Use route options instead of route defaults for view_argument_map

Here we go.

Looks good to me. Looks like it needs an issue summary though.

/me gets so sad if people don't review small patches

.

+++ b/core/modules/views/lib/Drupal/views/Plugin/views/display/PathPluginBase.php
@@ -200,7 +200,7 @@ protected function getRoute($view_id, $display_id) {
-    $route->setDefault('_view_argument_map', $argument_map);
+    $route->setOption('_view_argument_map', $argument_map);

+++ b/core/modules/views/lib/Drupal/views/Routing/ViewPageController.php
@@ -74,7 +75,7 @@ public function handle(Request $request) {
-    $map = $request->attributes->get('_view_argument_map', array());
+    $map = $request->attributes->get(RouteObjectInterface::ROUTE_OBJECT)->getOption('_view_argument_map', array());

This is a big improvement semantically, and its all internal anyway, so the extra verbosity is not a problem.

Sorry, I can't even begin to fathom how to read that new code, so passing this one onto alexpott.

If this kind of code is what #2124749: [meta] Stop using $request->attributes->get(MAGIC_KEY) as a public API is going to bring us all over, though, colour me concerned. :(

Well, this usecase would never be used by any custom/contrib module besides view so I don't give a shit about what people consider as DX.

Makes sense to me - and yep this is not a dx issue since it is all internal to views. I agree with Tim this is much more semantically correct.

Committed 52da190 and pushed to 8.x. Thanks!