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parameter specification variance #2215

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22 changes: 22 additions & 0 deletions conformance/results/mypy/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 24: Expected 1 errors
Line 31: Expected 1 errors
Line 47: Expected 1 errors
Line 23: Unexpected errors ['generics_paramspec_variance.py:23: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]']
Line 26: Unexpected errors ['generics_paramspec_variance.py:26: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 30: Unexpected errors ['generics_paramspec_variance.py:30: error: Missing return statement [empty-body]']
Line 37: Unexpected errors ['generics_paramspec_variance.py:37: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 46: Unexpected errors ['generics_paramspec_variance.py:46: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]']
"""
output = """
generics_paramspec_variance.py:15: error: Incompatible types in assignment (expression has type "ContravariantParamSpec[[int]]", variable has type "ContravariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:23: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:26: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:30: error: Missing return statement [empty-body]
generics_paramspec_variance.py:35: error: Incompatible types in assignment (expression has type "ContravariantParamSpecOld[[int]]", variable has type "ContravariantParamSpecOld[[object]]") [assignment]
generics_paramspec_variance.py:37: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:41: error: Missing return statement [empty-body]
generics_paramspec_variance.py:46: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]
"""
24 changes: 24 additions & 0 deletions conformance/results/pyrefly/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 15: Expected 1 errors
Line 24: Expected 1 errors
Line 31: Expected 1 errors
Line 41: Expected 1 errors
Line 14: Unexpected errors ['`ContravariantParamSpec[[object]]` is not assignable to `ContravariantParamSpec[[int]]` [bad-assignment]']
Line 23: Unexpected errors ['`CovariantParamSpec[[int]]` is not assignable to `CovariantParamSpec[[object]]` [bad-assignment]']
Line 26: Unexpected errors ['Unexpected keyword argument `contravariant` to ParamSpec [invalid-param-spec]']
Line 34: Unexpected errors ['`ContravariantParamSpecOld[[object]]` is not assignable to `ContravariantParamSpecOld[[int]]` [bad-assignment]']
Line 37: Unexpected errors ['Unexpected keyword argument `covariant` to ParamSpec [invalid-param-spec]']
Line 46: Unexpected errors ['`CovariantParamSpecOld[[int]]` is not assignable to `CovariantParamSpecOld[[object]]` [bad-assignment]']
"""
output = """
ERROR generics_paramspec_variance.py:14:39-45: `ContravariantParamSpec[[object]]` is not assignable to `ContravariantParamSpec[[int]]` [bad-assignment]
ERROR generics_paramspec_variance.py:23:39-46: `CovariantParamSpec[[int]]` is not assignable to `CovariantParamSpec[[object]]` [bad-assignment]
ERROR generics_paramspec_variance.py:26:24-42: Unexpected keyword argument `contravariant` to ParamSpec [invalid-param-spec]
ERROR generics_paramspec_variance.py:34:46-56: `ContravariantParamSpecOld[[object]]` is not assignable to `ContravariantParamSpecOld[[int]]` [bad-assignment]
ERROR generics_paramspec_variance.py:35:14-24: `ContravariantParamSpecOld[[int]]` is not assignable to variable `in_obj_old` with type `ContravariantParamSpecOld[[object]]` [bad-assignment]
ERROR generics_paramspec_variance.py:37:26-40: Unexpected keyword argument `covariant` to ParamSpec [invalid-param-spec]
ERROR generics_paramspec_variance.py:46:46-57: `CovariantParamSpecOld[[int]]` is not assignable to `CovariantParamSpecOld[[object]]` [bad-assignment]
ERROR generics_paramspec_variance.py:47:15-26: `CovariantParamSpecOld[[object]]` is not assignable to variable `out_int_old` with type `CovariantParamSpecOld[[int]]` [bad-assignment]
"""
40 changes: 40 additions & 0 deletions conformance/results/pyright/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 31: Expected 1 errors
Line 41: Expected 1 errors
Line 14: Unexpected errors ['generics_paramspec_variance.py:14:39 - error: Type "ContravariantParamSpec[(object)]" is not assignable to declared type "ContravariantParamSpec[(int)]"']
Line 23: Unexpected errors ['generics_paramspec_variance.py:23:39 - error: Type "CovariantParamSpec[(int)]" is not assignable to declared type "CovariantParamSpec[(object)]"']
Line 26: Unexpected errors ['generics_paramspec_variance.py:26:24 - error: "contravariant" is unknown parameter to ParamSpec (reportGeneralTypeIssues)']
Line 34: Unexpected errors ['generics_paramspec_variance.py:34:46 - error: Type "ContravariantParamSpecOld[(object)]" is not assignable to declared type "ContravariantParamSpecOld[(int)]"']
