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Merged
JelleZijlstra merged 7 commits into from
Aug 13, 2026
Merged

parameter specification/type variable tuple variance #2215

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92287d4
specify that type variable tuples and parameter specification should …
KotlinIsland Mar 9, 2026
5b4e853
fixup! specify that type variable tuples and parameter specification …
KotlinIsland Aug 12, 2026
4849cc3
Clarify TypeVarTuple bound support and Python availability
carljm Aug 13, 2026
653b023
Specify variance constructor options and availability
carljm Aug 13, 2026
8f86075
Infer variance for ParamSpec callback protocols
carljm Aug 13, 2026
30c322a
Point variance conformance tests to the current specification
carljm Aug 13, 2026
70d51d2
Correct Zuban mixed variance conformance scoring
carljm Aug 13, 2026
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1 change: 1 addition & 0 deletions conformance/pyproject.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ dependencies = [
"tomlkit",
"ty",
"types-markdown",
"typing-extensions>=4.16.0",
"zuban",
]

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9 changes: 9 additions & 0 deletions conformance/results/mypy/generics_mixed_variance_inference.toml
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conformant = "Pass"
conformance_automated = "Pass"
errors_diff = """
"""
output = """
generics_mixed_variance_inference.py:13: error: Incompatible types in assignment (expression has type "Mixed[bool, []]", variable has type "Mixed[int, []]") [assignment]
generics_mixed_variance_inference.py:16: error: Incompatible types in assignment (expression has type "Mixed[int, object, []]", variable has type "Mixed[int, int, []]") [assignment]
generics_mixed_variance_inference.py:21: error: Incompatible types in assignment (expression has type "Mixed[int, [bool]]", variable has type "Mixed[int, [int]]") [assignment]
"""
44 changes: 44 additions & 0 deletions conformance/results/mypy/generics_paramspec_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 15: Expected 1 errors
Line 30: Expected 1 errors
Line 90: Expected 1 errors
Line 111: Expected 1 errors
Line 117: Expected 1 errors
Line 126: Expected 1 errors
Line 132: Expected 1 errors
Line 151: Expected 1 errors
Line 31: Unexpected errors ['generics_paramspec_variance.py:31: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]']
Line 84: Unexpected errors ['generics_paramspec_variance.py:84: error: Incompatible types in assignment (expression has type "OutitP[[NamedArg(int, \\'a\\')]]", variable has type "OutitP[[int]]") [assignment]']
Line 86: Unexpected errors ['generics_paramspec_variance.py:86: error: Incompatible types in assignment (expression has type "OutitP[[int]]", variable has type "OutitP[[Arg(int, \\'a\\')]]") [assignment]']
Line 97: Unexpected errors ['generics_paramspec_variance.py:97: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 98: Unexpected errors ['generics_paramspec_variance.py:98: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 99: Unexpected errors ['generics_paramspec_variance.py:99: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
Line 133: Unexpected errors ['generics_paramspec_variance.py:133: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]']
Line 152: Unexpected errors ['generics_paramspec_variance.py:152: error: Incompatible types in assignment (expression has type "InferredCovariantParamSpecOld[[int]]", variable has type "InferredCovariantParamSpecOld[[object]]") [assignment]']
"""
output = """
generics_paramspec_variance.py:14: error: Incompatible types in assignment (expression has type "InvariantParamSpec[[int]]", variable has type "InvariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:21: error: Incompatible types in assignment (expression has type "ContravariantParamSpec[[int]]", variable has type "ContravariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:31: error: Incompatible types in assignment (expression has type "CovariantParamSpec[[int]]", variable has type "CovariantParamSpec[[object]]") [assignment]
generics_paramspec_variance.py:61: error: Incompatible types in assignment (expression has type "InitP[[NamedArg(int, 'a')]]", variable has type "InitP[[int]]") [assignment]
generics_paramspec_variance.py:63: error: Incompatible types in assignment (expression has type "InitP[[int]]", variable has type "InitP[[Arg(int, 'a')]]") [assignment]
generics_paramspec_variance.py:65: error: Incompatible types in assignment (expression has type "InitP[[Arg(int, 'b')]]", variable has type "InitP[[Arg(int, 'a')]]") [assignment]
generics_paramspec_variance.py:69: error: Incompatible types in assignment (expression has type "InitP[[int, str]]", variable has type "InitP[[int]]") [assignment]
generics_paramspec_variance.py:84: error: Incompatible types in assignment (expression has type "OutitP[[NamedArg(int, 'a')]]", variable has type "OutitP[[int]]") [assignment]
generics_paramspec_variance.py:86: error: Incompatible types in assignment (expression has type "OutitP[[int]]", variable has type "OutitP[[Arg(int, 'a')]]") [assignment]
generics_paramspec_variance.py:88: error: Incompatible types in assignment (expression has type "OutitP[[Arg(int, 'b')]]", variable has type "OutitP[[Arg(int, 'a')]]") [assignment]
