Fix constrained TypeVar inference for Never - #11737
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Distinguish a matched Never constraint from mapSubtypes returning Never when no constraints match. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Only preserve a Never solver result when the source is Never and the TypeVar explicitly declares Never, avoiding conditional-type inference changes found by mypy_primer. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Require the concrete source to exactly match a declared constraint before treating a Never solver result as explicit. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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Distinguish user-declared Never constraints from synthetic Never results so constrained inference changes only for the intended case. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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🔒 Automated review in progress — Rich Chiodo (@rchiodo) is auto-reviewing this PR. |
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Result: 🔴 Verification detailsVerification: Isolated verification observed failures that were not classified as caused by this PR: Dependency and test discovery preflight. The relevant tests could not be fully run in the isolated environment; this review is not fully verified. Summary: No meaningful test execution was possible in the disposable environment. Dependency preparation could not start because `pnpm` was unavailable, and the targeted Jest test could not start because `node` was unavailable. The PR adds focused regression coverage for explicit `Never` constraints, including ordering, aliases, nested and contravariant inference, repeated inference, and preserved fallback behavior. The build was also unavailable for the same missing runtime. Test runs: 1 failed, 2 not run
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Diff from mypy_primer, showing the effect of this PR on open source code: sympy (https://github.com/sympy/sympy)
+ .../projects/sympy/sympy/solvers/diophantine/diophantine.py:176:44 - error: Cannot access attribute "expand" for class "Basic"
+ Attribute "expand" is unknown (reportAttributeAccessIssue)
+ .../projects/sympy/sympy/solvers/diophantine/tests/test_diophantine.py:314:30 - error: Cannot access attribute "as_independent" for class "Basic"
+ Attribute "as_independent" is unknown (reportAttributeAccessIssue)
+ .../projects/sympy/sympy/solvers/diophantine/tests/test_diophantine.py:383:30 - error: Cannot access attribute "as_independent" for class "Basic"
+ Attribute "as_independent" is unknown (reportAttributeAccessIssue)
+ .../projects/sympy/sympy/solvers/ode/lie_group.py:619:61 - error: Operator "-" not supported for type "Unknown | Basic" (reportOperatorIssue)
+ .../projects/sympy/sympy/solvers/ode/nonhomogeneous.py:225:45 - error: Cannot access attribute "has" for class "tuple[Expr, int]"
+ Attribute "has" is unknown (reportAttributeAccessIssue)
- .../projects/sympy/sympy/solvers/ode/nonhomogeneous.py:223:22 - error: No overloads for "__new__" match the provided arguments (reportCallIssue)
- .../projects/sympy/sympy/solvers/ode/nonhomogeneous.py:223:25 - error: Argument of type "CRootOf | tuple[Expr, int]" cannot be assigned to parameter "arg" of type "Expr" in function "__new__"
- Type "CRootOf | tuple[Expr, int]" is not assignable to type "Expr"
- "tuple[Expr, int]" is not assignable to "Expr" (reportArgumentType)
- .../projects/sympy/sympy/solvers/ode/nonhomogeneous.py:238:40 - error: No overloads for "__new__" match the provided arguments (reportCallIssue)
- .../projects/sympy/sympy/solvers/ode/nonhomogeneous.py:238:50 - error: Argument of type "CRootOf | tuple[Expr, int]" cannot be assigned to parameter "arg" of type "Expr" in function "__new__"
- Type "CRootOf | tuple[Expr, int]" is not assignable to type "Expr"
- "tuple[Expr, int]" is not assignable to "Expr" (reportArgumentType)
- .../projects/sympy/sympy/solvers/ode/single.py:867:9 - error: Expression with type "tuple[ComplexInfinity | Unknown | Any, list[tuple[Unknown, Unknown]] | list[Unknown]] | tuple[ComplexInfinity | Unknown | Any, list[tuple[Unknown, Unknown]] | list[Unknown], list[tuple[Unknown, Unknown]] | list[Unknown]]" cannot be assigned to target tuple
- Type "tuple[ComplexInfinity | Unknown | Any, list[tuple[Unknown, Unknown]] | list[Unknown], list[tuple[Unknown, Unknown]] | list[Unknown]]" is incompatible with target tuple
- Tuple size mismatch; expected 2 but received 3 (reportAssignmentType)
+ .../projects/sympy/sympy/solvers/ode/single.py:2646:27 - error: Argument of type "One | NegativeOne | Zero | Integer | NaN | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number | Expr | Unknown | int" cannot be assigned to parameter "stop" of type "SupportsIndex" in function "__new__"
+ Type "One | NegativeOne | Zero | Integer | NaN | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number | Expr | Unknown | int" is not assignable to type "SupportsIndex"
+ "Expr" is incompatible with protocol "SupportsIndex"
+ "__index__" is not present (reportArgumentType)
- .../projects/sympy/sympy/solvers/ode/single.py:2652:9 - error: Operator "+=" not supported for types "Unknown | Any | Zero | One | NegativeOne | Integer | NaN | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number | Expr" and "Basic | Any | Unknown"
+ .../projects/sympy/sympy/solvers/ode/single.py:2652:9 - error: Operator "+=" not supported for types "One | NegativeOne | Zero | Integer | NaN | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number | Expr | Any | Unknown" and "Basic | Any | Unknown"
- .../projects/sympy/sympy/solvers/solveset.py:776:18 - error: Argument of type "Unknown | None" cannot be assigned to parameter "expr" of type "Expr" in function "together"