Line 37: Unexpected errors ['generics_paramspec_variance.py:37:26 - error: "covariant" is unknown parameter to ParamSpec (reportGeneralTypeIssues)']
Line 46: Unexpected errors ['generics_paramspec_variance.py:46:46 - error: Type "CovariantParamSpecOld[(int)]" is not assignable to declared type "CovariantParamSpecOld[(object)]"']
"""
output = """
generics_paramspec_variance.py:14:39 - error: Type "ContravariantParamSpec[(object)]" is not assignable to declared type "ContravariantParamSpec[(int)]"
  "ContravariantParamSpec[(object)]" is not assignable to "ContravariantParamSpec[(int)]"
    Type parameter "InP@ContravariantParamSpec" is invariant, but "(object)" is not the same as "(int)" (reportAssignmentType)
generics_paramspec_variance.py:15:10 - error: Type "ContravariantParamSpec[(int)]" is not assignable to declared type "ContravariantParamSpec[(object)]"
  "ContravariantParamSpec[(int)]" is not assignable to "ContravariantParamSpec[(object)]"
    Type parameter "InP@ContravariantParamSpec" is invariant, but "(int)" is not the same as "(object)" (reportAssignmentType)
generics_paramspec_variance.py:23:39 - error: Type "CovariantParamSpec[(int)]" is not assignable to declared type "CovariantParamSpec[(object)]"
  "CovariantParamSpec[(int)]" is not assignable to "CovariantParamSpec[(object)]"
    Type parameter "OutP@CovariantParamSpec" is invariant, but "(int)" is not the same as "(object)" (reportAssignmentType)
generics_paramspec_variance.py:24:11 - error: Type "CovariantParamSpec[(object)]" is not assignable to declared type "CovariantParamSpec[(int)]"
  "CovariantParamSpec[(object)]" is not assignable to "CovariantParamSpec[(int)]"
    Type parameter "OutP@CovariantParamSpec" is invariant, but "(object)" is not the same as "(int)" (reportAssignmentType)
generics_paramspec_variance.py:26:24 - error: "contravariant" is unknown parameter to ParamSpec (reportGeneralTypeIssues)
generics_paramspec_variance.py:34:46 - error: Type "ContravariantParamSpecOld[(object)]" is not assignable to declared type "ContravariantParamSpecOld[(int)]"
  "ContravariantParamSpecOld[(object)]" is not assignable to "ContravariantParamSpecOld[(int)]"
    Type parameter "InP@ContravariantParamSpecOld" is invariant, but "(object)" is not the same as "(int)" (reportAssignmentType)
generics_paramspec_variance.py:35:14 - error: Type "ContravariantParamSpecOld[(int)]" is not assignable to declared type "ContravariantParamSpecOld[(object)]"
  "ContravariantParamSpecOld[(int)]" is not assignable to "ContravariantParamSpecOld[(object)]"
    Type parameter "InP@ContravariantParamSpecOld" is invariant, but "(int)" is not the same as "(object)" (reportAssignmentType)
generics_paramspec_variance.py:37:26 - error: "covariant" is unknown parameter to ParamSpec (reportGeneralTypeIssues)
generics_paramspec_variance.py:46:46 - error: Type "CovariantParamSpecOld[(int)]" is not assignable to declared type "CovariantParamSpecOld[(object)]"
  "CovariantParamSpecOld[(int)]" is not assignable to "CovariantParamSpecOld[(object)]"
    Type parameter "OutP@CovariantParamSpecOld" is invariant, but "(int)" is not the same as "(object)" (reportAssignmentType)
generics_paramspec_variance.py:47:15 - error: Type "CovariantParamSpecOld[(object)]" is not assignable to declared type "CovariantParamSpecOld[(int)]"
  "CovariantParamSpecOld[(object)]" is not assignable to "CovariantParamSpecOld[(int)]"
    Type parameter "OutP@CovariantParamSpecOld" is invariant, but "(object)" is not the same as "(int)" (reportAssignmentType)
"""
7 changes: 7 additions & 0 deletions conformance/results/results.html
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Expand Up @@ -335,6 +335,13 @@ <h3>Python Type System Conformance Test Results</h3>
<th class="column col2 conformant">Pass</th>
<th class="column col2 conformant">Pass</th>
</tr>
<tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generics_paramspec_variance</th>
<th class="column col2 not-conformant">Unsupported</th>
<th class="column col2 not-conformant">Unsupported</th>
<th class="column col2 not-conformant">Unsupported</th>
<th class="column col2 not-conformant">Unsupported</th>
<th class="column col2 not-conformant">Unsupported</th>
</tr>
<tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;generics_scoping</th>
<th class="column col2 conformant">Pass</th>
<th class="column col2 conformant">Pass</th>
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30 changes: 30 additions & 0 deletions conformance/results/ty/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 15: Expected 1 errors
Line 24: Expected 1 errors
Line 35: Expected 1 errors
Line 47: Expected 1 errors
