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bpo-43224: Add tests for TypeVarTuple substitution in Annotated (GH-31846)

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Matthew Rahtz 2022-04-16 05:24:28 +01:00 • committed by GitHub
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commit f2bc12f0d5
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14
Lib/typing.py
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@ -2080,6 +2080,17 @@ class Annotated:
OptimizedList = Annotated[List[T], runtime.Optimize()]
OptimizedList[int] == Annotated[List[int], runtime.Optimize()]
- Annotated cannot be used with an unpacked TypeVarTuple::
Annotated[*Ts, Ann1] # NOT valid
This would be equivalent to
Annotated[T1, T2, T3, ..., Ann1]
where T1, T2 etc. are TypeVars, which would be invalid, because
only one type should be passed to Annotated.
"""
__slots__ = ()
@ -2093,6 +2104,9 @@ class Annotated:
raise TypeError("Annotated[...] should be used "
"with at least two arguments (a type and an "
"annotation).")
if _is_unpacked_typevartuple(params[0]):
raise TypeError("Annotated[...] should not be used with an "
"unpacked TypeVarTuple")
msg = "Annotated[t, ...]: t must be a type."
origin = _type_check(params[0], msg, allow_special_forms=True)
metadata = tuple(params[1:])