10000 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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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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65 changes: 65 additions & 0 deletions Lib/test/test_typing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7679,6 +7679,71 @@ 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.__parameters__, (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]])

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
114 changes: 69 additions & 45 deletions Lib/typing.py
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ADF8
Original file line number Diff line number Diff line change
Expand Up @@ -258,6 +258,16 @@ def _collect_parameters(args):
# We don't want __parameters__ descriptor of a bare Python class.
if isinstance(t, type):
continue

# `t` might be a tuple, when `ParamSpec` is substituted with
# `[T, int]`, or `[int, *Ts]`, etc.
if isinstance(t, tuple):
for x in t:
for collected in _collect_parameters([x]):
if collected not in parameters:
parameters.append(collected)
continue

if hasattr(t, '__typing_subst__'):
if t not in parameters:
parameters.append(t)
Expand Down Expand Up @@ -1444,54 +1454,68 @@ def _determine_new_args(self, args):

new_args = []
for old_arg in self.__args__:
self._make_substitution(old_arg, new_args, new_arg_by_param)
return tuple(new_args)

if isinstance(old_arg, type):
new_args.append(old_arg)
continue
def _make_substitution(self, old_arg, new_args, new_arg_by_param):
# Mutates `new_args` and inserts the correct new argument.
if isinstance(old_arg, type):
new_args.append(old_arg)
return

substfunc = getattr(old_arg, '__typing_subst__', None)
if substfunc:
new_arg = substfunc(new_arg_by_param[old_arg])
else:
subparams = getattr(old_arg, '__parameters__', ())
if not subparams:
new_arg = old_arg
else:
subargs = []
for x in subparams:
if isinstance(x, TypeVarTuple):
subargs.extend(new_arg_by_param[x])
else:
subargs.append(new_arg_by_param[x])
new_arg = old_arg[tuple(subargs)]

if self.__origin__ == collections.abc.Callable and isinstance(new_arg, tuple):
# Consider the following `Callable`.
# C = Callable[[int], str]
# Here, `C.__args__` should be (int, str) - NOT ([int], str).
# That means that if we had something like...
# P = ParamSpec('P')
# T = TypeVar('T')
# C = Callable[P, T]
# D = C[[int, str], float]
# ...we need to be careful; `new_args` should end up as
# `(int, str, float)` rather than `([int, str], float)`.
new_args.extend(new_arg)
elif _is_unpacked_typevartuple(old_arg):
# Consider the following `_GenericAlias`, `B`:
# class A(Generic[*Ts]): ...
# B = A[T, *Ts]
# If we then do:
# B[float, int, str]
# The `new_arg` corresponding to `T` will be `float`, and the
# `new_arg` corresponding to `*Ts` will be `(int, str)`. We
# should join all these types together in a flat list
# `(float, int, str)` - so again, we should `extend`.
new_args.extend(new_arg)
substfunc = getattr(old_arg, '__typing_subst__', None)
if substfunc:
new_arg = substfunc(new_arg_by_param[old_arg])
else:
subparams = getattr(old_arg, '__parameters__', ())
if not subparams:
new_arg = old_arg
else:
new_args.append(new_arg)

return tuple(new_args)
subargs = []
for x in subparams:
if isinstance(x, TypeVarTuple):
subargs.extend(new_arg_by_param[x])
else:
subargs.append(new_arg_by_param[x])
new_arg = old_arg[tuple(subargs)]

if self.__origin__ == collections.abc.Callable and isinstance(new_arg, tuple):
# Consider the following `Callable`.
# C = Callable[[int], str]
# Here, `C.__args__` should be (int, str) - NOT ([int], str).
# That means that if we had something like...
# P = ParamSpec('P')
# T = TypeVar('T')
# C = Callable[P, T]
# D = C[[int, str], float]
# ...we need to be careful; `new_args` should end up as
# `(int, str, float)` rather than `([int, str], float)`.
new_args.extend(new_arg)
elif _is_unpacked_typevartuple(old_arg):
# Consider the following `_GenericAlias`, `B`:
# class A(Generic[*Ts]): ...
# B = A[T, *Ts]
# If we then do:
# B[float, int, str]
# The `new_arg` corresponding to `T` will be `float`, and the
# `new_arg` corresponding to `*Ts` will be `(int, str)`. We
# 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:
sub_args = []
for x in old_arg:
self._make_substitution(x, sub_args, new_arg_by_param)
new_args.append(tuple(sub_args))
else:
new_args.append(new_arg)

def copy_with(self, args):
return self.__class__(self.__origin__, args, name=self._name, inst=self._inst,
Expand Down
2 changes: 2 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 +1,2 @@
Fix type substitution after ParamSpec substitution of the user generic with
a list with a TypeVar.
0