[wp-trac] [WordPress Trac] #43877: Do not run unnecessary `user_has_cap` filter if the caps to check for include `do_not_allow` already

[WordPress Trac]

#43877: Do not run unnecessary `user_has_cap` filter if the caps to check for
include `do_not_allow` already
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 Reporter:  flixos90         |      Owner:  (none)
     Type:  defect (bug)     |     Status:  new
 Priority:  normal           |  Milestone:  Awaiting Review
Component:  Role/Capability  |    Version:
 Severity:  normal           |   Keywords:  needs-patch needs-unit-tests
  Focuses:                   |
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 `do_not_allow` is a fake capability used essentially as a blacklist,
 saying that nobody can perform that action. It's typically returned in the
 `map_meta_cap()` result for an actual capability check. If `do_not_allow`
 is part of that array, it is immediately clear that the final result of
 the `WP_User::has_cap()` method will be `false`.

 Currently however, the following code in the function still executes,
 including a `user_has_cap` filter. Since we already know the return value
 if `do_not_allow` is present in the `$caps` array checked for, everything
 happening afterwards is entirely unnecessary overhead. Especially since
 [40993] it should be clear that nothing can get around a `do_not_allow`
 being present.

 For efficiency and possibly performance reasons, I suggest we check for
 `do_not_allow` right after the `map_meta_cap()` call, and if it is
 present, return false.

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Ticket URL: <https://core.trac.wordpress.org/ticket/43877>
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