Remove static generation bail-out from usePathname (#42440)

x-ref: [slack
thread](https://vercel.slack.com/archives/C035J346QQL/p1667504961058549)

## Bug

- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Errors have a helpful link attached, see `contributing.md`

## Feature

- [ ] Implements an existing feature request or RFC. Make sure the
feature request has been accepted for implementation before opening a
PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have a helpful link attached, see `contributing.md`

## Documentation / Examples

- [ ] Make sure the linting passes by running `pnpm build && pnpm lint`
- [ ] The "examples guidelines" are followed from [our contributing
doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)

Author: ijjk

packages/next/client/components/navigation.ts

@@ -87,7 +87,6 @@ export function useSearchParams() {
  * Get the current pathname. For example usePathname() on /dashboard?foo=bar would return "/dashboard"
  */
 export function usePathname(): string | null {
-  staticGenerationBailout('usePathname')
   return useContext(PathnameContext)
 }
 

test/e2e/app-dir/app-static.test.ts

@@ -54,6 +54,8 @@ describe('app-dir static/dynamic handling', () => {
         'dynamic-no-gen-params-ssr/[slug]/page.js',
         'dynamic-no-gen-params/[slug]/page.js',
         'hooks/use-pathname/[slug]/page.js',
+        'hooks/use-pathname/slug.html',
+        'hooks/use-pathname/slug.rsc',
         'hooks/use-search-params/[slug]/page.js',
         'ssr-auto/cache-no-store/page.js',
         'ssr-auto/fetch-revalidate-zero/page.js',
@@ -114,6 +116,11 @@ describe('app-dir static/dynamic handling', () => {
           srcRoute: '/blog/[author]/[slug]',
           dataRoute: '/blog/styfle/second-post.rsc',
         },
+        '/hooks/use-pathname/slug': {
+          dataRoute: '/hooks/use-pathname/slug.rsc',
+          initialRevalidateSeconds: false,
+          srcRoute: '/hooks/use-pathname/[slug]',
+        },
       })
       expect(manifest.dynamicRoutes).toEqual({
         '/blog/[author]/[slug]': {
@@ -128,6 +135,12 @@ describe('app-dir static/dynamic handling', () => {
           fallback: false,
           routeRegex: normalizeRegEx('^\\/blog\\/([^\\/]+?)(?:\\/)?$'),
         },
+        '/hooks/use-pathname/[slug]': {
+          dataRoute: '/hooks/use-pathname/[slug].rsc',
+          dataRouteRegex: '^\\/hooks\\/use\\-pathname\\/([^\\/]+?)\\.rsc$',
+          fallback: null,
+          routeRegex: '^\\/hooks\\/use\\-pathname\\/([^\\/]+?)(?:\\/)?$',
+        },
       })
     })
   }
@@ -405,7 +418,8 @@ describe('app-dir static/dynamic handling', () => {
       }
     })
 
-    describe('usePathname', () => {
+    // TODO: needs updating as usePathname should not bail
+    describe.skip('usePathname', () => {
       if (isDev) {
         it('should bail out to client rendering during SSG', async () => {
           const res = await fetchViaHTTP(next.url, '/hooks/use-pathname/slug')