bpo-46553: allow bare typing.ClassVar annotations #30983
Merged
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This is a simple matter of just adding
ClassVar
to the list of types allowed to be bare before the later call that raises for bare types.These are used in the wild and covered by dataclasses unit tests.
Several static type checkers support this pattern.
Note we adjust one test from
ClassVar[ClassVar]
toClassVar[ClassVar[int]]
so that it still fails. This is surprising, butnot a result of weirdness we're doing in this patch. This is a
limitation of the current way runtime type checking works that this case
is allowed when bare special forms are allowed. For example, before this
patch
ClassVar[Final]
is a valid runtime annotation despite nesting theseforms being generally disallowed, so it's expected allowing bare
ClassVar
makes
ClassVar[ClassVar]
valid as well.https://bugs.python.org/issue46553