Fixes for Python min and max versions

.github/workflows/build-neuron.yml

@@ -71,11 +71,11 @@ jobs:
     env:
       SDK_ROOT: $(xcrun --sdk macosx --show-sdk-path)
       OS_FLAVOUR: ${{matrix.os.flavour}}
-      # version of Python we will build NEURON with on MacOS
-      MACOSX_PY_VERSION: 3.12
+      # min minor supported version of Python
+      MIN_PYTHON_VERSION: '9'
+      # max minor supported version of Python
+      MAX_PYTHON_VERSION: '12'
       UNPRIVILEGED_USER: runner # User created+used inside Docker containers
-      # Extra software collections to be installed and enabled on CentOS7
-      SOFTWARE_COLLECTIONS_centos_7: devtoolset-9 rh-git218 rh-python38
 
     strategy:
       matrix:
@@ -92,7 +92,7 @@ jobs:
         - { vm: ubuntu-latest, container: "fedora:40", flavour: redhat }
         # Ubuntu 20.04 Docker image
         - { vm: ubuntu-latest, container: "ubuntu:20.04", flavour: debian }
-        # Ubuntu Latest (22.04, at time of writing) Docker image
+        # Ubuntu Latest (24.04, at time of writing) Docker image
         - { vm: ubuntu-latest, container: "ubuntu:latest", flavour: debian }
         # Debian Bullseye (11) Docker image
         - { vm: ubuntu-latest, container: "debian:bullseye", flavour: debian }
@@ -128,11 +128,12 @@ jobs:
         env:
           FLAVOUR_SCRIPT: scripts/install_${{matrix.os.flavour}}.sh
 
+      # MacOS has 3.13 as default, so we instead install the max supported one
       - if: ${{matrix.os.flavour}} == 'macOS'
-        name: Set up Python@${{ env.MACOSX_PY_VERSION }}
+        name: Set up Python@${{ env.MAX_PYTHON_VERSION }}
         uses: actions/setup-python@v5
         with:
-          python-version: ${{ env.MACOSX_PY_VERSION }}
+          python-version: "3.${{ env.MAX_PYTHON_VERSION }}"
 
       # Checkout the repository; do this before the privilege step so that we
       # can chown the result there

scripts/environment_macOS.sh

@@ -4,6 +4,7 @@ export SKIP_EMBEDED_PYTHON_TEST=true
 # Do not enable OpenMP on macOS
 export CORENRN_ENABLE_OPENMP=OFF
 # Use Bison from homebrew
-export PATH=/usr/local/opt/bison/bin:${PATH}
+PATH="$(brew --prefix)/opt/bison/bin:${PATH}"
 # Use Flex from homebrew
-export PATH=/usr/local/opt/flex/bin:${PATH}
+PATH="$(brew --prefix)/opt/flex/bin:${PATH}"
+export PATH

scripts/install_debian.sh

@@ -15,6 +15,26 @@ if [[ "${DO_NOT_INSTALL_BOOST}" != "true" ]]; then
 fi
 if [[ -z "${NRN_PYTHON}" ]]; then
   apt-get install -y python3-dev python3-venv
-  export NRN_PYTHON=$(command -v python3)
+
+  python_version="$(python3 -c 'import sys;print(sys.version_info.minor)')"
+  if [[ "${python_version}" -lt "${MIN_PYTHON_VERSION}" ]]
+  then
+      # install min supported Python version from external repo
+      apt-get install -y software-properties-common
+      add-apt-repository -y ppa:deadsnakes/ppa
+      apt-get install -y "python3.${MIN_PYTHON_VERSION}"
+      NRN_PYTHON="$(command -v "python3.${MIN_PYTHON_VERSION}")"
+      export NRN_PYTHON
+  elif [[ "${python_version}" -gt "${MAX_PYTHON_VERSION}" ]]
+  then
+      # we do not want to downgrade the default version (this is _very_ unlikely to happen on Ubuntu/Debian though)
+      printf "Distribution %s comes with a version of Python that is too new (%s) for NEURON\n" "$(cat /etc/lsb-release)" "3.${python_version}"
+      printf "Please downgrade it to at most Python %s\n" "3.${python_version}"
+      exit 1
+  else
+      NRN_PYTHON="$(command -v python3)"
+      export NRN_PYTHON
+  fi
+  # export to github env
   echo "NRN_PYTHON=${NRN_PYTHON}" >> $GITHUB_ENV
 fi

scripts/install_redhat_almalinux_8_10.sh

@@ -1,6 +1,7 @@
 #!/bin/bash
 # Enable the (official) PowerTools repository. This provides Ninja.
-dnf install -y dnf-plugins-core python38-devel gcc-toolset-9-gcc gcc-toolset-9-gcc-c++
-export NRN_PYTHON=$(command -v python3.8)
+dnf install -y dnf-plugins-core "python3${PYTHON_MIN_VERSION}-devel" gcc-toolset-9-gcc gcc-toolset-9-gcc-c++
+NRN_PYTHON="$(command -v "python3.${PYTHON_MIN_VERSION}")"
+export NRN_PYTHON
 echo "NRN_PYTHON=${NRN_PYTHON}" >> $GITHUB_ENV
 dnf config-manager --set-enabled powertools