SharedPtr: adopt_shared_from_owned

luna/include/luna/OwnedPtr.h

@@ -2,6 +2,8 @@
 #include <luna/Alloc.h>
 #include <luna/Result.h>
 
+template <typename T> class SharedPtr;
+
 template <typename T> class OwnedPtr
 {
   public:
@@ -38,6 +40,8 @@ template <typename T> class OwnedPtr
         return *m_ptr;
     }
 
+    template <typename Type> friend Result<SharedPtr<Type>> adopt_shared_from_owned(OwnedPtr<Type>&&);
+
   private:
     T* m_ptr;
 };

luna/include/luna/SharedPtr.h

@@ -1,6 +1,7 @@
 #pragma once
 #include <luna/Alloc.h>
 #include <luna/Atomic.h>
+#include <luna/OwnedPtr.h>
 #include <luna/Result.h>
 #include <luna/ScopeGuard.h>
 
@@ -119,3 +120,17 @@ template <typename T> Result<SharedPtr<T>> adopt_shared_if_nonnull(T* ptr)
     else
         return err(ENOMEM);
 }
+
+template <typename T> Result<SharedPtr<T>> adopt_shared_from_owned(OwnedPtr<T>&& other)
+{
+    T* ptr = other.m_ptr;
+    other.m_ptr = nullptr;
+
+    auto guard = make_scope_guard([&] { delete ptr; });
+
+    SharedPtr<T> shared_ptr = TRY(adopt_shared(ptr));
+
+    guard.deactivate();
+
+    return shared_ptr;
+}