Flarum\Core\Access\PostPolicy::scopePostVisibility PHP Method

    public function scopePostVisibility(ScopePostVisibility $event)
    {
        // When fetching a discussion's posts: if the user doesn't have permission
        // to moderate the discussion, then they can't see posts that have been
        // hidden by someone other than themself.
        if ($event->actor->cannot('editPosts', $event->discussion)) {
            $event->query->where(function ($query) use($event) {
                $query->whereNull('hide_time')->orWhere('user_id', $event->actor->id);
            });
        }
    }