Using a type alias with arguments in `case` block in a `match` statement gets the wrong error message with `parameters` instead of `arguments`

*Memo:

• mypy test.py
• mypy 1.19.1
• Python 3.14
• Windows 11

Using a type alias with arguments in case block in a match statement gets the wrong error message with parameters instead of arguments as shown below:

class Cls:
    def __init__(self, x: int, y: int):
        self.x = x
        self.y = y

type TA = Cls

match Cls(x=10, y=20):
    case TA(x=10, y=20):
        print("OK")

error: Class pattern class must not be a type alias with type parameters

So, the error message should be with arguments instead of parameters as shown below:

error: Class pattern class must not be a type alias with type arguments

Inizia riproducendo il report con mypy test.py usando mypy 1.19.1 e Python 3.14, quindi individua la diagnostica per un alias di tipo usato in un pattern di classe. Aggiorna la formulazione da “type parameters” a “type arguments” e verifica che l’esempio riporti il messaggio corretto.