Line 26: Unexpected errors ['generics_paramspec_variance.py:26:7: error[invalid-paramspec] The variance and bound arguments for `ParamSpec` do not have defined semantics yet']
Line 29: Unexpected errors ['generics_paramspec_variance.py:29:33: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`']
Line 30: Unexpected errors ['generics_paramspec_variance.py:30:23: error[empty-body] Function always implicitly returns `None`, which is not assignable to return type `(...) -> Unknown`', 'generics_paramspec_variance.py:30:32: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a return type annotation', 'generics_paramspec_variance.py:30:32: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`']
Line 37: Unexpected errors ['generics_paramspec_variance.py:37:8: error[invalid-paramspec] The variance and bound arguments for `ParamSpec` do not have defined semantics yet']
Line 40: Unexpected errors ['generics_paramspec_variance.py:40:29: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`']
Line 42: Unexpected errors ['generics_paramspec_variance.py:42:34: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a parameter annotation', 'generics_paramspec_variance.py:42:34: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`']
"""
output = """
generics_paramspec_variance.py:26:7: error[invalid-paramspec] The variance and bound arguments for `ParamSpec` do not have defined semantics yet
generics_paramspec_variance.py:29:33: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
generics_paramspec_variance.py:30:23: error[empty-body] Function always implicitly returns `None`, which is not assignable to return type `(...) -> Unknown`
generics_paramspec_variance.py:30:32: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a return type annotation
generics_paramspec_variance.py:30:32: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`
generics_paramspec_variance.py:31:34: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a parameter annotation
generics_paramspec_variance.py:31:34: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`
generics_paramspec_variance.py:37:8: error[invalid-paramspec] The variance and bound arguments for `ParamSpec` do not have defined semantics yet
generics_paramspec_variance.py:40:29: error[invalid-argument-type] `ParamSpec` is not a valid argument to `Generic`
generics_paramspec_variance.py:41:23: error[empty-body] Function always implicitly returns `None`, which is not assignable to return type `(...) -> Unknown`
generics_paramspec_variance.py:41:32: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a return type annotation
generics_paramspec_variance.py:41:32: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`
generics_paramspec_variance.py:42:34: error[invalid-type-form] Variable of type `ParamSpec` is not allowed in a parameter annotation
generics_paramspec_variance.py:42:34: error[invalid-type-form] The first argument to `Callable` must be either a list of types, ParamSpec, Concatenate, or `...`
"""
22 changes: 22 additions & 0 deletions conformance/results/zuban/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 24: Expected 1 errors
Line 31: Expected 1 errors
Line 47: Expected 1 errors
Line 23: Unexpected errors ['generics_paramspec_variance.py:23: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]']
Line 26: Unexpected errors ['generics_paramspec_variance.py:26: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 30: Unexpected errors ['generics_paramspec_variance.py:30: error: Missing return statement [empty-body]']
Line 37: Unexpected errors ['generics_paramspec_variance.py:37: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 46: Unexpected errors ['generics_paramspec_variance.py:46: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]']
"""
output = """
generics_paramspec_variance.py:15: error: Incompatible types in assignment (expression has type "ContravariantParamSpec[[int]]", variable has type "ContravariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:23: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:26: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:30: error: Missing return statement [empty-body]
generics_paramspec_variance.py:35: error: Incompatible types in assignment (expression has type "ContravariantParamSpecOld[[int]]", variable has type "ContravariantParamSpecOld[[object]]") [assignment]
generics_paramspec_variance.py:37: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:41: error: Missing return statement [empty-body]
generics_paramspec_variance.py:46: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]
"""
47 changes: 47 additions & 0 deletions conformance/tests/generics_paramspec_variance.py
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"""
Tests variance of ParamSpec.
"""

