Infer literal types in analyze_var_ref #11340
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mypy/types.py
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| # such a type directly into "None". So, "None" is not a valid parameter of | ||
| # LiteralType and is omitted from this list. | ||
| LiteralValue: _TypeAlias = Union[int, str, bool] | ||
| LiteralValue: _TypeAlias = Union[int, str, float, bool] |
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According to PEP 586, which describes Literal, floats are currently not allowed as Literals:
The following are provisionally disallowed for simplicity. We can consider allowing them in future extensions of this PEP.
Floats: e.g. Literal[3.14]. Representing Literals of infinity or NaN in a clean way is tricky; real-world APIs are unlikely to vary their behavior based on a float parameter.
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Thanks for pointing out!
| # If `var` has final_value, we could update its type with literal type. | ||
| if var.name in {'True', 'False'}: | ||
| return self.infer_literal_expr_type(var.name == 'True', 'builtins.bool') | ||
| if isinstance(var.final_value, int) or isinstance(var.final_value, str): |
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Literal[float] is illegal. And we actually treat bytes as str in mypy for convenience.
| and self.last_known_value == other.last_known_value) | ||
| and self.args == other.args) | ||
| # TODO: last_known_value is not set correctly at initializations of Literal type | ||
| # and self.last_known_value == other.last_known_value) |
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This change is not safe, since now two Instance objects that compare equal can have different hash values.
Since these support hashing, it seems necessary to also use last_known_value when comparing for equality. Otherwise all sorts of weird (and hard-to-debug) things could happen.
I think that fixing the value of last_known_value could be the way to go. Alternatively, it may be feasible to replace == with comparing type and args attributes in selected contexts only (e.g. replace i1 == i2 with i1.type == i2.type and i1.args == i2.args), but I'm not sure about this.
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| def infer_literal_expr_type(self, value: LiteralValue, fallback_name: str) -> Type: | ||
| def infer_literal_expr_type(self, value: LiteralValue, fallback_name: str, | ||
| fallback_typ: Optional[Instance] = None) -> Type: |
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This signature is now a bit awkward. I think that it would be better to always only take an Instance, and some callers can be updated to use self.named_type.
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Description
Partially fixes #11336.
This PR adds inferring for final types when analyzing vars.
The
last_known_valueof annotation types are set withNonecurrently, which would bring a lot of false positive when comparingInstance. I have to silence it temporally. We should check all the cases oflast_known_valueinitialization and then remove the comments in the following PRs.Test Plan
testFormatCallMatchingFinaltestFormatCallFinalChartestLiteralFineGrainedChainedViaFinalandtestLiteralFinalDirectInstanceTypesSupercedeInferredLiteral, which were wrong previously.