Support Python 3.9 (#1287)

Author: sbryngelson

.github/workflows/test-toolchain-compat.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ['3.10', '3.11', '3.12', '3.13', '3.14']
+        python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5

docs/postprocess_citations.py

@@ -7,6 +7,8 @@
 Usage: python3 postprocess_citations.py <html_output_dir>
 """
 
+from __future__ import annotations
+
 import re
 import sys
 from pathlib import Path

toolchain/bootstrap/python.sh

@@ -1,7 +1,7 @@
 #!/bin/bash
 
 MFC_PYTHON_MIN_MAJOR=3
-MFC_PYTHON_MIN_MINOR=10
+MFC_PYTHON_MIN_MINOR=9
 MFC_PYTHON_MIN_STR="$MFC_PYTHON_MIN_MAJOR.$MFC_PYTHON_MIN_MINOR"
 
 is_python_compatible() {

toolchain/mfc/gen_case_constraints_docs.py

@@ -8,6 +8,8 @@
 Also generates case design playbook from curated working examples.
 """  # pylint: disable=too-many-lines
 
+from __future__ import annotations
+
 import json
 import sys
 import subprocess

toolchain/mfc/params/ast_analyzer.py

@@ -7,6 +7,8 @@
 and case_constraints.md).
 """
 
+from __future__ import annotations
+
 import ast
 import re
 from dataclasses import dataclass, field

toolchain/mfc/params/generators/docs_gen.py

@@ -5,6 +5,8 @@
 organized by family with descriptions, types, and constraints.
 """
 
+from __future__ import annotations
+
 from typing import Any, Dict, List, Tuple
 from collections import defaultdict
 import re