Add nogil input to select a free-threaded Python build

.github/workflows/main.yml

@@ -9,12 +9,14 @@ jobs:
     strategy:
       matrix:
         include:
-        - {python: '3.7', debug: true}
-        - {python: '3.11-dev', debug: false}
-        - {python: '3.12-dev', debug: false}
+        - {python: '3.7', debug: true, nogil: false}
+        - {python: '3.11-dev', debug: false, nogil: false}
+        - {python: '3.12-dev', debug: false, nogil: false}
+        - {python: '3.13-dev', debug: false, nogil: true}
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v4
     - uses: ./.
       with:
         python-version: ${{ matrix.python }}
         debug: ${{ matrix.debug }}
+        nogil: ${{ matrix.nogil }}

README.md

@@ -34,6 +34,7 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
           # debug: true  # Optional, to select a Python debug build
+          # nogil: true  # Optional, to select a free-threaded Python build (3.13+ only)
       - run: python --version --version && which python
 ```
 
@@ -47,5 +48,9 @@ jobs:
 In either case, the actions's `debug` input can be used to install a
 debug build of the selected Python version, by adding `debug: true`.
 
+The `nogil` input can be used instead of `debug` to install an *experimental*
+free-threaded build of the selected Python version, by adding `nogil: true`
+Only available for Python 3.13 and later.
+
 [available nightly versions]: https://launchpad.net/~deadsnakes/+archive/ubuntu/nightly/+packages
 [available versions]: https://launchpad.net/~deadsnakes/+archive/ubuntu/ppa/+packages

action.yml

@@ -8,9 +8,13 @@ inputs:
     description: use debug version of python
     required: false
     default: false
+  nogil:
+    description: use free-threaded version of python
+    required: false
+    default: false
 runs:
   using: composite
   steps:
   - name: add deadsnakes ppa and install ${{ inputs.python-version }} ${{ inputs.debug == 'true' && '(debug)' || '' }}
-    run: ${{ github.action_path }}/bin/install-python ${{ inputs.python-version }} ${{ inputs.debug == 'true' && '--debug' || '' }}
+    run: ${{ github.action_path }}/bin/install-python ${{ inputs.python-version }} ${{ inputs.debug == 'true' && '--debug' || '' }} ${{ inputs.nogil == 'true' && '--nogil' || '' }}
     shell: bash

bin/install-python

@@ -36,7 +36,9 @@ def _print_call(*args: str) -> int:
 def main() -> int:
     parser = argparse.ArgumentParser()
     parser.add_argument('version')
-    parser.add_argument('--debug', action='store_true')
+    mut = parser.add_mutually_exclusive_group()
+    mut.add_argument('--debug', action='store_true')
+    mut.add_argument('--nogil', action='store_true')
     args = parser.parse_args()
 
     if args.version.endswith('-dev'):
@@ -54,11 +56,16 @@ def main() -> int:
         packages.append(f'{py}-distutils')
     if args.debug:
         packages.append(f'{py}-dbg')
+        py_executable = f'{py}-dbg'
+    elif args.nogil:
+        packages.append(f'{py}-nogil')
+        py_executable = f'{py}-nogil'
+    else:
+        py_executable = py
 
     envdir = os.path.expanduser(f'~/venv-{version}')
     bindir = os.path.join(envdir, 'bin')
     pip = os.path.join(bindir, 'pip')
-    py_executable = f'{py}-dbg' if args.debug else py
 
     groups = (
         Group.make(