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Fix crash on invalid type variable with ParamSpec #15953

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Merged
ilevkivskyi merged 4 commits into from
Aug 25, 2023
Merged

Fix crash on invalid type variable with ParamSpec #15953

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5d619ff
Fix crash on invalid type variable with ParamSpec
ilevkivskyi Aug 24, 2023
d9b97ab
Update mypy/typeanal.py
ilevkivskyi Aug 24, 2023
bfd5488
Fix zero count
ilevkivskyi Aug 24, 2023
c874edd
Use dedicated error; fix Parameters location
ilevkivskyi Aug 25, 2023
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15 changes: 10 additions & 5 deletions mypy/typeanal.py
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Original file line number Diff line number Diff line change
Expand Up @@ -458,11 +458,16 @@ def pack_paramspec_args(self, an_args: Sequence[Type]) -> list[Type]:
# These do not support mypy_extensions VarArgs, etc. as they were already analyzed
# TODO: should these be re-analyzed to get rid of this inconsistency?
count = len(an_args)
if count > 0:
first_arg = get_proper_type(an_args[0])
if not (count == 1 and isinstance(first_arg, (Parameters, ParamSpecType, AnyType))):
return [Parameters(an_args, [ARG_POS] * count, [None] * count)]
return list(an_args)
if count == 0:
return []
if count == 1 and isinstance(get_proper_type(an_args[0]), AnyType):
# Single Any is interpreted as ..., rather that a single argument with Any type.
# I didn't find this in the PEP, but it sounds reasonable.
return list(an_args)
if any(isinstance(a, (Parameters, ParamSpecType)) for a in an_args):
# Nested parameter specifications are not allowed.
return list(an_args)
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@JukkaL JukkaL Aug 25, 2023

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Another option might be to generate an error and return a list with a single any type.

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@ilevkivskyi ilevkivskyi Aug 25, 2023

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Yeah, currently this will say something like "Too many arguments", I will check if we can make error messages better on this.

return [Parameters(an_args, [ARG_POS] * count, [None] * count)]

def cannot_resolve_type(self, t: UnboundType) -> None:
# TODO: Move error message generation to messages.py. We'd first
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13 changes: 13 additions & 0 deletions test-data/unit/check-parameter-specification.test
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Expand Up @@ -1741,3 +1741,16 @@ def bar(x): ...

reveal_type(bar) # N: Revealed type is "Overload(def (x: builtins.int) -> builtins.float, def (x: builtins.str) -> builtins.str)"
[builtins fixtures/paramspec.pyi]

[case testParamSpecDecoratorOverloadNoCrashOnInvalidTypeVar]
from typing import Any, Callable, List
from typing_extensions import ParamSpec

P = ParamSpec("P")
T = 1

Alias = Callable[P, List[T]] # type: ignore
def dec(fn: Callable[P, T]) -> Alias[P, T]: ... # type: ignore
f: Any
dec(f) # No crash
[builtins fixtures/paramspec.pyi]
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