Fix ABI3T feature selection for free-threaded Python

.github/workflows/ci.yml

@@ -134,6 +134,7 @@ jobs:
 
     env:
       SETUPTOOLS_RUST_CARGO_PROFILE: dev
+      NOX_DEFAULT_VENV_BACKEND: ${{ matrix.platform.os == 'windows-latest' && startsWith(matrix.python-version, 'graalpy') && 'venv' || 'virtualenv' }}
     steps:
       - uses: actions/checkout@v7
 
@@ -207,7 +208,7 @@ jobs:
       - name: Setup python
         uses: actions/setup-python@v7
         with:
-          python-version: "3.x"
+          python-version: "3.11"
 
       - uses: dtolnay/rust-toolchain@stable
 
@@ -232,7 +233,7 @@ jobs:
       - name: Setup python
         uses: actions/setup-python@v7
         with:
-          python-version: "3.11"
+          python-version: "3.x"
 
       - name: Install abi3 wheel and run tests
         shell: bash
@@ -293,7 +294,7 @@ jobs:
       - name: Setup python
         uses: actions/setup-python@v7
         with:
-          python-version: "3.10" # must match the ubuntu version in the install, and also the version copied out of the docker image below
+          python-version: "3.10" # must match the build and test containers below
       - uses: dtolnay/rust-toolchain@stable
         with:
           targets: aarch64-unknown-linux-gnu
@@ -318,22 +319,16 @@ jobs:
           python -m build --no-isolation
           ls -la dist/
           unzip -l dist/*.whl  # debug all files inside wheel file
-      - uses: uraimo/run-on-arch-action@v3.2.1
-        name: Install built wheel
-        with:
-          arch: aarch64
-          distro: ubuntu22.04
-          dockerRunArgs: |
-            --volume "${PWD}/examples/namespace_package:/io"
-          install: |
-            apt-get update
-            apt-get install -y --no-install-recommends python3 python3-venv python3-pip
-          run: |
-            python3 -m venv .venv
-            source .venv/bin/activate
+      - uses: docker/setup-qemu-action@v4
+      - name: Install built wheel
+        run: |
+          docker run --rm --platform linux/arm64 \
+            -v "$PWD/examples/namespace_package:/io" \
+            python:3.10 bash -euxc '
             pip install namespace_package --no-index --find-links /io/dist/ --force-reinstall
             python -c "from namespace_package import rust; assert rust.rust_func() == 14"
             python -c "from namespace_package import python; assert python.python_func() == 15"
+          '
 
   test-cibuildwheel:
     runs-on: macos-latest

CHANGELOG.md

@@ -1,6 +1,9 @@
 # Changelog
 
 ## Unreleased
+### Fixed
+- Select PyO3's ABI3T features for limited-API builds targeting free-threaded Python.
+
 ### Packaging
 - Drop support for Python 3.9.
 - Bump `setuptools` minimum version to 83.0.

docs/building_wheels.md

@@ -8,7 +8,7 @@ A key choice to make is whether to upload [PEP 384](https://www.python.org/dev/p
 
 This chapter covers each of these options below.
 
-## Building for ABI3
+## Building for ABI3 and ABI3T
 
 `setuptools-rust` will automatically configure for the limited API when this is set in the `[bdist_wheel]` configuration section of [`setup.cfg`](https://setuptools.pypa.io/en/latest/deprecated/distutils/configfile.html#writing-the-setup-configuration-file):
 
