Add linting to CI via pre-commit

.flake8

@@ -0,0 +1,2 @@
+[flake8]
+max_line_length = 88

.github/PULL_REQUEST_TEMPLATE.md

@@ -8,4 +8,4 @@ It should describe the change to be made.
 
 Most PRs will require an issue number. Trivial changes, like fixing a typo,
 do not need an issue.
--->
+-->

.github/workflows/lint.yml

@@ -0,0 +1,14 @@
+name: Lint
+
+on: [push, pull_request, workflow_dispatch]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: "3.x"
+      - uses: pre-commit/action@v3.0.0

.pre-commit-config.yaml

@@ -0,0 +1,41 @@
+repos:
+  - repo: https://github.com/asottile/pyupgrade
+    rev: v3.2.2
+    hooks:
+      - id: pyupgrade
+        args: [--py37-plus]
+
+  - repo: https://github.com/psf/black
+    rev: 22.10.0
+    hooks:
+      - id: black
+        args: [--target-version=py37, --skip-string-normalization]
+
+  - repo: https://github.com/PyCQA/isort
+    rev: 5.10.1
+    hooks:
+      - id: isort
+        args: [--profile=black]
+
+  - repo: https://github.com/PyCQA/flake8
+    rev: 5.0.4
+    hooks:
+      - id: flake8
+        additional_dependencies: [flake8-2020]
+
+  - repo: https://github.com/pre-commit/pygrep-hooks
+    rev: v1.9.0
+    hooks:
+      - id: python-check-blanket-noqa
+
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.3.0
+    hooks:
+      - id: check-json
+      - id: check-merge-conflict
+      - id: check-yaml
+      - id: end-of-file-fixer
+      - id: trailing-whitespace
+
+ci:
+  autoupdate_schedule: quarterly

LICENSE

@@ -113,4 +113,4 @@ Affirmer's express Statement of Purpose.
   CC0 or use of the Work.
 
 For more information, please see
-<https://creativecommons.org/publicdomain/zero/1.0/>
+<https://creativecommons.org/publicdomain/zero/1.0/>

Makefile

@@ -38,6 +38,7 @@ help:
 	@echo "  linkcheck  to check all external links for integrity"
 	@echo "  doctest    to run all doctests embedded in the documentation (if enabled)"
 	@echo "  check      to run a check for frequent markup errors"
+	@echo "  lint       to lint all the files"
 	@echo "  versions   to update release cycle after changing release-cycle.json"
 
 .PHONY: clean
@@ -183,6 +184,11 @@ check: ensure-venv
 	# Ignore the tools and venv dirs and check that the default role is not used.
 	$(SPHINXLINT) -i tools -i $(VENVDIR) --enable default-role
 
+.PHONY: lint
+lint: venv
+	$(VENVDIR)/bin/python3 -m pre_commit --version > /dev/null || $(VENVDIR)/bin/python3 -m pip install pre-commit
+	$(VENVDIR)/bin/python3 -m pre_commit run --all-files
+
 .PHONY: serve
 serve:
 	@echo "The 'serve' target was removed, use 'htmlview' instead" \

_extensions/custom_roles.py

@@ -35,8 +35,9 @@ def role(name, rawtext, text, lineno, inliner, _options=None, _content=None):
         if text.startswith('!'):
             node = nodes.literal(rawtext, text[1:])
         else:
-            node = nodes.reference(rawtext, '', nodes.literal(rawtext, text),
-                                   refuri=url, internal=False)
+            node = nodes.reference(
+                rawtext, '', nodes.literal(rawtext, text), refuri=url, internal=False
+            )
         return [node], []
 
     return role

developer-workflow/lang-changes.rst

@@ -86,4 +86,3 @@ to inform others who may propose a similar language change in the future.
 .. _Ideas Discourse category: https://discuss.python.org/c/ideas/6
 .. _Status Quo Wins a Stalemate: https://www.curiousefficiency.org/posts/2011/02/status-quo-wins-stalemate.html
 .. _Justifying Python Language Changes: https://www.curiousefficiency.org/posts/2011/02/justifying-python-language-changes.html
-