build: broaden the ruff rule set and lint conanfile.py

Makefile

@@ -62,7 +62,8 @@ TIDY_SOURCES = $(shell find src tests -type f -name '*.cpp')
 # Conan's, not prettier's.
 PRETTIER_SOURCES = $(shell git ls-files '*.md' '*.json' '*.yml' '*.yaml' ':!conan.lock')
 MARKDOWN_SOURCES = $(shell git ls-files '*.md')
-PYTHON_SOURCES = scripts/
+# Lint and format conanfile.py alongside the first-party Python scripts
+PYTHON_SOURCES = scripts/ conanfile.py
 
 define require-tool
 	command -v $(1) >/dev/null || $(DIE) "$(1) not found"

README.md

@@ -221,15 +221,20 @@ make lint
 ```
 
 `make format` and `make format-check` cover C++ sources (clang-format), `CMakeLists.txt`
-(cmake-format, from the [cmakelang](https://cmake-format.readthedocs.io) package), Python scripts
-([ruff](https://docs.astral.sh/ruff/) format), and tracked Markdown/JSON/YAML files
-([prettier](https://prettier.io); `conan.lock` is excluded because Conan owns its formatting).
-`make lint` runs clang-tidy against the debug compilation database, `cmake-lint` on
-`CMakeLists.txt`, `ruff check` on `scripts/`, and
+(cmake-format, from the [cmakelang](https://cmake-format.readthedocs.io) package), Python sources in
+`scripts/` and `conanfile.py` ([ruff](https://docs.astral.sh/ruff/) format), and tracked
+Markdown/JSON/YAML files ([prettier](https://prettier.io); `conan.lock` is excluded because Conan
+owns its formatting). `make lint` runs clang-tidy against the debug compilation database,
+`cmake-lint` on `CMakeLists.txt`, `ruff check` on those Python sources, and
 [markdownlint](https://github.com/DavidAnson/markdownlint-cli2) on Markdown files. Any reported
 finding fails the target. CI pins all lint and format tool versions in
 [`.github/ci.env`](.github/ci.env).
 
+[`ruff.toml`](ruff.toml) extends Ruff's `E4`, `E7`, `E9`, and `F` defaults to all `E` checks, then
+adds import ordering (`I`), Python modernization (`UP`), likely bugs (`B`), simplification (`SIM`),
+Ruff-specific rules (`RUF`), and annotations (`ANN`). As with `.clang-tidy`, every finding fails the
+lint target.
+
 ## Coverage
 
 Build, test, and generate an HTML coverage report with an enforced line floor:

ruff.toml

@@ -1,3 +1,22 @@
 # 100 columns, matching the repo-wide convention (.clang-format, .cmake-format.yaml, and
 # .editorconfig/markdownlint all use 100); ruff's default is 88.
 line-length = 100
+
+[lint]
+# Ruff enables E4, E7, E9, and F by default. Add all E checks plus import ordering, Python
+# modernization, likely bugs, simplification, Ruff-specific rules, and annotations. As with
+# clang-tidy, every finding is an error. ANN keeps existing type annotations complete.
+select = ["E", "F", "I", "UP", "B", "SIM", "RUF", "ANN"]
+
+[lint.isort]
+# The local conan/ directory contains settings_user.yml, but its name shadows the third-party conan
+# package. isort's source detection therefore classifies `from conan import ConanFile` as
+# first-party and separates it from the conan.tools imports. Mark the package as third-party
+# explicitly.
+known-third-party = ["conan"]
+
+[lint.per-file-ignores]
+# Conan reads the recipe's options and default_options class attributes as dictionaries, so
+# RUF012's ClassVar/__init__ guidance does not apply. Conan also invokes recipe methods through an
+# untyped callback API, where the annotations required by ANN would add no useful information.
+"conanfile.py" = ["RUF012", "ANN"]

scripts/rename.py

@@ -12,11 +12,11 @@
 from __future__ import annotations
 
 import argparse
-from pathlib import Path
 import re
 import shutil
 import subprocess
 import sys
+from pathlib import Path
 
 OLD_SNAKE = "cpp_boilerplate"
 OLD_KEBAB = "cpp-boilerplate"