Type annotations for SharedDataMiddleware produce mypy errors in common circumstances

[alexdotgov2]

werkzeug/src/werkzeug/middleware/shared_data.py

Lines 102 to 113 in 5add63c

	def __init__(
	self,
	app: WSGIApplication,
	exports: (
	dict[str, str | tuple[str, str]]
	| t.Iterable[tuple[str, str | tuple[str, str]]]
	),
	disallow: None = None,
	cache: bool = True,
	cache_timeout: int = 60 * 60 * 12,
	fallback_mimetype: str = "application/octet-stream",
	) -> None:

exports is annotated as dict[str, str | tuple[str, str]] (plus the iterable case). Because dict is invariant, passing a simple dict[str, str] actually produces a mypy error! Users can work around this by manually annotating the data as dict[str, str | tuple[str, str]], but this is very unergonomic.

https://mypy-play.net/?mypy=latest&python=3.12&gist=7194ebea2b603890033453b8d735e232 is a minimal demonstration of this issue, and the recommended workaround: annotating the value as collections.Mapping instead.