8000 gh-88965: Fix type substitution of a list of types after initial `ParamSpec` substitution by sobolevn · Pull Request #102808 · python/cpython · GitHub
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gh-88965: Fix type substitution of a list of types after initial ParamSpec substitution #102808

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Merged
merged 5 commits into from
Mar 23, 2023
Merged

gh-88965: Fix type substitution of a list of types after initial ParamSpec substitution #102808

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55662cc
gh-88965: Fix type substitution of a list of types after initial `Pa…
sobolevn Mar 18, 2023
d33bfca
Add more tests and address review
sobolevn Mar 20, 2023
0bbcd1b
Merge branch 'main' into issue-88965
sobolevn Mar 21, 2023
30dc918
More expansive news entry
AlexWaygood Mar 23, 2023
b01e6a6
Merge branch 'main' into issue-88965
AlexWaygood Mar 23, 2023
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121 changes: 121 additions & 0 deletions Lib/test/test_typing.py
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8000
Original file line number Diff line number Diff line change
Expand Up @@ -7679,6 +7679,127 @@ def test_bad_var_substitution(self):
with self.assertRaises(TypeError):
collections.abc.Callable[P, T][arg, str]

def test_type_var_subst_for_other_type_vars(self):
T = TypeVar('T')
T2 = TypeVar('T2')
P = ParamSpec('P')
P2 = ParamSpec('P2')
Ts = TypeVarTuple('Ts')

class Base(Generic[P]):
pass

A1 = Base[T]
self.assertEqual(A1.__parame 8000 ters__, (T,))
self.assertEqual(A1.__args__, ((T,),))
self.assertEqual(A1[int], Base[int])

A2 = Base[[T]]
self.assertEqual(A2.__parameters__, (T,))
self.assertEqual(A2.__args__, ((T,),))
self.assertEqual(A2[int], Base[int])

A3 = Base[[int, T]]
self.assertEqual(A3.__parameters__, (T,))
self.assertEqual(A3.__args__, ((int, T),))
self.assertEqual(A3[str], Base[[int, str]])

A4 = Base[[T, int, T2]]
self.assertEqual(A4.__parameters__, (T, T2))
self.assertEqual(A4.__args__, ((T, int, T2),))
self.assertEqual(A4[str, bool], Base[[str, int, bool]])

A5 = Base[[*Ts, int]]
self.assertEqual(A5.__parameters__, (Ts,))
self.assertEqual(A5.__args__, ((*Ts, int),))
self.assertEqual(A5[str, bool], Base[[str, bool, int]])

A5_2 = Base[[int, *Ts]]
self.assertEqual(A5_2.__parameters__, (Ts,))
self.assertEqual(A5_2.__args__, ((int, *Ts),))
self.assertEqual(A5_2[str, bool], Base[[int, str, bool]])

A6 = Base[[T, *Ts]]
self.assertEqual(A6.__parameters__, (T, Ts))
self.assertEqual(A6.__args__, ((T, *Ts),))
self.assertEqual(A6[int, str, bool], Base[[int, str, bool]])

A7 = Base[[T, T]]
self.assertEqual(A7.__parameters__, (T,))
self.assertEqual(A7.__args__, ((T, T),))
self.assertEqual(A7[int], Base[[int, int]])

A8 = Base[[T, list[T]]]
self.assertEqual(A8.__parameters__, (T,))
self.assertEqual(A8.__args__, ((T, list[T]),))
self.assertEqual(A8[int], Base[[int, list[int]]])

A9 = Base[[Tuple[*Ts], *Ts]]
self.assertEqual(A9.__parameters__, (Ts,))
self.assertEqual(A9.__args__, ((Tuple[*Ts], *Ts),))
self.assertEqual(A9[int, str], Base[Tuple[int, str], int, str])

A10 = Base[P2]
self.assertEqual(A10.__parameters__, (P2,))
self.assertEqual(A10.__args__, (P2,))
self.assertEqual(A10[[int, str]], Base[[int, str]])

class DoubleP(Generic[P, P2]):
pass

B1 = DoubleP[P, P2]
self.assertEqual(B1.__parameters__, (P, P2))
self.assertEqual(B1.__args__, (P, P2))
self.assertEqual(B1[[int, str], [bool]], DoubleP[[int, str], [bool]])
self.assertEqual(B1[[], []], DoubleP[[], []])

B2 = DoubleP[[int, str], P2]
self.assertEqual(B2.__parameters__, (P2,))
self.assertEqual(B2.__args__, ((int, str), P2))
self.assertEqual(B2[[bool, bool]], DoubleP[[int, str], [bool, bool]])
self.assertEqual(B2[[]], DoubleP[[int, str], []])

