Make a missing name in mkUsageInfo into a panic

We really want to know about this!

diff --git a/compiler/iface/MkIface.lhs b/compiler/iface/MkIface.lhs
index ce6f4a3..8849b1e 100644 (file)
--- a/compiler/iface/MkIface.lhs
+++ b/compiler/iface/MkIface.lhs
@@ -855,7 +855,7 @@ mk_usage_info pit hsc_env this_mod direct_imports used_names
         | isWiredInName name = mv_map  -- ignore wired-in names
         | otherwise
         = case nameModule_maybe name of
-             Nothing  -> pprTrace "mkUsageInfo: internal name?" (ppr name) mv_map
+             Nothing  -> pprPanic "mkUsageInfo: internal name?" (ppr name)
              Just mod -> -- We use this fiddly lambda function rather than
                          -- (++) as the argument to extendModuleEnv_C to
                          -- avoid quadratic behaviour (trac #2680)