If we are given -Werror, then pass -Werror to cpp

diff --git a/compiler/main/SysTools.lhs b/compiler/main/SysTools.lhs
index 88d42ee..71a721e 100644 (file)
--- a/compiler/main/SysTools.lhs
+++ b/compiler/main/SysTools.lhs
@@ -350,8 +350,11 @@ runCpp :: DynFlags -> [Option] -> IO ()
 runCpp dflags args =   do
   let (p,args0) = pgm_P dflags
       args1 = args0 ++ args
-  mb_env <- getGccEnv args1
-  runSomethingFiltered dflags id  "C pre-processor" p args1 mb_env
+      args2 = if dopt Opt_WarnIsError dflags
+              then Option "-Werror" : args1
+              else                    args1
+  mb_env <- getGccEnv args2
+  runSomethingFiltered dflags id  "C pre-processor" p args2 mb_env
 
 runPp :: DynFlags -> [Option] -> IO ()
 runPp dflags args =   do