fix(nuxt): keep route param optionality when sibling is an index (#5300)

packages/nuxt/src/pages/utils.ts

@@ -211,14 +211,6 @@ function prepareRoutes (routes: NuxtPage[], parent?: NuxtPage) {
       route.name = route.name.replace(/-index$/, '')
     }
 
-    if (route.path === '/') {
-      // Remove ? suffix when index page at same level
-      routes.forEach((siblingRoute) => {
-        if (siblingRoute.path.endsWith('?')) {
-          siblingRoute.path = siblingRoute.path.slice(0, -1)
-        }
-      })
-    }
     // Remove leading / if children route
     if (parent && route.path.startsWith('/')) {
       route.path = route.path.slice(1)

packages/nuxt/test/pages.test.ts

@@ -96,18 +96,32 @@ describe('pages:generateRoutesFromFiles', () => {
     {
       description: 'should generate correct dynamic routes',
       files: [
+          `${pagesDir}/index.vue`,
           `${pagesDir}/[slug].vue`,
           `${pagesDir}/[[foo]]`,
           `${pagesDir}/[[foo]]/index.vue`,
           `${pagesDir}/[bar]/index.vue`,
-          `${pagesDir}/sub/[slug].vue`,
+          `${pagesDir}/nonopt/[slug].vue`,
+          `${pagesDir}/opt/[[slug]].vue`,
           `${pagesDir}/[[sub]]/route-[slug].vue`
       ],
       output: [
         {
-          name: 'sub-slug',
+          name: 'index',
-          path: '/sub/:slug',
+          path: '/',
-          file: `${pagesDir}/sub/[slug].vue`,
+          file: `${pagesDir}/index.vue`,
+          children: []
+        },
+        {
+          name: 'nonopt-slug',
+          path: '/nonopt/:slug',
+          file: `${pagesDir}/nonopt/[slug].vue`,
+          children: []
+        },
+        {
+          name: 'opt-slug',
+          path: '/opt/:slug?',
+          file: `${pagesDir}/opt/[[slug]].vue`,
           children: []
         },
         {