Print a more helpful error for find_thing

diff --git a/compiler/typecheck/TcEnv.lhs b/compiler/typecheck/TcEnv.lhs
index 388828e..c5d65c2 100644 (file)
--- a/compiler/typecheck/TcEnv.lhs
+++ b/compiler/typecheck/TcEnv.lhs
@@ -390,6 +390,8 @@ find_thing ignore_it tidy_env (ATyVar tv ty)
        bound_at = parens $ ptext SLIT("bound at:") <+> ppr (getSrcLoc tv)
     in
     returnM (tidy_env1, Just msg)
+
+find_thing _ _ thing = pprPanic "find_thing" (ppr thing)
 \end{code}
 
 \begin{code}