AK: Stop allowing implicit downcast with RefPtr and NonnullRefPtr

We were allowing this dangerous kind of thing:

RefPtr<Base> base;
RefPtr<Derived> derived = base;

This patch changes the {Nonnull,}RefPtr constructors so this is no
longer possible.

To downcast one of these pointers, there is now static_ptr_cast<T>:

RefPtr<Derived> derived = static_ptr_cast<Derived>(base);

Fixing this exposed a ton of cowboy-downcasts in various places,
which we're now forced to fix. :^)

1 files changed, 2 insertions, 2 deletions

diff --git a/Kernel/FileSystem/TmpFS.cpp b/Kernel/FileSystem/TmpFS.cpp
index e916a33980..20f5559488 100644
--- a/Kernel/FileSystem/TmpFS.cpp
+++ b/Kernel/FileSystem/TmpFS.cpp
@@ -307,8 +307,8 @@ KResult TmpFSInode::add_child(InodeIdentifier child_id, const StringView& name,
 
     String owned_name = name;
     FS::DirectoryEntry entry = { owned_name.characters(), owned_name.length(), child_id, 0 };
-    RefPtr<Inode> child_tmp = fs().get_inode(child_id);
-    NonnullRefPtr<TmpFSInode> child = static_cast<NonnullRefPtr<TmpFSInode>>(child_tmp.release_nonnull());
+    auto child_tmp = fs().get_inode(child_id);
+    auto child = static_ptr_cast<TmpFSInode>(child_tmp.release_nonnull());
 
     m_children.set(owned_name, { entry, move(child) });
     set_metadata_dirty(true);