As I was making this change, and adapting the mypy codebase to include some new stubs, I realized that the requirements.txt files tell you to run pip-compile --output-file=test-requirements.txt --strip-extras --allow-unsafe test-requirements.in, and thus have an implicit undeclared requirement on pip-tools. I tried adding this to build-requirements.txt but that broke some things so I put it in a new extra called dev instead.

Author: wyattscarpenter

pyproject.toml

@@ -65,6 +65,10 @@ python2 = []
 reports = ["lxml"]
 install-types = ["pip"]
 faster-cache = ["orjson"]
+dev = [
+  "pip-tools", # Not strictly needed for building per se, but pip-compile from this package is needed if you want to update the requirement files. (Word on the street is you can also use uv pip compile instead.)
+  "pip<24.3" # Needed to update the requirement files correctly with pip-tools ay ay ay https://github.com/jazzband/pip-tools/issues/2131
+]
 
 [project.urls]
 Homepage = "https://www.mypy-lang.org/"