From 066aafff70d34136bbbb7d3693249f848a2aa189 Mon Sep 17 00:00:00 2001
From: Sviatoslav Sydorenko <wk@sydorenko.org.ua>
Date: Wed, 10 May 2023 19:02:39 +0200
Subject: [PATCH] =?UTF-8?q?=F0=9F=8E=A8=20Migrate=20PEP=20517=20backend=20?=
 =?UTF-8?q?to=20`tomllib`+`tomli`?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

`tomllib` is a part of stdlib since Python 3.11 and `tomli` is used as
a fallback for the older Python versions. The latter is API-compatible
with the former.
---
 bin/pep517_backend/_backend.py             | 10 +++++++---
 bin/pep517_backend/_compat.py              | 11 +++++++++++
 docs/changelog-fragments/501.packaging.rst |  6 ++++++
 pyproject.toml                             |  2 +-
 4 files changed, 25 insertions(+), 4 deletions(-)
 create mode 100644 bin/pep517_backend/_compat.py
 create mode 100644 docs/changelog-fragments/501.packaging.rst

diff --git a/bin/pep517_backend/_backend.py b/bin/pep517_backend/_backend.py
index b4541ba45..b9117fa09 100644
--- a/bin/pep517_backend/_backend.py
+++ b/bin/pep517_backend/_backend.py
@@ -8,7 +8,6 @@
 from functools import wraps
 from pathlib import Path
 
-import toml
 from expandvars import expandvars
 from setuptools.build_meta import (  # noqa: F401  # Re-exporting PEP 517 hooks
     build_sdist, build_wheel, get_requires_for_build_sdist,
@@ -22,12 +21,17 @@
 
 from Cython.Build.Cythonize import main as cythonize_cli_cmd
 
+from ._compat import load_toml_from_string  # noqa: WPS436
 from ._transformers import (  # noqa: WPS436
     convert_to_kwargs_only, get_cli_kwargs_from_config,
     get_enabled_cli_flags_from_config,
 )
 
 
+PROJECT_ROOT_DIR = Path(__file__).parents[2].resolve()
+PYPROJECT_TOML_PATH = PROJECT_ROOT_DIR / 'pyproject.toml'
+
+
 def get_config():
     """Grab optional build dependencies from pyproject.toml config.
 
@@ -80,8 +84,8 @@ def get_config():
         # This section can contain cythonize options
         # NAME = "VALUE"
     """
-    config_file = (Path.cwd().resolve() / 'pyproject.toml').read_text()
-    config_toml = toml.loads(config_file)
+    config_file = PYPROJECT_TOML_PATH.read_text(encoding='utf-8')
+    config_toml = load_toml_from_string(config_file)
     return config_toml['tool']['local']['cythonize']
 
 
diff --git a/bin/pep517_backend/_compat.py b/bin/pep517_backend/_compat.py
new file mode 100644
index 000000000..f471d6d0f
--- /dev/null
+++ b/bin/pep517_backend/_compat.py
@@ -0,0 +1,11 @@
+"""Cross-interpreter compatibility shims."""
+
+try:
+    # Python 3.11+
+    from tomllib import loads as load_toml_from_string  # noqa: WPS433
+except ImportError:
+    # before Python 3.11
+    from tomli import loads as load_toml_from_string  # noqa: WPS433, WPS440
+
+
+__all__ = ('load_toml_from_string',)  # noqa: WPS410
diff --git a/docs/changelog-fragments/501.packaging.rst b/docs/changelog-fragments/501.packaging.rst
new file mode 100644
index 000000000..ba730fd7e
--- /dev/null
+++ b/docs/changelog-fragments/501.packaging.rst
@@ -0,0 +1,6 @@
+The ``toml`` build time dependency has been replaced with
+``tomli`` -- by :user:`webknjaz`
+
+The ``tomli`` distribution is only pulled in under Python
+versions below 3.11. On 3.11 and higher, the standard
+library module :py:mod:`tomllib` is now used instead.
diff --git a/pyproject.toml b/pyproject.toml
index a6c6a9fad..b6e82c4ad 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -3,7 +3,7 @@ requires = [
   # Essentials
   "Cython",  # needed by in-tree build backend `bin/pep517_backend.py`
   "setuptools>=45",  # needed by in-tree build backend `bin/pep517_backend.py`
-  "toml",  # needed by in-tree build backend `bin/pep517_backend.py`
+  "tomli; python_version < '3.11'",  # needed by in-tree build backend `bin/pep517_backend.py`
   "expandvars",  # needed by in-tree build backend for env vars interpolation
 
   # Plugins