Dart/Flutter linter rule: the type to index a map should be the key type of map?

[fzyzcjy]

Describe the rule you'd like to see implemented

For example, I have Map<int, int> m;. Then I can write down m['hello'] without any compile-time error, but of course, cannot find any element at runtime. I hope it will produce an error (or warning) at compile-time or lint time.

This is a big problem in many cases. For example, when I refactor Map<A, int> m into Map<B, int> m, I want to have compile-time errors for all accesses like m[some_var_of_type_A], instead of no compile-time errors and suddenly it explodes at runtime. As another example, the de-serialized JSON is of type Map<String, ...> but the key is actually a int. So it is tempting to do var userId=42; deserializedJson[userId] but only to find errors. Actually need to do deserializedJson[userId.toString()].

You know, dart's type system is so strong (even null safe!), and I really enjoy it since it catchs a LOT of bugs at compile-time. So I hope this problem can also be addressed at compile-time.

Thanks for any suggestions!

Examples

see above

Additional context

n/a

[srawlins]

Duplicate of #57844