From 3c2c05e4e52f69cefa23a1dc12ffa259def6004b Mon Sep 17 00:00:00 2001
From: Loic Gouarin <loic.gouarin@gmail.com>
Date: Tue, 11 Jul 2023 06:08:00 +0200
Subject: [PATCH] fix: extract_mesh (#110)

---
 include/samurai/utils.hpp | 8 ++++++++
 test/test_utils.cpp       | 2 ++
 2 files changed, 10 insertions(+)

diff --git a/include/samurai/utils.hpp b/include/samurai/utils.hpp
index 5f9c33744..fee068936 100644
--- a/include/samurai/utils.hpp
+++ b/include/samurai/utils.hpp
@@ -23,6 +23,9 @@ namespace samurai
     template <class F, class... CT>
     class field_function;
 
+    template <template <class T> class OP, class... CT>
+    class field_operator_function;
+
     namespace detail
     {
 
@@ -151,6 +154,11 @@ namespace samurai
         {
         };
 
+        template <template <class T> class OP, class... CT>
+        struct is_field_function<field_operator_function<OP, CT...>> : std::true_type
+        {
+        };
+
         template <class... T>
         auto& extract_mesh(const std::tuple<T...>& t)
         {
diff --git a/test/test_utils.cpp b/test/test_utils.cpp
index 72ad06363..c09e907e5 100644
--- a/test/test_utils.cpp
+++ b/test/test_utils.cpp
@@ -4,6 +4,7 @@
 
 #include <samurai/box.hpp>
 #include <samurai/field.hpp>
+#include <samurai/stencil_field.hpp>
 #include <samurai/uniform_mesh.hpp>
 #include <samurai/utils.hpp>
 
@@ -18,5 +19,6 @@ namespace samurai
         auto u = make_field<double, 1>("u", mesh);
 
         static_assert(detail::is_field_function<decltype(5 + u)>::value);
+        static_assert(detail::is_field_function<decltype(upwind(1, u))>::value);
     }
 }