Add mypy coverage for generate_sbom.py

Author: sethmlarson

.github/workflows/mypy.yml

@@ -9,6 +9,7 @@ on:
     paths:
       - ".github/workflows/mypy.yml"
       - "Lib/test/libregrtest/**"
+      - "Tools/build/generate_sbom.py"
       - "Tools/cases_generator/**"
       - "Tools/clinic/**"
       - "Tools/peg_generator/**"
@@ -34,6 +35,7 @@ jobs:
       matrix:
         target: [
           "Lib/test/libregrtest",
+          "Tools/build/",
           "Tools/cases_generator",
           "Tools/clinic",
           "Tools/peg_generator",

Tools/build/generate_sbom.py

@@ -78,7 +78,7 @@ def spdx_id(value: str) -> str:
     return re.sub(r"[^a-zA-Z0-9.\-]+", "-", value)
 
 
-def main():
+def main() -> None:
     root_dir = pathlib.Path(__file__).parent.parent.parent
     sbom_path = root_dir / "Misc/sbom.spdx.json"
     sbom_data = json.loads(sbom_path.read_bytes())

Tools/build/mypy.ini

@@ -0,0 +1,13 @@
+[mypy]
+files = Tools/build/generate_sbom.py
+pretty = True
+
+# Make sure Python can still be built
+# using Python 3.10 for `PYTHON_FOR_REGEN`...
+python_version = 3.10
+
+# ...And be strict:
+strict = True
+strict_concatenate = True
+enable_error_code = ignore-without-code,redundant-expr,truthy-bool,possibly-undefined
+warn_unreachable = True