ruff

ce06094a - [ty] Remove unnecessary `.expect()` call from `types/instance.rs` (#21527)

[ty] Remove unnecessary `.expect()` call from `types/instance.rs` (#21527) ## Summary The `.expect()` call here: https://github.com/astral-sh/ruff/blob/5dd56264fb4e394c9919cf897cab39f52ccba124/crates/ty_python_semantic/src/types/instance.rs#L816-L827 is the direct cause of the panic in https://github.com/astral-sh/ty/issues/1587. This patch gets rid of the panic by refactoring our `Protocol` enum so that the `Protocol::FromClass` variant holds a `ProtocolClass` instance rather than a `ClassType` instance (all the `.expect()` call was doing was attempting to convert form a `ClassType` to a `ProtocolClass`). I hoped that this would provide a fix for https://github.com/astral-sh/ty/issues/1587, but we still panic on the provided reproducible examples in that issue even with this PR. Nonetheless, I think this PR is a worthwhile change to make because: - It's probably slightly more efficient this way (we no longer have to re-verify that the wrapped class in a `Protocol::FromClass()` variant is a protocol class every time we want to access its interface) - It's nice to get rid of `.expect()` calls where possible, and this one seems definitely unnecessary - The _new_ panic message on this PR branch makes it much clearer what the underlying cause of the bug in https://github.com/astral-sh/ty/issues/1587 is: <details> <summary>New panic message</summary> ``` error[panic]: Panicked at /Users/alexw/.cargo/git/checkouts/salsa-e6f3bb7c2a062968/a885bb4/src/function/execute.rs:321:21 when checking `/Users/alexw/dev/ruff/foo.py`: `ClassLiteral < 'db >::explicit_bases_(Id(4c09)): execute: too many cycle iterations` info: This indicates a bug in ty. info: If you could open an issue at https://github.com/astral-sh/ty/issues/new?title=%5Bpanic%5D, we'd be very appreciative! info: Platform: macos aarch64 info: Version: ruff/0.14.5+60 (18a14bfaf 2025-11-19) info: Args: ["target/debug/ty", "check", "foo.py", "--python-version=3.14"] info: run with `RUST_BACKTRACE=1` environment variable to show the full backtrace information info: query stacktrace: 0: cached_protocol_interface(Id(6805)) at crates/ty_python_semantic/src/types/protocol_class.rs:790 1: is_equivalent_to_object_inner(Id(8003)) at crates/ty_python_semantic/src/types/instance.rs:667 2: infer_deferred_types(Id(1409)) at crates/ty_python_semantic/src/types/infer.rs:141 cycle heads: infer_definition_types(Id(140b)) -> iteration = 200, TypeVarInstance < 'db >::lazy_bound_(Id(5803)) -> iteration = 200 3: TypeVarInstance < 'db >::lazy_bound_(Id(5802)) at crates/ty_python_semantic/src/types.rs:8734 4: infer_definition_types(Id(140c)) at crates/ty_python_semantic/src/types/infer.rs:94 5: infer_deferred_types(Id(140a)) at crates/ty_python_semantic/src/types/infer.rs:141 6: TypeVarInstance < 'db >::lazy_bound_(Id(5803)) at crates/ty_python_semantic/src/types.rs:8734 7: infer_definition_types(Id(140b)) at crates/ty_python_semantic/src/types/infer.rs:94 8: infer_scope_types(Id(1000)) at crates/ty_python_semantic/src/types/infer.rs:70 9: check_file_impl(Id(c00)) at crates/ty_project/src/lib.rs:535 Found 1 diagnostic WARN A fatal error occurred while checking some files. Not all project files were analyzed. See the diagnostics list above for details. ``` </details> ## Test Plan All existing tests pass.