+ .../projects/sympy/sympy/solvers/solveset.py:776:18 - error: Argument of type "Expr | Unknown | None" cannot be assigned to parameter "expr" of type "Expr" in function "together"
- Type "Unknown | None" is not assignable to type "Expr"
+ Type "Expr | Unknown | None" is not assignable to type "Expr"
- .../projects/sympy/sympy/stats/crv_types.py:2546:9 - error: Method "_cdf" overrides class "SingleContinuousDistribution" in an incompatible manner
- Return type mismatch: base method returns type "None", override returns type "ComplexInfinity | Unknown"
- Type "ComplexInfinity | Unknown" is not assignable to type "None"
- "ComplexInfinity" is not assignable to "None" (reportIncompatibleMethodOverride)
- .../projects/sympy/sympy/stats/crv_types.py:2725:9 - error: Method "_cdf" overrides class "SingleContinuousDistribution" in an incompatible manner
- Return type mismatch: base method returns type "None", override returns type "Expr | Unknown"
- Type "Expr | Unknown" is not assignable to type "None"
- "Expr" is not assignable to "None" (reportIncompatibleMethodOverride)
- .../projects/sympy/sympy/stats/drv.py:269:22 - error: Argument of type "Generator[Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | int | None, None, None]" cannot be assigned to parameter "iterable" of type "Iterable[_SupportsSumNoDefaultT@sum]" in function "sum"
+ .../projects/sympy/sympy/stats/drv.py:269:22 - error: Argument of type "Generator[Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | int | None, None, None]" cannot be assigned to parameter "iterable" of type "Iterable[_SupportsSumNoDefaultT@sum]" in function "sum"
- "Generator[Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | int | None, None, None]" is not assignable to "Iterable[_SupportsSumNoDefaultT@sum]"
+ "Generator[Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | int | None, None, None]" is not assignable to "Iterable[_SupportsSumNoDefaultT@sum]"
- Type parameter "_T_co@Iterable" is covariant, but "Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | int | None" is not a subtype of "_SupportsSumNoDefaultT@sum"
+ Type parameter "_T_co@Iterable" is covariant, but "Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | int | None" is not a subtype of "_SupportsSumNoDefaultT@sum"
- Type "Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | int | None" is not assignable to type "_SupportsSumWithNoDefaultGiven"
+ Type "Self@Basic | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | int | None" is not assignable to type "_SupportsSumWithNoDefaultGiven"
- Type "Basic* | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | int | None" is not assignable to type "_SupportsSumWithNoDefaultGiven"
+ Type "Basic* | tuple[Unknown, ...] | Unknown | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | int | None" is not assignable to type "_SupportsSumWithNoDefaultGiven"
- .../projects/sympy/sympy/stats/drv_types.py:293:16 - error: Operator "*" not supported for types "Expr" and "tuple[Unknown, ...] | Unknown | Self@Basic | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic"
+ .../projects/sympy/sympy/stats/drv_types.py:293:16 - error: Operator "*" not supported for types "Expr" and "tuple[Unknown, ...] | Unknown | Self@Basic | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic"
- .../projects/sympy/sympy/stats/rv.py:473:25 - error: Argument of type "Expr | Lambda | Zero | One | Integral | Unknown | Probability | Self@Basic | tuple[Unknown, ...] | Sum | ZeroMatrix | NaN | Piecewise | Basic | int | NegativeOne | Integer | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number" cannot be assigned to parameter "args" of type "Expr | complex" in function "__new__"
+ .../projects/sympy/sympy/stats/rv.py:473:25 - error: Argument of type "Expr | Lambda | Zero | One | Integral | Unknown | Probability | Self@Basic | tuple[Unknown, ...] | Sum | ZeroMatrix | Add | NaN | Piecewise | Basic | int | NegativeOne | Integer | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number" cannot be assigned to parameter "args" of type "Expr | complex" in function "__new__"
- Type "Expr | Lambda | Zero | One | Integral | Unknown | Probability | Self@Basic | tuple[Unknown, ...] | Sum | ZeroMatrix | NaN | Piecewise | Basic | int | NegativeOne | Integer | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number" is not assignable to type "Expr | complex"
+ Type "Expr | Lambda | Zero | One | Integral | Unknown | Probability | Self@Basic | tuple[Unknown, ...] | Sum | ZeroMatrix | Add | NaN | Piecewise | Basic | int | NegativeOne | Integer | ComplexInfinity | Rational | Infinity | NegativeInfinity | Float | Number" is not assignable to type "Expr | complex"
- .../projects/sympy/sympy/stats/stochastic_process_types.py:1839:25 - error: Argument of type "tuple[Unknown, ...] | Unknown | Self@Basic | Sum | Expr | ZeroMatrix | Zero | NaN | Piecewise | Basic | Integral | Any | int" cannot be assigned to parameter "args" of type "Expr | complex" in function "__new__"
+ .../projects/sympy/sympy/stats/stochastic_process_types.py:1839:25 - error: Argument of type "tuple[Unknown, ...] | Unknown | Self@Basic | Sum | Expr | ZeroMatrix | Add | Zero | NaN | Piecewise | Basic | Integral | Any | int" cannot be assigned to parameter "args" of type "Expr | complex" in function "__new__"
... (truncated 1400 lines) ...
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Heejae Chang (heejaechang)
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Summary
Neverconstraint from theNeversentinel returned when no constrained TypeVar option matchesAny, incompatible inputs, andNeverpassed to TypeVars without an explicitNeverconstraintFixes #11736
Tests
pnpm --dir packages/pyright-internal exec jest typeEvaluator2.test --forceExitpnpm --dir packages/pyright-internal run build