From 25be6986e57be0bfea0b3616decaaa8e5b16876d Mon Sep 17 00:00:00 2001
From: john bowen <john.bowen42@gmail.com>
Date: Wed, 6 Sep 2023 18:32:16 -0700
Subject: [PATCH] Add static assert for generic lambdas

---
 src/serac/physics/heat_transfer.hpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/serac/physics/heat_transfer.hpp b/src/serac/physics/heat_transfer.hpp
index 81eaa354c..cfcc765e0 100644
--- a/src/serac/physics/heat_transfer.hpp
+++ b/src/serac/physics/heat_transfer.hpp
@@ -280,6 +280,16 @@ class HeatTransfer<order, dim, Parameters<parameter_space...>, std::integer_sequ
   struct ThermalMaterialIntegrand {
     ThermalMaterialIntegrand(MaterialType material) : material_(material) {}
 
+    // The template parameter MaterialType is meant to be a callable functor.  Due
+    // to nvcc's lack of support for generic lambdas (i.e. functions of the form
+    // auto lambda = [](auto) {}; ), this cannot be allowed.  In order for this code
+    // to be portable to CUDA platforms, the asserts below prevent serac from compiling
+    // if such a lambda is supplied.
+    class DummyArgumentType {};
+    static_assert(!std::is_invocable<MaterialType, DummyArgumentType&>::value);
+    static_assert(!std::is_invocable<MaterialType, DummyArgumentType*>::value);
+    static_assert(!std::is_invocable<MaterialType, DummyArgumentType>::value);
+
     template <typename X, typename T, typename dT_dt, typename Shape, typename... Params>
     auto operator()(X x, T temperature, dT_dt dtemp_dt, Shape shape, Params... params)
     {