Drop Python 2.7 (#936)

* Drop Python 2.7

The tooling situation around Python 2 has deteriorate to such a degree that
upholding compatibility is not tenable anymore for a volunteer-run project.

Signed-off-by: Hynek Schlawack <hs@ox.cx>

* Add newsfragment

* Run Python 3.5 under coverage to make up for Python 2.7

* Wait for py35 in parallel

* Remove fullmatch kludge

* Remove Python 2-specific code

* Revert empty slot test

Also disable pyupgrade on that file.

Signed-off-by: Hynek Schlawack <hs@ox.cx>

* We DO run under 3.5

* Remove __qualname__ workarounds

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* Update changelog.d/936.breaking.rst

Co-authored-by: Tin Tvrtković <tinchester@gmail.com>

* Compare methods using is

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Tin Tvrtković <tinchester@gmail.com>

.github/CONTRIBUTING.md

@@ -71,7 +71,7 @@ The official tag is `python-attrs` and helping out in support frees us up to imp
 
 - To run the test suite, all you need is a recent [*tox*].
   It will ensure the test suite runs with all dependencies against all Python versions just as it will in our [CI].
-  If you lack some Python versions, you can can always limit the environments like `tox -e py27,py38`, or make it a non-failure using `tox --skip-missing-interpreters`.
+  If you lack some Python versions, you can can always limit the environments like `tox -e py38,py39`, or make it a non-failure using `tox --skip-missing-interpreters`.
 
   In that case you should look into [*asdf*](https://asdf-vm.com) or [*pyenv*](https://github.com/pyenv/pyenv), which make it very easy to install many different Python versions in parallel.
 - Write [good test docstrings](https://jml.io/pages/test-docstrings.html).

.github/workflows/main.yml

@@ -23,7 +23,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["2.7", "3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "pypy-2.7", "pypy-3.7", "pypy-3.8"]
+        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "pypy-3.7", "pypy-3.8"]
 
     steps:
       - uses: actions/checkout@v3

.pre-commit-config.yaml

@@ -8,12 +8,20 @@ repos:
     hooks:
       - id: black
 
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v2.31.1
+    hooks:
+      - id: pyupgrade
+        args: [--py3-plus, --keep-percent-format]
+        exclude: "tests/test_slots.py"
+
   - repo: https://github.com/PyCQA/isort
     rev: 5.10.1
     hooks:
       - id: isort
         additional_dependencies: [toml]
         files: \.py$
+        language_version: python3.10  # needed for match
 
   - repo: https://github.com/PyCQA/flake8
     rev: 4.0.1

README.rst

@@ -117,7 +117,8 @@ Project Information
 its documentation lives at `Read the Docs <https://www.attrs.org/>`_,
 the code on `GitHub <https://github.com/python-attrs/attrs>`_,
 and the latest release on `PyPI <https://pypi.org/project/attrs/>`_.
-It’s rigorously tested on Python 2.7, 3.5+, and PyPy.
+It’s rigorously tested on Python 3.5+ and PyPy.
+The last version with Python 2.7 support is `21.4.0 <https://pypi.org/project/attrs/21.4.0/>`_.
 
 We collect information on **third-party extensions** in our `wiki <https://github.com/python-attrs/attrs/wiki/Extensions-to-attrs>`_.
 Feel free to browse and add your own!

changelog.d/936.breaking.rst

@@ -0,0 +1,6 @@
+Python 2.7 is not supported anymore.
+
+Dealing with Python 2.7 tooling has become too difficult for a volunteer-run project.
+
+We have supported Python 2 more than 2 years after it was officially discontinued and feel that we have paid our dues.
+All version up to 21.4.0 from December 2021 remain fully functional, of course.

conftest.py

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: MIT
 
-from __future__ import absolute_import, division, print_function
 
 from hypothesis import HealthCheck, settings
 

docs/index.rst

@@ -89,7 +89,6 @@ Full Table of Contents
    :maxdepth: 1
 
    license
-   python-2
    changelog
 
 

docs/why.rst

@@ -20,7 +20,7 @@ Whether they're relevant to *you* depends on your circumstances:
   There is a long list of features that were sacrificed for the sake of simplicity and while the most obvious ones are validators, converters, :ref:`equality customization <custom-comparison>`, or :doc:`extensibility <extending>` in general, it permeates throughout all APIs.
 
   On the other hand, Data Classes currently do not offer any significant feature that ``attrs`` doesn't already have.
-- ``attrs`` supports all mainstream Python versions, including CPython 2.7 and PyPy.
+- ``attrs`` supports all mainstream Python versions including PyPy.
 - ``attrs`` doesn't force type annotations on you if you don't like them.
 - But since it **also** supports typing, it's the best way to embrace type hints *gradually*, too.
 - While Data Classes are implementing features from ``attrs`` every now and then, their presence is dependent on the Python version, not the package version.

setup.py

@@ -32,8 +32,6 @@
     "License :: OSI Approved :: MIT License",
     "Operating System :: OS Independent",
     "Programming Language :: Python",
-    "Programming Language :: Python :: 2",
-    "Programming Language :: Python :: 2.7",
     "Programming Language :: Python :: 3",
     "Programming Language :: Python :: 3.5",
     "Programming Language :: Python :: 3.6",
@@ -56,7 +54,6 @@
         "hypothesis",
         "pympler",
         "pytest>=4.3.0",  # 4.3.0 dropped last use of `convert`
-        "six",
     ],
 }
 if (
@@ -143,7 +140,7 @@ def find_meta(meta):
         long_description_content_type="text/x-rst",
         packages=PACKAGES,
         package_dir={"": "src"},
-        python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*",
+        python_requires=">=3.5",
         zip_safe=False,
         classifiers=CLASSIFIERS,
         install_requires=INSTALL_REQUIRES,

src/attr/__init__.py

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: MIT
 
-from __future__ import absolute_import, division, print_function
 
 import sys
 

src/attr/_cmp.py

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: MIT
 
-from __future__ import absolute_import, division, print_function
 
 import functools