[BUGFIX] Resolve page with trailing slash requested without one

With #89091 pages with slugs containing trailing slash have
been enabled to be resolved when requested with trailing
slash in the request uri and have been a logical follow-up
of #86055.

In between an issue with language fallback chain have been
found, which allowed that a valid translated page could be
resolved with the default language slug even and reported
as #88715 and #96010. These issues have been solved with
https://review.typo3.org/c/Packages/TYPO3.CMS/+/75101 which
partly broke the original implemented behaviour for pages
with trailing slash slugs requested without a trailing slash.

This change now ensures pages are resolved containing a trailing
slash in their "slug" like "/my-page/subpage/" if requested without
the trailing slash like "https://domain.tld/my-page/subpage".

Additionally, tests are added to cover this case along with
other possible cases. This should detect future regressions.

The docblock return annotation for `PageRouter::matchRequest()` is
changed to the correct returned value, removing ignore pattern for
the phpstan baseline instead of increasing the counter.

Note: This change ensures that a page can be resolved in any
      constellation with trailing slash in record slug/not
      in record slug and requested with trailing slash/not
      requested slug. In both cases, already working and the
      now fixed variant are serving both potential duplicate
      content - if no correct cannonical url is provided.

Tackling the duplicate issue should be done in a dedicated
change for both cases.

Used command(s):

> Build/Scripts/runTests.sh -s phpstanGenerateBaseline

Resolves: #100990
Related: #96010
Related: #88715
Related: #89091
Related: #86055
Releases: main, 12.4, 11.5
Change-Id: I9f26c4500e2f812e8727b4b565570fcc579bf3e6
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/79679


Tested-by: core-ci <typo3@b13.com>
Tested-by: Stefan Bürk <stefan@buerk.tech>
Reviewed-by: Stefan Bürk <stefan@buerk.tech>

Build/phpstan/phpstan-baseline.neon

@@ -1060,11 +1060,6 @@ parameters:
 			count: 1
 			path: ../../typo3/sysext/core/Classes/Routing/PageRouter.php
 
-		-
-			message: "#^Method TYPO3\\\\CMS\\\\Core\\\\Routing\\\\PageRouter\\:\\:matchRequest\\(\\) should return TYPO3\\\\CMS\\\\Core\\\\Routing\\\\SiteRouteResult but returns TYPO3\\\\CMS\\\\Core\\\\Routing\\\\PageArguments\\.$#"
-			count: 3
-			path: ../../typo3/sysext/core/Classes/Routing/PageRouter.php
-
 		-
 			message: "#^Parameter \\#1 \\$callback of function array_map expects \\(callable\\(TYPO3\\\\CMS\\\\Core\\\\Routing\\\\Aspect\\\\AspectInterface\\)\\: mixed\\)\\|null, 'count' given\\.$#"
 			count: 1

typo3/sysext/core/Classes/Routing/PageRouter.php

@@ -92,7 +92,7 @@ class PageRouter implements RouterInterface
      * Finds a RouteResult based on the given request.
      *
      * @param RouteResultInterface|SiteRouteResult|null $previousResult
-     * @return SiteRouteResult
+     * @return RouteResultInterface|PageArguments
      * @throws RouteNotFoundException
      */
     public function matchRequest(ServerRequestInterface $request, RouteResultInterface $previousResult = null): RouteResultInterface
@@ -182,9 +182,9 @@ class PageRouter implements RouterInterface
                 return $this->buildPageArguments($matchedRoute, $result, $request->getQueryParams());
             }
         } catch (ResourceNotFoundException $e) {
-            // Second try, look for /my-page even though the request was called via /my-page/ and the slash
-            // was not part of the slug, but let's then check again
-            if (substr($prefixedUrlPath, -1) === '/') {
+            if (str_ends_with($prefixedUrlPath, '/')) {
+                // Second try, look for /my-page even though the request was called via /my-page/ and the slash
+                // was not part of the slug, but let's then check again
                 try {
                     $result = $matcher->match(rtrim($prefixedUrlPath, '/'));
                     /** @var Route $matchedRoute */
@@ -197,6 +197,21 @@ class PageRouter implements RouterInterface
                 } catch (ResourceNotFoundException $e) {
                     // Do nothing
                 }
+            } else {
+                // Second try, look for /my-page/ even though the request was called via /my-page and the slash
+                // was part of the slug, but let's then check again
+                try {
+                    $result = $matcher->match($prefixedUrlPath . '/');
+                    /** @var Route $matchedRoute */
+                    $matchedRoute = $fullCollection->get($result['_route']);
+                    // Only use route if page language variant matches current language, otherwise
+                    // handle it as route not found.
+                    if ($this->isRouteReallyValidForLanguage($matchedRoute, $language)) {
+                        return $this->buildPageArguments($matchedRoute, $result, $request->getQueryParams());
+                    }
+                } catch (ResourceNotFoundException $e) {
+                    // Do nothing
+                }
             }
         }
         throw new RouteNotFoundException('No route found for path "' . $urlPath . '"', 1538389998);