fix clippy::toplevel_ref_arg and ::manual_map

compiler/rustc_ty_utils/src/structural_match.rs

@@ -13,7 +13,7 @@ use rustc_trait_selection::traits::{ObligationCause, ObligationCtxt};
 /// Note that this does *not* recursively check if the substructure of `adt_ty`
 /// implements the traits.
 fn has_structural_eq_impls<'tcx>(tcx: TyCtxt<'tcx>, adt_ty: Ty<'tcx>) -> bool {
-    let ref infcx = tcx.infer_ctxt().build();
+    let infcx = &tcx.infer_ctxt().build();
     let cause = ObligationCause::dummy();
 
     let ocx = ObligationCtxt::new(infcx);