generics_paramspec_variance.py:92: error: Incompatible types in assignment (expression has type "OutitP[[int, str]]", variable has type "OutitP[[int]]") [assignment]
generics_paramspec_variance.py:97: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:98: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:99: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:100: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:101: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:102: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
generics_paramspec_variance.py:110: error: Incompatible types in assignment (expression has type "InvariantParamSpecOld[[bool]]", variable has type "InvariantParamSpecOld[[int]]") [assignment]
generics_paramspec_variance.py:121: error: Incompatible types in assignment (expression has type "ContravariantParamSpecOld[[int]]", variable has type "ContravariantParamSpecOld[[object]]") [assignment]
generics_paramspec_variance.py:133: error: Incompatible types in assignment (expression has type "CovariantParamSpecOld[[int]]", variable has type "CovariantParamSpecOld[[object]]") [assignment]
generics_paramspec_variance.py:142: error: Incompatible types in assignment (expression has type "InferredContravariantParamSpecOld[[int]]", variable has type "InferredContravariantParamSpecOld[[object]]") [assignment]
generics_paramspec_variance.py:152: error: Incompatible types in assignment (expression has type "InferredCovariantParamSpecOld[[int]]", variable has type "InferredCovariantParamSpecOld[[object]]") [assignment]
"""
16 changes: 8 additions & 8 deletions conformance/results/mypy/generics_typevartuple_basic.toml
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Expand Up @@ -3,19 +3,19 @@ notes = """
Does not enforce that tuples captured by `TypeVarTuple` are same length.
"""
output = """
generics_typevartuple_basic.py:42: error: Argument 1 to "Array" has incompatible type "Height"; expected "tuple[Height, Width]" [arg-type]
generics_typevartuple_basic.py:43: error: Argument 1 to "Array" has incompatible type "tuple[Batch, Width]"; expected "tuple[Batch, Height, Width]" [arg-type]
generics_typevartuple_basic.py:45: error: Argument 1 to "Array" has incompatible type "tuple[Time, Batch, Width, Height]"; expected "tuple[Time, Batch, Height, Width]" [arg-type]
generics_typevartuple_basic.py:52: error: Free type variable expected in Generic[...] [misc]
generics_typevartuple_basic.py:53: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:56: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:59: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:65: error: Unexpected keyword argument "covariant" for "TypeVarTuple" [misc]
generics_typevartuple_basic.py:43: error: Argument 1 to "Array" has incompatible type "Height"; expected "tuple[Height, Width]" [arg-type]
generics_typevartuple_basic.py:44: error: Argument 1 to "Array" has incompatible type "tuple[Batch, Width]"; expected "tuple[Batch, Height, Width]" [arg-type]
generics_typevartuple_basic.py:46: error: Argument 1 to "Array" has incompatible type "tuple[Time, Batch, Width, Height]"; expected "tuple[Time, Batch, Height, Width]" [arg-type]
generics_typevartuple_basic.py:53: error: Free type variable expected in Generic[...] [misc]
generics_typevartuple_basic.py:54: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:57: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:60: error: TypeVarTuple "Shape" is only valid with an unpack [valid-type]
generics_typevartuple_basic.py:66: error: Too many positional arguments for "TypeVarTuple" [misc]
generics_typevartuple_basic.py:67: error: Unexpected keyword argument "bound" for "TypeVarTuple" [misc]
generics_typevartuple_basic.py:100: error: Cannot infer value of type parameter "Shape" of "multiply" [misc]
generics_typevartuple_basic.py:101: error: Cannot infer value of type parameter "Shape" of "multiply" [misc]
generics_typevartuple_basic.py:107: error: Can only use one type var tuple in a class def [misc]
generics_typevartuple_basic.py:111: error: Can only use one type var tuple in a class def [misc]
"""
conformance_automated = "Fail"
errors_diff = """
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51 changes: 51 additions & 0 deletions conformance/results/mypy/generics_typevartuple_variance.toml
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conformant = "Unsupported"
conformance_automated = "Fail"
errors_diff = """
Line 14: Expected 1 errors
Line 18: Expected 1 errors
Line 21: Expected 1 errors
Line 28: Expected 1 errors
Line 31: Expected 1 errors
Line 34: Expected 1 errors
Line 68: Expected 1 errors
Line 79: Expected 1 errors
Line 83: Expected 1 errors
Line 90: Expected 1 errors
Line 107: Expected 1 errors
Line 29: Unexpected errors ['generics_typevartuple_variance.py:29: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[object]", variable has type "ContravariantTypeVarTuple[int]") [assignment]']
Line 30: Unexpected errors ['generics_typevartuple_variance.py:30: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[*tuple[object, ...]]", variable has type "ContravariantTypeVarTuple[*tuple[int, ...]]") [assignment]']
Line 33: Unexpected errors ['generics_typevartuple_variance.py:33: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[*tuple[int, ...]]", variable has type "ContravariantTypeVarTuple[int]") [assignment]']
