Only special case struct fields for intra-doc links, not enum variants

Variants are already handled by `resolve_str_path_error`, rustdoc doesn't need to consider them separately.

Author: jyn514

src/librustdoc/passes/collect_intra_doc_links.rs

@@ -643,28 +643,22 @@ impl<'a, 'tcx> LinkCollector<'a, 'tcx> {
                 if ns != Namespace::ValueNS {
                     return None;
                 }
-                debug!("looking for variants or fields named {} for {:?}", item_name, did);
+                debug!("looking for fields named {} for {:?}", item_name, did);
                 // FIXME: this doesn't really belong in `associated_item` (maybe `variant_field` is better?)
-                // NOTE: it's different from variant_field because it resolves fields and variants,
+                // NOTE: it's different from variant_field because it only resolves struct fields,
                 // not variant fields (2 path segments, not 3).
                 let def = match tcx.type_of(did).kind() {
-                    ty::Adt(def, _) => def,
+                    ty::Adt(def, _) if !def.is_enum() => def,
                     _ => return None,
                 };
-                let field = if def.is_enum() {
-                    def.all_fields().find(|item| item.ident.name == item_name)
-                } else {
-                    def.non_enum_variant().fields.iter().find(|item| item.ident.name == item_name)
-                }?;
-                let kind = if def.is_enum() { DefKind::Variant } else { DefKind::Field };
+                let field = def.non_enum_variant().fields.iter().find(|item| item.ident.name == item_name)?;
                 Some((
                     root_res,
                     format!(
-                        "{}.{}",
-                        if def.is_enum() { "variant" } else { "structfield" },
+                        "structfield.{}",
                         field.ident
                     ),
-                    Some((kind, field.did)),
+                    Some((DefKind::Field, field.did)),
                 ))
             }
             Res::Def(DefKind::Trait, did) => tcx