fix: refuse Python 3.8 in every build script

Only generate_pack.py and pipeline.py checked the interpreter. verify.py,
slots.py, validate_pr.py, cross_reference.py and the probe tools started
under 3.8 and stopped halfway on a str.removeprefix AttributeError. The
check now lives in common.py, which every build script imports, and in
core_probe.py and region_check.py, which do not. generate_site.py imports
common before siterender, which raised a TypeError at load under 3.8.

pyproject.toml

@@ -16,7 +16,8 @@ description = "BIOS collection manager for retrogaming platforms"
 # install.py is the only entry point a user runs before cloning, and both
 # bootstraps accept 3.8, so the floor stays where the bootstraps put it. That
 # floor covers install.py alone: the build scripts under scripts/ need 3.9
-# (pipeline.py checks it), and CI runs the test suite on 3.12.
+# (common.py, which every build script imports, checks it), and CI runs the
+# test suite on 3.12.
 requires-python = ">=3.8"
 dependencies = [
     "pyyaml",

scripts/campaign.py

@@ -83,14 +83,17 @@ from collections.abc import Callable, Iterator, Sequence
 from dataclasses import dataclass, field
 from pathlib import Path
 
-import yaml
-
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 
+# First: core_probe stops an interpreter older than 3.9 before anything else
+# fails on it.
+import core_probe
+
+import yaml
+
 import autorun
 import campaign_profiles
 import campaign_rules as rules
-import core_probe
 import measurement_records as mr
 
 ROOT = Path(__file__).resolve().parent.parent

scripts/common.py

@@ -20,6 +20,15 @@ import sys
 import zipfile
 from pathlib import Path
 
+# Every build script imports this module. verify.py, slots.py, validate_pr.py
+# and cross_reference.py started under 3.8 and stopped halfway on a
+# str.removeprefix AttributeError, which named no version.
+if sys.version_info < (3, 9):
+    sys.exit(
+        f"{Path(sys.argv[0]).name} needs Python 3.9 or newer, "
+        f"this is {sys.version.split()[0]}"
+    )
+
 
 try:
     import yaml

scripts/core_probe.py

@@ -40,6 +40,14 @@ from collections.abc import Iterable, Iterator, Sequence
 from dataclasses import dataclass, field
 from pathlib import Path
 
+# The probe tools do not import common.py, which states the 3.9 floor for the
+# other scripts. Under 3.8 they stopped on a str.removesuffix AttributeError.
+if sys.version_info < (3, 9):
+    sys.exit(
+        f"{Path(sys.argv[0]).name} needs Python 3.9 or newer, "
+        f"this is {sys.version.split()[0]}"
+    )
+
 ROOT = Path(__file__).resolve().parent.parent
 MIN_BENCH_REPETITIONS = 5
 DEFAULT_WORK_DIR = ROOT / "tmp" / "core_probe"

scripts/generate_site.py

@@ -14,7 +14,6 @@ Usage:
 
 from __future__ import annotations
 
-from siterender import SECTION_LABELS, WIKI_SRC_DIR
 import argparse
 import csv
 import hashlib
@@ -64,6 +63,7 @@ from common import (
     unique_emulator_profiles,
     yaml_load,
 )
+from siterender import SECTION_LABELS, WIKI_SRC_DIR
 from artifacts import ArtifactLockBusy, artifact_lock
 from artifacts import json_text as _json_text
 from cross_reference import FileConsumers, entry_target, held_copy

scripts/region_check.py

@@ -36,6 +36,14 @@ import urllib.request
 from collections.abc import Callable, Iterable
 from pathlib import Path
 
+# The probe tools do not import common.py, which states the 3.9 floor for the
+# other scripts. Under 3.8 they stopped on a str.removesuffix AttributeError.
+if sys.version_info < (3, 9):
+    sys.exit(
+        f"{Path(sys.argv[0]).name} needs Python 3.9 or newer, "
+        f"this is {sys.version.split()[0]}"
+    )
+
 sys.path.insert(0, str(Path(__file__).resolve().parent))
 
 import yaml  # noqa: E402

tests/test_audit_regressions.py

@@ -136,6 +136,41 @@ class ReadmeRegressions(unittest.TestCase):
         self.assertNotIn("SyntaxError", proc.stderr)
         self.assertIn("generate_pack.py needs Python 3.9", proc.stderr)
 
+    def test_every_script_names_the_floor_under_an_older_interpreter(self):
+        """Only generate_pack.py and pipeline.py checked the version. verify.py,
+        slots.py, validate_pr.py and cross_reference.py started under 3.8 and
+        stopped halfway on a str.removeprefix AttributeError."""
+        import shutil  # noqa: PLC0415
+
+        python38 = shutil.which("python3.8")
+        if python38 is None:
+            if os.environ.get("CI"):
+                self.fail("CI must provide python3.8")
+            self.skipTest("no python3.8 on PATH")
+        commands = (
+            ["verify.py", "--emulator", "handy"],
+            ["verify.py", "--platform", "batocera"],
+            ["validate_pr.py", "--json", "README.md"],
+            ["cross_reference.py", "--emulator", "handy"],
+            ["slots.py"],
+            ["identity.py"],
+            ["generate_site.py", "--help"],
+            ["campaign.py", "--help"],
+            ["region_check.py", "--help"],
+        )
+        for command in commands:
+            with self.subTest(command=" ".join(command)):
+                # -E -s rather than -I: -I drops the script's folder from
+                # sys.path, so the imports would fail before any check.
+                proc = subprocess.run(
+                    [python38, "-E", "-s", f"scripts/{command[0]}", *command[1:]],
+                    cwd=ROOT, capture_output=True, text=True, timeout=60,
+                    check=False,
+                )
+                self.assertEqual(proc.returncode, 1, proc.stderr)
+                self.assertNotIn("Traceback", proc.stderr)
+                self.assertIn(f"{command[0]} needs Python 3.9", proc.stderr)
+
     def test_the_floor_interpreter_imports_every_script(self):
         """Every module under scripts/ is loaded by a real interpreter of the
         floor version, as the installer's 3.8 floor is proven by running it.