Add Ruff and mypy configuration files (#283)

## Summary

I think it's useful that running `ruff check` or `mypy` enforces the configuration we enforce in CI.

check.py

@@ -54,19 +54,9 @@ def run():
     )
     args = parser.parse_args()
 
-    # Lints:
-    #   Sort imports
-    #   Unused import
-    #   Unused variable
-    check_args = ["--select", "I,F401,F841"]
+    check_args = []
     format_args = []
-    mypy_args = [
-        "pythonbuild",
-        "check.py",
-        "build-linux.py",
-        "build-macos.py",
-        "build-windows.py",
-    ]
+    mypy_args = []
 
     if args.fix:
         check_args.append("--fix")

mypy.ini

@@ -0,0 +1,9 @@
+[mypy]
+warn_no_return = True
+warn_redundant_casts = True
+warn_return_any = True
+warn_unused_configs = True
+warn_unused_ignores = True
+warn_unreachable = True
+
+files = pythonbuild,check.py,build-linux.py,build-macos.py,build-windows.py

pythonbuild/utils.py

@@ -44,10 +44,10 @@ def supported_targets(yaml_path: pathlib.Path):
     targets = set()
 
     for target, settings in get_targets(yaml_path).items():
-        for platform in settings["host_platforms"]:
-            if sys.platform == "linux" and platform == "linux64":
+        for host_platform in settings["host_platforms"]:
+            if sys.platform == "linux" and host_platform == "linux64":
                 targets.add(target)
-            elif sys.platform == "darwin" and platform == "macos":
+            elif sys.platform == "darwin" and host_platform == "macos":
                 targets.add(target)
 
     return targets
@@ -305,9 +305,7 @@ def download_entry(key: str, dest_path: pathlib.Path, local_name=None) -> pathli
     assert isinstance(size, int)
     assert isinstance(sha256, str)
 
-    local_name = local_name or url[url.rindex("/") + 1 :]
-
-    local_path = dest_path / local_name
+    local_path = dest_path / (local_name or url[url.rindex("/") + 1 :])
     download_to_path(url, local_path, size, sha256)
 
     return local_path
@@ -466,7 +464,7 @@ def add_licenses_to_extension_entry(entry):
         if "path_static" in link or "path_dynamic" in link:
             have_local_link = True
 
-        for key, value in DOWNLOADS.items():
+        for value in DOWNLOADS.values():
             if name not in value.get("library_names", []):
                 continue
 

ruff.toml

@@ -0,0 +1,2 @@
+[lint]
+select = ["F", "I", "B"]