future-required-type-annotation (FA102)
Derived from the flake8-future-annotations linter.
Fix is always available.
What it does
Checks for uses of PEP 585- and PEP 604-style type annotations in Python
modules that lack the required from __future__ import annotations import
for compatibility with older Python versions.
Why is this bad?
Using PEP 585 and PEP 604 style annotations without a from __future__ import annotations import will cause runtime errors on Python versions prior to
3.9 and 3.10, respectively.
By adding the __future__ import, the interpreter will no longer interpret
annotations at evaluation time, making the code compatible with both past
and future Python versions.
This rule respects the target-version setting. For example, if your
project targets Python 3.10 and above, adding from __future__ import annotations
does not impact your ability to leverage PEP 604-style unions (e.g., to
convert Optional[str] to str | None). As such, this rule will only
flag such usages if your project targets Python 3.9 or below.
Example
Use instead:
Fix safety
This rule's fix is marked as unsafe, as adding from __future__ import annotations
may change the semantics of the program.