Improve detection of TYPE_CHECKING blocks imported from typing_extensions or _typeshed

[zanieb]

Improves detection of types imported from typing_extensions. Removes the hard-coded list of supported types in typing_extensions; instead assuming all types could be imported from typing, _typeshed, or typing_extensions.

The typing extensions package appears to re-export types even if they do not need modification.

Adds detection of if typing_extensions.TYPE_CHECKING blocks. Avoids inserting a new if TYPE_CHECKING block and from typing import TYPE_CHECKING if typing_extensions.TYPE_CHECKING is used (closes #8427)

[zanieb]

It looks like at

ruff/crates/ruff_linter/src/importer/mod.rs

Lines 135 to 139 in 1e173f7

	let (type_checking_edit, type_checking) = self.get_or_import_symbol(
	&ImportRequest::import_from("typing", "TYPE_CHECKING"),
	at,
	semantic,
	)?;

we need to check if a typing_extensions.TYPE_CHECKING block is used before inserting the typing.TYPE_CHECKING block to actually solve the issue.

[github-actions]

ruff-ecosystem results

Linter (stable)

✅ ecosystem check detected no linter changes.

Linter (preview)

✅ ecosystem check detected no linter changes.

[charliermarsh]

I decided to remove this behavior in which we check if the member is part of typing_extensions. We could retain it... but that list may vary over time, so hard-coding it makes Ruff less future-proof.

[zanieb]

Hm what's the effect of this then? Is it a breaking change?

[charliermarsh]

It's not breaking, it's more lax (the net effect is that we consider all imports from typing_extensions to be treated equivalently to typing, rather than the allow-list that we encoded of specific members). But let's back it out.

[charliermarsh]

@zanieb - I decided to finish this one up -- feel free to review and merge.

[zanieb]

fyi using matches! really broke things because target here isn't what you wanted — it's capturing second item in the slice not using the provided target.

[zanieb]

fixed in 545bd30 — not sure how else to write it