Fixed deriving of associated data types

[ghc-hetmet.git] / compiler / typecheck / TcInstDcls.lhs

diff --git a/compiler/typecheck/TcInstDcls.lhs b/compiler/typecheck/TcInstDcls.lhs
index 0dbb775..d314e1e 100644 (file)
--- a/compiler/typecheck/TcInstDcls.lhs
+++ b/compiler/typecheck/TcInstDcls.lhs
@@ -179,7 +179,10 @@ tcInstDecls1 tycl_decls inst_decls deriv_decls
                -- (4) Compute instances from "deriving" clauses; 
                -- This stuff computes a context for the derived instance
                -- decl, so it needs to know about all the instances possible
-       ; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls deriv_decls
+                -- NB: class instance declarations can contain derivings as
+                --     part of associated data type declarations
+       ; (deriv_inst_info, deriv_binds) <- tcDeriving tycl_decls inst_decls 
+                                                      deriv_decls
        ; addInsts deriv_inst_info   $ do {
 
        ; gbl_env <- getGblEnv