Request: Optional config to warn when a parameter annotation could use `Mapping` instead of `Dict` or `Sequence` instead of `List`

• Are you reporting a bug, or opening a feature request?
  Feature request

Basically, I think it would be nice if mypy could warn when the user could be giving their function immutable versions of the argument types instead of mutable ones. For example:

def len_greater_than_three(input_list: List[int]) -> bool: # Warning: Could use read only type Sequence instead of List for parameter 1.
    return len(input_list) > 3

Being prompted to use immutable types when you're not mutating the input could improve the usability of mypy quite a bit since it would result in functions who's parameters are covariant much more often. It's also convenient to know when a function isn't mutating its arguments based on its annotation, and the desire to default to using immutable types wherever possible probably makes sense for a lot of users.

Inizia esaminando l’issue #8484 e le convenzioni esistenti di mypy per la diagnostica e la configurazione. Definisci il comportamento di avviso opzionale per i parametri annotati con tipi mutabili, quindi verifica che l’esempio venga segnalato solo quando il parametro non viene modificato e che l’impostazione sia configurabile.