Redefinition of function arguments can give unclear error message

With

import typing
# simulate an untyped module function
def function() -> typing.Any:
    return []

def foo(var: list|str) -> list:
   # insert a lot of code so that it's totally unobvious that "var" is a function parameter
    var = function()
    return var

You get the output

$ mypy ./test2.py 
test2.py:8: error: Incompatible return value type (got "list[Any] | str", expected "list[Any]")  [return-value]
Found 1 error in 1 file (checked 1 source file)
$ mypy--version
mypy 1.10.0 (compiled: yes)

which is technically correct, as var was defined as list[Any] | str as a parameter. But if you don't realise that, say there is a ton of code between where that's defined and where the return value is, you are left looking at var = function(); return var and wondering why the heck function() has been inferred to return list[Any] | str.

For a "standard" redefinition a [no-redef] warning comes out making it fairly clear. It would be great if somehow it remembered function arguments too, and then put out for this case Name "var" already defined as function parameter on line 7 which would make this very clear.

提供された Python の再現コードから始め、mypy 1.10.0 で実行して現在の戻り値エラーを確認します。通常の再定義に対する既存の [no-redef] 診断を追跡し、関数パラメーターの再定義がどこで処理されているかを特定します。サンプルがパラメーター名とその宣言行を明確な診断とともに報告すれば完了です。