update the const in StatefulShellRouteData generation (#8502)

fixes：flutter/flutter#161305 
also fix some typos: statefull* -> stateful*

Author: hannah-hyj

packages/go_router_builder/CHANGELOG.md

@@ -1,3 +1,6 @@
+## 2.7.4
+
+- Fixes an issue by removing unnecessary `const` in StatefulShellRouteData generation.
 
 ## 2.7.3
 

packages/go_router_builder/lib/src/route_config.dart

@@ -118,7 +118,7 @@ class StatefulShellRouteConfig extends RouteBaseConfig {
   Iterable<String> classDeclarations() => <String>[
         '''
 extension $_extensionName on $_className {
-  static $_className _fromState(GoRouterState state) => const $_className();
+  static $_className _fromState(GoRouterState state) =>${routeDataClass.unnamedConstructor!.isConst ? ' const' : ''}   $_className();
 }
 '''
       ];

packages/go_router_builder/pubspec.yaml

@@ -2,7 +2,7 @@ name: go_router_builder
 description: >-
   A builder that supports generated strongly-typed route helpers for
   package:go_router
-version: 2.7.3
+version: 2.7.4
 repository: https://github.com/flutter/packages/tree/main/packages/go_router_builder
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+go_router_builder%22
 

packages/go_router_builder/test_inputs/statefull_shell_branch_data.dart renamed to packages/go_router_builder/test_inputs/stateful_shell_branch_data.dart

@@ -0,0 +1,25 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:go_router/go_router.dart';
+
+@TypedStatefulShellRoute<StatefulShellRouteNoConstConstructor>(
+  branches: <TypedStatefulShellBranch<StatefulShellBranchData>>[
+    TypedStatefulShellBranch<BranchAData>(),
+  ],
+)
+class StatefulShellRouteNoConstConstructor extends StatefulShellRouteData {}
+
+@TypedStatefulShellRoute<StatefulShellRouteWithConstConstructor>(
+  branches: <TypedStatefulShellBranch<StatefulShellBranchData>>[
+    TypedStatefulShellBranch<BranchAData>(),
+  ],
+)
+class StatefulShellRouteWithConstConstructor extends StatefulShellRouteData {
+  const StatefulShellRouteWithConstConstructor();
+}
+
+class BranchAData extends StatefulShellBranchData {
+  const BranchAData();
+}

packages/go_router_builder/test_inputs/statefull_shell_branch_data.dart.expect renamed to packages/go_router_builder/test_inputs/stateful_shell_branch_data.dart.expect

@@ -0,0 +1,28 @@
+RouteBase get $statefulShellRouteNoConstConstructor =>
+    StatefulShellRouteData.$route(
+      factory: $StatefulShellRouteNoConstConstructorExtension._fromState,
+      branches: [
+        StatefulShellBranchData.$branch(),
+      ],
+    );
+
+extension $StatefulShellRouteNoConstConstructorExtension
+    on StatefulShellRouteNoConstConstructor {
+  static StatefulShellRouteNoConstConstructor _fromState(GoRouterState state) =>
+      StatefulShellRouteNoConstConstructor();
+}
+
+RouteBase get $statefulShellRouteWithConstConstructor =>
+    StatefulShellRouteData.$route(
+      factory: $StatefulShellRouteWithConstConstructorExtension._fromState,
+      branches: [
+        StatefulShellBranchData.$branch(),
+      ],
+    );
+
+extension $StatefulShellRouteWithConstConstructorExtension
+    on StatefulShellRouteWithConstConstructor {
+  static StatefulShellRouteWithConstConstructor _fromState(
+          GoRouterState state) =>
+      const StatefulShellRouteWithConstConstructor();
+}