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bpo-44791: Fix substitution of ParamSpec in Concatenate with different parameter expressions (GH-27518)

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* Substitution with a list of types returns now a tuple of types.
* Substitution with Concatenate returns now a Concatenate with
  concatenated lists of arguments.
* Substitution with Ellipsis is not supported.
This commit is contained in:
Serhiy Storchaka 2022-01-27 14:34:55 +02:00 • committed by GitHub
parent 82bce54614
commit ecfacc362d
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4 changed files with 65 additions and 5 deletions
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12
Lib/typing.py
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@ -604,7 +604,7 @@ def Concatenate(self, parameters):
raise TypeError("The last parameter to Concatenate should be a "
"ParamSpec variable.")
msg = "Concatenate[arg, ...]: each arg must be a type."
parameters = tuple(_type_check(p, msg) for p in parameters)
parameters = (*(_type_check(p, msg) for p in parameters[:-1]), parameters[-1])
return _ConcatenateGenericAlias(self, parameters)
@ -1274,6 +1274,16 @@ class _ConcatenateGenericAlias(_GenericAlias, _root=True):
_typevar_types=(TypeVar, ParamSpec),
_paramspec_tvars=True)
def copy_with(self, params):
if isinstance(params[-1], (list, tuple)):
return (*params[:-1], *params[-1])
if isinstance(params[-1], _ConcatenateGenericAlias):
params = (*params[:-1], *params[-1].__args__)
elif not isinstance(params[-1], ParamSpec):
raise TypeError("The last parameter to Concatenate should be a "
"ParamSpec variable.")
return super().copy_with(params)
class Generic:
"""Abstract base class for generic types.