David Peter 2296627528 [red-knot] Precise inference for identity checks (#14109) ... ## Summary Adds more precise type inference for `… is …` and `… is not …` identity checks in some limited cases where we statically know the answer to be either `Literal[True]` or `Literal[False]`. I found this helpful while working on type inference for comparisons involving intersection types, but I'm not sure if this is at all useful for real world code (where the answer is most probably *not* statically known). Note that we already have *type narrowing* for identity tests. So while we are already able to generate constraints for things like `if x is None`, we can now — in some limited cases — make an even stronger conclusion and infer that the test expression itself is `Literal[False]` (branch never taken) or `Literal[True]` (branch always taken). ## Test Plan New Markdown tests		2024-11-05 19:48:52 +01:00
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instances	[red-knot] Literal special form (#13874)	2024-11-05 01:45:46 +00:00
byte_literals.md	[red-knot] have mdformat wrap mdtest files to 100 columns (#14020)	2024-10-31 21:00:51 +00:00
identity_tests.md	[red-knot] Precise inference for identity checks (#14109)	2024-11-05 19:48:52 +01:00
integers.md	[red-knot] Type inference for comparisons between arbitrary instances (#13903)	2024-10-26 18:19:56 +00:00
non_boolean_returns.md	[red-knot] have mdformat wrap mdtest files to 100 columns (#14020)	2024-10-31 21:00:51 +00:00
strings.md	[red-knot] Format mdtest Python snippets more concisely (#13905)	2024-10-24 11:09:31 +00:00
tuples.md	[red-knot] have mdformat wrap mdtest files to 100 columns (#14020)	2024-10-31 21:00:51 +00:00
unions.md	[red-knot] have mdformat wrap mdtest files to 100 columns (#14020)	2024-10-31 21:00:51 +00:00
unsupported.md	[red-knot] Type inference for comparisons between arbitrary instances (#13903)	2024-10-26 18:19:56 +00:00