# Specification: https://typing.readthedocs.io/en/latest/spec/generics.html#semantics


from typing import Callable, Generic, ParamSpec

class ContravariantParamSpec[**InP]:
def f(self, *args: InP.args, **kwargs: InP.kwargs): ...

in_obj: ContravariantParamSpec[object] = ContravariantParamSpec()
in_int: ContravariantParamSpec[int] = in_obj # OK
in_obj = in_int # E


class CovariantParamSpec[**OutP]:
def f(self, fn: Callable[OutP, None]) -> None: ...


out_int: CovariantParamSpec[int] = CovariantParamSpec()
out_obj: CovariantParamSpec[object] = out_int # OK
out_int = out_obj # E

InP = ParamSpec("InP", contravariant=True)


class ContravariantParamSpecOld(Generic[InP]):
def in_f(self) -> Callable[InP, None]: ... # OK
def out_f(self, fn: Callable[InP, None]) -> None: ... # E

in_obj_old: ContravariantParamSpecOld[object] = ContravariantParamSpecOld()
in_int_old: ContravariantParamSpecOld[int] = in_obj_old # OK
in_obj_old = in_int_old # E

OutP = ParamSpec("OutP", covariant=True)


class CovariantParamSpecOld(Generic[OutP]):
def in_f(self) -> Callable[OutP, None]: ... # E
def out_f(self, fn: Callable[OutP, None]) -> None: ... # OK


out_int_old: CovariantParamSpecOld[int] = CovariantParamSpecOld()
out_obj_old: CovariantParamSpecOld[object] = out_int_old # OK
out_int_old = out_obj_old # E
11 changes: 5 additions & 6 deletions docs/spec/generics.rst
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Expand Up @@ -2712,13 +2712,12 @@ The algorithm for computing the variance of a type parameter is as follows.

For each type parameter in a generic class:

1. If the type parameter is variadic (``TypeVarTuple``) or a parameter
specification (``ParamSpec``), it is always considered invariant. No further
inference is needed.
1. If the type parameter is variadic (``TypeVarTuple``) it is always
considered invariant. No further inference is needed.

2. If the type parameter comes from a traditional ``TypeVar`` declaration and
is not specified as ``infer_variance`` (see below), its variance is specified
by the ``TypeVar`` constructor call. No further inference is needed.
2. If the type parameter comes from a traditional ``TypeVar``/``ParamSpec``
declaration and is not specified as ``infer_variance`` (see below), its
variance is specified by the constructor call. No further inference is needed.

3. Create two specialized versions of the class. We'll refer to these as
``upper`` and ``lower`` specializations. In both of these specializations,
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