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Reconsider constraints involving parameter specifications #15272

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merged 5 commits into from
Aug 9, 2023
Merged

Reconsider constraints involving parameter specifications #15272

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0cf8a66
Reconsider constraints involving parameter specifications
A5rocks May 19, 2023
e9f8774
Merge branch 'master' into fix-paramspec-constraints
A5rocks Jul 2, 2023
a979083
Quick fix, I think
A5rocks Jul 7, 2023
2480ac6
Add some tests (even if one has the wrong result)
A5rocks Jul 7, 2023
9d41d9c
Test and behavior fixes
A5rocks Jul 8, 2023
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70 changes: 53 additions & 17 deletions mypy/constraints.py
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Original file line number Diff line number Diff line change
Expand Up @@ -685,25 +685,33 @@ def visit_instance(self, template: Instance) -> list[Constraint]:
)
elif isinstance(tvar, ParamSpecType) and isinstance(mapped_arg, ParamSpecType):
suffix = get_proper_type(instance_arg)
prefix = mapped_arg.prefix
length = len(prefix.arg_types)

if isinstance(suffix, CallableType):
prefix = mapped_arg.prefix
from_concat = bool(prefix.arg_types) or suffix.from_concatenate
suffix = suffix.copy_modified(from_concatenate=from_concat)

if isinstance(suffix, (Parameters, CallableType)):
# no such thing as variance for ParamSpecs
# TODO: is there a case I am missing?
# TODO: constraints between prefixes
prefix = mapped_arg.prefix
suffix = suffix.copy_modified(
suffix.arg_types[len(prefix.arg_types) :],
suffix.arg_kinds[len(prefix.arg_kinds) :],
suffix.arg_names[len(prefix.arg_names) :],

constrained_to = suffix.copy_modified(
suffix.arg_types[length:],
suffix.arg_kinds[length:],
suffix.arg_names[length:],
)
res.append(Constraint(mapped_arg, SUPERTYPE_OF, suffix))
res.append(Constraint(mapped_arg, SUPERTYPE_OF, constrained_to))
elif isinstance(suffix, ParamSpecType):
res.append(Constraint(mapped_arg, SUPERTYPE_OF, suffix))
suffix_prefix = suffix.prefix
constrained = suffix.copy_modified(
prefix=suffix_prefix.copy_modified(
suffix_prefix.arg_types[length:],
suffix_prefix.arg_kinds[length:],
suffix_prefix.arg_names[length:],
)
)
res.append(Constraint(mapped_arg, SUPERTYPE_OF, constrained))
else:
# This case should have been handled above.
assert not isinstance(tvar, TypeVarTupleType)
Expand Down Expand Up @@ -755,6 +763,8 @@ def visit_instance(self, template: Instance) -> list[Constraint]:
template_arg, ParamSpecType
):
suffix = get_proper_type(mapped_arg)
prefix = template_arg.prefix
length = len(prefix.arg_types)

if isinstance(suffix, CallableType):
prefix = template_arg.prefix
Expand All @@ -764,16 +774,22 @@ def visit_instance(self, template: Instance) -> list[Constraint]:
if isinstance(suffix, (Parameters, CallableType)):
# no such thing as variance for ParamSpecs
# TODO: is there a case I am missing?
# TODO: constraints between prefixes
prefix = template_arg.prefix

suffix = suffix.copy_modified(
suffix.arg_types[len(prefix.arg_types) :],
suffix.arg_kinds[len(prefix.arg_kinds) :],
suffix.arg_names[len(prefix.arg_names) :],
suffix.arg_types[length:],
suffix.arg_kinds[length:],
suffix.arg_names[length:],
)
res.append(Constraint(template_arg, SUPERTYPE_OF, suffix))
elif isinstance(suffix, ParamSpecType):
suffix_prefix = suffix.prefix
constrained = suffix.copy_modified(
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prefix=suffix_prefix.copy_modified(
suffix_prefix.arg_types[length:],
suffix_prefix.arg_kinds[length:],
suffix_prefix.arg_names[length:],
)
)
res.append(Constraint(template_arg, SUPERTYPE_OF, suffix))
else:
# This case should have been handled above.
Expand Down Expand Up @@ -942,9 +958,19 @@ def visit_callable_type(self, template: CallableType) -> list[Constraint]:
prefix_len = len(prefix.arg_types)
cactual_ps = cactual.param_spec()

cactual_prefix: Parameters | CallableType
if cactual_ps:
cactual_prefix = cactual_ps.prefix
else:
cactual_prefix = cactual

max_prefix_len = len(
[k for k in cactual_prefix.arg_kinds if k in (ARG_POS, ARG_OPT)]
)
prefix_len = min(prefix_len, max_prefix_len)

# we could check the prefixes match here, but that should be caught elsewhere.
if not cactual_ps:
max_prefix_len = len([k for k in cactual.arg_kinds if k in (ARG_POS, ARG_OPT)])
prefix_len = min(prefix_len, max_prefix_len)
res.append(
Constraint(
param_spec,
Expand All @@ -958,7 +984,17 @@ def visit_callable_type(self, template: CallableType) -> list[Constraint]:
)
)
else:
res.append(Constraint(param_spec, SUBTYPE_OF, cactual_ps))
# earlier, cactual_prefix = cactual_ps.prefix. thus, this is guaranteed
assert isinstance(cactual_prefix, Parameters)

constrained_by = cactual_ps.copy_modified(
prefix=cactual_prefix.copy_modified(
cactual_prefix.arg_types[prefix_len:],
cactual_prefix.arg_kinds[prefix_len:],
cactual_prefix.arg_names[prefix_len:],
)
)
res.append(Constraint(param_spec, SUBTYPE_OF, constrained_by))

# compare prefixes
cactual_prefix = cactual.copy_modified(
Expand Down
30 changes: 30 additions & 0 deletions test-data/unit/check-parameter-specification.test
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Original file line number Diff line number Diff line change
Expand Up @@ -1543,6 +1543,36 @@ def identity(func: Callable[P, None]) -> Callable[P, None]: ...
def f(f: Callable[P, None], *args: P.args, **kwargs: P.kwargs) -> None: ...
[builtins fixtures/paramspec.pyi]

[case testComplicatedParamSpecReturnType]
# regression test for https://github.com/python/mypy/issues/15073
from typing import TypeVar, Callable
from typing_extensions import ParamSpec, Concatenate

R = TypeVar("R")
P = ParamSpec("P")

def f(
) -> Callable[[Callable[Concatenate[Callable[P, R], P], R]], Callable[P, R]]:
def r(fn: Callable[Concatenate[Callable[P, R], P], R]) -> Callable[P, R]: ...
return r
[builtins fixtures/paramspec.pyi]

[case testParamSpecToParamSpecAssignment]
# minimized from https://github.com/python/mypy/issues/15037
# ~ the same as https://github.com/python/mypy/issues/15065
from typing import Callable
from typing_extensions import Concatenate, ParamSpec

P = ParamSpec("P")

def f(f: Callable[Concatenate[int, P], None]) -> Callable[P, None]: ...

x: Callable[
[Callable[Concatenate[int, P], None]],
Callable[P, None],
] = f
[builtins fixtures/paramspec.pyi]

[case testParamSpecDecoratorAppliedToGeneric]
# flags: --new-type-inference
from typing import Callable, List, TypeVar
Expand Down