Line 55: Unexpected errors ['generics_typevartuple_variance.py:55: error: Unexpected keyword argument "infer_variance" for "TypeVarTuple" [misc]']
Line 73: Unexpected errors ['generics_typevartuple_variance.py:73: error: Unexpected keyword argument "contravariant" for "TypeVarTuple" [misc]']
Line 84: Unexpected errors ['generics_typevartuple_variance.py:84: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTupleOld[object]", variable has type "ContravariantTypeVarTupleOld[int]") [assignment]']
Line 87: Unexpected errors ['generics_typevartuple_variance.py:87: error: Unexpected keyword argument "covariant" for "TypeVarTuple" [misc]']
Line 108: Unexpected errors ['generics_typevartuple_variance.py:108: error: Incompatible types in assignment (expression has type "InferredContravariantTypeVarTupleOld[object]", variable has type "InferredContravariantTypeVarTupleOld[int]") [assignment]']
"""
output = """
generics_typevartuple_variance.py:15: error: Incompatible types in assignment (expression has type "InvariantTypeVarTuple[object]", variable has type "InvariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:17: error: Incompatible types in assignment (expression has type "InvariantTypeVarTuple[*tuple[object, ...]]", variable has type "InvariantTypeVarTuple[*tuple[int, ...]]") [assignment]
generics_typevartuple_variance.py:20: error: Incompatible types in assignment (expression has type "InvariantTypeVarTuple[*tuple[int, ...]]", variable has type "InvariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:29: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[object]", variable has type "ContravariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:30: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[*tuple[object, ...]]", variable has type "ContravariantTypeVarTuple[*tuple[int, ...]]") [assignment]
generics_typevartuple_variance.py:33: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTuple[*tuple[int, ...]]", variable has type "ContravariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:42: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[object]", variable has type "CovariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:45: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[bool, object]", variable has type "CovariantTypeVarTuple[int, int]") [assignment]
generics_typevartuple_variance.py:46: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[object, bool]", variable has type "CovariantTypeVarTuple[int, int]") [assignment]
generics_typevartuple_variance.py:47: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[object, object]", variable has type "CovariantTypeVarTuple[int, int]") [assignment]
generics_typevartuple_variance.py:48: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[*tuple[object, ...]]", variable has type "CovariantTypeVarTuple[*tuple[int, ...]]") [assignment]
generics_typevartuple_variance.py:51: error: Incompatible types in assignment (expression has type "CovariantTypeVarTuple[*tuple[int, ...]]", variable has type "CovariantTypeVarTuple[int]") [assignment]
generics_typevartuple_variance.py:55: error: Unexpected keyword argument "infer_variance" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:56: error: Unexpected keyword argument "covariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:56: error: Unexpected keyword argument "contravariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:57: error: Unexpected keyword argument "covariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:57: error: Unexpected keyword argument "infer_variance" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:58: error: Unexpected keyword argument "contravariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:58: error: Unexpected keyword argument "infer_variance" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:69: error: Incompatible types in assignment (expression has type "InvariantTypeVarTupleOld[object]", variable has type "InvariantTypeVarTupleOld[int]") [assignment]
generics_typevartuple_variance.py:73: error: Unexpected keyword argument "contravariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:84: error: Incompatible types in assignment (expression has type "ContravariantTypeVarTupleOld[object]", variable has type "ContravariantTypeVarTupleOld[int]") [assignment]
generics_typevartuple_variance.py:87: error: Unexpected keyword argument "covariant" for "TypeVarTuple" [misc]
generics_typevartuple_variance.py:97: error: Incompatible types in assignment (expression has type "CovariantTypeVarTupleOld[object]", variable has type "CovariantTypeVarTupleOld[int]") [assignment]
generics_typevartuple_variance.py:108: error: Incompatible types in assignment (expression has type "InferredContravariantTypeVarTupleOld[object]", variable has type "InferredContravariantTypeVarTupleOld[int]") [assignment]
generics_typevartuple_variance.py:116: error: Incompatible types in assignment (expression has type "InferredCovariantTypeVarTupleOld[object]", variable has type "InferredCovariantTypeVarTupleOld[int]") [assignment]
"""
27 changes: 16 additions & 11 deletions conformance/results/mypy/protocols_variance.toml
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Original file line number Diff line number Diff line change
@@ -1,15 +1,20 @@
conformant = "Pass"
conformant = "Partial"
notes = """
False report of ParamSpec variance keywords.
