Support "stub_distribution" and "upload" metadata fields (#9256)

CONTRIBUTING.md

@@ -176,6 +176,9 @@ supported:
 * `extra_description` (optional): Can be used to add a custom description to
   the package's long description. It should be a multi-line string in
   Markdown format.
+* `stub_distribution` (optional): Distribution name to be uploaded to PyPI.
+  This defaults to `types-<distribution>` and should only be set in special
+  cases.
 * `obsolete_since` (optional): This field is part of our process for
   [removing obsolete third-party libraries](#third-party-library-removal-policy).
   It contains the first version of the corresponding library that ships
@@ -183,6 +186,9 @@ supported:
 * `no_longer_updated` (optional): This field is set to `true` before removing
   stubs for other reasons than the upstream library shipping with type
   information.
+* `upload` (optional): This field is set to `false` to prevent automatic
+  uploads to PyPI. This should only used in special cases, e.g. when the stubs
+  break the upload.
 
 In addition, we specify configuration for stubtest in the `tool.stubtest` table.
 This has the following keys:

tests/check_consistent.py

@@ -17,11 +17,22 @@ from packaging.specifiers import SpecifierSet
 from packaging.version import Version
 from utils import VERSIONS_RE, get_all_testcase_directories, get_gitignore_spec, spec_matches_path, strip_comments
 
-metadata_keys = {"version", "requires", "extra_description", "obsolete_since", "no_longer_updated", "tool"}
+metadata_keys = {
+    "version",
+    "requires",
+    "extra_description",
+    "stub_distribution",
+    "obsolete_since",
+    "no_longer_updated",
+    "upload",
+    "tool",
+}
 tool_keys = {"stubtest": {"skip", "apt_dependencies", "extras", "ignore_missing_stub", "platforms"}}
 extension_descriptions = {".pyi": "stub", ".py": ".py"}
 supported_stubtest_platforms = {"win32", "darwin", "linux"}
 
+dist_name_re = re.compile(r"^[a-z0-9]([a-z0-9._-]*[a-z0-9])?$", re.IGNORECASE)
+
 
 def assert_consistent_filetypes(
     directory: Path, *, kind: str, allowed: set[str], allow_nonidentifier_filenames: bool = False
@@ -40,7 +51,7 @@ def assert_consistent_filetypes(
         if entry.is_file():
             if not allow_nonidentifier_filenames:
                 assert entry.stem.isidentifier(), f'Files must be valid modules, got: "{entry}"'
-                bad_filetype = f'Only {extension_descriptions[kind]!r} files allowed in the "{directory}" directory; got: {entry}'
+            bad_filetype = f'Only {extension_descriptions[kind]!r} files allowed in the "{directory}" directory; got: {entry}'
             assert entry.suffix == kind, bad_filetype
         else:
             assert entry.name.isidentifier(), f"Directories must be valid packages, got: {entry}"
@@ -150,6 +161,11 @@ def check_metadata() -> None:
             # Check that the requirement parses
             Requirement(dep)
 
+        if "stub_distribution" in data:
+            assert dist_name_re.fullmatch(data["stub_distribution"]), f"Invalid 'stub_distribution' value for {distribution!r}"
+
+        assert isinstance(data.get("upload", True), bool), f"Invalid 'upload' value for {distribution!r}"
+
         assert set(data.get("tool", [])).issubset(tool_keys.keys()), f"Unrecognised tool for {distribution}"
         for tool, tk in tool_keys.items():
             for key in data.get("tool", {}).get(tool, {}):