Add a panic for lookupPred EqPred

It's possible that returning Nothing was the right thing to do here,
but the comment and variable name indicated that it was written for
implicit parameters, so make it a panic for now just in case.

diff --git a/compiler/typecheck/Inst.lhs b/compiler/typecheck/Inst.lhs
index be7c14a..560bf4b 100644 (file)
--- a/compiler/typecheck/Inst.lhs
+++ b/compiler/typecheck/Inst.lhs
@@ -832,7 +832,8 @@ lookupPred pred@(ClassP clas tys)
                        ; return Nothing }
        }}
 
-lookupPred ip_pred = return Nothing    -- Implicit parameters
+lookupPred (IParam {}) = return Nothing        -- Implicit parameters
+lookupPred (EqPred {}) = panic "lookupPred EqPred"
 
 record_dfun_usage dfun_id 
   = do { hsc_env <- getTopEnv