Remove unused templates from the Admin theme

They seem to be unused.

All three came in with the Gin merge (9fc3187d, #3556948) and were never wired up: default_admin declares no hook_theme(), and its hook_theme_registry_alter() repoints only toolbar and menu__toolbar at templates/navigation.

The navigation module's hook_theme() registers top_bar*, block__navigation, navigation_menu, navigation_content_top and navigation__messages — no menu_region base hook, so there's nothing for menu-region--top/middle/bottom to attach to.

Nothing includes them from Twig either.

Worth adding menu-region--bottom.html.twig to the scope, looks like that is the same situation.

Can we update the issue summary to still follow the standard issue template please. To include your findings.

Since they're not used probably safe to go ahead and remove them.

Looks like these two are also unused?

core/themes/default_admin/templates/page/page--clone.html.twig
core/themes/default_admin/templates/page/page--group.html.twig

Cleaned up the summary LGTM.

This doesn't account for #7 - are we going to include those here or open a new issue? For me I'd include them here if they're dead code and just remove 'menu' from the issue title.

Re #7/#10: the page templates aren't unused in the same way.

These page templates are picked up automatically from the URL.

Visit /group/1 and Drupal looks for page--group.html.twig on its own, no theme hook needed. Core has no /group or /clone paths, but the Group and Quick Node Clone contrib modules do, and both templates apply the node edit layout to those pages.

So deleting them changes how those sites look.

The menu region templates have no such fallback and can never render.

I'd keep this issue to those, and open a separate one for the page templates or add them here if we prefer, but then it's an intentional change for contrib, not just cleanup of unused stuff.

Support for contrib modules should not be in core: it's up to contrib modules to provide their own templates. This was different for Gin when it was in contrib, which is where these templates come from.

I also marked it fine as I thought since it’s experimental theme we had more leeway

You are right.

I've broadened the scope and pushed the removal of page--clone.html.twig and page--group.html.twig to the MR.

It would be good to indeed update the issue title accordingly, since it no longer only covers the menu region templates. Thanks!

Also removed input--submit--paragraph-action.html.twig.

It only overrides the input__submit__paragraph_action suggestion, which comes from the contrib Paragraphs module, paragraph_action appears nowhere else in core.

I also opened #3621155: Remove contrib-specific selectors from the Admin theme CSS as a follow-up. The same contrib leftovers exist in the theme's CSS (Paragraphs, Smart Date, Inline Entity Form, Views Bulk Operations, plus some unused contrib toolbar icons).

Nice fine, lets ship this one.

Committed and pushed 41e2e84c1b4 to main and c24fd0dbd44 to 11.x. Thanks!