Improve error message for non-matching file name

I changed the "File name does not match module name" error message so
that it prints out both the declared module name and the expected
module name (before, it was only printing the declared module name.)

diff --git a/compiler/main/GHC.hs b/compiler/main/GHC.hs
index bd6eee6..00a9339 100644 (file)
--- a/compiler/main/GHC.hs
+++ b/compiler/main/GHC.hs
@@ -1898,8 +1898,9 @@ summariseModule hsc_env old_summary_map is_boot (L loc wanted_mod) maybe_buf exc
 
        when (mod_name /= wanted_mod) $
                throwDyn $ mkPlainErrMsg mod_loc $ 
-                             text "file name does not match module name"
-                             <+> quotes (ppr mod_name)
+                             text "File name does not match module name:" 
+                             $$ text "Saw:" <+> quotes (ppr mod_name)
+                              $$ text "Expected:" <+> quotes (ppr wanted_mod)
 
                -- Find the object timestamp, and return the summary
        obj_timestamp <- getObjTimestamp location is_boot