From 627661158e107ad959b4dbcfd3b9264ebb14ca22 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Tue, 24 Feb 2026 17:17:34 -0500
Subject: [PATCH] Add move version of rcp_dynamic_cast()

---
 include/rcp.h  | 17 +++++++++++++++++
 test/tests.cpp | 26 ++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/include/rcp.h b/include/rcp.h
index fbcd38c..3d5a4df 100644
--- a/include/rcp.h
+++ b/include/rcp.h
@@ -174,6 +174,9 @@ public:
     {
         return T::create(std::forward<Args>(args)...);
     }
+
+    template <typename V, typename W>
+    friend rcp<V> rcp_dynamic_cast(rcp<W> && other);
 };
 
 template <typename T, typename U>
@@ -182,6 +185,20 @@ rcp<T> rcp_dynamic_cast(const rcp<U> & other)
     return rcp<T>(dynamic_cast<T *>(other.get_raw()));
 }
 
+template <typename T, typename U>
+rcp<T> rcp_dynamic_cast(rcp<U> && other)
+{
+    T * p = dynamic_cast<T *>(other.ptr);
+    if (p)
+    {
+        other.ptr = nullptr;
+        rcp<T> result;
+        result.ptr = p;
+        return result;
+    }
+    return rcp<T>();
+}
+
 #define rcp_managed_root(classname) \
     public: \
         void rcp_inc() const \
diff --git a/test/tests.cpp b/test/tests.cpp
index d4dac69..ef3d6f1 100644
--- a/test/tests.cpp
+++ b/test/tests.cpp
@@ -234,6 +234,30 @@ void test_dynamic_cast_success()
     assert(back->v == 1.5);
 }
 
+void test_dynamic_cast_move_success()
+{
+    int constructed_before = mybase_construct;
+    int destructed_before = mybase_destruct;
+    {
+        rcp<MyBase> base = MyDerived::create(1.5);
+        rcp<MyDerived> derived = rcp_dynamic_cast<MyDerived>(std::move(base));
+        assert(!base);
+        assert(derived);
+        assert(derived->v == 1.5);
+        assert(mybase_destruct == destructed_before);
+    }
+    assert(mybase_construct == constructed_before + 1);
+    assert(mybase_destruct == destructed_before + 1);
+}
+
+void test_dynamic_cast_move_failure()
+{
+    rcp<MyBase> base = MyBase::create(1, 2);
+    rcp<MyDerived> derived = rcp_dynamic_cast<MyDerived>(std::move(base));
+    assert(!derived);
+    assert(base);
+}
+
 void test_dynamic_cast_failure()
 {
     rcp<MyBase> base = MyBase::create(1, 2);
@@ -258,5 +282,7 @@ int main(int argc, char * argv[])
     test_move_upcast();
     test_dynamic_cast_success();
     test_dynamic_cast_failure();
+    test_dynamic_cast_move_success();
+    test_dynamic_cast_move_failure();
     return 0;
 }