[ty] Fix false-positive unsupported-operator for "symmetric" TypeVars#22756
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charliermarsh merged 1 commit intomainfrom Jan 23, 2026
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[ty] Fix false-positive unsupported-operator for "symmetric" TypeVars#22756charliermarsh merged 1 commit intomainfrom
unsupported-operator for "symmetric" TypeVars#22756charliermarsh merged 1 commit intomainfrom
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charliermarsh
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Typing conformance results improved 🎉The percentage of diagnostics emitted that were expected errors increased from 77.33% to 77.41%. The percentage of expected errors that received a diagnostic held steady at 69.23%. Summary
False positives removedDetails
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charliermarsh
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(I think this isn't quite right, revisiting.) |
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unsupported-operator for symmetric TypeVarsunsupported-operator for "symmetric" TypeVars
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I think this fix makes sense, but I'm not certain if there's a more "general" fix or whether this should be happening at a deeper level. |
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I think this fix makes sense, but I'm not certain if there's a more "general" fix or whether this should be happening at a deeper level.
I think you're right that this is a more pointed fix than what we (at least eventually) want.
For one, this only handles binary operators, not arbitrary method calls:
class A:
def method2(self, x: A) -> A: ...
def method3(self, x: A, y: A) -> A: ...
class B:
def method2(self, x: B) -> B: ...
def method3(self, x: B, y: B) -> B: ...
def f[T: (A, B)](a: T, b: T, c: T):
# both of these should be okay
a.method2(b)
a.method3(b, c)And another case we have to consider is an overloaded function:
class A: ...
class B: ...
@overload
def func(x: A, y: A) -> A: ...
@overload
def func(x: B, y: B) -> B: ...
def f[T: (A, B)](a: T, b: T):
# should be okay
func(a, b)But, I think to solve all of these examples in general, we need the new solver. That would let us create a constraint set that constrains both arguments (and the receiver that we did member lookup on!) simultaneously.
So given that, I'm okay with it landing this version as a stop-gap, since it definitely resolves some real false positives.
This was referenced Jan 23, 2026
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Union the return types Add more tests Also support unary Limit to symmetric typevar Simplfiy tests
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* main: (62 commits) [`refurb`] Do not add `abc.ABC` if already present (`FURB180`) (#22234) [ty] Add a new `assert-type-unspellable-subtype` diagnostic (#22815) [ty] Avoid duplicate syntax errors for `await` outside functions (#22826) [ty] Fix unary operator false-positive for constrained TypeVars (#22783) [ty] Fix binary operator false-positive for constrained TypeVars (#22782) [ty] Fix false-positive `unsupported-operator` for "symmetric" TypeVars (#22756) [`pydocstyle`] Clarify which quote styles are allowed (`D300`) (#22825) [ty] Use distributed versions of AND and OR on constraint sets (#22614) [ty] Add support for dict literals and dict() calls as default values for parameters with TypedDict types (#22161) Document `-` stdin convention in CLI help text (#22817) [ty] Make `infer_subscript_expression_types` a method on `Type` (#22731) [ty] Simplify `OverloadLiteral::spans` and `OverloadLiteral::parameter_span` (#22823) [ty] Require both `*args` and `**kwargs` when calling a `ParamSpec` callable (#22820) [ty] Handle tagged errors in conformance (#22746) Add `--color` cli option to force colored output (#22806) Identify notebooks by LSP didOpen instead of `.ipynb` file extension (#22810) [ty] Fix docstring rendering for literal blocks after doctests (#22676) [ty] Update salsa to fix out-of-order query validation (#22498) [ty] Inline cycle initial and recovery functions (#22814) [ty] Pass the generic context through the decorator (#22544) ...
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Summary
When a TypeVar has value constraints (e.g.,
TypeVar("Scalar", int, float)), we were reportingunsupported-operatorbecause the constrained TypeVars were being treated like unions -- we checked every possible combination, rather than understanding that both occurrences of the same TypeVar must have the same type.