mirror of https://github.com/astral-sh/ruff
add failing tests
This commit is contained in:
Douglas Creager
parent
33b942c7ad
commit
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@ -12,8 +12,7 @@ a particular constraint set hold_.
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## Concrete types
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## Concrete types
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For concrete types, constraint implication is exactly the same as subtyping. (A concrete type is any
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For concrete types, constraint implication is exactly the same as subtyping. (A concrete type is any
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fully static type that is not a typevar. It can _contain_ a typevar, though — `list[T]` is
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fully static type that does not contain a typevar.)
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considered concrete.)
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```py
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```py
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from ty_extensions import ConstraintSet, is_subtype_of, static_assert
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from ty_extensions import ConstraintSet, is_subtype_of, static_assert
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@ -191,4 +190,199 @@ def mutually_constrained[T, U]():
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static_assert(not given_int.implies_subtype_of(T, str))
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static_assert(not given_int.implies_subtype_of(T, str))
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```
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```
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## Compound types
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All of the relationships in the above section also apply when a typevar appears in a compound type.
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```py
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from typing import Never
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from ty_extensions import ConstraintSet, static_assert
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class Covariant[T]:
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def get(self) -> T:
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raise ValueError
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def given_constraints[T]():
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static_assert(not ConstraintSet.always().implies_subtype_of(Covariant[T], Covariant[int]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Covariant[T], Covariant[bool]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Covariant[T], Covariant[str]))
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# These are vacuously true; false implies anything
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Covariant[T], Covariant[int]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Covariant[T], Covariant[bool]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Covariant[T], Covariant[str]))
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# For a covariant typevar, (T ≤ int) implies that (Covariant[T] ≤ Covariant[int]).
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given_int = ConstraintSet.range(Never, T, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Covariant[T], Covariant[int]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[bool]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[str]))
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given_bool = ConstraintSet.range(Never, T, bool)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_bool.implies_subtype_of(Covariant[T], Covariant[int]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_bool.implies_subtype_of(Covariant[T], Covariant[bool]))
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static_assert(not given_bool.implies_subtype_of(Covariant[T], Covariant[str]))
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def mutually_constrained[T, U]():
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# If (T = U ∧ U ≤ int), then (T ≤ int) must be true as well, and therefore
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# (Covariant[T] ≤ Covariant[int]).
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given_int = ConstraintSet.range(U, T, U) & ConstraintSet.range(Never, U, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Covariant[T], Covariant[int]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[bool]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[str]))
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# If (T ≤ U ∧ U ≤ int), then (T ≤ int) must be true as well, and therefore
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# (Covariant[T] ≤ Covariant[int]).
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given_int = ConstraintSet.range(Never, T, U) & ConstraintSet.range(Never, U, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Covariant[T], Covariant[int]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[bool]))
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static_assert(not given_int.implies_subtype_of(Covariant[T], Covariant[str]))
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```
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Many of the relationships are reversed for typevars that appear in contravariant types.
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```py
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class Contravariant[T]:
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def set(self, value: T):
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pass
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def given_constraints[T]():
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static_assert(not ConstraintSet.always().implies_subtype_of(Contravariant[int], Contravariant[T]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Contravariant[bool], Contravariant[T]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Contravariant[str], Contravariant[T]))
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# These are vacuously true; false implies anything
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Contravariant[int], Contravariant[T]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Contravariant[bool], Contravariant[T]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Contravariant[str], Contravariant[T]))
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# For a contravariant typevar, (T ≤ int) implies that (Contravariant[int] ≤ Contravariant[T]).
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# (The order of the comparison is reversed because of contravariance.)
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given_int = ConstraintSet.range(Never, T, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Contravariant[int], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[bool], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[str], Contravariant[T]))
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given_bool = ConstraintSet.range(Never, T, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_bool.implies_subtype_of(Contravariant[int], Contravariant[T]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_bool.implies_subtype_of(Contravariant[bool], Contravariant[T]))
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static_assert(not given_bool.implies_subtype_of(Contravariant[str], Contravariant[T]))
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def mutually_constrained[T, U]():
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# If (T = U ∧ U ≤ int), then (T ≤ int) must be true as well, and therefore
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# (Contravariant[int] ≤ Contravariant[T]).
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given_int = ConstraintSet.range(U, T, U) & ConstraintSet.range(Never, U, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Contravariant[int], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[bool], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[str], Contravariant[T]))
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# If (T ≤ U ∧ U ≤ int), then (T ≤ int) must be true as well, and therefore
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# (Contravariant[int] ≤ Contravariant[T]).
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given_int = ConstraintSet.range(Never, T, U) & ConstraintSet.range(Never, U, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Contravariant[int], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[bool], Contravariant[T]))
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static_assert(not given_int.implies_subtype_of(Contravariant[str], Contravariant[T]))
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```
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For invariant typevars, subtyping of the typevar does not imply subtyping of the compound type in
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either direction. But an equality constraint on the typevar does.
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```py
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class Invariant[T]:
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def get(self) -> T:
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raise ValueError
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def set(self, value: T):
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pass
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def given_constraints[T]():
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static_assert(not ConstraintSet.always().implies_subtype_of(Invariant[T], Invariant[int]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Invariant[T], Invariant[bool]))
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static_assert(not ConstraintSet.always().implies_subtype_of(Invariant[T], Invariant[str]))
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# These are vacuously true; false implies anything
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Invariant[T], Invariant[int]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Invariant[T], Invariant[bool]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(ConstraintSet.never().implies_subtype_of(Invariant[T], Invariant[str]))
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# For an invariant typevar, (T ≤ int) does not imply that (Invariant[T] ≤ Invariant[int]).
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given_int = ConstraintSet.range(Never, T, int)
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[int]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[bool]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[str]))
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# It also does not imply the contravariant ordering (Invariant[int] ≤ Invariant[T]).
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static_assert(not given_int.implies_subtype_of(Invariant[int], Invariant[T]))
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static_assert(not given_int.implies_subtype_of(Invariant[bool], Invariant[T]))
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static_assert(not given_int.implies_subtype_of(Invariant[str], Invariant[T]))
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# But (T = int) does imply both.
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given_int = ConstraintSet.range(int, T, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Invariant[T], Invariant[int]))
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Invariant[int], Invariant[T]))
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static_assert(not given_int.implies_subtype_of(Invariant[bool], Invariant[T]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[bool]))
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static_assert(not given_int.implies_subtype_of(Invariant[str], Invariant[T]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[str]))
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def mutually_constrained[T, U]():
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# If (T = U ∧ U ≤ int), then (T ≤ int) must be true as well. But because T is invariant, that
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# does _not_ imply that (Invariant[T] ≤ Invariant[int]).
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given_int = ConstraintSet.range(U, T, U) & ConstraintSet.range(Never, U, int)
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[int]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[bool]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[str]))
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# If (T = U ∧ U = int), then (T = int) must be true as well. That is an equality constraint, so
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# even though T is invariant, it does imply that (Invariant[T] ≤ Invariant[int]).
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given_int = ConstraintSet.range(Never, T, U) & ConstraintSet.range(Never, U, int)
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# TODO: no error
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# error: [static-assert-error]
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static_assert(given_int.implies_subtype_of(Invariant[T], Invariant[int]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[bool]))
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static_assert(not given_int.implies_subtype_of(Invariant[T], Invariant[str]))
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```
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[subtyping]: https://typing.python.org/en/latest/spec/concepts.html#subtype-supertype-and-type-equivalence
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[subtyping]: https://typing.python.org/en/latest/spec/concepts.html#subtype-supertype-and-type-equivalence
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