bin scripts: Use the NoReturn type hint

The NoReturn type hint should be used to ensure the return type of
methods calling no-return methods are not falsely enforced to an
Optional return type.

Add the NoReturn type hint as needed and clear up existing Optional
returns together with any corresponding casts affected by the
above.

While there, also fix formatting.

1 files changed, 6 insertions, 7 deletions

diff --git a/bin/just-mr.py b/bin/just-mr.py
index 21413546..4b79c295 100755
--- a/bin/just-mr.py
+++ b/bin/just-mr.py
@@ -22,7 +22,7 @@ import sys
 import tempfile
 import time
 import zlib
-from typing import Any, Dict, List, Optional, Set, Tuple, Union, cast
+from typing import Any, Dict, List, NoReturn, Optional, Set, Tuple, Union, cast
 
 from argparse import ArgumentParser
 from pathlib import Path
@@ -140,7 +140,7 @@ def log(*args: str, **kwargs: Any) -> None:
     print(*args, file=sys.stderr, **kwargs)
 
 
-def fail(s: str, exit_code: int = 65) -> None:
+def fail(s: str, exit_code: int = 65) -> NoReturn:
     log(f"Error: {s}")
     sys.exit(exit_code)
 
@@ -701,7 +701,7 @@ def distdir_tree_id_file(content: str) -> str:
                         content)
 
 
-def distdir_checkout(desc: Json, repos: Json):
+def distdir_checkout(desc: Json, repos: Json) -> List[str]:
     """ Logic for processing the distdir repo type.
     """
     content: Dict[str, str] = {}
@@ -783,7 +783,7 @@ def distdir_checkout(desc: Json, repos: Json):
     ]
 
 
-def checkout(desc: Json, *, name: str, repos: Json) -> Optional[List[str]]:
+def checkout(desc: Json, *, name: str, repos: Json) -> List[str]:
     repo_desc = resolve_repo(desc, repos=repos)
     repo_type = repo_desc.get("type")
     if repo_type == "git":
@@ -965,8 +965,7 @@ def fetch(*,
             return os.path.commonpath([path, base]) == base
 
         # warn if fetch_dir is in invocation workspace
-        if g_WORKSPACE_ROOT and is_subpath(cast(str, fetch_dir),
-                                           g_WORKSPACE_ROOT):
+        if g_WORKSPACE_ROOT and is_subpath(fetch_dir, g_WORKSPACE_ROOT):
             repo = repos.get(main, {}).get("repository", {})
             repo_path = repo.get("path", None)
             if repo_path is not None and repo.get("type", None) == "file":
@@ -993,7 +992,7 @@ Warning: Writing distribution files to workspace location '{fetch_dir}',
             print("%r --> %r (content: %s)" % (repo, distfile, content))
             archive_fetch(repo_desc, content)
             shutil.copyfile(cas_path(content),
-                            os.path.join(cast(str, fetch_dir), distfile))
+                            os.path.join(fetch_dir, distfile))
 
     sys.exit(0)