B3 = DoubleP[P, [bool, bool]]
self.assertEqual(B3.__parameters__, (P,))
self.assertEqual(B3.__args__, (P, (bool, bool)))
self.assertEqual(B3[[int, str]], DoubleP[[int, str], [bool, bool]])
self.assertEqual(B3[[]], DoubleP[[], [bool, bool]])

B4 = DoubleP[[T, int], [bool, T2]]
self.assertEqual(B4.__parameters__, (T, T2))
self.assertEqual(B4.__args__, ((T, int), (bool, T2)))
self.assertEqual(B4[str, float], DoubleP[[str, int], [bool, float]])

B5 = DoubleP[[*Ts, int], [bool, T2]]
self.assertEqual(B5.__parameters__, (Ts, T2))
self.assertEqual(B5.__args__, ((*Ts, int), (bool, T2)))
self.assertEqual(B5[str, bytes, float],
DoubleP[[str, bytes, int], [bool, float]])

B6 = DoubleP[[T, int], [bool, *Ts]]
self.assertEqual(B6.__parameters__, (T, Ts))
self.assertEqual(B6.__args__, ((T, int), (bool, *Ts)))
self.assertEqual(B6[str, bytes, float],
DoubleP[[str, int], [bool, bytes, float]])

class PandT(Generic[P, T]):
pass

C1 = PandT[P, T]
self.assertEqual(C1.__parameters__, (P, T))
self.assertEqual(C1.__args__, (P, T))
self.assertEqual(C1[[int, str], bool], PandT[[int, str], bool])

C2 = PandT[[int, T], T]
self.assertEqual(C2.__parameters__, (T,))
self.assertEqual(C2.__args__, ((int, T), T))
self.assertEqual(C2[str], PandT[[int, str], str])

C3 = PandT[[int, *Ts], T]
self.assertEqual(C3.__parameters__, (Ts, T))
self.assertEqual(C3.__args__, ((int, *Ts), T))
self.assertEqual(C3[str, bool, bytes], PandT[[int, str, bool], bytes])

def test_paramspec_in_nested_generics(self):
# Although ParamSpec should not be found in __parameters__ of most
# generics, they probably should be found when nested in
Expand Down
33 changes: 26 additions & 7 deletions Lib/typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -255,10 +255,17 @@ def _collect_parameters(args):
"""
parameters = []
for t in args:
# We don't want __parameters__ descriptor of a bare Python class.
if isinstance(t, type):
continue
if hasattr(t, '__typing_subst__'):
# We don't want __parameters__ descriptor of a bare Python class.
pass
elif isinstance(t, tuple):
# `t` might be a tuple, when `ParamSpec` is substituted with
# `[T, int]`, or `[int, *Ts]`, etc.
for x in t:
for collected in _collect_parameters([x]):
if collected not in parameters:
parameters.append(collected)
elif hasattr(t, '__typing_subst__'):
if t not in parameters:
parameters.append(t)
else:
Expand Down Expand Up @@ -1441,10 +1448,12 @@ def _determine_new_args(self, args):
raise TypeError(f"Too {'many' if alen > plen else 'few'} arguments for {self};"
f" actual {alen}, expected {plen}")
new_arg_by_param = dict(zip(params, args))
return tuple(self._make_substitution(self.__args__, new_arg_by_param))

def _make_substitution(self, args, new_arg_by_param):
"""Create a list of new type arguments."""
new_args = []
for old_arg in self.__args__:

for old_arg in args:
if isinstance(old_arg, type):
new_args.append(old_arg)
continue
Expand Down Expand Up @@ -1488,10 +1497,20 @@ def _determine_new_args(self, args):
# should join all these types together in a flat list
# `(float, int, str)` - so again, we should `extend`.
new_args.extend(new_arg)
elif isinstance(old_arg, tuple):
# Corner case:
# P = ParamSpec('P')
# T = TypeVar('T')
# class Base(Generic[P]): ...
# Can be substituted like this:
# X = Base[[int, T]]
# In this case, `old_arg` will be a tuple:
new_args.append(
tuple(self._make_substitution(old_arg, new_arg_by_param)),
)
else:
new_args.append(new_arg)

return tuple(new_args)
return new_args

def copy_with(self, args):
return self.__class__(self.__origin__, args, name=self._name, inst=self._inst,
Expand Down
7 changes: 7 additions & 0 deletions Misc/NEWS.d/next/Library/2023-03-18-14-59-21.gh-issue-88965.kA70Km.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
typing: Fix a bug relating to substitution in custom classes generic over a
:class:`~typing.ParamSpec`. Previously, if the ``ParamSpec`` was substituted
with a parameters list that itself contained a :class:`~typing.TypeVar`, the
``TypeVar`` in the parameters list could not be subsequently substituted. This
is now fixed.

Patch by Nikita Sobolev.
0