.. option:: --allow-redefinition
	This is an older variant of
	:option:`--allow-redefinition-new <mypy --allow-redefinition-new>`.

	We have no plans to remove this flag, but we expect that
	:option:`--allow-redefinition-new <mypy --allow-redefinition-new>`
	will replace this flag for new use cases eventually.

The flag --allow-redefinition-new added by #18727 enhances inference of new variables, as the PR description says

Infer union types for simple variables from multiple assignments, if the variable isn't annotated.

This feature is rather orthogonal to the --allow-redefinition flag. In fact,

> mypy --version
mypy 1.18.2 (compiled: yes)

> mypy redef.py --allow-redefinition
Success: no issues found in 1 source file

> mypy redef.py --allow-redefinition-new --local-partial-types
redef.py:3: error: List comprehension has incompatible type List[list[str]]; expected List[str]  [misc]
Found 1 error in 1 file (checked 1 source file)

with the example in the doc of --allow-redefinition

def process(items: list[str]) -> None:
    # 'items' has type list[str]
    items = [item.split() for item in items]
    # 'items' now has type list[list[str]]