From e93606b62b51b748c8686406e128b04c6ac9fb87 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Paul=20K=C3=BChner?=
 <56360279+schnellerhase@users.noreply.github.com>
Date: Tue, 27 Aug 2024 13:05:19 +0200
Subject: [PATCH] Fix bug in `create_functionspace` (#3355)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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* Fix issue 3345

* Remove {}

* Update cpp/test/fem/functionspace.cpp

Co-authored-by: Jørgen Schartum Dokken <dokken92@gmail.com>

* {} style

---------

Co-authored-by: Jørgen Schartum Dokken <dokken92@gmail.com>
---
 cpp/dolfinx/fem/utils.h        |  4 ++++
 cpp/test/CMakeLists.txt        |  1 +
 cpp/test/fem/functionspace.cpp | 30 ++++++++++++++++++++++++++++++
 3 files changed, 35 insertions(+)
 create mode 100644 cpp/test/fem/functionspace.cpp

diff --git a/cpp/dolfinx/fem/utils.h b/cpp/dolfinx/fem/utils.h
index 619a9e02d7c..7f79dfb00ef 100644
--- a/cpp/dolfinx/fem/utils.h
+++ b/cpp/dolfinx/fem/utils.h
@@ -775,6 +775,10 @@ FunctionSpace<T> create_functionspace(
         "Cannot specify value shape for non-scalar base element.");
   }
 
+  if (mesh::cell_type_from_basix_type(e.cell_type())
+      != mesh->topology()->cell_type())
+    throw std::runtime_error("Cell type of element and mesh must match.");
+
   std::size_t bs = value_shape.empty()
                        ? 1
                        : std::accumulate(value_shape.begin(), value_shape.end(),
diff --git a/cpp/test/CMakeLists.txt b/cpp/test/CMakeLists.txt
index 53ece3f893f..e652537d80c 100644
--- a/cpp/test/CMakeLists.txt
+++ b/cpp/test/CMakeLists.txt
@@ -40,6 +40,7 @@ add_executable(
   common/sub_systems_manager.cpp
   common/index_map.cpp
   common/sort.cpp
+  fem/functionspace.cpp
   mesh/distributed_mesh.cpp
   common/CIFailure.cpp
   refinement/interval.cpp
diff --git a/cpp/test/fem/functionspace.cpp b/cpp/test/fem/functionspace.cpp
new file mode 100644
index 00000000000..faf3b7233dd
--- /dev/null
+++ b/cpp/test/fem/functionspace.cpp
@@ -0,0 +1,30 @@
+// Copyright (C) 2024 Paul Kühner
+//
+// This file is part of DOLFINX (https://www.fenicsproject.org)
+//
+// SPDX-License-Identifier:    LGPL-3.0-or-later
+
+#include <catch2/catch_test_macros.hpp>
+
+#include <basix/finite-element.h>
+
+#include <dolfinx/fem/FunctionSpace.h>
+#include <dolfinx/fem/utils.h>
+#include <dolfinx/mesh/Mesh.h>
+#include <dolfinx/mesh/generation.h>
+
+using namespace dolfinx;
+
+TEST_CASE("Create Function Space (mismatch of elements)", "[functionspace]")
+{
+  auto mesh = std::make_shared<mesh::Mesh<double>>(
+      dolfinx::mesh::create_rectangle<double>(
+          MPI_COMM_SELF, {{{0, 0}, {1, 1}}}, {1, 1}, mesh::CellType::triangle));
+
+  auto element = basix::create_element<double>(
+      basix::element::family::P, basix::cell::type::interval, 1,
+      basix::element::lagrange_variant::unset,
+      basix::element::dpc_variant::unset, false);
+
+  CHECK_THROWS(fem::create_functionspace<double>(mesh, element, {}));
+}