296d67a496
## Summary Currently for something like `X = typing.Tuple[str, str]`, we infer the value of `X` as `object`. That's because `Tuple` (like many of the symbols in the typing module) is annotated as a `_SpecialForm` instance in typeshed's stubs:23382f5f8c/crates/red_knot_vendored/vendor/typeshed/stdlib/typing.pyi (L215)and we don't understand implicit type aliases yet, and the stub for `_SpecialForm.__getitem__` says it always returns `object`:23382f5f8c/crates/red_knot_vendored/vendor/typeshed/stdlib/typing.pyi (L198-L200)We have existing false positives in our test suite due to this:23382f5f8c/crates/red_knot_python_semantic/resources/mdtest/annotations/annotated.md (L76-L78)and it's causing _many_ new false positives in #16872, which tries to make our annotation-expression parsing stricter in some ways. This PR therefore adds some small special casing for `KnownInstanceType` variants that fallback to `_SpecialForm`, so that these false positives can be avoided. ## Test Plan Existing mdtest altered. Cc. @MatthewMckee4
Markdown files within the mdtest/ subdirectory are tests of type inference and type checking;
executed by the tests/mdtest.rs integration test.
See crates/red_knot_test/README.md for documentation of this test format.