From 9b8715e70612868b597b1d28a738be0ed8dcc6e9 Mon Sep 17 00:00:00 2001
From: Hannes Vogt <hannes@havogt.de>
Date: Mon, 11 Nov 2024 09:35:30 +0100
Subject: [PATCH] fix copy assignment of tuple containing refs (#1811)

---
 include/gridtools/common/tuple.hpp     | 11 +++++++++--
 tests/unit_tests/common/test_hymap.cpp | 12 ++++++++++++
 tests/unit_tests/common/test_tuple.cpp | 12 ++++++++++++
 3 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/include/gridtools/common/tuple.hpp b/include/gridtools/common/tuple.hpp
index 8c2346c0d..5e772ecf4 100644
--- a/include/gridtools/common/tuple.hpp
+++ b/include/gridtools/common/tuple.hpp
@@ -28,13 +28,20 @@ namespace gridtools {
 
             tuple_leaf(tuple_leaf const &) = default;
             tuple_leaf(tuple_leaf &&) = default;
-            tuple_leaf &operator=(tuple_leaf const &) = default;
-            tuple_leaf &operator=(tuple_leaf &&) = default;
 
             constexpr GT_FUNCTION tuple_leaf() noexcept : m_value() {}
 
             template <class Arg, std::enable_if_t<std::is_constructible_v<T, Arg &&>, int> = 0>
             constexpr GT_FUNCTION tuple_leaf(Arg &&arg) noexcept : m_value(std::forward<Arg>(arg)) {}
+
+            constexpr GT_FUNCTION tuple_leaf &operator=(tuple_leaf const &other) noexcept {
+                m_value = other.m_value;
+                return *this;
+            }
+            constexpr GT_FUNCTION tuple_leaf &operator=(tuple_leaf &&other) noexcept {
+                m_value = std::move(other.m_value);
+                return *this;
+            }
         };
 
         template <size_t I, class T>
diff --git a/tests/unit_tests/common/test_hymap.cpp b/tests/unit_tests/common/test_hymap.cpp
index 91e4fc470..af73cb23d 100644
--- a/tests/unit_tests/common/test_hymap.cpp
+++ b/tests/unit_tests/common/test_hymap.cpp
@@ -222,5 +222,17 @@ namespace gridtools {
             EXPECT_EQ(88, at_key<b>(testee));
         }
 
+        TEST(assignment, references) {
+            double testee_a = 0.;
+            double testee_b = 0.;
+            hymap::keys<a, b>::values<double &, double &> testee{testee_a, testee_b};
+            double src_a = 3.5;
+            double src_b = 88;
+            hymap::keys<a, b>::values<double &, double &> src{src_a, src_b};
+            testee = src;
+            EXPECT_EQ(3.5, at_key<a>(testee));
+            EXPECT_EQ(88, at_key<b>(testee));
+        }
+
     } // namespace
 } // namespace gridtools
diff --git a/tests/unit_tests/common/test_tuple.cpp b/tests/unit_tests/common/test_tuple.cpp
index 94c356863..8f699ca72 100644
--- a/tests/unit_tests/common/test_tuple.cpp
+++ b/tests/unit_tests/common/test_tuple.cpp
@@ -205,6 +205,18 @@ namespace gridtools {
             EXPECT_EQ(1.5, get<1>(testee));
         }
 
+        TEST(tuple, copy_assign_nested_ref) {
+            int src_int = 1;
+            double src_double = 1.5;
+            int dst_int = 0;
+            double dst_double = 0.;
+            tuple<tuple<int &, double &>> src = {{src_int, src_double}};
+            tuple<tuple<int &, double &>> testee = {{dst_int, dst_double}};
+            testee = src;
+            EXPECT_EQ(1, get<0>(get<0>(testee)));
+            EXPECT_EQ(1.5, get<1>(get<0>(testee)));
+        }
+
         TEST(one_tuple, copy_assign) {
             tuple<int> src = {1};
             tuple<int> testee;