProgramError _ -> fm (show ge)
+                  CmdLineError _ -> fm ("<command line>: " ++ show ge)
+                  _              -> do
+                                    progName <- getProgName
+                                    fm (progName ++ ": " ++ show ge)
+                exitWith (ExitFailure 1)
             ) $
   inner