Mypy should warn about conditions whose value can be deduced

Feature

Mypy can warn about left and right operands of conditions its value mypy can deduce. Unfortunately, it cannot do so for conditions consisting of one operand.

Pitch

val = 1337

if val is not None:
    pass

if val is not None and True:
    pass

Mypy can hint about the pointless left hand operand in the second if. Unfortunately, it does not do so for the first if. Supporting this use case would help the programmer to simplify her code by suggesting conditions to remove.

and True の例における無意味な左辺オペランドに対する mypy の既存の診断から始め、その診断を生成している実装とテストを見つけてください。単一オペランドのケース if val is not None のカバレッジを追加し、既存の動作を後退させることなく、mypy が削除可能な条件を報告することを確認してください。