From 012bbea249419ff5f5e49c51e9a59cc2c6a7ac72 Mon Sep 17 00:00:00 2001
From: Bryton Flecker <fleckerbr@gmail.com>
Date: Wed, 21 Jan 2026 22:30:20 -0600
Subject: [PATCH] Fix etl::tuple template signature error in pair assignment
 operator (#1265)

* Fix etl::tuple template signature error in pair assignment operator

* Remove AppVeyor build status badge

Removed AppVeyor build status badge from README.

* Update README.md

* Update etl::tuple to explicitly use etl::pair or std::pair in assignment operator

* Added tests for etl::tuple assignment from pair

---------

Co-authored-by: Bryton Flecker <bflecker@swe.com>
Co-authored-by: John Wellbelove <jwellbelove@users.noreply.github.com>
---
 include/etl/tuple.h | 20 +++++++--------
 test/test_tuple.cpp | 62 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 10 deletions(-)

diff --git a/include/etl/tuple.h b/include/etl/tuple.h
index dbdbdaa2..dde08d13 100644
--- a/include/etl/tuple.h
+++ b/include/etl/tuple.h
@@ -562,9 +562,9 @@ namespace etl
     //*********************************
     /// Assign from lvalue pair tuple type.
     //*********************************
-    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>, etl::enable_if_t<NTypes == 2U, int> = 0>
+    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>(), etl::enable_if_t<NTypes == 2U, int> = 0>
     ETL_CONSTEXPR14
-    tuple& operator =(pair<U1, U2>& p)
+    tuple& operator =(ETL_OR_STD::pair<U1, U2>& p)
     {
       get_value()            = p.first;
       get_base().get_value() = p.second;
@@ -575,9 +575,9 @@ namespace etl
     //*********************************
     /// Assign from const lvalue pair tuple type.
     //*********************************
-    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>, etl::enable_if_t<NTypes == 2U, int> = 0>
+    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>(), etl::enable_if_t<NTypes == 2U, int> = 0>
     ETL_CONSTEXPR14
-    tuple& operator =(const pair<U1, U2>& p)
+    tuple& operator =(const ETL_OR_STD::pair<U1, U2>& p)
     {
       get_value()            = p.first;
       get_base().get_value() = p.second;
@@ -588,9 +588,9 @@ namespace etl
     //*********************************
     /// Assign from rvalue pair tuple type.
     //*********************************
-    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>, etl::enable_if_t<NTypes == 2U, int> = 0>
+    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>(), etl::enable_if_t<NTypes == 2U, int> = 0>
     ETL_CONSTEXPR14
-    tuple& operator =(pair<U1, U2>&& p)
+    tuple& operator =(ETL_OR_STD::pair<U1, U2>&& p)
     {
       get_value()            = etl::forward<U1>(p.first);
       get_base().get_value() = etl::forward<U2>(p.second);
@@ -601,12 +601,12 @@ namespace etl
     //*********************************
     /// Assign from const rvalue pair tuple type.
     //*********************************
-    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>, etl::enable_if_t<NTypes == 2U, int> = 0>
+    template <typename U1, typename U2, size_t NTypes = number_of_types<THead, TTail...>(), etl::enable_if_t<NTypes == 2U, int> = 0>
     ETL_CONSTEXPR14
-      tuple& operator =(const pair<U1, U2>&& p)
+    tuple& operator =(const ETL_OR_STD::pair<U1, U2>&& p)
     {
-      get_value()            = etl::forward<U1>(p.first);
-      get_base().get_value() = etl::forward<U2>(p.second);
+      get_value()            = p.first;
+      get_base().get_value() = p.second;
 
       return *this;
     }
diff --git a/test/test_tuple.cpp b/test/test_tuple.cpp
index d84940d9..918541e0 100644
--- a/test/test_tuple.cpp
+++ b/test/test_tuple.cpp
@@ -777,5 +777,67 @@ namespace
       CHECK_EQUAL(etl::get<2>(tp), s);
     }
 #endif
+
+    //*************************************************************************
+    TEST(test_assign_from_lvalue_pair)
+    {
+      ETL_OR_STD::pair<int, Data> p(1, Data("2"));
+
+      etl::tuple<int, Data> tp(0, Data(""));
+
+      tp = p;
+
+      int  i = etl::get<0>(tp);
+      Data d = etl::get<1>(tp);
+
+      CHECK_EQUAL(1, i);
+      CHECK_EQUAL(std::string("2"), d.value);
+    }
+
+    //*************************************************************************
+    TEST(test_assign_from_const_lvalue_pair)
+    {
+      const ETL_OR_STD::pair<int, Data> p(1, Data("2"));
+
+      etl::tuple<int, Data> tp(0, Data(""));
+
+      tp = p;
+
+      int  i = etl::get<0>(tp);
+      Data d = etl::get<1>(tp);
+
+      CHECK_EQUAL(1, i);
+      CHECK_EQUAL(std::string("2"), d.value);
+    }
+
+    //*************************************************************************
+    TEST(test_assign_from_rvalue_pair)
+    {
+      etl::tuple<int, Data> tp(0, Data(""));
+
+      tp = ETL_OR_STD::pair<int, Data>(1, Data("2"));
+
+      int  i = etl::get<0>(tp);
+      Data d = etl::get<1>(tp);
+
+      CHECK_EQUAL(1, i);
+      CHECK_EQUAL(std::string("2"), d.value);
+    }
+
+    //*************************************************************************
+    TEST(test_assign_from_const_rvalue_pair)
+    {
+      const ETL_OR_STD::pair<int, Data> p(1, Data("2"));
+
+      etl::tuple<int, Data> tp(0, Data(""));
+
+      tp = static_cast<const ETL_OR_STD::pair<int, Data>&&>(p);
+
+      int  i = etl::get<0>(tp);
+      Data d = etl::get<1>(tp);
+
+      CHECK_EQUAL(1, i);
+      CHECK_EQUAL(std::string("2"), d.value);
+    }
   }
 }