From 66da52fdeb3cd7708bb5e1baa6883667232d2d21 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Tue, 19 Mar 2019 17:08:35 +1100
Subject: [PATCH] expected: add a trivial move constructor

---
 expected.hpp | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/expected.hpp b/expected.hpp
index a240813d..e93d6735 100644
--- a/expected.hpp
+++ b/expected.hpp
@@ -46,7 +46,18 @@ namespace cruft {
         using error_type = ErrorT;
 
         expected () = delete;
-        expected (expected &&);
+        expected (expected &&rhs)
+        {
+            destroy ();
+            if (rhs) {
+                m_valid = true;
+                ::new (&m_store.value) ValueT (std::move (rhs.value ()));
+            } else {
+                m_valid = false;
+                ::new (&m_store.error) unexpected<ErrorT> (std::move (rhs.error ()));
+            }
+        }
+
         expected& operator=(expected &&);
         expected (expected const&);
         expected& operator=(expected const&);
@@ -71,12 +82,7 @@ namespace cruft {
 
         ~expected ()
         {
-            if (m_valid) {
-                m_store.value.~ValueT ();
-                m_valid = false;
-            } else {
-                m_store.error.~unexpected<ErrorT> ();
-            }
+            destroy ();
         }
 
         ValueT&
@@ -137,6 +143,16 @@ namespace cruft {
         explicit operator bool() const noexcept { return has_value (); }
 
     private:
+        void destroy (void)
+        {
+           if (m_valid) {
+                m_store.value.~ValueT ();
+                m_valid = false;
+            } else {
+                m_store.error.~unexpected<ErrorT> ();
+            }
+        }
+
         bool m_valid = false;
 
         union storage_t {