Improve the default setting of 'show_in_admin_bar'

[ipm-frommen]

Currently, the default setting of show_in_admin_bar is defined as true === $args->show_in_menu.

Suppose, I have the custom post types CPT_A and CPT_B, and I put the menu of the latter one below the menu of the former one ('show_in_menu' => 'edit.php?post_type=cpt_a').
Unless I also define 'show_in_admin_bar' => true, for CPT_B there won't be any _Edit post_ node in the admin bar.

This is, in my opinion, not the desired behavior.
If the default value for show_in_admin_bar were to be set with respect to the presence of show_in_menu - and not by strict comparison with it - the admin bar node in question would be made available automagically.

Diff is attached.

[SergeyBiryukov]

Introduced in [18261].

[SergeyBiryukov]

In 30041:

When using 'show_in_menu' as a default value for 'show_in_admin_bar' in register_post_type(), cast to boolean instead of requiring a strict match.

props ipm-frommen.
fixes #30092.

[nacin]

The commit message for [30041] isn't clear on whether it was understood that this was a functionality change.

[18261] intentionally made it so it would be hidden from the admin bar in this situation, and the code comment (which wasn't changed here) tried to indicate that, though not very clearly. Basically: You'll get it in the admin bar if your post type is a top-level item. If it's buried underneath another item, then you won't see it in the admin bar. There is no "Add New" menu, it's merely a button, so I'm not sure it makes sense to make it so prominent in the toolbar. (At the same time, it could be argued it needs to be exposed somewhere, and this would be a good place for it.)

I am not sure I disagree with this change, but I wanted to be sure everyone understood what's going on here.

[ipm-frommen]

I submitted this ticket as well as the patch because I didn't see (and still don't) any reason for a post type, which is accessible through the menu, not being accessible through the admin bar.

@nacin, do you see anything that might speak against making publicly accessible post types also accessible in the admin bar?

[nacin]

Adding too much of any UI anywhere means the user can't find what they're looking for. If the post type is deliberately buried within another menu, I think it's logical to think it is less important than some other post types, and does not need to be yet another post type in the toolbar.

An underlying motivation was also that putting a post type under a menu would remove the "Add New" menu, which may have been a desired aspect. That said, this was done in 3.1, prior to the creation of the create_posts cap, which was 3.5.