"""
output = """
protocols_variance.py:21: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
protocols_variance.py:40: error: Invariant type variable "T3" used in protocol where contravariant one is expected [misc]
protocols_variance.py:56: error: Invariant type variable "T1" used in protocol where contravariant one is expected [misc]
protocols_variance.py:61: error: Covariant type variable "T1_co" used in protocol where contravariant one is expected [misc]
protocols_variance.py:62: error: Cannot use a covariant type variable as a parameter [misc]
protocols_variance.py:66: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
protocols_variance.py:71: error: Contravariant type variable "T1_contra" used in protocol where covariant one is expected [misc]
protocols_variance.py:72: error: Cannot use a contravariant type variable as return type [misc]
protocols_variance.py:104: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
protocols_variance.py:15: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]
protocols_variance.py:22: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
protocols_variance.py:41: error: Invariant type variable "T3" used in protocol where contravariant one is expected [misc]
protocols_variance.py:57: error: Invariant type variable "T1" used in protocol where contravariant one is expected [misc]
protocols_variance.py:62: error: Covariant type variable "T1_co" used in protocol where contravariant one is expected [misc]
protocols_variance.py:63: error: Cannot use a covariant type variable as a parameter [misc]
protocols_variance.py:67: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
protocols_variance.py:72: error: Contravariant type variable "T1_contra" used in protocol where covariant one is expected [misc]
protocols_variance.py:73: error: Cannot use a contravariant type variable as return type [misc]
protocols_variance.py:105: error: Invariant type variable "T1" used in protocol where covariant one is expected [misc]
"""
conformance_automated = "Pass"
conformance_automated = "Fail"
errors_diff = """
Line 15: Unexpected errors ['protocols_variance.py:15: error: The variance and bound arguments to ParamSpec do not have defined semantics yet [misc]']
"""
9 changes: 8 additions & 1 deletion conformance/results/pycroscope/callables_annotation.toml
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Original file line number Diff line number Diff line change
@@ -1,5 +1,10 @@
conformance_automated = "Pass"
conformant = "Partial"
notes = """
Does not support callback protocols with PEP 695 ParamSpec type parameters.
"""
conformance_automated = "Fail"
errors_diff = """
Line 115: Unexpected errors ['./callables_annotation.py:115:38: Traceback (most recent call last):', './callables_annotation.py:115:4: Traceback (most recent call last):']
"""
output = """
./callables_annotation.py:25:4: Missing required positional argument at position 1 [incompatible_call]
Expand All @@ -14,6 +19,8 @@ output = """
./callables_annotation.py:59:4: Ellipsis must be used directly in Callable[..., T], not in Callable[[...], T] [invalid_annotation]
./callables_annotation.py:91:0: Incompatible assignment: expected (int, /, **Any[explicit]) -> str, got () -> str [incompatible_assignment]
./callables_annotation.py:93:0: Incompatible assignment: expected (int, /, **Any[explicit]) -> str, got (*, a: int) -> str [incompatible_assignment]
./callables_annotation.py:115:38: Traceback (most recent call last):
./callables_annotation.py:115:4: Traceback (most recent call last):
./callables_annotation.py:159:4: Incompatible assignment: expected ./callables_annotation.py.Proto5[Any[explicit]], got ./callables_annotation.py.Proto8 [incompatible_assignment]
./callables_annotation.py:172:4: Incompatible assignment: expected .Callback2[Any[ellipsis_callable]] = (int, /, ****P) -> str, got () -> str [incompatible_assignment]
./callables_annotation.py:187:4: Incompatible assignment: expected (str, /, **Any[explicit]) -> str, got (int, str, /) -> str [incompatible_assignment]
Expand Down
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