Force Python interpreter version to be major version 3

CMakeLists.txt

@@ -18,6 +18,8 @@ include(DuneMacros)
 set(DUNE_PYTHON_INSTALL_EDITABLE 1)
 set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -DDUNE_ISTL_SUPPORT_OLD_CATEGORY_INTERFACE=1")
 
+dune_python_force_version(3)
+
 # start a dune project with information from dune.module
 dune_project()
 

python/setup.py

@@ -29,6 +29,7 @@ setup(name='dune.codegen',
       description='Performance optimizing form compiler for the Dune project',
       author='Dominic Kempf <dominic.kempf@iwr.uni-heidelberg.de>',
       url='https://gitlab.dune-project.org/dominic/dune-codegen.git',
+      python_requires='>=3',
       packages=['dune.codegen',
                 'dune.codegen.blockstructured',
                 'dune.codegen.cgen',