Add specialized operator=() to handle nullptr assignment

include/rcp.h

@@ -23,6 +23,7 @@
 #pragma once
 
 #include <atomic>
+#include <cstddef>
 #include <functional>
 #include <type_traits>
 
@@ -59,6 +60,16 @@ public:
         }
     }
 
+    rcp & operator=(nullptr_t) noexcept
+    {
+        if (ptr)
+        {
+            ptr->rcp_dec();
+            ptr = nullptr;
+        }
+        return *this;
+    }
+
     rcp & operator=(const rcp & other)
     {
         if (ptr != other.ptr)

tests.cpp

@@ -448,6 +448,25 @@ void test_external_class()
     assert(external_destruct == before + 2);
 }
 
+void test_assign_nullptr()
+{
+    int constructed_before = mybase_construct;
+    int destructed_before = mybase_destruct;
+    {
+        rcp<MyBase> base = MyBase::create(6, 6);
+        assert(mybase_construct == constructed_before + 1);
+        assert(mybase_destruct == destructed_before);
+        base = nullptr;
+        assert(mybase_construct == constructed_before + 1);
+        assert(mybase_destruct == destructed_before + 1);
+        base = nullptr;
+        assert(mybase_construct == constructed_before + 1);
+        assert(mybase_destruct == destructed_before + 1);
+    }
+    assert(mybase_construct == constructed_before + 1);
+    assert(mybase_destruct == destructed_before + 1);
+}
+
 int main(int argc, char * argv[])
 {
     test_class_hierarchy();
@@ -477,5 +496,6 @@ int main(int argc, char * argv[])
     test_hash();
     test_class_template();
     test_external_class();
+    test_assign_nullptr();
     return 0;
 }