Tidy the code that checks for type parameters in associated const paths.

Author: quantheory

src/librustc_typeck/check/mod.rs

@@ -3763,21 +3763,34 @@ pub fn resolve_ty_and_def_ufcs<'a, 'b, 'tcx>(fcx: &FnCtxt<'b, 'tcx>,
                                                         &'a [ast::PathSegment],
                                                         def::Def)>
 {
+
+    // Associated constants can't depend on generic types.
+    fn have_disallowed_generic_consts<'a, 'tcx>(fcx: &FnCtxt<'a, 'tcx>,
+                                                def: def::Def,
+                                                ty: Ty<'tcx>,
+                                                span: Span,
+                                                node_id: ast::NodeId) -> bool {
+        match def {
+            def::DefAssociatedConst(..) => {
+                if ty::type_has_params(ty) || ty::type_has_self(ty) {
+                    fcx.sess().span_err(span,
+                                        "Associated consts cannot depend \
+                                         on type parameters or Self.");
+                    fcx.write_error(node_id);
+                    return true;
+                }
+            }
+            _ => {}
+        }
+        false
+    }
+
     // If fully resolved already, we don't have to do anything.
     if path_res.depth == 0 {
-        // Associated constants can't depend on generic types.
         if let Some(ty) = opt_self_ty {
-            match path_res.full_def() {
-                def::DefAssociatedConst(..) => {
-                    if ty::type_has_params(ty) || ty::type_has_self(ty) {
-                        fcx.sess().span_err(span,
-                                            "Associated consts cannot depend \
-                                             on type parameters or Self.");
-                        fcx.write_error(node_id);
-                        return None;
-                    }
-                }
-                _ => {}
+            if have_disallowed_generic_consts(fcx, path_res.full_def(), ty,
+                                              span, node_id) {
+                return None;
             }
         }
         Some((opt_self_ty, &path.segments, path_res.base_def))
@@ -3795,18 +3808,8 @@ pub fn resolve_ty_and_def_ufcs<'a, 'b, 'tcx>(fcx: &FnCtxt<'b, 'tcx>,
         let item_name = item_segment.identifier.name;
         match method::resolve_ufcs(fcx, span, item_name, ty, node_id) {
             Ok((def, lp)) => {
-                // Associated constants can't depend on generic types.
-                match def {
-                    def::DefAssociatedConst(..) => {
-                        if ty::type_has_params(ty) || ty::type_has_self(ty) {
-                            fcx.sess().span_err(span,
-                                                "Associated consts cannot depend \
-                                                 on type parameters or Self.");
-                            fcx.write_error(node_id);
-                            return None;
-                        }
-                    }
-                    _ => {}
+                if have_disallowed_generic_consts(fcx, def, ty, span, node_id) {
+                    return None;
                 }
                 // Write back the new resolution.
                 fcx.ccx.tcx.def_map.borrow_mut()