-rnMethodBinds cls sig_fn gen_tyvars binds
- = foldM do_one (emptyBag,emptyFVs) (bagToList binds)
- where do_one (binds,fvs) bind = do
- (bind', fvs_bind) <- rnMethodBind cls sig_fn gen_tyvars bind
- return (bind' `unionBags` binds, fvs_bind `plusFV` fvs)
+rnMethodBinds cls sig_fn binds
+ = do { checkDupRdrNames meth_names
+ -- Check that the same method is not given twice in the
+ -- same instance decl instance C T where
+ -- f x = ...
+ -- g y = ...
+ -- f x = ...
+ -- We must use checkDupRdrNames because the Name of the
+ -- method is the Name of the class selector, whose SrcSpan
+ -- points to the class declaration; and we use rnMethodBinds
+ -- for instance decls too
+
+ ; foldlM do_one (emptyBag, emptyFVs) (bagToList binds) }
+ where
+ meth_names = collectMethodBinders binds
+ do_one (binds,fvs) bind
+ = do { (bind', fvs_bind) <- rnMethodBind cls sig_fn bind
+ ; return (binds `unionBags` bind', fvs_bind `plusFV` fvs) }