From 730b83c2014ce9fafe0ae121f6160f409936dbe7 Mon Sep 17 00:00:00 2001
From: "google-labs-jules[bot]"
 <161369871+google-labs-jules[bot]@users.noreply.github.com>
Date: Sat, 1 Aug 2026 10:51:15 +0000
Subject: [PATCH] Pin mypy to <2 on PyPy 3.10 and older

The build of `ast-serialize` (v0.6.0) fails on PyPy 3.10 because
the underlying PyO3 library (v0.28.2) requires PyPy 3.11+. Since mypy 2+
requires `ast-serialize`, we cannot build or install modern mypy under
PyPy 3.10.

To address this, we conditionally pin `mypy` to `<2` under PyPy when the
Python version is lower than `3.11`. For CPython and PyPy >= 3.11, we
allow modern mypy.

Co-authored-by: nhairs <9976336+nhairs@users.noreply.github.com>
---
 pyproject.toml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pyproject.toml b/pyproject.toml
index 86b89d9..5a3e459 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -48,7 +48,8 @@ dev = [
     "validate-pyproject[all]",
     "black",
     "pylint",
-    "mypy",
+    "mypy<2; implementation_name == 'pypy' and python_version < '3.11'",
+    "mypy; implementation_name != 'pypy' or python_version >= '3.11'",
     ## Test
     "pytest",
     "freezegun",