@@ -17,6 +17,10 @@ This chapter covers each of these options below.
 py_limited_api=cp37  # replace with desired minimum Python version
 ```
 
+When targeting free-threaded Python 3.15 or newer, this selects PyO3's ABI3T
+features instead of ABI3. Set `py_limited_api=cp315` or newer for these builds,
+as PyO3's ABI3T support requires Python 3.15 or newer.
+
 If using a `pyproject.toml`-based build, then save the above in a file and use the `DIST_EXTRA_CONFIG` environment variable to instruct `setuptools` to pick up this extra configuration. (`DIST_EXTRA_CONFIG` is documented [on this page](https://setuptools.pypa.io/en/latest/deprecated/distutils/configfile.html#writing-the-setup-configuration-file) of the `setuptools` docs.)
 
 It is also possible to pass this setting via the command line, e.g.

setuptools_rust/build.py

@@ -789,19 +789,20 @@ def _binding_features(
     elif ext.binding is Binding.PyO3:
         features = {"pyo3/extension-module"}
         if ext.py_limited_api == "auto":
+            abi = "abi3t" if get_config_var("Py_GIL_DISABLED") else "abi3"
             if isinstance(py_limited_api, str):
                 python_version = py_limited_api[2:]
-                features.add(f"pyo3/abi3-py{python_version}")
+                features.add(f"pyo3/{abi}-py{python_version}")
             elif py_limited_api:
-                features.add("pyo3/abi3")
+                features.add(f"pyo3/{abi}")
         return features
     elif ext.binding is Binding.RustCPython:
         return {"cpython/python3-sys", "cpython/extension-module"}
     else:
         raise PlatformError(f"unknown Rust binding: '{ext.binding}'")
 
 
-_PyLimitedApi = Literal["cp37", "cp38", "cp39", "cp310", "cp311", "cp312", True, False]
+_PyLimitedApi = str | bool
 
 
 def _override_cargo_default_target(plat_name: str, env: Env) -> str | _Platform:

tests/test_build.py

@@ -1,7 +1,10 @@
 from unittest import mock
 
+import pytest
+
 from setuptools_rust._utils import Env
-from setuptools_rust.build import _override_cargo_default_target
+from setuptools_rust.build import _binding_features, _override_cargo_default_target
+from setuptools_rust.extension import Binding, RustExtension
 
 NO_ENV = Env(None)
 
@@ -35,3 +38,54 @@ def test_adjusted_local_rust_target_macos():
         assert (
             _override_cargo_default_target("macosx-", NO_ENV) == "x86_64-apple-darwin"
         )
+
+
+@pytest.mark.parametrize(
+    "gil_disabled,py_limited_api,feature",
+    [
+        (None, "cp315", "abi3-py315"),
+        (0, False, None),
+        (0, True, "abi3"),
+        (0, "cp39", "abi3-py39"),
+        (0, "cp315", "abi3-py315"),
+        (1, False, None),
+        (1, True, "abi3t"),
+        (1, "cp315", "abi3t-py315"),
+        (1, "cp316", "abi3t-py316"),
+    ],
+)
+def test_binding_features_target_abi(gil_disabled, py_limited_api, feature):
+    ext = RustExtension("test")
+    with mock.patch(
+        "setuptools_rust.build.get_config_var", return_value=gil_disabled
+    ) as get_config_var:
+        features = _binding_features(ext, py_limited_api)
+    get_config_var.assert_called_once_with("Py_GIL_DISABLED")
+    expected = {"pyo3/extension-module"}
+    if feature is not None:
+        expected.add(f"pyo3/{feature}")
+    assert features == expected
+
+
+@pytest.mark.parametrize("py_limited_api", [True, False])
+def test_binding_features_explicit_limited_api(py_limited_api):
+    with pytest.warns(DeprecationWarning, match="RustExtension.py_limited_api"):
+        ext = RustExtension("test", py_limited_api=py_limited_api)
+    with mock.patch("setuptools_rust.build.get_config_var") as get_config_var:
+        assert _binding_features(ext, "cp315") == {"pyo3/extension-module"}
+    get_config_var.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "binding,expected",
+    [
+        (Binding.NoBinding, set()),
+        (Binding.Exec, set()),
+        (Binding.RustCPython, {"cpython/python3-sys", "cpython/extension-module"}),
+    ],
+)
+def test_binding_features_other_bindings(binding, expected):
+    ext = RustExtension("test", binding=binding)
+    with mock.patch("setuptools_rust.build.get_config_var") as get_config_var:
+        assert _binding_features(ext, "cp315") == expected
+    get_config_var.assert_not_called()