deprecate RustExtension.py_limited_api

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## Unreleased
+### Changed
+- Deprecate `py_limited_api` option to `RustExtension` in favour of always using `"auto"` to configure this from `bdist_wheel`. [#410](https://github.com/PyO3/setuptools-rust/pull/410)
+
 ## 1.8.1 (2023-10-30)
 ### Fixed
 - Fix regression in `install_extension` crashing since 1.8.0. [#380](https://github.com/PyO3/setuptools-rust/pull/380)

README.md

@@ -56,7 +56,6 @@ target = "hello_world._lib"  # The last part of the name (e.g. "_lib") has to ma
                              # but you can add a prefix to nest it inside of a Python package.
 path = "Cargo.toml"      # Default value, can be omitted
 binding = "PyO3"         # Default value, can be omitted
-py-limited-api = "auto"  # Default value, can be omitted
 ```
 
 Each extension module should map directly into the corresponding `[lib]` table on the

docs/building_wheels.md

@@ -4,19 +4,36 @@ Because `setuptools-rust` is an extension to `setuptools`, the standard [`python
 (or [`pip wheel --no-deps . --wheel-dir dist`](https://pip.pypa.io/en/stable/cli/pip_wheel/)) can be used to build distributable wheels.
 These wheels can be uploaded to PyPI using standard tools such as [twine](https://github.com/pypa/twine).
 
-`setuptools-rust` supports building for the [PEP 384](https://www.python.org/dev/peps/pep-0384/) "stable" (aka "limited") API when the `py_limited_api` option is set on the `[bdist_wheel]` section of `setup.cfg`.
-If using PyO3 bindings for `RustExtension`, then the correct [`pyo3/abi3`](https://pyo3.rs/v0.14.5/features.html#abi3) sub-feature is automatically enabled.
-In this way, abi3 wheels can be uploaded to make package distributors' roles easier, and package users installing from source with `pip install .` can use optimizations specific to their Python version.
+A key choice to make is whether to upload [PEP 384](https://www.python.org/dev/peps/pep-0384/) "stable" (aka "limited") API wheels which support multiple Python versions in a single binary, or to build individual artifacts for each Python version. There is a longer discussion of this [in the PyO3 docs](https://pyo3.rs/latest/building_and_distribution#py_limited_apiabi3).
 
-This chapter of the documentation explains two possible ways to build wheels for multiple Python versions below.
+This chapter covers each of these options below.
 
-## Using `cibuildwheel`
+## Building for ABI3
+
+`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):
+
+```ini
+[bdist_wheel]
+py_limited_api=cp37  # replace with desired minimum Python version
+```
+
+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.
+
+```
+python -m build --config-settings=--build-option=--py-limited-api=cp37
+```
+
+## Building for multiple Python versions
+
+### Using `cibuildwheel`
 
 [`cibuildwheel`][cibuildwheel] is a tool to build wheels for multiple platforms using Github Actions.
 
 The [`rtoml` package does this, for example](https://github.com/samuelcolvin/rtoml/blob/143ee0907bba616cbcd5cc58eefe9000fcc2b5f2/.github/workflows/ci.yml#L99-L195).
 
-## Building manually
+### Building manually
 
 Place a script called `build-wheels.sh` with the following contents in your project root (next to the `setup.py` file):
 
@@ -27,7 +44,7 @@ Place a script called `build-wheels.sh` with the following contents in your proj
 
 This script can be used to produce wheels for multiple Python versions.
 
-### Binary wheels on linux
+#### Binary wheels on linux
 
 To build binary wheels on linux, you need to use the [manylinux docker container](https://github.com/pypa/manylinux). You will run the `build-wheels.sh` from above inside that container.
 
@@ -54,7 +71,7 @@ hello_rust-0.1.0-cp39-cp39-linux_x86_64.whl           hello_rust-0.1.0-cp39-cp39
 
 It is possible to use any of the `manylinux` docker images: `manylinux1`, `manylinux2010` or `manylinux2014`. (Just replace `manylinux2014` in the above instructions with the alternative version you wish to use.)
 
-### Binary wheels on macOS
+#### Binary wheels on macOS
 
 For building wheels on macOS it is sufficient to use one of the default `python -m build` or `pip wheel --no-deps . --wheel-dir dist` commands.
 

examples/hello-world-setuppy/setup.py

@@ -14,7 +14,6 @@
             #     in Cargo.toml and the function name in the `.rs` file,
             #     but you can add a prefix to nest it inside of a Python package.
             path="Cargo.toml",  # Default value, can be omitted
-            py_limited_api="auto",  # Default value, can be omitted
             binding=Binding.PyO3,  # Default value, can be omitted
         )
     ],

examples/hello-world/pyproject.toml

@@ -19,7 +19,6 @@ find = { where = ["python"] }
 # Private Rust extension module to be nested into Python package
 target = "hello_world._lib"  # The last part of the name (e.g. "_lib") has to match lib.name in Cargo.toml,
                              # but you can add a prefix to nest it inside of a Python package.
-py-limited-api = "auto"  # Default value, can be omitted
 binding = "PyO3"  # Default value, can be omitted
 # See reference for RustExtension in https://setuptools-rust.readthedocs.io/en/latest/reference.html
 

examples/rust_with_cffi/setup.py

@@ -17,7 +17,7 @@
     packages=find_packages(where="python"),
     package_dir={"": "python"},
     rust_extensions=[
-        RustExtension("rust_with_cffi.rust", py_limited_api="auto"),
+        RustExtension("rust_with_cffi.rust"),
     ],
     cffi_modules=["cffi_module.py:ffi"],
     install_requires=["cffi"],

setuptools_rust/extension.py

@@ -107,22 +107,7 @@ class RustExtension:
         optional: If it is true, a build failure in the extension will not
             abort the build process, and instead simply not install the failing
             extension.
-        py_limited_api: Similar to ``py_limited_api`` on
-            ``setuptools.Extension``, this controls whether the built extension
-            should be considered compatible with the PEP 384 "limited API".
-
-            - ``'auto'``: the ``py_limited_api`` option of
-              ``bdist_wheel`` will control whether the extension is
-              built as a limited api extension. The corresponding
-              ``pyo3/abi3-pyXY`` feature will be set accordingly.
-              This is the recommended setting, as it allows
-              to build a version-specific extension for best performance.
-
-            - ``True``: the extension is assumed to be compatible with the
-              limited abi. You must ensure this is the case (e.g. by setting
-              the ``pyo3/abi3`` feature).
-
-            - ``False``: the extension is version-specific.
+        py_limited_api: Deprecated.
     """
 
     def __init__(
@@ -180,6 +165,13 @@ def __init__(
                 DeprecationWarning,
             )
 
+        if self.py_limited_api != "auto":
+            warnings.warn(
+                "`RustExtension.py_limited_api` is deprecated, use [bdist_wheel] configuration "
+                "in `setup.cfg` or `DIST_EXTRA_CONFIG` to build abi3 wheels.",
+                DeprecationWarning,
+            )
+
     def get_lib_name(self, *, quiet: bool) -> str:
         """Parse Cargo.toml to get the name of the shared library."""
         metadata = self.metadata(quiet=quiet)